Anyone that uses shrink fit tooling in there cnc can you help me out with something? I am working on an engraver project and making a spindle for it. I was thinking of making 2 holders to go into the spindle as these two will prob be my most common. I am looking to get an idea on the size of the shrink fit needed to hold a 1/4" and a 1/8" shank. I checked the machinery’s handbook and from what i was seeing i need .0005-.0015 interference fit for the holders?
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Shrink fit tooling
- Thread starter Brento
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Generally speaking shrink fits (and force fits) are .001" per inch of diameter. Engravers generally use either taper fits or collets for holding engraving tools, as they usually need to be removed for sharpening.
This is for a pantograph engraver so idk exactly what tools i will be using but i have a few tools in mind that i may use. My idea was to make a spindle that can take an arbor and hold it in with 2 set screw 180° from each other and then a shrink fit of the cutting tool. I am still in design but i figured this may be the cheapest way to do it as i can make the holders all from scratch. If not then i would have to look into some ER11 prob which would then cost me more money into the project.
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You could make your own collets to hold the engravers. Then somehow squeeze the collets. I made a simple collet by slitting a tube at 90 degrees from one end, then flipping the piece and rotating it 45 degrees and cutting two slots at 90 degrees from each other. I used it to hold my DTI. 3/8" to 4mm collet. Didn't take very long to make a collet.
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So make a copy of a collet chuck, or something like it. Or a split collar with a screw tightening the split. You have machines - you are limited only by your imagination!
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The recommended 0.001" per inch interference for shrink fits mean you want 0.000125" of interference on your 1/8" cutter shanks. That is an _extremely_ tight tolerance to hold on your homemade holders, never mind the tolerance of the tool shanks themselves.
ER-11 collets cover the 1/8 and 1/4" range and are available at a variety of price points from many sources. I've seen them as low as $5 each ($10 for a set of one 1/8" and one 1/4" with free shipping - from china of course). Or you can get higher quality ones from $10 to $20 each. Straight shank ER-11 collet chucks are also available really cheap.
If you have a really tight budget and absolutely want or need to make it yourself, and you have a lathe with a compound you should be able to turn tapers. Make a simple collet holder and then bang out a bunch of collet blanks at the same compound setting so the tapers match. You could copy the ER-11 dimensions to let you use an ER-11 nut if you don't want to make the fairly complex nut (ID threads, etc). Or just make it all yourself. Something with the main taper similar to an ER-11 but a flat front instead of a front taper could be easier to crank out in volume.
Dimensions for ER-11 collets:
ER-11 collets cover the 1/8 and 1/4" range and are available at a variety of price points from many sources. I've seen them as low as $5 each ($10 for a set of one 1/8" and one 1/4" with free shipping - from china of course). Or you can get higher quality ones from $10 to $20 each. Straight shank ER-11 collet chucks are also available really cheap.
If you have a really tight budget and absolutely want or need to make it yourself, and you have a lathe with a compound you should be able to turn tapers. Make a simple collet holder and then bang out a bunch of collet blanks at the same compound setting so the tapers match. You could copy the ER-11 dimensions to let you use an ER-11 nut if you don't want to make the fairly complex nut (ID threads, etc). Or just make it all yourself. Something with the main taper similar to an ER-11 but a flat front instead of a front taper could be easier to crank out in volume.
Dimensions for ER-11 collets: