Re: Cheap vs expensive collets and nuts for aluminum surface finish?
hello again
One of the collets is too big for half my 1/4" end mills.
check upper play; for example, a 6mm collet, should have it's bore >6mm, but less than 6 +0.015eq; if your colett is too big, then simply don't use it
One is too tight to fit half of them in one of my collet nuts. The 3rd one mostly works in both nuts
hold the nut in your palm, then insert the collet into it; flip it 180* degrees, by holding only the nut : the collet must fall, just because of gravity; if this doesn't happen, then extra useless force is required each time you mount a tool; you can machine the nuts, in order to increase this play
but it's not always as tight as I'd like
this is mostly because of the play between collet thread and nut thread; a smaller play gives more confidence, while a bigger play makes it feel loose, even if you tighten it
you can go on a spree, and buy whatever stuff you wish to buy
here are a few recomandations :
... check all collets bore, to be within spec
... check contact between collets and chuck, again, to be towards the bigger diameter, and for at least circa 80% of collet's taper length
... make sure that you use collets designed for h7 clamping range, otherwise, the bigger the range, the greater the overhang, as collets face won't be as close to the chuck
... for small collets, or for big collets that clamp small tools, is better to have more grooves, since less grooves means that the collet is more rigid, thus, when you tighten it, less force will be transmited to the clamp area; the more grooves, the more elastic the collet is, thus it will transmit more force towards the inside
... check the collet chucks:
...... check their threads, and find out their tolerances; you may craft incremenal threads, that you use as a gauge for your chucks, then you may decide to machine one nut size to fit them all, or, for example, only for whatever chuck, to machine a nut that is more special; thus machine your own nuts, adjusting their specs to your chucks; off course, bearing types are a bit more difficult to machine ( it may be possible to replace with a normal nut and a thrust washer, as being said by mactec a while ago, but so far i didn't acualy have experience with this; still, it sounds promising ); if you buy a bearing type, you may have the surprise to see that it doesn't fit well with your actual collets and/or chucks
...... chuck face to be smooth, burfree, perpendicular to chuck axis; some low cost chucks don't have this, but this is not always critical; for example, you can have the face with marks from the saw cut, and still no problems, as long as nice chamfers are there
check for burs at the begining/end of the threads ( chuck , nut ), since they are not always deburred, and sometimes they can generate problems
if you decide to go crafting your own, i can help with specific details if you wish : i have done chucks and nuts (for er and other collet systems), and lately, with the edm wire, i think i could handle also collets, but i didn't so far / kindly
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