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The vageries of import collets

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  • #16
    Originally posted by A.K. Boomer View Post


    Wow --- that's brutal and being forced both directions and they still hold up, Tim's correct then - it is more of a cheap problem, maybe hardinge anneals their collets close to the shank end for flexibility/durability
    That's right and annealing them close to the shank would probably be another step in the mfg. process. Something cheap collet mfg.'s would not take.
    But I'me sure you all know Hardinge collets are of a much higher quality than the Chinese stuff.
    I've never had this issue with any of my Lyndex collets.

    JL................

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    • #17
      Notice the lack of a stress relieving hole at the end of the expansion slots in the broken collet.

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      • #18
        I picked up 29 piece 5C set from Shars. Went to use it with 1" Alum stock. I had to use 2 flat blades jammed into the slots to expand it enough to take the stock. I'm not impressed. I thought they were a little better than that. I can't afford a high end set of collets. Not sure what to do.

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        • #19
          It has been said before, "You get what you pay for." Not arguing with those who choose to save money, just saying it.

          I have two sets of import (Chinese?) collets: R8s and 5Cs. I use the R8s on my mill all the time: the 5Cs only occasionally. So far, so good. I also have a very mixed set of name brand ones for my SB lathe and a set of ER-11s (from Israel) for my Unimat. No real problems with any of them.

          My philosophy is use them until they break or exhibit other problems and then replace them, probably individually. My funds are limited so that works for me.

          Side note: I am frankly surprised that I am the owner of not one, but four sets of collets. I go back a long way in this hobby as I purchased my Unimat when I was in my 20s or earlier and that was 50+ years ago. I can remember looking at collets and collet closers. drooling, and thinking that I could never afford such luxuries. So there was no way that I was going to purchase a set of name brand, US made collets. And there still isn't unless it would be for a HIGH profit project or job. And that is not likely at this point. But then, I also drooled over things like rotary tables, milling machines, and a host of other things that sit in my shop today.
          Paul A.
          SE Texas

          Make it fit.
          You can't win and there is a penalty for trying!

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          • #20
            Originally posted by Paul Alciatore View Post
            It has been said before, "You get what you pay for." Not arguing with those who choose to save money, just saying it.
            Yep, all the problems mentioned in this thread (re inexpensive collets) are well known, and are due to cutting corners during manufacturing.

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            • #21
              Well --- DR's statement is very powerful, I never know anyone or never have myself "power closed" a collet with nothing in it and would immediately expect it to shatter, the fact that hardinge can be spread back open means they at least anneal the threaded end some, still would not trust the thing running true after that but they are way more durable then what Tim was dealing with...

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              • #22
                Cheap or not they could last many years - even lifetime if the initial problem was solved or you just found a way to deal with it better like maybe a better chamfer leading in,

                I just checked my 1/2" and 5/16" and they are both .001" tight, to me that's non-issue and with R-8 I actually like not having an endmill drop out accidentally when I unclamp my drawbar,

                But - like I say if your using a 5/c to chuck with then it could ruin your whole procedure and if I had to get clearance here's how id go about it, id just build a piece of scrap oversize on one end by about .005 and small enough on the other to fit in my dewalt --- put the de-walt on low, put the scrap piece into the collet to spread it and then rotate in the drill and heat down where the collets reliefs meet the start of their cuts, at least your heating uniformly and you won't end up with one/third of the tangs giving it all up and maybe throwing your collet out of center...

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                • #23
                  Thanks for the interesting discussion. In this particular instance I was wanting to use the offending collet for the 3rd operation. I had some relatively fragile parts with a nice finish, and wanted to handle them without damage to that finish. So, I tried a sample. The slots scratched my nice, smooth finish. Might have been able to polish the ID, thereby de burring the slots. But the part was still hard to push in, and difficult to remove. The point of the post was to remind us to inspect anything that comes into our shops. If you have an issue with something, it's good to notify the vendor in a timely manner. I've had this collet for maybe 10 years, and it's a little late for returns now! That is, if I could remember where I got them!

                  As for tight collets in general, I see the point about not having an endmill fall out before I can tighten the drawbar. On the other hand, I don't want to slice my old, dry, thin skin on a end mill that doesn't want to fit into a collet without a fight. If my stock or cutter is not of nominal diameter, then that's another matter.

                  So, anyway, thanks for taking the time to reply!
                  I cut it off twice; it's still too short
                  Oregon, USA

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                  • #24
                    Connor you said you had one that would not take 1 inch stock...now be fair and Mic the 1 inch please.
                    first thing I will do if it does not fit.

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                    • #25
                      I used to work in a factory that had dozens if not hundreds of automatic screw machines. They ran production and handled millions of parts. Of course the collets would wear. Instead of buying new collets we would grind them oversize and send them out for hard chrome. Once we got them back we would put them in a fixture on an ID grinder and tighten them up a little bit to spring them closed a little, then grind them. That way when there was no tension on them they would be slightly oversize and allow the automation to load the parts without any problems with interference fit. It would seem like most quality collets are made this way.

                      To the OP. It seems like you could take a torch and adjust it to a small flame and just heat a dot in the middle of the area between the slots and then quickly cool them with a spray of water. That should spring them open and still hold size when they close. At least that's what I would try.

                      Brian
                      Last edited by bborr01; 02-14-2020, 11:24 AM.
                      OPEN EYES, OPEN EARS, OPEN MIND

                      THINK HARDER

                      BETTER TO HAVE TOOLS YOU DON'T NEED THAN TO NEED TOOLS YOU DON'T HAVE

                      MY NAME IS BRIAN AND I AM A TOOLOHOLIC

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                      • #26
                        I have experienced the undersize issue with a few of the import collets, but yesterday my ship came in and I hopefully won't need to worry about it anymore. Found a set of 31 5C collets, all sizes from 1/16 to 1 1/16 in 16th increments with a few other sizes and duplicates mix in and a handful of 3J collets I plan to sell to offset the cost. All for the princely sum of $100 CAD (about $75 USD these days). Made me pretty happy after a crappy week.

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                        • #27
                          This is the response I received from Shars this morning regarding their collets..

                          " 5c collets are no expansion. They are +0000 by nature. 1" 5c will not accept 1" round stock, the stock needs to be slightly undersized or the next size collet used. ER collets are a range in which they work in, 5c does not

                          Regards


                          Shars Tool"

                          That's not what I was taught with regard to 5C collets... WTF, a 1" won't take 1" stock?

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                          • #28
                            I will say it again Mic it.. cuz if it 1.004 it ain't the collets fault. If its.996 then a different story.
                            You got to decide, come here to grumble, at least be fair about it...

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                            • #29
                              Originally posted by Connor View Post
                              This is the response I received from Shars this morning regarding their collets..

                              " 5c collets are no expansion. They are +0000 by nature. 1" 5c will not accept 1" round stock, the stock needs to be slightly undersized or the next size collet used. ER collets are a range in which they work in, 5c does not

                              Regards


                              Shars Tool"

                              That's not what I was taught with regard to 5C collets... WTF, a 1" won't take 1" stock?
                              A 1" collet, whatever type is, as I understand it, normally at least a couple thou over, and takes up to maybe 10 thou under without too much hassle. Spring collets ARE limited range, maybe up to +5 and -10. That's not to say they spring open to that +5 automatically, just that that might likely not damage them.

                              If you have 1" "nominal" rod, good luck, might be sloppy, might not go in. If you have 1" TGP, it should slide right in. Drill rod, I'd expect to go in easily also.

                              Just about every used collet I have bought has been sprung open a bit (for whatever reason, I'm not speculating on that here). I have never seen one that was under, but I only have a couple dozen collets, a mix of new and old, and do not use them that much. Would if I did more turret lathe work.

                              If 1" material would not go n, was it chamfered, was it on-size, etc?

                              Even so, the collet should not have broken like that.

                              And I am used to seeing collets with a "grip length", beyond which it is relieved at least a little, maybe 10 thou, but something. That way even if you cram in something full depth, it is not going to be able to wedge the base of the spring area, which would be apt to break it. (I am not saying you did that).

                              That collet is full depth, no relief, but the spring thickness has enough meat to do the relief. Bad collet is what it seems, not tempered, no relief, etc.
                              Last edited by J Tiers; 02-14-2020, 03:21 PM.
                              1601

                              Keep eye on ball.
                              Hashim Khan

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                              • #30
                                I'd wager that collet was already cracked before you ever tried to expand it- likely came that way from the factory. Note the dark line on the inner edge of the cracked face, a strong indicator a crack already existed, and had drawn in some oil from a previous job. At some point it was going to fail anyway, at least it did so outside of an actual job, and didn't kill a workpiece or worse.

                                On the quality of collets, I have virtually never run across "on size" stock. I deal with aluminum mostly, and if I buy a stick of 1", it can be anywhere from 0.995" to 1.010", Most commonly it's around 1.001" to 1.002".

                                As such, I eventually wound up with I think as many as four 1" collets- some no-name import which is right on 1.000", two Hardinges of indeterminate use and age, one of which is about 1.003" and the other about 1.005", and one of a German, I think, brand, which is about 1.009". So with a little checking, it's easy to find a collet that will work best with whatever material I wound up with that day.

                                Doc.
                                Doc's Machine. (Probably not what you expect.)

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