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Discussion Starter #1
any ideas on making tool to punch /cut out donuts , foam rubber sheet. Looking for any thoughts on this, will be making silifoams. I 've thought about sharpening a piece of tubing to make inner hole, wondering if anyone has made anything to cut out inner and outer at same time....thanks:wave:
 

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concentric punches

Try to search through more of Hobby Talk. I saw a photo of one that one of the pros had built. It appeared to be two commercial hand punches joined together with a pin through them. I suppose you would need a cylinder to fill the gap between them, keeping the cutters concentric. It did not look to difficult to construct, and would probably cut better than sharpened tubing.

When I made a few sili-foams, I punched the two holes independently, making the outer diameter a little larger than I wanted, then I ground it down to the correct size. This is only practical if you are making small quantities.

Good Luck!
 

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Discussion Starter #3
tabco

thanks, I will probably do it the same way that you have done, just looking for a cleaner cut line.
going to find some tubing toaday & sharpen it up, see how it goes..

Alittle info, if anyone is looking for donut material, I went toa rubber supply house, yesterday and they gave me a sample of some neopreme rubber, 1/2" thick and enough to make tires for ever....
 

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I used leather hole punches,the ones that are just a hollow tube/cheap ones:thumbsup:
Like Tab says,the outer one was always cut big for truing,and you had to be semi good at eyeballing the second cut.
And i agree with Tab for a couple pair at a time it's okay;)
 

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Jeff,even cheaper,i got mine through Princess Auto up here,which is our glorified Harbour Freight in Canada,lol.They are just a bunch of sharpened hollow tubes
That dual one looks like it might work,:thumbsup:
Rick
 

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Hello Rick, Yeah these are a little expensive but they have the one punch ID / OD and they have the concentric problem figured out for punching 2 holes at once. I just wanted to do some digging and see what I could find, besides there might be a small market for a well designed tool.

I have the HF set of punches myself and they do a good job, keep them sharp, I use a scarp piece of the sound deadening board to punch into to avoid damaging the punches. They really work good if you rub a sharpening stone across them just a bit, inside and out.

Rick you may have to post the link to the tire truer you made, I am sure that hog could easily true up a tire, regardless of how bad you miss the center.

Boosted
 

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Years ago I took a old 1/24th slot rim and glued a piece of tubing to the indise. to cut inner hole place an axle in the given hole and drilled a hole in a block of wood to allow the cut tire a relief area . it worked pretty good I bought the Foam stamps from hobby lobby for making donuts. I used my drill press to do the work.
Clyde-0-mite
 

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I took small steel tube, welded it to a washer then welded a larger tube to the same large washer, trimmed and sharpend as needed.

JS
 

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Hi folk, years ago I faced this problem and put the same idea which Hornet did. And get rid from this problem. Anyway all the above participants perform well and expose the idea very well...
 
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