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  • Tell me about collets please

    My 12" x 28" lathe has an MT5 taper in the end of the main spindle. There is no measurable run-out. The 3 jaw chuck has about 0.003" total indicated run-out, which seems to be to be about normal for 3 jaw chucks in general. If I considered going to a collet system instead of the 3 jaw chuck, what would I need. I know of about three different collet closing options. One is a drawbar which extends thru the spindle and it tightened at the far end, similar to a milling machine, which pulls a collet into a recessed taper to close the collet. I have also seen a large handwheel that fits at the business end of the spindle, and turning it by hand tightens or releases the collet. A friend of mine has what looks like a chuck on his South Bend lathe, but it isn't a chuck. A collet slides or screws into it and the "chuck key" tightens it to pull a collet into a taper in the front of it and closes the collet. Which of these systems is most common and which is the most economical. The only reason I would consider a collet set up is a higher degree of accuracy in the work I do on my lathe. There appear to be many different sizes or grades of collet as well, ranging from MT2 up to MT 5. Any information would be greatly appreciated.---Brian
    Brian Rupnow
    Design engineer
    Barrie, Ontario, Canada

  • #2
    When I got my Harrison 12” lathe there was an adaptor in the headstock to accommodate a collet, a tube through the mandrel and hand wheel to tighten the collet at the back it was a Harrison accessory according to the label, it’s fairly straightforward, there was also a nose thread ( I have a threaded Chuck) cover
    i still have the bits and collets but never really use imperial sizes, it’s all metric over here and at the time couldn’t find a metric set
    the collets are the same ones you’d find with a spin indexer or collet block (5c, I’m not sure)
    mark

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    • #3
      I have a lever-action 5C collet closer on my 14" Logan. With this system, the drawbar is a tube (about 1.25" ID) with a knurled ring on the outboard end of the headstock which you turn to engage the collet. The lever is then pushed outwards (drawing the collet in to the spindle) to grip the work, or inwards to release it. It is very useful and, if you can manage it, I highly recommend it: everything stays on the lathe except for a nosepiece for the spindle which is what actually causes the collet to close.

      The next step down from this, in terms of convenience, is the handwheel style, which is basically the same thing except there is no lever, and turning the handwheel of the drawbar closes the collet completely, again using the nosepiece to close the collet. The ID of the drawbar should be about the same, as the only difference is the presence of the lever mechanism. I'm pretty sure this stays installed on the lathe as well, but am not sure.

      Below this is the basic drawbar, which is usually a threaded rod run through the spindle and a nosepiece to close the collet. Both pieces are removed from the lathe when not in use.

      The above describes 5C options, for the most part. I have only seen basic drawbar systems for MT collets. MT collets do not require the nosepiece if the collet taper matches your spindle taper (an MT5 collet for an MT5 spindle).

      An alternative to the drawbar-through-the-spindle approach is ER collets: these mount on the nose of the spindle, in your case with an MT5-shank ER chuck (requiring its own drawbar), and the collet is drawn into the chuck using a nut. I have used these on threaded spindles and those Sieg-style flanged spindles, neither of which requires a drawbar to hold the ER chuck in place.

      I'm not going to go into the merits of 5C and ER, or whether MT collets are worth pursuing - I'm sure there will plenty of opinions flying back and forth on that one. I am very happy with 5C, and find it to be a very versatile system.

      Comment


      • #4
        I finallly finished my 5C holder setup a couple of years ago. The holder zeros out consistently within a tenth or two with each mounting provided my spindle thread is clean.

        Now to test my 5C collets.... They ranged from near zero to maybe a .0005 runout in a couple of cases to more like .001 to .0015 for most of them to a bit over .003 in one case. The worst collet was replaced with a South Bend Asian collet from Grizzly. It turned out to be one of the better ones in my set.

        A short while back I bought a set of ER32 collets and a ER32 chuck with 5C shank to let me chuck items up in my lathes 5C holder as well as the various 5C holders and spindexer I've already got. Chucking up the holder in my 5C setup I found that the ER taper had about .002 runout. I put my light duty tool post grinding setup to work and after zeroing out the compound to the proper angle I touched up the taper. This reduced the runout to around .0005 to .0007'ish.

        From there checking runout of the ER collets with sized pins I found that they too varied from down around a half thou up to around .002'ish. This is with cheap import collets.

        Oh, in one case with a roughly .001 runout on the ER collet I turned the collet around a bit and managed nearly zero runout.... .at least at the nose. 2 inches out it was wobbling around a thou and a half.

        So depending on my needs I might use the collets (I do like them!). But if I really do want dead nutz true I'll turn a spud mandrel or drill and bore a recess which lets me lightly push fit the part. Or I will find and stock in a few cheap 5C emergency collets which I can drill and bore true to my own needs. Amazon has a cheap import emergency collet for $14 each.

        The moral and, for me at least, rude awakening in this story is that collets are not the automatic route to consistency as we might hope for.
        Chilliwack BC, Canada

        Comment


        • #5
          Hello Brian - cooking hot out this way today. Last year I invested in some 5C collet sets, square and hex collet holders, a 5C collet chuck for the lathe . I really find them handy in many ways. The collet holders work well in the mill vise to for many applications. One I really find handy is milling a hex or square on round stock.They hold small parts much better than a chuck. I can dial the collet chuck in to less than .001. The more you use them the more you find how useful they are, at least in my opinion.
          Just thought of another reason I like the 5C and that is its hollow right through so you can put longer stock through it and through the lathe spindle. The same goes for the collet holders, long stock can go right through and out the back end.
          Last edited by Cuttings; 06-26-2021, 04:49 PM.
          Larry - west coast of Canada

          Comment


          • #6
            The 5C spindle nose collet chuck with chuck key is a good way to go. On some lathes, when you do the lever or handwheel 5C closer, the collet is hard to reach with a cutting tool. You have to get the carriage as far left as possible, then crank the compound left to get there. With the collet chuck, the collet is a few inches to the right, about where you would be with a normal chuck. Then everything is easy to reach. It's a lot like using a 3 jaw chuck, only with collets.

            Another one I like is the ER40 collet chuck that has a D1-4 backplate and adjust-tru for the collet. You can dial the collet in to very small runout, although once it's set, don't usually need to move it. I have and use all the different setups mentioned in this thread. I do use the lever collet closer a lot, as well.
            Kansas City area

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            • #7
              I have a 5C collet chuck with a D1-5 mount over the years I have gotten a complete set of fractional and metric collets. I also have several 5E collets that can be bored out to any diameter. I got 5C collets because all of the shops I worked in used them and I have never regretted that decision.

              frankie

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              • #8
                I recommend 5c collets for their versatility and wide availability, while ER collets give more range in diameter with fewer collets. For 5c collet closers, I would rate lever type most desirable, handwheel with draw-tube second, spindle-nose mounted (handwheel and chuck-key type) third. The spindle nose mounted are most useful when the spindle bore will not allow for the 1-3/8" diameter draw-tube. There are lots of other types of collets, but 5c and ER are by far the most commonly available, which means most reasonably priced. Of course, for maximum versatility get both types. For 5c with draw-tube closer you will need a spindle nose adapter to fit your MT5 spindle.
                It's all mind over matter.
                If you don't mind, it don't matter.

                Comment


                • #9
                  Brian you have a good deal of talent at machining.
                  The choice of work holding in a lathe is simple, do you want speed or do you want a very high level of accuracy?

                  If both are required the cost will be well beyond what a home shop is likely to spend.

                  Simple collet systems such as 5C will allow rapid manual part changes, hundreds of parts per day may be produced by unskilled operators once set up. One may easily hold .001" in the X axis on existing parts or ground stock.
                  If however the collet system is not "dead length" the Z axis dimensions will suffer.

                  Ask yourself these questions.
                  Do I make 1000 model engines per year?
                  Is adjusting a 4 jaw chuck to nearly 0 runout costing me money?



                  Comment


                  • #10
                    You could also just get a set-tru 3-jaw. My buck stays spot-on once adjusted for a given size. As for collets, you might not get what you pay for. I paid about $300 for what I thought would be a 'better' quality chinese set, 1/16 - 1 1/8 in 64ths. They were junk. Some were not even through or relief-ground to size, preventing stock from passing through.

                    I use a Bison 5C chuck (D1-4) and I like it. Its very well made, but pretty slow compared to a lever. Be aware that some draw tubes for levers can cost you thru-feed capability in the larger sizes.
                    Southwest Utah

                    Comment


                    • #11
                      I have been machining for over 60 years and I would not be without collets. 5c collets are probably the most common. I have 5c in sets imperial and metric and square and hex. Also 5c step collets can hold short pieces
                      with diameters 4 inches or larger. Also 5c emergency collets can be bored to any special size needed. Also I often use 5c inside collets to hold on the inside of parts , These inside collets are dead length collets and z axis will hold true. Hardinge also makes dead length collets. One other thing about 5c collets is they often can be moved from lathe to another machine like grinder or mill. As there are many kinds of tooling like indexers that use 5c collets.I also have 2j collets in sets and rubberflex collets that go to 1 3/8 dia with a Harding collet chuck. With a lever collet closer it is easy to open and close collets in seconds. Even with the spindle running. To see an inside collet working google Rovi collets. Or check you tube. Jim Sehr

                      Comment


                      • #12
                        One thing often overlooked on ER collets is the need to pass stock completely through the grip area of the collet or it won't clamp properly. With the 5C if need arises you can clamp on a very small length.
                        Southwest Utah

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                        • #13
                          Thank you for the information gentlemen. I will probably stick with my 3 jaw chuck. Now that I am retired, I can't justify purchasing a collet set up, but I did want to know a bit more about them.---Brian
                          Brian Rupnow
                          Design engineer
                          Barrie, Ontario, Canada

                          Comment


                          • #14
                            Brian --
                            I have a total of $50 in my ER collet setup for the lathe. That's including the new collets from eBay, and a nut fro Mari tool. I started with a piece of large round bar and made it to fit the spindle on one end, and the ER dimensions on the other. Run-out etc. is undetectable even with my best indicators because the collet tapers were machined in place -- I think it was worth it for the time and aggravation savings since I tend to use a lot of standard stock sizes.
                            25 miles north of Buffalo NY, USA

                            Comment


                            • #15
                              Don't give up on the idea yet. Keep it in the back of your mind. Even a reduced set of 5Cs (every 1/16 rather than 1/64) you will find very useful. A handwheel type drawtube using an inexpensive needle thrust bearing is a very suitable HSM project, as is a M5 to 5C adapter, especially if you have a tool post grinder. (I don't recall if you do.) For careful hobby use it doesn't need to be hardened, and even 1018 steel would work well enough. I was lucky enough to score about 10 4C collets (perfect for my little lathe with a M4 spindle taper) in exchange for a bottle of Wild Turkey. Made the rest myself and they've been a pleasure to use for 30 years so far.

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