D1-6 Chuck

Dick, Let me try to get this answer started. Others will correct my mistakes, I'm sure.

D type mounts seat on the taper, not the back face. The cams pull the chuck onto the mount. The cams studs are adjustable in the chuck (usually by screwing them in or out) and should be adjusted so the cams need to be turned 1/4 to 3/8 turn to lock. Some people seem to think they need to turn the lock further to get a good seat - not true.

Accuracy of a D mount is in the tapered mating surface. Indicate the lathe taper and gently clean any nicks. If it runs out, the spindle is bent. Then clean and gently deburr the internal taper on the chuck. If these two surfaces are clean and true, you will get the best alignment (often within a .0001 or so). Cleanliness and surface condition of the other parts of the chuck or collet closer will then be the other places where runnout / wobble can occur.

"Cleanliness is next to high fidelity" Stan Freberg

Karl Pearson

Thanks much. This is what I thought but I didn't want to do anything until I was sure. The chuck is touching the backing plate on one side. I've been trying to tighten the other side down tighter but then realized that that would make it farther out of true. I'll take a slight facing cut off of the face of the spindle plate so as to give a little clearance. Thanks again, Dick

Dick,

Before you go cutting anything. I've never seen a D1-6 chuck or face plate that needed cutting. There have been dings on the face of the lathe spindle, there have been dings on the face of the taper, there have been dings on the female face of the chuck,

But, think about it. Both the lathe and the chuck were manufactured and checked to D1-6 specs. They were designed and manufactured to work together. Barring true damage, they should do so.

Either one or the other is twisted, dinged or has been damaged. If you take a cut on the spindle face, you will never be able to fix any problem that exists.

Indicate, Indicate, Indicate. Find out where the problem is.

If the spindle is bent, it may just be the headstock bearing that is not properly seated or is worn out (not likely). If the problem is just that one locking stud is mis adjusted, skinning the lathe face will just intrduce another problem.

My guess is that the chuck is rocking on some hard to detect bump somewhere. Use you finger, use you eye, gently run a file on the non-working surfaces, clean everything and adjust the cams so they are all tightening the same amount.

Then try different sequences of tightening the cams

If you got a lathe or a chuck that had been redone, and you don't know it, try putting three small pieces equally spaced on the taper then mount the chuck. If it seats thern, you know one side of the taper is too big / small. In the unlikely chance that is true it will take some time to search out the dimensions and some patience to inpect them both,

Greetings Karl, The D mount chuck should contact both the taper AND the back face. Often times the chuck, faceplate, etc. will have been bored oversize so that only the back face of the chuck contacts the back face of the spindle. The chuck should fit such that it requires a little tap to jar it loose. On the spindle of the lathe there should be two lines at

90 degrees to each other extending radially from the cam tightening hole. When the camlock is tightened there is a line on the cam that should fall between the two lines on the spindle. Everything else you have said about chips, dents, bumps, etc. is absolutely true. ERS

Eric is absolutely right. BOTH the taper and the back face must be in contact. I had a similar problem with a new lathe (a big one). They had to send a new chuck that would seat properly. Do not grind or turn the spindle face or taper... your lathe will be ruined forever. Small dings can be removed with a file, or in the case of a hardened spindle, a diamond file. The tolerances on a camlock chuck are very close. Clean your taper and face on both chuck and spindle every time you change chucks. It'll same you time in the long run.

Mark

"Eric R Snow" wrote:

The D mount chuck should contact both the taper AND the back face. Often times the chuck, faceplate, etc. will have been bored oversize so that only the back face of the chuck contacts the back face of the spindle. The chuck should fit such that it requires a little tap to jar it loose. On the spindle of the lathe there should be two lines at

90 degrees to each other extending radially from the cam tightening hole. When the camlock is tightened there is a line on the cam that should fall between the two lines on the spindle. Everything else you have said about chips, dents, bumps, etc. is absolutely true. ERS

Thanks Eric. I knew someone would set me straight. I hadn't heard of anyone boring a chuck (!) Ugh - bad vibes there. And I'd forgotten about the lines for the cams - been a few years since I've retired and I am working from memory.

Karl

You may want to use some Hi-Spot dye to find out where the chuck is touching the spindle face. If it is in two spots roughly 180 degrees apart, the chuck is pretty clearly warped. Assuming it is a 2-part chuck, you may be able to face it carefully, after removing the pins, or just replace the backing plate with a brand new one. You can also use the dye to check contact between the spindle taper and backplate taper. Many collet chucks have adjusting screws similar to the Buck Adjust-Tru scheme on 3-jaw chucks. The backplate mounts to the spindle, the chuck mounts with some slop to the backplate, and the screws position it radially to dial it in to perfect center. If you have such a chuck, mount the backplate by it self, make sure you can mount it repeatably, ignore whether it is perfectly aligned, and then face the part of the backplate the chuck mounts to. Then, align the chuck for perfect radial alignment.

Jon

Sorry to take so long to get back to the forum. Actually, there was a lot of jury rigging done on this lathe. It started out as a Jet 12X40 lathe with a 2.25X8 threaded backing plate. I bought a Harding Collet Chuck and collets on e-bay for a good price. I was going to put the chuck on a backing plate and lock it in place with some set screws so that it wouldn't loosen. When the chuck arrived it also had the front part of the lathe spindle with it. Apparently the man just cut it off with a hacksaw. I decided to mount this D1-6 spindle part onto my lathe so as to make going to a 3 or 4 jaw would be easier. I trued the back of this spindle up and had a 4"X 1" piece of steel welded onto the back of this and bored it out to the same size as bearing retainer that is on the Jets spindle. I then ground out the inside of this D1-6 spindle to 2.6" as it did have a morse taper in there. Once this was done I took a pice of 4" round steel stock, bored and threaded it to fit the spindle on the Jet.I drilled and tapped 4 set screws in this "bushing". I then screwed it on as tight as I could and turned it down while mated on the lathe to the same size as the D1-6 spindle bore. Once everything was mounted and tightened up the D1-6 spindle face appeared to be running true but the register on the front I could see wasn't real true.When the Collet closer was mounted it was out of true and I could see light between the faces on one half and the faces were together on the other half. What I ended up doing was to make a slight facing cut on the D1-6 spindle face and then I matched up the angle on the register and cleaned it up till it was running true. When I mounted the collet chuck this time it now runs pretty close to dead nuts. I agree with what you fellows have said about not normally making any cuts to the spindle facings but in this instance it couldn't hurt anything as if it wouldn't have worked I could always took everything back off and went back to my old system. Thanks again fella's Dick