Announcement

Collapse
No announcement yet.

collets 101?

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • collets 101?

    I nned to learn something about collets and lathes.

    Specifically - I have a Grizzly 4003G lathe, D1-5 spindle. A friend of mine had an extra set of 5C collets by 1/16ths. He also had 2 collets blocks - one 4 sided and one hex. The set includes one lever tightener - very short lever basically a screw ring and a cam lever, and 2 loose screw rings for tightening the collets.

    Something of a PITA to set up, essentially have to put the work into the collet and holder, tighten up the ring, then install the whole works into the lathe chuck, true it up, and hope for the best. If the work isn't tight enough in the collet - you have to take the thing out of the lathe and retighten.

    I've found it difficult to get decent tightening using the screw rings alone. I built a collar and set screw tightening aid - but it needs some work.

    I was thinking about building a through the spindle tightener - I still may do that, but the collet blocks really don't seat on the face of the chuck - so whatever tension you put on the collet to tighten it is also trying to slip the collet block axially in the chuck jaws.

    So whats the right way to use a collet on a lathe? I've looked at collet chucks - but they are running something like $800 +/- which is a little pricey for something I don't know how much I'm going to use.

  • #2
    Use a collet chuck on the lathe. Those blocks you are trying to use are intended for use on mills or grinders, not a lathe. Using them on a lathe is only really good for protecting the work from jaw marks since it will be no more accurate than the chuck.

    Comment


    • #3
      The best way to go is a lever collet closer. Those are great with 5C collets and would work fine on your lathe.

      Comment


      • #4
        Originally posted by Johnh57 View Post
        So whats the right way to use a collet on a lathe? I've looked at collet chucks - but they are running something like $800 +/- which is a little pricey for something I don't know how much I'm going to use.
        The right way, chuck removed, collet adapter slid into the front of the spindle bore (some lathe spindle are ground to take collets directy), draw tube inserted from the rear of the spindle bore to tighten collets. Grizz probably offered a spindle adapter and drawtube as an option for your lathe.

        Comment


        • #5
          Collet blocks are just 'emergency' methods to use a collet in a lathe. Idealy you want a collet chuck, but I find the blocks are great for doing off centered turning and for turning things smaller then your cluck can grip.

          Heres also a little page of info comparing collets: http://www.prototypemachining.ca/Art...ghtCollet.html
          Play Brutal Nature, Black Moons free to play highly realistic voxel sandbox game.

          Comment


          • #6
            You can buy a nice used Hardinge (Sjogren) 5C speed chuck with D1-5 on eBay for about $300. Level collet closer, as suggested by Toolguy is another excellent option. If you want to spend less, look into regular 5C chucks. There are Chinese ones you can buy for about $140 plus D1-5 adapter, but you'll need to spend some time to make one work barely acceptably. Frankly, I wouldn't go this route. Spend more and get a good stuff: more convenient (like speed chuck) and well made. As for the collet set, the best way would be to buy one by 1/64" (you'll come to it anyway, despite the fact that you'll hardly ever need to use some of them). The bare minimum is a set by 1/32", IMO. Just make sure you realize that you won't be able to upgrade your 1/32" set to 1/64" one by buying the missing collets as a set. You'll either need to buy them individually or go for a whole new 1/64" set.
            Last edited by MichaelP; 07-03-2013, 03:01 PM.

            Comment


            • #7
              "Collets 101": you said it.

              So, the main idea of using a collet in a lathe is to achieve maximum accuracy (minimum run out) in a fast and easy to use work holding device. So the collet is mounted either directly in the spindle taper or in a simple, sleeve like adapter that fits in that spindle taper. This assumes that the spindle taper is the most concentric feature of the mounting area - we are talking about tenths here. If an adapter must be used, it does add a bit of error to the set-up, but this can be held to a very small amount. So, if the collet itself is well made then it is probably the most accurate way of mounting a part in the lathe. Also, the collet closer is usually easy and FAST to operate either by a hand wheel or a lever at the outer end of the spindle. Thus the use of collets is fast, easy, and accurate. That is the normal theory behind using collets in a lathe.

              The four and six sided collet blocks that you speak of are intended for fast indexing (2, 3, 4, or 6 divisions) when used clamped to a flat surface like a fixed vise jaw or a milling machine, grinder,- or drill press table. This is where they are normally used. I am sure that they can be used in a lathe chuck as you describe, but this would be considered a rather special situation and not recommended for normal use.

              If you want to use those 5C collets on your lathe, you should get a proper collet attachment. If the spindle bore is large enough for a sleeve type adapter, you can buy or make one of those along with a collet closer made from a tube, threaded for the collet on the end, and a handwheel. This tube would pass through the spindle to pull the collet closed.

              But most likely, your lathe does not have sufficient room inside the spindle for an adapter and you will need a collet chuck. Yes, there are some that can cost $800 or more. But there are less expensive ones available or you could always make one. My SB-9 has a rather small spindle opening and I have an old, thoroughly worn out 3 jaw chuck that I plan to make a collet chuck from. I will use the main body and the scroll plate to provide a means of closing the collet with a nut plate mounted to the scroll plate. A completely new front will be made to hold the collets. By machining it in place, on the lathe where it will be used, I hope to achieve good accuracy/run out.
              Paul A.

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

              Comment


              • #8
                Why are you putting the workpiece in a collet instead of just putting it in the chuck? I'm missing something here.

                Comment


                • #9
                  Soft jaws, and you could skip the collets for a lot of work.

                  Comment


                  • #10
                    Originally posted by Forestgnome View Post
                    Why are you putting the workpiece in a collet instead of just putting it in the chuck? I'm missing something here.
                    My 8" 4 jaw chuck won't grip under 1/2" or so. (maybe its 3/8?")
                    Under that size, I use 5C collets and hold the square block in my 4 jaw and dial it in as normal.

                    Else I have to make some kind of adapator to hold it. (aka: a collet)

                    Although sometimes I have been known to place a small object in a keyed drill chuck thats on a 1/2" arbor I insert into my lathe 4 jaw chuck.
                    Play Brutal Nature, Black Moons free to play highly realistic voxel sandbox game.

                    Comment


                    • #11
                      How about a back plate and then a 5C collet chuck from ARC Eurotrade? It is a hobby quality (meaning it isn't file-hard, but tough), but the concentricity is really good.
                      Amount of experience is in direct proportion to the value of broken equipment.

                      Comment


                      • #12
                        Little more homework to do. Current specs for this lathe is that the spindle bore is 40 mm and a MT#5 taper. So If I want to use the spindle I need a MT5 to 5c collet adaptor and a lever through the spindle collet tightener. I see no reason I couldn't make the lever tightener. I'll have to confirm the specs on the machine haven't changed since I purchased mine. Probably ought to check runout on the spindle before I get to carried away.

                        Thanks for the help.

                        Comment


                        • #13
                          Lever type collet closers are not that simple. Either buy one or just make a standard draw tube. Those are easy to make.

                          Comment


                          • #14
                            Unless you need it right now I would be making one with the draw tube or bar. I made one up from plans in one of the Home shop Machinist books. "The shop Wisdom of Phillip Duclos" page 44. Old lathe Collet adapters. I made it up for the 10 inch Atlas and it works very well. It is not hardened but really, it's for the Atlas. Anyways, it was a nice project that was a big money saver. Mike

                            Comment


                            • #15
                              I have a Grizzly 4003 I have had for like 13 years, its paid for itself many times over, I have a good assortment of 5 c collets and had a 5c chuck on it for a bit....I decided to get a ER40 collet chuck plate from Tools4cheap, after I got a backplate and got it machined for the step on the ER chuck plate its been on for like a month, its awesome .0004 run out, and the ER collets seem to have a wider gripping limit. I could never get better than .001 out of my 5c chuck and it was a pain to get collets in and out.....your millage may vary....

                              Comment

                              Working...
                              X