Open Source Aircraft Design for CNC?

[JNicol]

Hi Everyone,

I wanted to start a conversation about the potential of an open source aircraft design that could be built using CNC? With 8' x 4' CNC machines being relatively available (one kit can be purchased for $2,000 - $3,000) and CNC services like Ponoko that can be used to outsource, it appears to be a quick and cheap way to get an aircraft built....? My biggest problem with trying to fly is the affordability of building and owning an aircraft. I love the EAA magazine and Homebuilt magazine etc, but my eyes glaze over when I see kits that can be completed for "only" $40,000 etc. I realize that there are cheaper kits, but I was thinking about one that had plans that could be downloaded and built using a CNC machine to speed the construction up and use relatively inexpensive materials. My eyes lit up when I saw what was being achieved by open source projects such as Wikihouse: http://www.wikihouse.cc/

(http://www.wikihouse.cc/)There is also work being done on the Volksplane to create CAD drawings of the plans in Yahoo Groups. I was wondering if there were any collaborative efforts out there to generate an open source aircraft design specifically for CNC? If not, why not! I can imagine downloading a design and cutting out the parts for construction like a giant meccano set. You could probably cut out the parts for an entire small aircraft in a few hours! I can see a group of builders purchasing a CNC machine between them and mass producing the parts for a group build. It would be really great if we could get an ultra-low cost aircraft in the works that could get more people building and flying! If there is interest, would anyone like to start something like this as a movement?

:)

Regards,
John Nicol

[spungey]

I am 100% behind all kinds of OS efforts. We really are an OS community and should share with like-minded ones.

Have you checked into availability of CNC machines at TechShop locations around the country? Also, I wonder who would be doing the 3-d modeling and what data formats will be needed.

[JNicol]

Well, the 3D design, modelling etc would be part of the open source effort. It might be that perhaps an out-of-copyright design could be re-purposed? EDIT: actually maybe an updated Fly Baby would do the trick? The work would probably have to go into re-designing some of the components to make them easy to cut and assemble and perhaps create tabs and slots for pieces to fit together.

The formats would be standard CAD, probably dxf or whatever, with output to CNC file formats such as g-code, stl and so on. I am sure that there are CNC machines available at various Maker-spaces around the world that builders can send the files to for manufacture. The Ponoko service is only one.

Here is a picture of work that is being done to convert the Evans Volksplane into CAD:

657

So even this could be turned into CNC-ready files, but it hasn't been optimized for CNC as it would still be built in the traditional way. I think that there is an opportunity to make the designs more even more builder friendly. It would be neat to have a completely open source design that could be built upon and improved for the homebuilder community. I know that there are some talented designers out there and well given that there are 175000 EAA members, even a tiny .5% of interest would be almost 900 contributors.

[Eric Page]

This is something I'd be very interested in, at least as a builder. I lack the engineering knowledge or CAD skills to be a design contributor, but it certainly sounds like a great idea.

[Eric Witherspoon]

I'm having trouble envisioning exactly what you're asking for / thinking about trying to do.

So split it up:
Looking for the lowest cost.
Looking to use CNC for some reason.
Looking to generate low build time.
Looking to have builders work together to build multiple copies, with some benefit of that to be defined.
Create a new design that meets ? objectives...

My impression is that "open source" for a whole NEW aircraft design is impossible. Nobody's going to agree what the objectives are, and unless there's an arbitration board (or Office of the Chief Engineer) or the like, it will just diverge in a bunch of different directions.

Besides, if creating a new design isn't really the main objective of your inquiry, why not support one of the plans vendors out there? They worked many, many hours, built test parts, flew stuff that didn't work so well and worked it out - all to give you the rights to copy their success for just a couple hundred $. I'm sure they'd be thrilled to find out you have gathered together 10-20 like-minded individuals willing to stand on their shoulders to get into the sky.

[JNicol]

OK, so every idea starts off with a discussion and then we start drilling down to details. I am not trying to boil the ocean, as I said "I wanted to start a conversation".

If you read my post again, you will see that I said perhaps it would start off with an out-of-copyright design, or something like the EAA fly baby. That way it has already been proven and there are no major design hurdles. The re-design comes about with making the parts readily machined by CNC and able to be put together more easily. For example, instead of a rib being made up of 20 separate parts, it is cut out as a single piece from ply. Also, why CNC? I gave the example of the wikihouse. I have built my own CNC machine and it is a very quick way to fabricate parts. Saying that, I do appreciate the devils advocate to challenge and question as it makes us consider the details and alternative ways ahead.
Here is a link to a CNC kit that I think could be built and used by the average homebuilder: http://buildyourcnc.com/CNCMachineKits.aspx

I agree that starting off by trying to do a new design is crazy, that is why I suggested replicating something already designed. Having a design committee and so on will create a million dollar composite electric, solar powered truck built with recycled milk cartons. I am not sure having plans vendors is the way ahead unless they make the design available as open source. People can still make money from open source by providing the parts, printed blueprints, consulting and whatever. There are many companies that are making money from open source, so the business model is proven. I believe that it would also allow improvements and updates easily available back into the project.

So to reflect back some high-level objectives (but again, not trying to advocate any one idea this is just a discussion to see if people are interested):

1. Low cost. I don't know what the parameters are yet, but I would be hoping that it would be under $4000 minus engine and instruments as a first stab in the dark. I note that the fly baby needs about 10 sheets of plywood plus spruce, metal, hardware etc, so probably fits in that price range, but I think that redesign for CNC ply manufacture could bring that BOM down. Even if the BOM didn't come down, perhaps the cost savings are transferred to lower build time?
2. CNC, so that parts are easily manufactured. It would also mean that parts are consistent with tight tolerances, can be replicated over and over, and customized as required. (Also means that a builder can get the parts from multiple sources, not just one manufacturer.)
3. Low build time. Maybe under 100 hours for the build minus engine, instruments and perhaps fabric covering, but again, depends on the design. I am sort of hoping that it would all fit together like a big constructor set and even easier than the majority of kits out there now. Again, the wikihouse concept in execution.
4. Type? Maybe something that would fit into the Ultralight or Sport light category. My personal preference would be a two seat side by side. That would immediate cut out the fly baby, but maybe start off with a single seat existing design like the fly baby and then move to something else if it is successful.

Thanks for listening folks.

:cool:

John Nicol

[rwanttaja]

Basic question I have, is can you reliably use CNC machining with wood parts? All of the CNC stuff I've previously seen have been with aluminum. Can these small "home" CNC machines carve a spruce wing spar 13 feet long?

John mentions the Fly Baby as an example of a potential open-source aircraft. Like many older wood homebuilts, the wood parts for the Fly Baby are often a "cut to fit" design rather than "cut to this exact shape and dimension." To be able to CNC them, someone would have to basically build an aircraft while taking careful dimensions for the CAD work.

Folks in the Fly Baby community have already generated CAD files for most of the steel and aluminum parts, but of course, the main structure is wood.

A better candidate would be the Murphy JDM-8, an all-metal Fly-Baby-Class airplane. However, there is usually some resistance to single-seat airplanes. The Thorp T-18 might be a better pick.

Ron Wanttaja

[Eric Witherspoon]

For your $4k airframe target, my guess at this point is riveted sheet metal will be the lowest cost. In large part because if it's 6061, it doesn't have to be painted. This keeps build time, weight, and cost down.

The other reason is, I think that $4k is the starting point for the fabric and finishes of a fabric-covered design, unless it's an open-tube-fuselage (like some versions of the Belite) with only the wing/tail being covered. So with the desire to not look excessively cheap, or not look like a pod-and-tube design, but to have a "real airplane" shape, but still fall into a "low cost" category, riveted metal will be the way to go. (See, I'm imposing my desirements - pod-and-tube may be more the trade you're looking for...)

This also falls right into line with getting some benefit from CNC - doesn't have to be matched-hole, but at least the skins can have all the pilot holes in the right places, then just clamp it together and drill through. Pod-and-tube will be a bunch of tubes and cables - not stuff that CNC is going to help with much, though the interfacing brackets may be done more quickly.

Blind rivets are quick, though more expensive than driven. Such a design, though, could allow the builder to choose - lower cost or quicker/easier.

So, here's where your $4k goes:
$1500 for 6061 aluminum sheet and angles.
$500-700 for pulled rivets (much less for driven).
$1200 for nuts/bolts/washers/cables/cotter pins/castle nuts/fairleads/wheels/tires/brakes - really. And I'm leaving out the hundreds for all the stuff that goes between the firewall and the engine...
$300 worth of steel for engine mount, control sticks, control pushrods, etc., or $2000+ for someone to weld it all up and paint it for you.

Then we still haven't got:
Couple hundred for a canopy bubble / windshield (though it might be open-cockpit w/ just a windshield)
Couple hundred for a cowling (though you might do a nose-bowl and sheet metal sides)
Couple hundred for wheel pants (maybe concede it's too slow for these to matter much...but they look so good...)
Couple hundred for gear legs (though the BK-1 has an interesting configuration of just Al bar stock with some custom axle weldments)

Anyway, say you finish off those above "non bare airframe" costs for another $2k.

Then there's an engine. Say this thing is really light/tiny (single-seater for build time, reduced parts count, and cost, of course). Even a 2-cyl VW-based engine is $3-4.5k, and 4-cyl VW's are in the $5-7k range. Pick a number - $5k for engine. Ok, we're at 11k now, and it still doesn't have a fuel tank. Or a prop. Oh, and electric start might make it more popular (add another $1k).

So, fuel tank, prop, panel, radio, seat pad, antenna, engine monitoring stuff - easy to spend another $3k there and still be very basic.

So you're looking at $14k bare-bones, no electric start. And you said you wanted a 2-seater.

A used Rans S-12 is starting to look pretty good. Quicker to get (just write a check), known performance, factory behind it for support...

But it kind of makes me wonder if there might be a way to get plans for that Murphy...

[JNicol]

Basic question I have, is can you reliably use CNC machining with wood parts? All of the CNC stuff I've previously seen have been with aluminum. Can these small "home" CNC machines carve a spruce wing spar 13 feet long?



Hi Ron,

Yes it can cut wood very well.... the wikihouse project I quote is basically 4 x 8 sheets of baltic ply. The same machines can also cut aluminum, plexy sheet and whatever....

Here is a link to a shopbot cutting wood on youtube (a 4x8 sheet used to create a workstation). Lots of videos there actually of this type of machine. http://www.youtube.com/watch?v=e6965cKlNqA&feature=related
(http://www.youtube.com/watch?v=e6965cKlNqA&feature=related)
The link that I gave above for the CNC kit, is itself cut on a CNC machine out of baltic ply and obviously needs to be of high accuracy in order to create another CNC machine. These particular machines have an accuracy of 0.0007" and it is made out of ply......

The bed of the machine is 8' long. You can cut longer pieces by indexing them. So you could cut a 13' length, or longer.

John

[JNicol]

For your $4k airframe target, my guess at this point is riveted sheet metal will be the lowest cost. In large part because if it's 6061, it doesn't have to be painted. This keeps build time, weight, and cost down.


So you're looking at $14k bare-bones, no electric start. And you said you wanted a 2-seater.


Well I think I would like to challenge the conventional thinking and push the boundaries a bit here. Maybe there is a hybrid solution of wood and aluminum I don't know. I do know that the CNC systems I am thinking of are capable of machining both.... I think it is a matter of adapting a design with this new technology in mind. I link swinging a hammer like most people in the forums, but I am also lazy I guess. If I can spew out 10 ribs in half an hour instead of in a month, then I would like to do that. Many kits are manufactured using CNC already, but a part you buy already machined might cost $200 when it is comprised of a $5 piece of metal and 10 minutes in the mill. Nothing wrong with that of course, but if I can now build my own 4' x 8' CNC for under $3000 (plus computer) and I could manufacture 99% of the parts required for my aircraft in maybe less than a week, I think that is pretty powerful! Having a really easy step-by-step construction plan would be the other really important element of course. IKEA, but with aircraft.... and without the annoying little allen keys. Yes, I said I ideally wanted a two seater, but I did also say that starting off with a one seater would probably be easier initially to prove the concept. I appear to be repeating myself....

There are no kits that I am aware of that include the CNC files to allow you to do this, so I thought that this would be a neat thing. I would personally prefer Open Source so that we are a little bit more in control of the destiny of it and let any builder that wants it, build it for themselves. There will be ample opportunity for people to make their money along the way if they want to I am sure.

[spungey]

Both J and Eric are right.

If some tyro builder (me for instance) had ready access to a CNC mill, then plans start to look more appealing as opposed to kits. For instance I can hand build a couple representative ribs, then get the mill to make the rest, all exactly right, in far less time than I'd spend screwing them up. I'd only need to pay for (some portion of) the mill, the raw parts, and cleanup. OTOH, I'm never going to financially compete with some factory's economies of scale. Nor expertise.

------

The "open source" part of this is ready availability of plans for well-known, proven, approved, parts that we could make ourselves rather than purchase. As we build up a body of items and parts useful for all airplanes, then more and more opportunities arise for totally new and/or custom aircraft design. It's not so much about making a complete OS airplane ... yet.

For example, suppose we make good wire harnesses, axles, struts, ribs, antenna ground planes, engine mounts, control horns, etc. with CNC and make the plans available? Once proven and approved, that makes the FAA examiner's job easier too. All kinds of things we can now reliably make ourselves.

While not everything can become open and/or automated, we don't have to stop with hardware parts. How about an avionics stack built on reliable solid-state sensor and an android tablet? Or software-defined radio? We probably can't do open-source looms for carbon fiber, but our local club might be able to do some kind community vacuum bagging tool.

3-d CAD? I will look into it a bit. I have not played with any of it so don't know much. Google has something free. Autodesk just released a crippled free version of Inventor. (It will do components but not assemblies.) No idea what SolidWorks might or might not have, nor what's on FOSS software places.

The second big starting issue is "repository." Do we know where and/or how we want to store and distribute the designs?

[FlyBoyJon]

Greetings,

The idea of building and having my own CNC shop is very appealing and its use in homebuilding certainly has many benefits.

I would agree with several of the comments that CNC makes a much more appreciable difference in the building of metal aircraft over wood, just from a parts-per-material-piece perspective.

As for OS, I am a huge supporter of OS as a general rule, but in this instance I am not sure if that is the best starting point for some of the same reasons previously mentioned. IMHO the best starting point would be to get a working group together to define the goals/direction of the over-all idea you have in mind first. After things are a bit more defined, begin building the interest group network, followed by growing geographically oriented "workshop groups" to start building the CNC equipment as well as promoting local training in the computer skills and how-to seminars while building the OS library as Richard suggested.

With all of the resources in play, thinking about a large, massive really, project like development of CNC versions of public domain designs would be the next logical step. After coordinating and executing at least one public domain design project, including the build and test flying, moving into a OS original design would seem a lot more likely.

As I said, I fully support the idea of OS and have thought of similar groups myself. What has always killed the idea for me has been the back-office end of a project like this. I have managed non-profit organizations and been a/the lead on projects with hundreds of volunteers, both technical and "unskilled" (I hate that term), and it is the administrative end that is the truly daunting part of the process.

Due to a relatively recent negative experience, I have not been inclined to be the originator of any such projects. But I am interested in participating in something like this.

If you (John) or anyone else is interested in taking this idea beyond the "boards", I would like to participate. My contact info is below.

[JNicol]

Hi Jonathan,

Thank you for your thoughts on this topic. I am interested in taking this further, so will make contact separately. I too have had a negative experience and mine was with a museum not-for-profit aircraft restoration project a few years ago. I bailed early on because it was so poorly organized, with no thought about how to effectively manage the talented volunteers they had.

In any case, agree with a strawman approach first to validate the concept. Might not work, but it might too, so a solid plan at the start is the foundation to build on.

Richard,

You read my mind on taking it further with avionics and other systems. I think that is a logical step down the road and I think that we should take advantage of new manufacturing methods and new directions in mobile computing technologies. Probably a whole other thing there.

(BTW, my day job is a Principle Engineer (Software) with Lockheed Martin.)

I think that just having 2-3 people to figure out some high-level details and objectives and then throw it open for comment is probably the way to go at this early stage.

Thanks for the discussion and well, lets see what happens.

Regards,
John Nicol

[spungey]

John,
Please add me to your off-list discussion. richard@ytivarg.com

Jonathan,
Thanks for joining up. However, I too am leery of "let's get organized and steer" rhetoric. The fear of chaos--rather than self-organization--emerging is natural, but I think misplaced. Some organization makes sense. Do we, should we, and how would we provide CNC machines or services to our local chapters for instance? Too many times I've been burned like John by well-meaning people who wanted to help but knew only how to meddle. It sounds like you too have had some bad medicine here. If we can work through that then I'm game.

John (again),
I knew I was reading a kindred spirit. Sr. Software and Systems Engineer (in Portland.) :-) I'm working with cars though, more's the pity. I agree. An OS avionics stack can and probably should be sidelined for now, but certainly not forgotten.

now back to work

[rwanttaja]

For something like this, your best bet will be a small (offline) team. Otherwise, you'll be inundated with "It should be tandem seating" "Design it to use a Subaru" "It should be high wing instead" "What about floats" "Pushrod ailerons would be better" "Why not make it a taildragger" sorts of interference. Get 2-3 guys together, decide on an approach, and go with it.

Ron Wanttaja

[JNicol]

Agreed, thanks for your thoughts Ron.

I did find a neat aircraft being built using CNC methods as a kit. It is the JDT Aeromax here: http://www.jdtmini-max.com/AMax.pdf

(http://www.jdtmini-max.com/AMax.pdf)Definitely along the lines of what I was thinking. CNC built, in this case with a CNC laser. But the principle is the same as what I was thinking of in terms of manufactured parts, easy assembly, labeled parts etc. I was thinking a bit more extreme, with a newer construction technique and providing the CNC files for people to do it themselves. In any case, I think we have a small initial team assembled and will resurface if all goes well with more points for discussion and wider input. As I said, might not work, but won't know until we investigate further and figure out if it is doable.

John

[gyrojohn]

When we designed the HoneyBee G2 one of our design goals was to take maximum advantage of CNC and Cad. I agree that this is the way to get precision in low production numbers while keeping cost affordable.
The biggest single cost is the powerplant. The lighter the better but if one goes too small then engine choices are reduced. From my experience it would be about as easy to start clean as to try to adapt an existing design. Also one should look at other materials and assembly techniques. Look at the Cricket for example of different building materials that could fit with CNC methods.

[BillGoulding]

I registered just to participate in this discussion.

I agree with many of Eric's points here: http://eaaforums.org/showthread.php?484-Open-Source-Aircraft-Design-for-CNC&p=3724&viewfull=1#post3724

(http://eaaforums.org/showthread.php?484-Open-Source-Aircraft-Design-for-CNC&p=3724&viewfull=1#post3724)In fact, you only have to look at Zenith's designs to see how all metal aircraft can be reasonably made with CNC.

As a point of intrest, there are already people using this general approach using existing, closed-source designs.

Robert Haines designed his own CNC that he sells plans for here: http://www.hainesengineering.com/cnc/

(http://www.hainesengineering.com/cnc/)He subsequently used this CNC to begin scratch-building a Zenith CH650, as Zenith provides a plans-only option for this aircraft.

This approach requires first digitizing the plans, and generating g-code or similar. Robert has stated on zenith.aero that the time required to do this is roughly equivalent to the time required to manually lay out cuts on aluminum sheet. Real time gains are apparently only made on the second airframe. I suppose that spare parts are easily come by though.

The OS approach would mean that these steps would not be required to be done by the builder; instead the efforts of the contributors would be amortized over every plane built.

I think that many of the CH750 design elements would lend themselves to this sort of project. IE. All Metal Construction, 'squared' fuselage, etc.

[spungey]

Bill, please contact John off-list and ask to join our working group. Our initial thoughts were leaning toward wood. It looks like you have a lot of value to add to our discussion.

[jim.bo12345]

Agreed, thanks for your thoughts Ron.

I did find a neat aircraft being built using CNC methods as a kit. It is the JDT Aeromax here: http://www.jdtmini-max.com/AMax.pdf

(http://www.jdtmini-max.com/AMax.pdf)Definitely along the lines of what I was thinking. CNC built, in this case with a CNC laser. But the principle is the same as what I was thinking of in terms of manufactured parts, easy assembly, labeled parts etc. I was thinking a bit more extreme, with a newer construction technique and providing the CNC files for people to do it themselves. In any case, I think we have a small initial team assembled and will resurface if all goes well with more points for discussion and wider input. As I said, might not work, but won't know until we investigate further and figure out if it is doable.

John

John,

I strongly agree with you and would like to join the group. I left private message to you on the forum. Please reply, so I can join. I am a SolidWorks user, so I am sure, I can contribute.

Thanks in advance, jim.bo12345

[Jeffrey Meyer]

Hi Folks,
I also want to join this thread - so here's my first 2 cent salvo:
* Like jim.bo I will gladly contribute files from SolidWorks with which I have considerable experience.
* In addition I also have some aeronautical/mechanical engineering experience and will gladly attempt to answer questions in that area if I can.
* It seems to me that the baseline for this group focuses on 2D CNC machines powered by stepper motors & drivers - routers, laser cutters, punches, etc.. It's important to emphasize the 2D (as opposed to 3D) because the price of 2D equipment and software is an order of magnitude cheaper and less complicated than 3D equipment. Also, the home CNC machines/kits almost universally can accept DXF files which are essentially 2D. There is an abundance of cheap/free software which can generate DXF files. 5 minutes on Google will find you stepper motors, stepper motor drivers and software to translate DXF into CNC G-code.
* SolidWorks is a great tool for creating geometry, but IMHO the big issue is where to get the geometry to translate into DXF. I seriousely doubt that the scratch-from-plans/kit manufacturers will cooperate in supplying CAD geometry (2D or 3D) or allowing us to digitze their plans or reverse engineer their parts for our own group use. It's a copyright issue. Nobody can stop me from making a copy of a product for my own personal, non-profit use - but it's a different story if we as a group make several copies thereby reducing the manufacturer's profits on his intellectual property - maybe I'm wrong but at the very best it doesn't seem ethical and is probably not legal. I don't know - I'm not a lawyer.
* Sorry to be a party-pooper but I do have 2 suggeted ways out: 1. Rethink the option of design-from-scratch suitable for home CNC, or 2. Negociate a deal with one of the scratch-from-plans/kit manufacturers. Number 2 is a subject of give-and-take (both sides have to feel that they gained something) - so what do we have to give that would be of benefit to the manufacturer? On the other hand number 1 is not as daunting or as crazy as one might think. Based on the adage that comes from the R/C modeling world: Attatch a big enough engine to your kitchen table and it will also fly. Yes, it won't be the best flyer - but it will be quick to build and cheap. The disadvantage comes from another adage: A camel is defined as horse designed by a committee.

My 2 cents seems to have expanded into $2 - so I'll stop here.

Jeffrey

[Sonex1517]

I can't add much of value to the conversation except to state THIS IS AN AWESOME IDEA!

[Dana]

We had a discussion like this over on homebuiltairplanes.com a while ago. The general consensus was that the OS model makes a lot less sense for hardware than it does for software, where anybody can test the latest build without any significant investment. With an aircraft design, it's much more difficult... who approves the latest "official version? And how do you approve a design change without building and verifying a prototype? But to wait for a prototype to be verified could take a long time...

It might make sense for an "orphaned" design that's static. The OpenEZ project is one such attempt. The VPs might be another; I'm less familiar with that. A good choice might be a Quicksilver ultralight... many have cloned them, and the Quicksilver company no longer makes a true 103 legal version.

[Brian E. Evans]

Before I retired I used to program sheet metal files for CNC routers, Both stepper and servomotor kind. As somebody has already said, it is quicker to lay one out by hand if you are only making one part, on the other hand, parts like ribs and gussets on such a machine can save hours and be a godsend. I think the part of this that has to be looked at closely is the 51% rule. If you program the machine, run it and the parts are yours, then I think there is no problem. If somebody runs the machine, and makes these parts , then sells them or gives them to you, then I think you have just stepped into the area the FAA is looking at very closely right now.
Brian Evans.

[JNicol]

Hi Folks,
I also want to join this thread - so here's my first 2 cent salvo:
* Like jim.bo I will gladly contribute files from SolidWorks with which I have considerable experience.
* In addition I also have some aeronautical/mechanical engineering experience and will gladly attempt to answer questions in that area if I can.


Hi Jeffrey,

Thanks for that, I will send a PM with my contact details.




* It seems to me that the baseline for this group focuses on 2D CNC machines powered by stepper motors & drivers - routers, laser cutters, punches, etc.. It's important to emphasize the 2D (as opposed to 3D) because the price of 2D equipment and software is an order of magnitude cheaper and less complicated than 3D equipment. Also, the home CNC machines/kits almost universally can accept DXF files which are essentially 2D. There is an abundance of cheap/free software which can generate DXF files. 5 minutes on Google will find you stepper motors, stepper motor drivers and software to translate DXF into CNC G-code.



You got it, with the abundance of open source hardware projects dedicated to CNC, from gantry systems through to controllers as well as software, this is a great time to jump in and see how we can leverage it for homebuilder use. Now just to add a little to the conversation, there are software applications out there that can slice 3D models that can be cut and carved in 2D slices and then re-assembled into 3D objects. (www.vectric.com (http://www.vectric.com)) Think of now cutting out a plug or mold for composite building.... (cowls, fuel tanks, wings, fuselage etc). Also maybe a windshield form that is assembled from foam slices and then the acrylic/lexan heated and molded over that form... now think of using that same cnc machine to build a chair and ottoman out of wood to sit in and admire all that work....




* SolidWorks is a great tool for creating geometry, but IMHO the big issue is where to get the geometry to translate into DXF. I seriousely doubt that the scratch-from-plans/kit manufacturers will cooperate in supplying CAD geometry (2D or 3D) or allowing us to digitze their plans or reverse engineer their parts for our own group use. It's a copyright issue. Nobody can stop me from making a copy of a product for my own personal, non-profit use - but it's a different story if we as a group make several copies thereby reducing the manufacturer's profits on his intellectual property - maybe I'm wrong but at the very best it doesn't seem ethical and is probably not legal. I don't know - I'm not a lawyer.



Yes, that is why the plans would likely need to be designed from scratch with the open source model in mind from the start.



* Sorry to be a party-pooper but I do have 2 suggeted ways out: 1. Rethink the option of design-from-scratch suitable for home CNC, or 2. Negociate a deal with one of the scratch-from-plans/kit manufacturers. Number 2 is a subject of give-and-take (both sides have to feel that they gained something) - so what do we have to give that would be of benefit to the manufacturer? On the other hand number 1 is not as daunting or as crazy as one might think. Based on the adage that comes from the R/C modeling world: Attatch a big enough engine to your kitchen table and it will also fly. Yes, it won't be the best flyer - but it will be quick to build and cheap. The disadvantage comes from another adage: A camel is defined as horse designed by a committee.



I would say that we should probably proceed with number 1 and see where we get to. If a plans supplier wants to donate for number 2, then that would be great, but again, even if we go with number 2, there would still need to be re-design for CNC manufacture and assembly as there are few designs out there if any that would comply with the overall vision that we have to make this as quick and simple as possible with associated instructions, video and content we are ultimately trying to achieve. This will become apparent as we begin to go public with this..... more to follow.... :-)

[JNicol]

Before I retired I used to program sheet metal files for CNC routers, Both stepper and servomotor kind. As somebody has already said, it is quicker to lay one out by hand if you are only making one part, on the other hand, parts like ribs and gussets on such a machine can save hours and be a godsend. I think the part of this that has to be looked at closely is the 51% rule. If you program the machine, run it and the parts are yours, then I think there is no problem. If somebody runs the machine, and makes these parts , then sells them or gives them to you, then I think you have just stepped into the area the FAA is looking at very closely right now.
Brian Evans.

That is a good point. In Canada, you can "build your own aircraft, provided you construct, assemble or oversee the construction, by other persons, of at least 51% of the total number of items assembled during the project". By overseeing the construction of these parts, or assembly, you are in the clear. In the US, the major portion rule would apply.... I am not a lawyer and far from expert in this area so don't know. I would see that supplying the components as part of a "quick-build" option following the lead of other kit manufacturers might be the rule of thumb if anyone wanted to supply the parts for the open source aircraft.

[Jeffrey Meyer]

That is a good point. In Canada, you can "build your own aircraft, provided you construct, assemble or oversee the construction, by other persons, of at least 51% of the total number of items assembled during the project". By overseeing the construction of these parts, or assembly, you are in the clear. In the US, the major portion rule would apply.... I am not a lawyer and far from expert in this area so don't know. I would see that supplying the components as part of a "quick-build" option following the lead of other kit manufacturers might be the rule of thumb if anyone wanted to supply the parts for the open source aircraft.

I don't think this is an issue and I'll illustrate by taking it to an extreme: It's conceivable that a future homebuilt kit will consist of a package containing raw materials and a CNC machine. All the builder has to do is set up the machine in his living room, feed in the raw materials and press a button marked "build". Both the Canadian "number of items" rule and the US "major portion" rule have been complied to. What I'm trying to say is that the CNC machine and its programs are simply tools, and I don't think the regulators have placed any restrictions on the tools we may use. I suggest we simply go ahead and make our CNC machines, program them, enjoy building our aircraft and leave the knit-picking to the law makers.

[jim.bo12345]

Hi all,

To figure out the most efficient use of the CNC router will be decided in practice. Since CNC routers have 3 axis, intuitively it would make sense to start to think in 3D. I have personally already ordered a plan and this book http://www.amazon.com/Build-Your-Machine-Technology-Action/dp/1430224894 to become familiar with it's capability. As far as what is the most efficient software combination to use with it, again we will be able to tell over time.

As far as I am concerned, a CNC foam cutter also in order, since foam ribs are lighter the wood (presumably). But again, during the first phase of the project, those things will come out.

Now both of those tools are expensive, but I can see a scenario, that once there is a proven, standardized design agreed, each EAA chapters could build one for their members use, so they can be leveraged. Or in parts of the world where there are no EAA chapters, interested group of people/communities can invest in shared CNC tools.

As far as design to build, I tend to agree that a proven design that CAN be built with CNC tools (even though it is not designed for it) a good starting point. There is so many other things that needs to be done in an early phase of an open source project, that the design is the last thing one wants to worry about.

Once the group gets over the initial hurdles, than it makes sense to create a design optimized for CNC tools specifically and for cost generally.

Dana bought up a good point that questions <<who approves the design, and changes in the design?>>. I think the strength of a open group method is that there is a lot of people will join hopefully. Among those there will be some qualified aeronautical and structural engineers, some master craftsman. I expect that some of the group members will have access eventually to some of the sophisticated FEA http://www.sv.vt.edu/classes/MSE2094_NoteBook/97ClassProj/num/widas/history.html and CFD http://en.wikipedia.org/wiki/Computational_fluid_dynamics tools so we can verify structures and aerodynamic changes. Although traditional configuration airplane design is well understood, optimization is always difficult for any single designer. But in a group setting we can work in a divide and conquer mode, i.e., each of the group member can specialize on area that are well within their competency. So one of the main group "charter" could be to develop those sound PROCESSES that lead to sound decisions (the other to store the design, performance, test and manufacturing information). In other word, if a member of a group does know how similar tests were done before, does know, what test report format he/she needs to use to report the result, and there are qualified members willing to to do a "design review", I see no obstacle, why the format wouldn't work. Of course the whole thing depends on a competent leadership, but I am positive about it that it CAN be done, but of course time will tell how well.

Brian mentions 51% kit related issues. In my mind, the group should not supply parts (only design and process related info). If the CNC files (g-code) is available, anyone can go to a local CNC shop or hopefully an EAA chapter and make their own parts. I don't think the FAA requires us to build our own CNC machines.

In summary, I think it COULD work and if it does work, it has the potential to seriously to reduce the entry cost barrier of flying. Again in my personal opinion, if we can't make an airplane that beats the average car both in price and performance, why bother?

jim.bo

[Jeffrey Meyer]

You got it, with the abundance of open source hardware projects dedicated to CNC, from gantry systems through to controllers as well as software, this is a great time to jump in and see how we can leverage it for homebuilder use. Now just to add a little to the conversation, there are software applications out there that can slice 3D models that can be cut and carved in 2D slices and then re-assembled into 3D objects. (www.vectric.com (http://www.vectric.com)) Think of now cutting out a plug or mold for composite building.... (cowls, fuel tanks, wings, fuselage etc). Also maybe a windshield form that is assembled from foam slices and then the acrylic/lexan heated and molded over that form... now think of using that same cnc machine to build a chair and ottoman out of wood to sit in and admire all that work....
:-)

Yes, SolidWorks can also slice up the 3D geometry to make such plugs. Now all we need is the geometry...


I would say that we should probably proceed with number 1 and see where we get to. If a plans supplier wants to donate for number 2, then that would be great, but again, even if we go with number 2, there would still need to be re-design for CNC manufacture and assembly as there are few designs out there if any that would comply with the overall vision that we have to make this as quick and simple as possible with associated instructions, video and content we are ultimately trying to achieve. This will become apparent as we begin to go public with this..... more to follow.... :-)

Glad to see that we're on the same wavelength. So, let's start pushing the cart. The way I see it this is a team effort - I can't do it on my own and I suspect that nobody else will claim that they can. But we have strength in numbers - of the 4000 odd forum members we only need 20 or 30 enthusiasts to identify with the idea. As such, we have to lay down some ground rules to prevent the horse from looking like a camel. Some comments/suggestions:
1. This is not just a team - it's a cyber team. We all have to practice restraint, flexibility and tolerance of eachothers' ideas and opinions, but we can't please everybody all the time.
2. This forum is the main line of communication and we are an international team so we don't have the advantage of frequent face-to-face meetings. Again flexibility and tolerance is the name of the game.
3. We need to work to a predefined plan with well defined activities and milestones. For example, I suggest the following:
* Through this forum specify the type and mission of the aircraft we want. The milestone is freezing of the spec.
* Preliminary layout and design through sketches and pictures. The milestone is a preliminary layout of the aircraft and specification of the required CNC machine to produce it.
* More detailed general layout as well as specification of the aircraft powerplant. Milestone is exact 3D CAD model of the external geometry.
* Division into sub-groups to deal with various activities - CNC machine, Wings, Undercarriage, Fuel system, Controls, Cockpit, Fuselage, Empennage, engine, electricals, documentation, etc.
* Design of main structural elements and layout of equipment. Milestone is reports and analyses required by the regulatory authoroties.
* Detail design of all parts including DXF files for CNC. Milestone is the first CNC part produced on our machine.
* It may be prudent to build a 1:4 scale R/C model just to give everybody the confidence that the thing will fly.

I've probably left out a great deal but hopefully it's a start.
Am I crazy to think that this will work?

[jim.bo12345]

Hi all,

I just noticed this plane, designed for CNC. Building hours claimed to be 160-250 hours (see the bottom of the page). http://www.skykits.com/Comparison.html Now that is closer to my liking and shows the true potential of CNC based plans...

jim.bo

[JNicol]

Yes, SolidWorks can also slice up the 3D geometry to make such plugs. Now all we need is the geometry...


Glad to see that we're on the same wavelength. So, let's start pushing the cart. The way I see it this is a team effort - I can't do it on my own and I suspect that nobody else will claim that they can. But we have strength in numbers - of the 4000 odd forum members we only need 20 or 30 enthusiasts to identify with the idea. As such, we have to lay down some ground rules to prevent the horse from looking like a camel. Some comments/suggestions:
1. This is not just a team - it's a cyber team. We all have to practice restraint, flexibility and tolerance of eachothers' ideas and opinions, but we can't please everybody all the time.
2. This forum is the main line of communication and we are an international team so we don't have the advantage of frequent face-to-face meetings. Again flexibility and tolerance is the name of the game.

I've probably left out a great deal but hopefully it's a start.
Am I crazy to think that this will work?

Agree with everything you have just said..... but to focus effort, the initial team have also created an Open Source initiative including a .org website. What we would like to do is get a source forge environment set up for the avionics side eventually and a resource repository for the plans, files and so on fairly soon. The EAA forum is not the best place for us to do this, but a great place to stir up interest and post progress! We still have some minor housekeeping to do and should be ready to open the doors in the next couple of days....




* It may be prudent to build a 1:4 scale R/C model just to give everybody the confidence that the thing will fly.


Yes! Working on a prototype now (from a well-known aircraft type), which is a 1/4 scale model.... I wasn't planning on making it fly because I have zero R/C experience, but someone in the team might want to do that.

[Jeffrey Meyer]

Hi all,

I just noticed this plane, designed for CNC. Building hours claimed to be 160-250 hours (see the bottom of the page). http://www.skykits.com/Comparison.html Now that is closer to my liking and shows the true potential of CNC based plans...

jim.bo

You've just taken a giant stride for mankind - started the question of the specification. Some comments:
1. Do we want GA, LSA, hang-glider, etc.?
2. Do we want all-metal, composites or hybrid? (I prefer a sleek composite machine).
3. Metal cutting CNC machines (Router, Laser, Water jet, punches) need to be somewhat more robust and rigid than foam and wood cutting machines. Laser cutting heads are quite expensive (thousands).

[Jeffrey Meyer]

Agree with everything you have just said..... but to focus effort, the initial team have also created an Open Source initiative including a .org website. What we would like to do is get a source forge environment set up for the avionics side eventually and a resource repository for the plans, files and so on fairly soon. The EAA forum is not the best place for us to do this, but a great place to stir up interest and post progress! We still have some minor housekeeping to do and should be ready to open the doors in the next couple of days....

The tension is killing me ...





Yes! Working on a prototype now (from a well-known aircraft type), which is a 1/4 scale model.... I wasn't planning on making it fly because I have zero R/C experience, but someone in the team might want to do that.

I'll be happy to make and fly the model and include some telemetry and data logging - sort of a flying wind tunnel.

[JNicol]

The tension is killing me ...





I'll be happy to make and fly the model and include some telemetry and data logging - sort of a flying wind tunnel.

Hi Jeffrey,

I sent you a PM, did you get it?

[jim.bo12345]

You've just taken a giant stride for mankind - started the question of the specification. Some comments:
1. Do we want GA, LSA, hang-glider, etc.?
2. Do we want all-metal, composites or hybrid? (I prefer a sleek composite machine).
3. Metal cutting CNC machines (Router, Laser, Water jet, punches) need to be somewhat more robust and rigid than foam and wood cutting machines. Laser cutting heads are quite expensive (thousands).

Jeffrey,

John is working hard behind the scenes to put together the open source framework. It will come soon....

Until then I just speak for myself.

I am not looking this as a differentiation between the various class of airplanes or technologies. I am looking this as a differentiation between affordability or not. Whatever technologies and planes takes us closer to that, I am happy with it. A young kid only need a single seater to get into aviation, a young couple a 2-seater, an older couple with kids a 4-seater, a hunter/outdoor person a STOL, so we all have individual needs and need different planes. But affordability and quick build is the common thread.

As I mentioned before, unless price, performance and operating expense can compete with a car, it is a hard sell for a normal person.

CNC based machines certainly can reduce part creation time, but there is assembly time and only reducing part counts that can effect that seriously. As far as the various technologies available to build, I favor the appropriate technologies for its use. For example, I see to often a "metal" airplane, a "composite" airplane, a "wood" airplane, but in reality, each area have its optimum material. For highly stressed area like spar probably carbon fiber is optimum, for reducing parts in the wing probably solid foam core is optimum, for wing skin something that only needs minimum finish is optimum (aluminum? or plywood? or honeycomb?). Of course none of that address operating cost (needs a small empty weight) and storage cost (needs foldable wing). So I hope the open plane organization address all these these issues over time in a systematic way, so at the end both the aviation community and general public wins. Because that is the real goal.

I see potential as a entry level single seat CNC plane both the Volksplane and the Hummel Bird. But both of those planes needs to loose some serious weight using carbon spars and using different lighter but still CNC based technologies. But the potential is there. If those planes could be redesigned to be under 250 lbs empty weight, we would have some good little fun planes. But I am going too far ahead, so lets stop here.

jim.bo

[Jeffrey Meyer]

Hi Jeffrey,

I sent you a PM, did you get it?

Nope!

[jim.bo12345]

Hi all,

Why we are waiting for John, why don't we start identifying possible candidates to CNC based conversion? I would assume, one would look for planes with minimum compound curves.

I don't mean to suggest that we take an existing design and convert that to CNC, since there a legal issues there, rather to identify existing designs and part types that we can look and say, "Wow, we can do that with CNC "better, faster and cheaper". In other words to start to flow the CNC creative juices.

I assume, anyone who built airplane can already identify parts, where this process is applicable, so I assume, we will have plenty of candidates. If possible include a link or a picture to see what are you thinking is appropriate for CNC.

So if nothing else, we will have a little database of ideas for the "next CNC plane design".

Jim.bo

[Jeffrey Meyer]

Jeffrey,

John is working hard behind the scenes to put together the open source framework. It will come soon....

Until then I just speak for myself.

I am not looking..........
jim.bo

OK - I don't want to tread on any corns or crash any parties. Let me know if and when I can help.

[jim.bo12345]

Jeffrey, check your forum email. I sent you one. Did you get it?

jim.bo

[jim.bo12345]

Just FYI,

On the link attached, I can see some good idea, create not just the rib parts with the CNC, but also the assembly fixtures. http://www.steenaero.com/Products/wing_kits.cfm

j (http://www.steenaero.com/Products/wing_kits.cfm)im.bo

[Jeffrey Meyer]

Got it.

[JNicol]

Hi Jeffrey, Send me an email to john_nicol at hotmail dot com

[JNicol]

Hi Everyone,

We are continuing our planning for the Open Source Aircraft initiative and would like to ask the community for assistance in filling the following roles to help us with this planning. We are after:

Aircraft Designer/Aeronautical Engineer to assist in putting the groups ideas into action;
Wordpress developer and administrator for the .org website.
If you are interested, send me a PM and I will send more details. Thanks!

Regards,

[spungey]

Sorry about the delay replying. It's been a crazy month.


We had a discussion like this over on homebuiltairplanes.com a while ago. The general consensus was that the OS model makes a lot less sense for hardware than it does for software, where anybody can test the latest build without any significant investment. With an aircraft design, it's much more difficult... who approves the latest "official version? And how do you approve a design change without building and verifying a prototype? But to wait for a prototype to be verified could take a long time....

The OS model makes sense, but you must first abandon the idea that anyone approves anything. Let me say it again. No .. one .. approves .. anything. (Except where approval is needed now.) When you go open source, then you also--to a certain extent--forego traditional ownership rights.

There's two ways to look at this. The first is that it's your A**! Ultimately you and you alone are the one who will pay if a corner gets cut, literally or figuratively. That means that you, and you alone are the ultimate arbiter of what's "approved." You don't want to contribute any design or part until it's know. Naturally a prudent builder would get some expert advice. :-) The second is the flip side. With dozens (for instance) of well-known rib patterns for various NACA or custom wings, you as a designer/customizer have more control with less cost. You are free to take an existing design and modify it without incurring the wrath of anyone except the gods of gravity. And that brings us back to the first.

In practice, the person who introduces some airplane design also specifies certain patterns, parts and behaviors when that design is contributed. Any changes to a part is a change to the design--with the same issues one encounters changing a known design now--you're making a new airplane. Hopefully in the OS world you test it and then contribute back to the community so others can reproduce and build upon your work. You could in theory gain some kind of intellectual property protection on some or all of what you do, but it'd be better for all of us if you kept the chain of non-commercial improvements intact.

Also, once enough tests and successes are demonstrated on a part, a design, a pattern, a grouping of parts ... then that part design, pattern or subsystem becomes a known quantity for the FAA examiner, making flight approval easier.

In short, OS makes a lot of sense. It's just ... different ... with hardware than it is with software.
--
Richard Johnson
open source evangelist (and now OS avionics)
http://makerplane.org

[JNicol]

Just to clarify as well, the idea with this initiative is that the "official" versions of the OS aircraft would have gone through prototyping and flight testing before releasing the plans. It would be the modifications, customizations and enhancements that are contributed that would not necessarily have been through that process. If these are accepted by the community and are tested then of course this is acknowledged and peer reviewed just like any other project. These changes would go back into the main design or be accepted as enhancements. The process is evolving as we are still in the early stages, but just be assured that any changes are not necessarily just submitted and then flown.

John

[spungey]

I left out a couple of important points from my post yesterday. (Sleep probably really does help.) :-)

First, while I did say "no one approves", I neglected to say, " ... but everyone attests." When the design is available and everyone can make, test, measure, and dissect it, then everyone has the opportunity (and in aviation, a duty) to report weaknesses and attempt to design better bits. It's like having a thousand monkeys pulling on your rib truss, and reporting weaknesses when something breaks.

I never meant to imply a callous regard to safety. I think that open source makes things safer. Safety is critical. Safety is an outgrowth of testability, measurability, and repeatability. Having a publicly-known and "anyone can make one" design for every part actually improves safety of the part. It's the same thing we discovered about encryption -- the public algorithms are all more secure than the secret ones because all of the dark corners have lots of lights shining on them.


Second is the issue of authenticity. Suppose I design a special aileron hinge (for instance) and I test it on my airplane. It works great and analysis says it should be good for 10,000 +/- 200 hours MTBF. Then I make that design, plans, and instructions available. How do you know the design you got is actually the one I sent out? After all anyone can tinker with it, right?

The answer is "digital signature." Anyone providing a part, design, etc. needs to provide a signature on the work. Techniques are known and available that prove that any document is identical in every respect to an intended original. This guarantees that (if you verify it) you have the right part. In essence this is approval. (Here is where I eat crow and say, "OK, the creator approves it ... and notes the precise conditions under which it works, how well test it is, etc.")

Related to this of course is your responsibility, when you choose to make and use that part, to actually run some numbers and make sure it will actually work with your particular airplane and not prematurely fail. Once you do, then you can report how well it works in your design and make life that much easier for the next guy.

Hope that clears things up, or at least provokes some discussion. :-)

[JNicol]

Hi Everyone,

It has been a while, but just to update people that have been following this thread. We launched "The Hangar Workshop" today on the MakerPlane website www.makerplane.org (http://www.makerplane.org). This is a repository for open source aviation related projects. We have several open source avionics hardware projects kindly provided by Matjaz Vidmar. These need TLC to complete their documentation and some may require rework, but it is a great start to the database! We also have a placeholder for the MakerPlane v1.0 LSA. This repository is a free resource for anyone that wants to start up an open source aviation project and manage it with a team. It has tools including bug and version tracking, document and file storage, forum and task management tools and so on.

Also, we will be at AirVenture next month with our very own booth and will have a couple of forum slots to talk about MakerPlane! At the booth we will have a scale model of MPv1.0 as well as a CNC machine. Please stop by and have a chat with us!

[Kiwi ZK-CKE]

Just a demonstration about how CNC machining can build wooden aircraft parts - here a a video of parts for a DH mosquito rebuild being produced in New Zealand. If the technology can produce a 54ft span wooden wing, a small homebuilt should be a piece of cake!


http://www.youtube.com/watch?v=fmQhoPXwXsI&amp;feature=share

[JNicol]

[QUOTE=Kiwi ZK-CKE;17574]Just a demonstration about how CNC machining can build wooden aircraft parts - here a a video of parts for a DH mosquito rebuild being produced in New Zealand. If the technology can produce a 54ft span wooden wing, a small homebuilt should be a piece of cake!

That is just awesome! That is exactly what we are trying to accomplish with the first design. Optimize it for CNC from the start and provide the appropriate CAD files ready to be converted to g-code for the specific CNC machine that people have. We are also looking to provide g-code for those CNC routers that we will be using in-house for those that have the same ones.

BTW, I am an ex-pat Kiwi...... ;)

[Brian E. Evans]

One of the difficulties of generating G code for different CNC machines is that not all machines are equal . Some use line numbers , others do not, some can use higher level codes, others reduce the inputs to X Y and Z steps in two of three thousanth of an inch, with files that are horrendusly long. There is no one size fits all here, which is really what is trying to be achieved.
Brian Evans.

[Rootski]

I love this idea. Might be a candidate for a kickstarter?

[Kiwi ZK-CKE]

The issues with different CNC machines using different coding or languages isn't an issue, almost without exception the CNC software that drives the machines will import a CAD File (either Solidworks or Autocad) and convert it to the coordinates that the machine needs, based on the particular config of the machine. With precise CAD files, it will be up to the end user to convert to whatever they need - the end result however are components that are absolutely accurate and identical, no matter where they are made. Its a principle already widely used in general industry - the Chinese are particularly good at cloning CAD files to make "cheap alternative" products! the idea has a lot of merit - no longer do you buy a roll of paper plans, you get a disc with the CAD file and start carving from there... Wooden aircraft arent my thing, but good luck with the concept. Its sort of the "social media" method of construction - the way for the new century. Dream big!

[JNicol]

Wooden aircraft arent my thing, but good luck with the concept. Its sort of the "social media" method of construction - the way for the new century. Dream big!

Actually our first design will probably be mainly composite with wooden bits and metal here and there. Also, we have other open source aviation related files that we will be populating up in the project repository including avionics, tools, 3D objects for 3D printers etc. This means that people don't have to wait for the aircraft design to hopefully get some value out of open source aviation. People can check out the repository on our site. Matjaz Vidmar kindly gave us permission to use the avionics files that he has published on his website as a starting point and although they need updating, hopefully someone will pick up that task and move it forward. If nothing else, it provides a great starting point for new projects and may give people some inspiration at least.

[JNicol]

One of the difficulties of generating G code for different CNC machines is that not all machines are equal . Some use line numbers , others do not, some can use higher level codes, others reduce the inputs to X Y and Z steps in two of three thousanth of an inch, with files that are horrendusly long. There is no one size fits all here, which is really what is trying to be achieved.
Brian Evans.

Hi Brian,

We will be supplying the CAD files which can be then used to convert to g-code specific to a users requirements and as I indicated, we will also be supplying the native g-code for anyone that might be using the same CNC machine and want to use the same settings. This is just for convenience only. The default will always be the CAD files.

John

[kmacht]

Cool idea. I built an oversize JGRO wood router that can handle a 2'x4' sheet of wood. Total cost of the machine was around $800. I have used it a number of times while building my plans built Sonex. For your plane I would suggest not giving up the idea of being able to use aluminum sheetmetal on the router. I have been able to cut out the .025 wing ring blanks on the router as well as make wood form to bend the flanges over. The aluminum cut just like plywood but at a slightly slower feed rate. The key with aluminum sheet is to make sure it has something under it (MDF works great) and have a starter hole for the router to make an initial plunge cut through.

Keith

[Jeffrey Meyer]

Hi Kieth,
Thanks for the input - can you give us a few pointers/links on how to build such a router.
What software do you use?

Jeffrey

[JNicol]

Hi Everyone,

Jeffrey has created a small scale prototype composite seat for MakerPlane v1.0 in order to work through some manufacturing techniques and to get feedback on instructional material. So we would definitely want some feedback from the community as we make progress! Also, we will be at Oshkosh next month and have secured a booth in the Innovation Centre to talk to people about our open source projects and what we are up to!

2071

We have decided to run a small competition to see other seat builds based on Jeffrey's plans. If you bring your completed full-scale seat to Oshkosh to show us and the rest of the world, we will give you a free, very cool, limited edition, rare, collectors item embroidered MakerPlane Open Source Aviation shirt! If you are not attending Oshkosh, post up pix of your seat in our forum and the team will vote on the best one and send you a shirt! Hey in a couple of hundred years they will be worth millions on eBay!

http://makerplane.org/forum/viewtopic.php?f=5&t=79
(http://makerplane.org/forum/viewtopic.php?f=5&t=79)
It would certainly help us out and at the end of the day, you will have your very own MakerPlane chair to sit on and make airplane noises! :cool:

2072

Have a great day!

[kmacht]

Hi Kieth,
Thanks for the input - can you give us a few pointers/links on how to build such a router.
What software do you use?

Jeffrey

The best place to go to find out how to build your own is cnczone.com. There is a forum there for DIY CNC routers.

http://www.cnczone.com/forums/diy-cnc_router_table_machines/

The JGRO router is probably the simplest to build requiring only some basic wood working tools but it isn't the fastest or most ridgid machine out there. I took the basic design, scaled it up and added things like antibacklash nuts, ball bearings on the ACME leadscrews, a bunch of gussetts to stiffen up the gantry, and some larger pipe for the roller skate bearings to ride on. A friend and I built the machine over a weeks time between christmas and new years.

As for software I use Vectric Aspire to generate most of the G-code and tool paths and then use Mach 3 to actually run the stepper motors. There are less expensive products out there from Vectric such as Cut 2d if you are only interested in cutting out flat 2 dimensional objects. If you are into Linux there is also a bunch of free software out there. Take a look around on the cnczone.com forums as there are specific sub forums for all the different software packages there.

Keith