Headstock/Tailstock Alignment Issues

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karlkuehn

karlkuehn

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I'm having a small issue with my headstock/tailstock being out of alignment vertically, not horizontally, and after some research (fancy name for creative googling), I found the following article that is really helpful. Since I've seen this issue come up on the forums before, I figured I'd post it here (some of you have probably seen it), and thank Jim Rodgers for taking the time to put it together.

http://jlrodgers.com/images/lathe_alignment.pdf
 
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Originally posted by wdcav1952

Nice article. I was going to suggest that perhaps you had your headstock shoved up your tailstock, but perhaps this is a better solution. ;)
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Cav, I know this is a specialty of your's but I wish that perhaps you would learn to remove your headstock from your tailstock![:0]
 
Originally posted by MLKWoodWorking

Originally posted by wdcav1952

Nice article. I was going to suggest that perhaps you had your headstock shoved up your tailstock, but perhaps this is a better solution. ;)
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Cav, I know this is a specialty of your's but I wish that perhaps you would learn to remove your headstock from your tailstock![:0]
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Imitation is the sincerest form of flattery. :D
 
The fact that the point of a spur center and a live center meet perfectly when they are positioned together does not mean that the lathe is properly aligned. That idea is an absolute absolute myth and i get irritated every time I see the statement. I'm a little busy right now with the trivia contest and a few other things so I don't have time for a full explanation; but I will make myself a note and return to this subject later. If you ponder the question for a little while, I think you will understand the correctness of my assertion. Additionally, that article by Mr. Rogers has some flawed thinking. More later.
 
Randy's correct, it's also important that the line though the points is parallel to the lathe bed on both axes. Axises? Axii? Whatever the plural is...

essentially, using a double ended morse taper would probably be a good check to make sure the tapers are inline with each other rather than just making the tips point at each other.

Cav, I've never been so insulted! I rarely have my headstock in such a position, but I am guilty of occasionally having my thumb stuck in the tailstock. You cad! Evil man. No wonder I hate going to the dentist. [:p]
 
Originally posted by Randy_

The fact that the point of a spur center and a live center meet perfectly when they are positioned together does not mean that the lathe is properly aligned. That idea is an absolute absolute myth and i get irritated every time I see the statement. I'm a little busy right now with the trivia contest and a few other things so I don't have time for a full explanation; but I will make myself a note and return to this subject later. If you ponder the question for a little while, I think you will understand the correctness of my assertion. Additionally, that article by Mr. Rogers has some flawed thinking. More later.
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I basically agree with you Randy. The thing I hate to see is the oval pen thing. It is impossible to turn an oval without an eccentric set up. The proper term is out of concentric, meaning the barrel and the tube are not rotating true on the same axis. A mis-alignment in the head and tail stock wont cause this. It can cause some wear on your center point, but with a full length mandrel this is minimal. If you could 'mis-align' your tail stock and head stock on purpose, say 1", you would still be able to turn good pens, because the size is determined by hand held tools, if the mandrel is not wobbling anyway, at which point you would have non-concentric barrel-to-tube. I bet if you would measure your 'out of round' barrels, they will measure round.
 
Hmmmm....

Won't a bent mandrel, or 'whip' in the center of the mandrel create an oval pen? If the headstock and tailstock aren't aligned, doesn't the tailstock (placed in the center of the mandrel) cause it to bend on every revolution?

Wish I'd have paid more attention in Physics...[V]
 
Originally posted by karlkuehn

Hmmmm....

Won't a bent mandrel, or 'whip' in the center of the mandrel create an oval pen? If the headstock and tailstock aren't aligned, doesn't the tailstock (placed in the center of the mandrel) cause it to bend on every revolution?

Wish I'd have paid more attention in Physics...[V]
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I did pay attention in physics, and I still don't understand what the heck you guys are talking about!!!!!!!!:D
 
Originally posted by wdcav1952

Originally posted by karlkuehn

Hmmmm....

Won't a bent mandrel, or 'whip' in the center of the mandrel create an oval pen? If the headstock and tailstock aren't aligned, doesn't the tailstock (placed in the center of the mandrel) cause it to bend on every revolution?

Wish I'd have paid more attention in Physics...[V]
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I did pay attention in physics, and I still don't understand what the heck you guys are talking about!!!!!!!!:D
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If it's any help, next time you're drilling on a tooth, take your little dremel bit and bend it with a pair of pliers. [}:)]

Nothing explains a concept like a bloody visual aid.

I'm going to go throw up now, just from thinking about that. Yahghgh![xx(]
 
If it's any help, next time you're drilling on a tooth, take your little dremel bit and bend it with a pair of pliers. [}:)]

Nothing explains a concept like a bloody visual aid.

I'm going to go throw up now, just from thinking about that. Yahghgh![xx(]
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Not the same thing, (not to mention the thought I will have next time I go to the dentist, he may wonder why I laugh), however, the mis-alignment will cause issues if you drill on the lathe. The entry end of the blank will have a larger hole, and taper towards the back end. Again, don't get oval-ness and concentricity mixed up. When you turn on a bent mandrel, you see a nice round blank looking like it is running nice and centered around the axis, but at the same time your mandrel is wobbling inside the blank around the axis, like a jump rope(though that might help the visual:)).
 
Originally posted by Randy_

The fact that the point of a spur center and a live center meet perfectly when they are positioned together does not mean that the lathe is properly aligned.....If you ponder the question for a little while, I think you will understand the correctness of my assertion.
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Randy;

I had been having much trouble drilling on my lathe, yet it worked very well and seemingly accurately for pen turning. After reading this post of yours I immediately realized what you were talking about and where my problem lay.

To save a lot of re-writing, I will repost here the letter I just sent to JetTools customer service dept describing the problem ----

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Dear Sirs;

I have had my new JML-1014VSI lathe for almost a year now. I do not know if this issue can be addressed under warranty or not since it took me several months before the problem was apparent.

The problem is a misaligned tailstock and headstock. When I unpacked the lathe, the first thing I did was to install a dead center in the headstock and a live center in the tailstock. The alignment of the points of these two seemed near perfect. The real problem came about however whenever -some months later- I began trying to drill on the lathe. I bought a new Barracuda2 chuck system, and when I put a drill bit in a Jacobs chuck and mounted it in the tailstock, and tried to drill a cylindrical piece of wood mounted in the jaws of the Barracuda chuck mounted on the spindle, the drill bit described a circle instead of boring a hole dead center. Subsequently I began to test for misalignment. I mounted a 9 inch long, dead straight 7MM steel mandrel with a dimple in the end in the Jacobs chuck and slid the tailstock forward so that the end of the rod almost touched the dead center mounted in the headstock. My digital calipers show it to be just over 0.100 out of alignment. The headstock/tailstock when close together do not show this misalignment, but when extended 8 inches or so away, it becomes immediately apparent. The tailstock is pointed away from dead center, both downward and toward the operator.

The question is; what can be done to remedy this problem? If the misalignment were in the horizontal plane only, I would try to use shims under the tailstock to correct it; but the sideways misalignment would dictate that the raised bar that holds the tailstock straight be ground down on the sides so as to allow the tailstock to be moved in that plane also. Would a new tailstock assembly possibly correct this problem? Is there some way to rebore the morse taper in the old tailstock?

Any answers or solutions you have that might help address this problem would be greatly appreciated by me. Thank you.

sincerely,

Dan Blaylock

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Soooo......my question to the group is, does anyone here know of a solution, other than trying to order a brand new tailstock, for a problem such as this??

Even if I were to order a new tailstock, there seems to be no guarantee that it will be any straighter. :( I do not know what to do on this one. Any help or suggestions that any of you experienced turners here have will be MOST welcome.

Thanks.
 
Hi Dan:

There are any number of things that could cause the problem you are experiencing. I’ll comment on a few that come to mind, which may or may not help solve your difficulty.

First thing to do is check out the mounting of the lathe. If you have it bolted down to a bench or stand, the bolts may not be equally tightened and this could cause the bed to twist creating some offset. Same problem if the bolts are equally tightened. I don’t think a twisted lathe bed could account for all of the offset that you are seeing (0.1†is a pretty big offset); but it might be part of the problem.

Now, before you check out the lathe, you might want to look a little closer at the Jacobs chuck. Make a close examination of the Morse taper arbor and be sure there are no nicks or burrs that might keep it from seating properly in the TS quill. Dress the taper smooth with a fine file or stone if you do find a burr. You also need to be sure the MT opening in the TS quill is very clean as a metal chip or piece of wood dust could keep the arbor from seating properly. I always blow out the opening with compressed air or wipe it out with a paper towel moistened with a little solvent of some sort. If there is something really stuck in the hole use of a small diameter wire brush may be necessary.

OK, now that you are sure things are clean, the Jacobs chuck can be checked out? Basically, this involves putting the chuck and mandrel in the TS in different rotational positions and seeing if the offset you are observing remains constant. Put the chuck in the TS and note the size and direction of the offset. Use a magic marker to put a reference mark on the chuck. Now remove the chuck from the TS, rotate it 90°, stick it back in the TS, and see if the offset is the same. Do those twice more to see if the offset stays the same or changes. If the offset changes, the Jacobs chuck is contributing to the problem.

Just so happens I have a JET non-VS model and a Jacobs chuck so I looked at mine and the offset is very much less than what you have with yours. The horizontal offset on mine was spot on zero or at as close to zero as my eye could distinguish. The vertical offset was about 1/2 mm or 0.02â€â€¦..the mandrel was a hair below the center in the headstock. There is usually some movement in the TS that can be used for adjustment if it is necessary. Lots of vertical adjustment and significantly less horizontal adjustment. I loosened the TS clamp and wiggled the TS left and right to see how much horizontal motion there was. On my lathe there was only about 1/2 mm of total motion so there would not be enough to resolve an offset like what you are seeing on your lathe. As to vertical movement, there is much more movement available that should ever need to adjust an offset. After some rough trig calculations, I figured I needed a shim about 0.0067†thick under the “inboard†end of the TS. Being curious to see whether my math was anywhere near to correct, I looked around the house for something I could use for shims since I didn’t have any brass shimstock and settled on a dead beer can. The BC material was about 0.004†thick so I used a double thickness and that worked out very well. The vertical offset that I observed on my lathe disappeared. The alignment of mandrel end and HS center were as close to zero as my eye could determine!!

Another thing that could be part of the problem is debris located between the TS and the lathe bed. Loosen the TS clamp and remove the TS from the lathe. Examine the lathe bed and the underside of the TS carefully for burrs or debris. Use compressed air or a cloth moistened with a solvent to clean off both the lathe bed and the underside of the TS. If you detect a burr or rough spot, you can try to smooth it off with a very fine file or stone; but be careful not to take off too much material. After wiping the various parts with the solvent, be sure to recoat with some shop oil to prevent rusting. I don’t know if any of this will solve your difficulty; but it is worth a shot. If none of this helps, a call to JET is in order. I apologize if any of this is overly simplistic. It is always difficult to evaluate the skill level of a poster on the Internet.

Best of luck. Hope you get your problem resolved.
 
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