I am making a 5C collet chuck. I plan to bore the hole and finish by lapping then bore the 10 degree angle. My question is should I obtain a set of collets first and lap to size or is size pretty much standard between brands. If I pick up a set of collets at a swap meet what should I look for? Other than obvious nicks and dings is there other misuse that I would look for?
Also is a full set in 1/64 increments recommended or is this overkill? Thanks
Check the collets for galling in the bore, i have seen a lot of used collets that have that problem and are out of tollerence. A full set is handy but pricey so you may want to start by getting 16th increments first and adding the rest as you need them. Also get the collets that have the internal thread at the back end so you can use collet stops when you want to crank out a bunch of work thats the same lenght this is a handy feature to have. Don't forget to check the threads on the back end for wear, nothing like having a collet that won't close.
Good quality collets are ground to a high tolerance for a good fit in a hole of 1.250" +000/-.0002". That's a tolerance of plus nothing, minus 2 tenths of a thou. You should get at least one good collet for a plug guage.
Lyndex, Brown & Sharpe, and Hardinge are names to look for.
In a set of 1/4" to 1", you'll have at least 30 collets taking up space that you may never use. Collets are good for repeat accuracy when chucking multiple items of the same size--if you have a job where you need to chuck up a multiple odd-64ths piece of one size, then just buy or make that collet. I believe you can buy collet blanks of soft steel for that purpose.
I would stay away from the Lyndex collets. They're mid-ranged in price but my experience with them is the quality is no better than the cheapo import collets. I bought a set of Lyndex collets but had to send them back- several of them had threads out of spec and the run-out on all the collets was just so-so.
I ended up buying a full 1/64" set of the cheapo Enco collets on sale. Runout is acceptable (better than the Lyndex ones). A few in the set had dinged threads but Enco replaced them without a hassle. I supplemented this cheap set with a selected number of Hardinge collets in the common sizes I use often (1", 3/4", 1/2", 3/8").
Having the full set of sizes is great for one off and quick repair type work- I know I can grip any size round workpiece from 1-1/8" on down, without having a collet compressed or expanded more than about 0.007" from its nominal size. Compressing or expanding a collet that much is pushing it a little bit, but as these are cheapo collets I don't sweat that, and this approach has worked fine. I use the collets a lot more than I even thought I would, and I'm using my 3 jaw a lot less now.
I also found that buying a low cost "collet block set" allows the collet set to be very useful on my milling machine for holding round workpieces for milling or drilling operations. The block set along with your standard milling vise gives you quick simple indexing and angle setup capabilities, definitely a lot of bang for the buck for the low cost of the collet block set (less than $50).
Unlike many people on this NG, I never use 5C collets for holding tooling. I use them almost exclusively in 5C collet fixturing where runout is much less critical. So I buy my collets from Grizzly, and I have no complaints about their fit or finish. In fact, after 10 years of owning my Grizzly set I have no knowledge that they are in any way less than perfect. So save yourself some $$ if you can get away with it.