While I have a Bison collet chuck for my lathe I also have a collet closer I made and used before I bought the Bison collet chuck. I almost tossed the homemade collet closer but decided to hold off for a while. Eventually, I found myself using the homemade closer because of the 30 second set-up time. My 3-Jaw chuck has very little runout.
As you can see the bushing that closes the collet is held in a regular
3-Jaw chuck. It would also work in a 4-jaw independent chuck if chuck runout was an issue. The yellow line lets me know where the keyway key is located.
The draw bar is 1" water pipe with one end threaded for the 5C collet and a handle welded to the opposite end. A delrin ring about in the middle helps guide the drawbar to the collet threads. The delrin bearing near the handle is a thrust bearing and also centers the draw bar to the spindle bore.
The Draw bar handle is a piece of 3" CRS welded to the water pipe.
This is a handy collet closer almost anyone can make that already has a lathe and a few pieces of scrap steel. I realize it is not perfect but I find myself using fairly often because of the quick set-up.
Rather than use a chuck though, I made a piece to fit in the spindle...a number 5 taper I think, and then fit the collet to it. The drawbar, like yours is a piece of pipe.
I machined a hand wheel and tigged it to the back of the spindle where it rides. The whole thing takes less than a minute to set up and is very handy for the small stuff. I machined my arbor while it was in position with light clean up cuts. Most of the colletes run less than .0003 which is probably as good as I Can expect on a Chinese lathe.
Thanks for the pictures. Its always good to see what others are doing.
I have thought about setting up for 5c on my 12x36. I think I heard Grizzly has the 5MT to 5C adapters but I wondered about making one. I just don't know how hard it is to get the measurements right. I don't have a lot of stuff for doing internal angular measurements and setups.
How hard is it? Does the newer Machinery's Handbook have specs? I am at work and my old 1942 (11th edition, I got from my Grandfather) does not have the angle but does have the body sizes and thread.
The draw bar should be easy if I can make the adapter for the spindle nose.
When you make the collet closing bushing turn the ID and the OD at the same time for concentricity and straightness reasons. I used a long piece of CRS for turning the bushing then parted the bushing off. Use a 5C collet for a gage. I recomend measuring a few collets to be sure the ID is large enough to accept the collets. I have some newer collets that are tight on the ID.
One more thing. The drawbar handle is 3 or 4" in diamenter. Drill a hole in the outer diameter for a cheater bar for additional tightening. Always remember to remove the cheater bar before starting the lathe.
I don't mean to ask a stupid question but how do I turn an ID and OD at the same time? Do you mean not to remove it from the chuck? If so I would think if you turn the outside first the wall would be to thin and deflect between the MT5 and the C5, but I'm no expert so I'm just trying to learn. Would it be better to turn the OD, cut it off and insert it into the spindle and turn the inside? If I'm wrong please let me know because I've been looking at doing the same thing for my Jet lathe with an MT5 taper spindle.
I was going to look in my newer MHB when I got home but thanks for that drawing.
I also wondered about turning the MT then putting in place to turn the 5C but maybe there is the possibility of spinning or pulling it loose when doing the bore...makes more sense to do it as you say.
How long does the bushing have to be? Does it need to support the collet for its full length? Seems like ones I've seen like for SB lathes were shortish for the length of the collet.
Or you can make it from bar stock. As for how, I would rough turn the straight ID and fit to a spud/mandrel. Then rough and finish turn the OD to fit spindle (MT5, MT4.5, stub MT5, whatever). Then fit the adapter into the spindle, marked for orientation, and finish turn/polish the ID for the 5C in-situ. This should give you about the best repeatable/low run out possible for that spindle.
The ones I've seen leave the OD threads of the 5C exposed behind the bushing. My OEM Rockwell is like that.
The ones I've seen leave the OD threads of the 5C exposed behind the bushing.
Good point Russ. Nothing gained by having the 5C collet threads inside the bushing.
When turning in the lathe we usually think of the larger diameters being toward the lathe head and the smaller diameters toward the tailstock. But on occasion we need do the opposite. Some machinist have left hand toolbits special ground for this purpose and will feed from left to right.
To turn the ID and OD at the same time you will need additional bar stock.
The bar stock will need to extend far enough from the chuck to turn the entire bushing plus a little extra for cutoff. Bore the hole and taper for the 5C collet. The OD can be any diameter but a flang or head will be needed on the adaptor bushing so it does not work itself back into the chuck jaws. The flang can be any adaquat width and any diameter. To turn the OD you will need to allow for the flange or head then plunge your tool striaght into the bushing then feed from right to left. You could start out with a parting tool and form the bushing flange by turning a slot. Then use the slot to advance the turning tool then feed from right to left like normal turning. When done either saw or part off the bushing from the bar stock.
Here is a picture of the adapter. Its a Morse Taper 5# with the collet taper in it. The drawbar threads into the back of the collet and pulls it into the adapter,which tightens it.
Here is a picture of it in the lathe. Your lathe must have a spindle hole large enough to house the drawbar. I put some extra length on mine s that is sticks out a ways from the face of the flange that holds the chuck to allow my apron to reach it all.
Here is a picture of the drawbar handwheel.
This set up has turned many small pieces. I dont know what I'd do without it.
consider making an adapter for the spindle. one of the luxuries of collets is the concentric repeatability to a fraction of a thou, and much of that advantage is taken away by holding it in the three jaw....anything larger than a morse 4 1/2 MT will fit a 5c, otherwise you're making a collet chuck
JimGlass wrote:When you make the collet closing bushing turn the ID and the OD at the same time for concentricity and straightness reasons. I,
Jim
I'd give the opposite advice in this instance. you are right normally, this is how you get the ID & OD concentric. However here, you have a chance for intentionally making them eccentric to compensate for the scroll error; the main reason 3 jaws aren't super accurate - there is scroll error, and it changes over the scroll but it should be consistent at any particular diameter - in other words at x dia the run out should be repeatable.
making the collet holder compensate for this repeatable error is easily done. Turn the OD, then stamp a #1 somewhere and align this with jaw number 1. Now do all the internal work. ID & OD will be eccentric by the chuck's error at that diameter. Every time you pop the holder in, make sure the mark is aligned with Jaw 1 and run out of the ID should be minimized if the chuck is tightened about the same amount
You bring up an excellent point and your technique never crossed my mind. Partly because my bushing was made on a lathe at work then used on my lathe at home. I read your post 2 or 3 times before I understood your meaning.
It would be better to turn the OD first then bore the ID with the bushing in the chuck the way it will used and also marking the bushing and the chuck so the bushing is installed with the same orientation each time.
I also have a bushing like the one shown in Bob's pic but never made a draw bar for it. They can be purchased from MSC for around $75. That bushing could also be made by turning the OD then inserting it into the spindle taper. Bore the ID with the bushing already in the spindle. The most accurate machining technique.
Jim
but how do I turn an ID and OD at the same time? Do you mean not to remove it from the chuck? If so I would think if you turn the outside first the wall would be to thin and deflect between the MT5 and the C5, but I'm no expert so I'm just trying to learn. Would it be better to turn the OD, cut it off and insert it into the spindle and turn the inside? If I'm wrong please let me know because I've been looking at doing the same thing for my Jet lathe with an MT5 taper spindle.
