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How to hold small work in lathe?

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  • How to hold small work in lathe?

    My 12x36 lathe is not big but when I have the 4-jaw chuck mounted I cannot work on anything of 9mm or so diameter. How to get around this problem?

    I am thinking collets. Do I need to make a set of special collets or should parallel sided collets be available?

    Other options...
    Mount a smaller chuck in the 4-jaw?
    Make/buy a collet chuck that I can hold in the 4-jaw (I have er-32 collets)?
    Build a shop crane so that I can easily change out the 4-jaw?
    Add another (smaller) lathe to the famous concrete bench?

  • #2
    John, when I faced a similar problem, I took a short length of aluminium rod, dialled it in, drilled it down its centre a wee bit larger than the work-piece's diameter, slit it lengthwise with a hacksaw, and used it as a cheap and cheerful collet, taking care to keep the chuck jaws away from the slit.
    Cheap, quick, and accurate enough for me.

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    • #3
      A 5C collet chuck held in a 3 jaw scroll chuck, very handy for small diameter work.
      This one is dead length as well.

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      • #4
        Originally posted by The Artful Bodger View Post
        Add another (smaller) lathe to the famous concrete bench?
        See? If you think about enough you can always justify buying a new machine.
        I personally machined a screw on collect chuck with a through-hole for er-32 collets. But i only have a 9 inch lathe so the 4-jaw is not very heavy.

        Tom - Spotsylvania, VA

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        • #5
          Thanks Mike, that would certainly get me past where I am now. John

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          • #6
            Originally posted by Bented View Post
            A 5C collet chuck held in a 3 jaw scroll chuck, very handy for small diameter work.
            This one is dead length as well.
            Thanks, I do not have 5C collets but that does give me ideas!

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            • #7
              https://www.ebay.com/sch/i.html?_fro...dkw=er32+chuck

              or this (you could make it adjustable):

              https://www.ebay.com/itm/23302372229...AAAOSwj91cHY4z

              what i sometimes do is stick an er32-mt chuck with an adaper in the spindle to turn between centers. lath chuck has to be big enough.

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              • #8
                depends on how small and convenient you want it. What Mike describes is a very basic, inexpensive and there for the taking approach that works. More suitable imo if its a somewhat rare occurrence. Collets are a fantastic addition to any lathe. Every lathe I have has collets and they are the most frequently used work holding device. ER can certainly work, split collets are a little better. You could also add a smaller 4 jaw to the collection.

                Always fun adding another machine to the stable. A smaller lathe is a big help with small parts, e.g. 100 collets between .1mm and 8mm gives you lots of options...but is complete over kill if just occasionally need to run 1/4" or 1/8" stock.
                Last edited by Mcgyver; 05-11-2021, 09:37 AM.
                in Toronto Ontario - where are you?

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                • #9
                  You can use your er32 collets with a parallel shank holder in the four jaw. A c32 parallel shank, or a collet plate would both be easy to hold.
                  Alternately, a little 100mm, 4" chuck would also be easy to hold in your main chuck, either 3 or 4 jaw.
                  Last edited by old mart; 05-11-2021, 09:14 AM.

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                  • #10
                    Your path of least resistance here is to buy a square bodied er32 collet block and dial it in on your 4 jaw. Arc eurotrade sell the John Stevenson blocks. I have a pair of square and hex, and find them indispensable. They really shine when you need to move something from lathe to mill and maintain orientation. Something I use them for a lot.

                    Of course a 5c collet block works too, I have one also, but you said you don't have 5c collets, so that option is more expensive.

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                    • #11
                      Collet blocks are very useful, they come in square or hexagon bodies, I have one of these plates mounted on a lathe backplate, but it would fit in your chuck directly.

                      https://www.ebay.co.uk/itm/133620353...UAAOSwVPNf6FNc

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                      • #12
                        Originally posted by old mart View Post
                        Alternately, a little 100mm, 4" chuck would also be easy to hold in your main chuck, either 3 or 4 jaw.
                        If you don’t want to go the collet route, I was going to suggest this.

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                        • #13
                          I've used Old Mart's suggestion for a bunch of years now. When I found this little 3.25" / 80mm four jaw direct screw mount chuck on a SALE counter I knew it would be handy as I'd run into that same minimum size issue on the four jaw. Over the 20'ish years I've had it now I've used it for both re-centering of second operations as well as "proper" four jaw applications for holding odd shapes to zero in on a needed operation.

                          My 3 jaw won't quite hold a 5/32" drill so size on it has seldom been an issue. And when faced with that I've used a spare small size Jacob chuck to hold the part and hold the chuck in my 3 jaw. But with that I have the roughly .003" runout in my 3 jaw to worry about. So where it has mattered I tend to take the time to set up the little four jaw. And as you know when we're working on the really small things suddenly a little runout looks like a lot more. So the little auxiliary four jaw wins the day as I can dial in the part where a collet chuck with round shaft in the 3 jaw would still have the runout.

                          I don't recall the direct thread size. I think it was 3/4" and a fairly fine pitch. But the stub arbor I made was from some 1" round stock. It was apparently too small to get a clean 1" out of it so I turned it down to the next size down for a 7/8" collet. But I've always used it like this.

                          Normally I don't like a lot of overhang and avoid it at almost all costs where at all possible. But the only time I use this setup is for small parts and secondary operations. So lighter cuts are the norm and it's worked out just lovely.

                          Click image for larger version

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                          Chilliwack BC, Canada

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                          • #14
                            I went onto Amazon and found THIS OPTION. But as you can see from the first picture it has the same issue. The one I showed above has jaws that angle in to about a .05" wide edge so I can easily hold right down to 1/16". But you can see that the Sandu chuck has wider gripping edges which means the minimum size is larger.

                            I can't seem to find one that looks like the one I found.

                            EDITED TO ADD-

                            Ebay has a few options in the 70 to 80mm range. But while at least steel (watch out for the zinc junk) they are out of India. And recent reviews of Indian tooling are not great. But THIS ONE at least has the desirable small width to the gripping areas to let you hold small items. And it looks like the MT arbor just screws off and you could make a parallel shank arbor to hold in the 3 jaw or in a collet.
                            Last edited by BCRider; 05-11-2021, 11:58 AM.
                            Chilliwack BC, Canada

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                            • #15
                              Reading the first post again it sounds like you are just looking to hold stock and that it's not for any higher degree of centering accuracy but simply to hold some stock. That being the case I'd say that an ER32 chuck sounds like it would be fine for a lot of uses.

                              The trick might be to find one with a thru hole so you don't need to cut the stock to length. With that in mind look around at options for a 5C shank to ER32 chuck. The one I bought recently easily passes 3/4" stock through the body. And it has a parallel portion leading to the 5C taper which is not relieved like some. So a little slip of shim stock to protect the surface and it could be gripped neatly in your four jaw.

                              Checking some online sources... You'll have a better chance of a good size through hole if you look for options that have the 5C internal thread on the end. Some seem to have the size for a milling machine drawbar instead of the proper 5C size.
                              Chilliwack BC, Canada

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