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Tom Downey
01-18-2012, 12:33 PM
Any one have suggestions on how to cut a 1" thick piece of rubber block and get a smooth surface?
The material is black rubber 4" square and 1" inch thick, I need to make a 3.5" round pad.

got any tricks?

Bill Berson
01-18-2012, 01:20 PM
You can try freezing the rubber to make it hard so it cuts like wood.
It's been decades since I tried this, and I can't remember if it worked or not.

Mike Switzer
01-18-2012, 01:46 PM
I'm wondering if a Greenlee hole punch would do it (if you dont mind a small hole in the center)

Tom Downey
01-18-2012, 01:48 PM
You can try freezing the rubber to make it hard so it cuts like wood.
It's been decades since I tried this, and I can't remember if it worked or not.
I don't think my freezer will get that cold, it would take a dose of N2 or something.

Bill Berson
01-18-2012, 04:49 PM
The freezer should be about 0 degrees.
I have used liquid propane at -44 degrees. To get a cup of liquid propane, hold a propane bottle upside down and let some out. About half will evaporate and then the remaining liquid will be -44.
Do it outside, of course, and wear gloves.

Tom Downey
01-18-2012, 05:22 PM
I have been contemplating using a 3.5" hole saw modified by removing the teeth and grinding a knife edge on it. Gluing the rubber block to a board, and clamping that to the drill press table, and running the drill press as slow as it will go. adding lubrication for the blade.

the propane sounds a little scary.

Bill Berson
01-18-2012, 06:51 PM
I think they sell dry ice at Safeway.

Tom Downey
01-18-2012, 10:06 PM
I think they sell dry ice at Safeway.

I wonder how cold you would have to get the rubber to cut it on a lathe?

nrpetersen
01-19-2012, 09:51 AM
Dry Ice & a lathe - I think that's the best idea. Silicon grease will help any cutter or knife slide thru the rubber. It depends a lot on the physical properties of the rubber block though.

Tom Downey
01-19-2012, 11:35 AM
Dry Ice & a lathe - I think that's the best idea. Silicon grease will help any cutter or knife slide thru the rubber. It depends a lot on the physical properties of the rubber block though.
The material will be here today, I have a steel plate that has been turned round at about 5' I think I'll try gluing the rubber to that and try cutting the rubber on my lathe with the modified hole saw in the tail stock. That way I won't worry about holding the rubber, or getting enough pressure on saw, or frost bite :)

martymayes
01-19-2012, 11:45 AM
I wonder how cold you would have to get the rubber to cut it on a lathe?

I've cut fairly hard rubber on a lathe, high speed and knive edge cutter.

Bill Berson
01-19-2012, 02:21 PM
I used a 1.5" hole saw to cut 1" rubber on my drill press. It worked OK at room temp.

Norman Langlois
01-19-2012, 07:13 PM
Modifying a hole saw will work. be sure to sharpen only the inside beveling towards the outside this will ensure the cut goes straighter. I have made similar cutters for making holes in such rubber, for bolts that way. removing the plug will be your only worry after that .no need to use the centering drill ether. [As per your plan with the plate] your only failing will be the adheasive to the plate.try something at the corners like drive points. an alternative would be to simply press your cutter through with a hydraulic press.lube and sharp will make it happen.
regards

Tim Ryan
01-20-2012, 11:06 AM
I have used my mill with a ½” end mill installed and had reasonable results. I believe I had the spindle speed as high as the mill would turn. It wasn’t like you cut it with a razor blade but the proper shape was made. This was done with the rubber at room temperature. The 1" thick rubber was screwed to a block of wood and bolted to a rotary table. If I did it again I would try gluing the rubber to an aluminum plate with 1300L adhesive and cleaning the adhesive off with MEK after the part was finished. I finish shaped the rubber on my lathe using a die grinder with a 2” sanding disc installed. The rubber I used was pretty soft so I didn’t feel it would cut well on the lathe. I attached a picture of the finished tire on my boys stroller project. Good luck.
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Tom Downey
01-21-2012, 09:41 PM
Step 1, make a 6" circle from scrap Oak, mount it in the lathe, and turn surface flat and sand smooth, then apply common rubber cement from local hardware and allow to dry.
1431
Step 2, Clean the rubber block and apply contact cement and allow to dry.
Step 3, join the rubber block and wooden circle being sure it really sticks.
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Step 4, manufacture holder for a Dremil tool motor, that will allow it to be held by the carriage of the lathe, and mount to the carriage cross feed.
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Step 5, Run the Lathe at a very slow speed, and feed the dremil tool into the turning rubber block using a 3/8 square ended router bit. This will cut the outer circumference.
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Step 5, adjust the carriage to cut center hole, and proceed to cut away the center, and remove the wooden block from the lathe
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Step 6, remove the rubber part from the wooden block and place the rubber part back into the lathe and using a 1/2" sander bit in the dremil adjust center hole unit it fits shaft.
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Place the shaft in the lathe and adjust the outer circumference to fit the cylinder in the same manner.
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And that is how you make a Fairchild strut seal.
All the knives didn't work but the dremil cut it with no sweat.

Mike Switzer
01-21-2012, 09:46 PM
cool...

tmadison
02-12-2012, 12:32 PM
I'm impressed with the results acheived with the lathe and Dremel. Can anyone provide sources for rubber stock?

Matt Gonitzke
02-12-2012, 12:37 PM
Very cool...:)

Tom Downey
02-12-2012, 02:52 PM
I'm impressed with the results acheived with the lathe and Dremel. Can anyone provide sources for rubber stock?

google jewelers supplies or http://www.fusionbeads.com/shop/product/31925/ they are ll over the net .

Christopher Ingram
02-12-2012, 05:28 PM
Whenever I have needed to put holes in rubber for body mounts etc. I have used a piece of pipe of the correct I.D, beveled the edge then just heated it up with my torch and made the hole. Works like a champ and leaves a better/smother edge than cutting.

Keep it simple out there,
Chris

Tom Downey
02-12-2012, 09:28 PM
Whenever I have needed to put holes in rubber for body mounts etc. I have used a piece of pipe of the correct I.D, beveled the edge then just heated it up with my torch and made the hole. Works like a champ and leaves a better/smother edge than cutting.

Keep it simple out there,
Chris

When I tried that the neighbors though the shop was on fire, and it left a hole way to big to seal around the steel tube.