CNC plans - DIY kit? Thoughts?

[Cap'n Jack]

To be economical, the shop would have to have both a CNC laser and a CNC punch. At this point you are talking about a shop with a couple of million bucks tied up in tools and a minimum shop rate of well past 100$ an hour. Initial setup and proofing is going require considerable amounts of time and resources. Simply the process of correctly nesting the parts to minimize material wastage and efficiently cycle the materials thru the tools will eat up more time. For the cost of setting this up, one could probably buy a full set of standard kits for everything that Van's has available, and still have money left over for engines and props for a couple of them.

Yes, that is the sort of shop I was thinking about. Nesting the parts would be part of the plans that are submitted. Using standard sheets, that will be difficult the first time while developing the programs for the machines, and easy thereafter. The cycling through the tools is probably something that can be done, too, as part of the plans a person gets, as I'm assuming, perhaps incorrectly, that there are similarities between the machines used in different shops.

[CraigCantwell]

Cap: There isn't a shop out there that will let outside files of any type be loaded onto their machines. When a file for a job comes in, it's loaded on an isolated machine and a CAD guy runs a variety of cleanup processes on it. Once it's ready, it's then moved to a CAM processor and then ports to a POST processor, which then generates the G code specific to the machine. It's then run in simulation for a period of time to identify tooling path errors, cut or punch errors and any machine operation errors. When I was doing CAD/CAM work, even a simple machining file took several hours to complete the path from computer to actually loading and cycling through the first part.

There are contract shops out there that will do the work, but you will pay for significant shop time for the first pass. For everything laid out on a 4'x12' sheet of AL, you are probably looking well north of 5 grand for the punch work and probably at least that for the laser work. Onsey- twosey type work doesn't really interest the guy with millions of dollars worth of machines on the floor, so they aren't going to be quick and you will pay dearly to have the work done.

I've contacted a few job shops about some small work before and the quotes are crazy high. Last one was some waterjet work.... about 20 minutes of time on the machine, but I would have to buy a complete hour to cover setup time, plus the CAM time of at least another hour. Let's say I could buy all new drills and rotobroaches for every hole on the parts, do it my self and have less money involved.

[mmarien]

I did the majority of my project with CNC. I bought a 6040 CNC router when I started the ribs. I had a local place CNC cut a plexiglass jig as my router wasn't big enough. The local place was happy to do the plexiglass jig. I know another place that will CNC laser cut 4x12 sheets of aluminum no problem. I'm not sure why the holes need to be punched.

I did all the small plexiglass parts and all the wood rib parts. For sure my ribs were accurate because of the CNC. Putting the rib jig together was just a matter of assembling the parts in the pre drilled holes.





I also had all the metal parts CNC laser cut locally. My CNC router can't cut 4130 steel. All of the stuff I outsourced was from the DXF files I supplied. They did the conversion to gcode and optimized the parts on the material I supplied. The cost was a few $ per part. Money well spent.



I recently learned how to cut Aluminum with my CNC router.





The parts I did myself were converted to from dxf to gcode with some software I purchased (~$150). For sure adding a CNC router to your inventory of tools adds another level of skills needed to complete a project whether it's DIY or outsourced. For me, the $2G I spent on the CNC router and learning to use it was time and money well spent.

As mentioned most of the kits are already done with CNC. I think it's a good idea to start sharing CNC code for plans built projects. Sky's the limit when you put your mind to it.

[Cap'n Jack]

I did the majority of my project with CNC. I bought a 6040 CNC router when I started the ribs. I had a local place CNC cut a plexiglass jig as my router wasn't big enough. The local place was happy to do the plexiglass jig. I know another place that will CNC laser cut 4x12 sheets of aluminum no problem. I'm not sure why the holes need to be punched.

I did all the small plexiglass parts and all the wood rib parts. For sure my ribs were accurate because of the CNC. Putting the rib jig together was just a matter of assembling the parts in the pre drilled holes.





I also had all the metal parts CNC laser cut locally. My CNC router can't cut 4130 steel. All of the stuff I outsourced was from the DXF files I supplied. They did the conversion to gcode and optimized the parts on the material I supplied. The cost was a few $ per part. Money well spent.



I recently learned how to cut Aluminum with my CNC router.





The parts I did myself were converted to from dxf to gcode with some software I purchased (~$150). For sure adding a CNC router to your inventory of tools adds another level of skills needed to complete a project whether it's DIY or outsourced. For me, the $2G I spent on the CNC router and learning to use it was time and money well spent.

As mentioned most of the kits are already done with CNC. I think it's a good idea to start sharing CNC code for plans built projects. Sky's the limit when you put your mind to it.

Those images look really nice. How easy is it to run your files on a machine made by a different company? Now that you have your parts optimized, I'd think you could give or sell those files to someone building the same model of plane, so long as they also bought plans from whoever is authorized to sell them (avoids copyright problems). Thanks for sharing your experience!

[mmarien]

I'm not an expert when it comes to CNC machines but gcode is universal to CNC machines as far as I know. The program I use doesn't produce any machine specific code. Here is an example:

( Made using CamBam - http://www.cambam.co.uk )
( Rib Nose 9/22/2016 6:18:08 PM )
( T3 : 0.125 )
G20 G90 G91.1 G64 G40
G0 Z0.125
( T3 : 0.125 )
T3 M6
( Profile1 )
G17
M3 S1000
G0 X-0.0613 Y6.363
G0 Z0.1
G1 F10.0 Z-0.05
G3 F30.0 X-0.0274 Y6.1925 I26.433 J5.1783

This is the start of the gcode for the rib nose pieces seen in the pictures I posted above. To cut out one rib nose piece from 1/4" plywood, I move the router bit to a place on the wood piece and zero the router. When I run the code it cuts out one nose piece. I move the router and zero it again for the next piece. I believe I could use the same gcode on any CNC machine and it will cut out a same nose piece as my CNC router.

However, the gcode is based on a specific size router bit. Put in the different size router bit (or laser cut the part) with the same gcode and your part will be a different size. I've made that mistake a few times.

For sure when I outsourced the cutting, they had a program that read my drawing files and optimized the layout on my material in a few seconds. There was no extra charge for that. However, all the work was in preparing the drawing files in a format they could read. It wasn't gcode. It was AutoCAD DXF format which is a standard drawing format that plenty of programs can read. With that in mind, the DXF files are probably more useful than the gcode files.

There is no doubt that my CNC router is my favorite tool. It makes very accurate and precise parts over and over again. Would the drawing files or gcode be worthwhile to the next builder? Probably depending on how they used them. Would kit suppliers be willing to supply digital drawings or gcode? Probably not for free. Unless you have your own CNC equipment it's probably less expensive to have the kit supplier supply the parts rather than the gcode. If it's a plans built and you are sharing gcode on a user forum, that is a different story.

I don't believe there are any copyright issues. All the work I did to create the gcode is my original work.

[DaleB]

I don't think you'll find a kit manufacturer eager to share CAD files to let other people mass produce the parts they're trying to sell. It's got to be a tough enough road as it is trying to sell kits.

In my case, I toyed with the idea of making drawings and generating gcode to cut out some parts for my project. I decided that I could probably do it twice or three times (or 10) in the time it would take me to do that work. None of it would interest the rest of the tiny handful of people building the same airplane I am, I'm afraid. If the design used more CNC-friendly parts than it does, it might be a different story.

But to answer the question about running Gcode on different machines... Gcode is a standard language, more or less, but portability would be about nil. Every machine is different in how it can handle "feeds & speeds", and even the controllers are different in how they handle some commands. The code CamBam produced that worked on mmarien's machine would probably not work so well on my much different machine driven by LinuxCNC and using a very different spindle motor, etc. There are also differences in how zeroing the tool is handled, etc.

It's the same with 3D printing. If you look at 3D printer objects (like on Thingiverse), they're not distributed as gcode because every printer is different. My I3 Mega requires different settings, speeds, temperatures, etc. than my brother-in-law's delta-style printer, even though they both are driven by gcode.

[Cap'n Jack]

I don't think you'll find a kit manufacturer eager to share CAD files to let other people mass produce the parts they're trying to sell. It's got to be a tough enough road as it is trying to sell kits.

In my case, I toyed with the idea of making drawings and generating gcode to cut out some parts for my project. I decided that I could probably do it twice or three times (or 10) in the time it would take me to do that work. None of it would interest the rest of the tiny handful of people building the same airplane I am, I'm afraid. If the design used more CNC-friendly parts than it does, it might be a different story.

But to answer the question about running Gcode on different machines... Gcode is a standard language, more or less, but portability would be about nil. Every machine is different in how it can handle "feeds & speeds", and even the controllers are different in how they handle some commands. The code CamBam produced that worked on mmarien's machine would probably not work so well on my much different machine driven by LinuxCNC and using a very different spindle motor, etc. There are also differences in how zeroing the tool is handled, etc.

It's the same with 3D printing. If you look at 3D printer objects (like on Thingiverse), they're not distributed as gcode because every printer is different. My I3 Mega requires different settings, speeds, temperatures, etc. than my brother-in-law's delta-style printer, even though they both are driven by gcode.

I disagree about someone mass-producing parts. When I buy plans, I'm buying a license to use the plans to build one airplane. If I want to build another plane of the same type for a family member, the plans I've seen indicate I'm supposed to buy another set of plans and they will have a different serial number than the first set. Buying the CAD files would fall under the same license agreement- I can use that code for a single plane. Beyond that, I could see such code as an up sale. Vans, Sonex, and others sell plans, kits, and quick-build kits. Each step up is a higher cost to the builder. I see this as being between plans and a kit, and priced accordingly. Someone who only sells plans, Hummelbird(?), might see increased sales if parts could be made more easily.

Having said that, I'm reading from mmarien's real-life experience that there isn't much savings in money over a kit that exists.

[Cap'n Jack]

I'm not an expert when it comes to CNC machines but gcode is universal to CNC machines as far as I know. The program I use doesn't produce any machine specific code. Here is an example:



This is the start of the gcode for the rib nose pieces seen in the pictures I posted above. To cut out one rib nose piece from 1/4" plywood, I move the router bit to a place on the wood piece and zero the router. When I run the code it cuts out one nose piece. I move the router and zero it again for the next piece. I believe I could use the same gcode on any CNC machine and it will cut out a same nose piece as my CNC router.

However, the gcode is based on a specific size router bit. Put in the different size router bit (or laser cut the part) with the same gcode and your part will be a different size. I've made that mistake a few times.

For sure when I outsourced the cutting, they had a program that read my drawing files and optimized the layout on my material in a few seconds. There was no extra charge for that. However, all the work was in preparing the drawing files in a format they could read. It wasn't gcode. It was AutoCAD DXF format which is a standard drawing format that plenty of programs can read. With that in mind, the DXF files are probably more useful than the gcode files.

There is no doubt that my CNC router is my favorite tool. It makes very accurate and precise parts over and over again. Would the drawing files or gcode be worthwhile to the next builder? Probably depending on how they used them. Would kit suppliers be willing to supply digital drawings or gcode? Probably not for free. Unless you have your own CNC equipment it's probably less expensive to have the kit supplier supply the parts rather than the gcode. If it's a plans built and you are sharing gcode on a user forum, that is a different story.

I don't believe there are any copyright issues. All the work I did to create the gcode is my original work.

Thanks much for your answers. My only concern with copyright is that it is possible to make parts without the original plans. I certainly wouldn't expect the code for free from the vendor, either the plans owner or someone else. I see a lot of value in giving someone a pile of metal and a USB drive and getting a kit plane back. I also see there is a bit of effort making code that can be easily and quickly used, and that effort is worth some money.

[Cap'n Jack]

Cap: There isn't a shop out there that will let outside files of any type be loaded onto their machines. When a file for a job comes in, it's loaded on an isolated machine and a CAD guy runs a variety of cleanup processes on it. Once it's ready, it's then moved to a CAM processor and then ports to a POST processor, which then generates the G code specific to the machine. It's then run in simulation for a period of time to identify tooling path errors, cut or punch errors and any machine operation errors. When I was doing CAD/CAM work, even a simple machining file took several hours to complete the path from computer to actually loading and cycling through the first part.

There are contract shops out there that will do the work, but you will pay for significant shop time for the first pass. For everything laid out on a 4'x12' sheet of AL, you are probably looking well north of 5 grand for the punch work and probably at least that for the laser work. Onsey- twosey type work doesn't really interest the guy with millions of dollars worth of machines on the floor, so they aren't going to be quick and you will pay dearly to have the work done.

I've contacted a few job shops about some small work before and the quotes are crazy high. Last one was some waterjet work.... about 20 minutes of time on the machine, but I would have to buy a complete hour to cover setup time, plus the CAM time of at least another hour. Let's say I could buy all new drills and rotobroaches for every hole on the parts, do it my self and have less money involved.

So there's no way to get (eventually) a file that could be sent to any shop and run? I'm not talking about a guy like me, who knows very little, creating a solidworks file that needs to be cleaned up. I thinking someone like, for example, Vans, who already has good files made by professionals. I buy plans that include good, usable CNC files. I'm not understanding, maybe the machines are so different?