Tailstock off center (?) - need advice

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JasonM

JasonM

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Joined
Jul 6, 2008
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175
Location
Waxahachie, Tx. USA
I've recently started turning between centers and have moved away from the mandrel. However, with the mandrel now out of place, I've noticed that what I thought was a warped/overtightened mandrel problem may have actually been magnified by centers out of alignment.

When I move the TS all the way over, my HS and TS centers do not meet point-to-point. They are slightly off from each other. Naturally, there is a small amount of play in the TS when it's loosened to move up and down the bed. But the attached photo shows the situation when the TS is tightened down.

I've verified that the live and dead centers (both of which are fairly new) are properly seated in their respective stocks. And this misalignment shows ups regardless of how much or little the live center is retracted into the TS.

How do I true this up?
 

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Jason is it up /down or left /right or both? Studying the picture it looks left/ right but I cant tell if up/ down is correct. You may have to lightly file the bottom of the tail stock on one side to allow it to move over. Possibly adding shim stock to the other side to help keep it pushed over. I take it you have checked the head stock to make sure it cant be adjusted. Filing should be a last resort.
 
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As far as I can tell its a left/right issue. It's difficult to say for certain whether or not there is any up/down. But for sure the live center is coming in left of the dead center.

I'm not familiar with the headstock being adjustable, but I'll look closer when I get home for work. Thanks for the input!!
 
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Just a thought here but I notice a bunch of saw dust in your picture. I would recommend a good cleaning. Perhaps a piece of wood or some other shaving is under the tail stock and throwing it off when you tighten everything down. Before you breakout the files and the big hammer I would check that everything is factory stock.
 
It looks like you have a Jet. There should be four bolts on the headstock which you can loosen to make slight adjustments left to right. Hopefully that will do it! Height misalignment is much more difficult to deal with!
 
I had to file the tailstock I adapted to my lathe. I used a large flat file and went slowly checking frequently. I used the digital calipers to make sure I kept it parallel. Your head stock may be bolted to the bed in such a way that it could be loosened and slid to one side of the bolt holes. THats off quite a bit. Any chance you can contact the manufacturer or reseller of the lathe and see if they will replace it before you file on it?
 
Another thing to check is whether the lathe is level and that there is no twist in the lathe. Sometimes adjusting a foot (or using a shim) can bring things back into alignment.

Ed
 
My wood lathes have play in the fitting of the tailstock to the ways. Not lots, but visible in the alifnment test you are checking. I found that I need to push on the front of the tailstock spindle as I lock it down to get the best alignment. That tested consistent along the ways (laser bore site in a collet). Wood lathes control on the inside of the ways and may need to be cleaned from time to time also. A bit of CA glue slopped on the unside can make a difference.

Figure out where things need to be firm and lock it down to test.
 
I spoke to a former Jet Representative about this problem on my 1642, and he said that +- 1/64" was acceptable standard from the factory.

I leveled the machine best I could and go most of the front to back solved. But I still had quite a bit of up/down offcenter. Jet then sent me two tailstocks to correct the problem. I finally took the best of the three, and filed the bottom until I had it closer than I started with.

But I need to work on it some more because my center bushings for pens are still fretting...

A machinist trick is to place a razor blade between the centers to check the direction that it's off center. Once the razor blade stands vertically true, you know you've got it dead on.
 
KenV said:
My wood lathes have play in the fitting of the tailstock to the ways. Not lots, but visible in the alifnment test you are checking. I found that I need to push on the front of the tailstock spindle as I lock it down to get the best alignment. That tested consistent along the ways (laser bore site in a collet). Wood lathes control on the inside of the ways and may need to be cleaned from time to time also. A bit of CA glue slopped on the unside can make a difference.

Figure out where things need to be firm and lock it down to test.
Click to expand...

My Delta does the same way. Meaning a little "twist" from left to right in the tail stock. Some shimming would probably take care of it but I just give it that twist before tightening and it's fine.
 
Thank you all for advice. Proof once again how great this site is with people willing to help.

To answer the quick questions:
- yep, it's a jet midi.
- I have it on one of the jet lathe stands and feel pretty comfortable with the level and twisting.

Tonight I'll make sure there is no sawdust or flakes throwing the TS off (the picture was immediately following some work that didn't come out as planned and was the catalyst for the closer inspection) and I'll look at the adjustment bolts mentioned.

Thanks all. I'll let you know how things come out.

=)
 
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Few gotchas:


tail stock tension is not right

Fouling in hs/ts tapering,

rotate the bit 1/4 or 1/2 turn and recheck

Loosen the tail stock see if any dirt etc under the banjo, rotate the locking washer on the bottom center, one side may pull more than the other.

Screw threads are more problematic than standard MT shafts, you can eye ball the head with nothing on it at speed, will have wobble if its not true

Almost all issues like this is tail stock fouling.
 
If the tailstock in not adjustable and if the machine is level (which is probably less important unless it is a large and heavy machine) you can use some CA glue to built the tailstock up where it fits into the ways and smoothly file it down till it is perfectly aligned.

This is if the unlocked tailstock will twist into alignment when unlocked, if it won't some filing of the tailstock till it comes into alignment will be needed and the CA can then be used to build up whatever corner or side then has too much clearance against the bed ways.

Not a permanent fix, but it can last surprisingly long and careful measurement before and after fitting it for comparisons will tell you what size shims will be needed to make a more permanent fix when it needs it.

You could also use a hard metal to build the tailstock up in place of shims, such as a fairly low temperature but still hard silver solder, brass rod which will require more skill and care, or even welding if you have the facilities and skill to do welding on cast iron.

Height alignment can also be done this way.
 
Oh btw, head Dow to the local gunship and get a spray bottle of dry film moly lube. Spray the entire bed, under the banjo, under tail stock, screw threads, clamp washers and lever joints.
 
Simple fact is every lathe can have this very same problem. It is not specific to a vendor either. Replacing brand A with brand B for a common simple fix solution that happens with ALL lathe is quite retarded.

Some typo's in my earlier post,

gunship = gunshop.
Dow = down
dirt etc under the banjo = dirt etc under the tail stock.
 
Checked it out a little closer. Cleaned it out, and adjusted the tension on the locking washer under the TS just a tad (it was a touch loose).

This brought the points about half of the way back into alignment. But it is still slightly off.

I couldn't find any adjustment bolts like those mentioned. Just the four that actually connect to the headstock assembly to the bed.

With the weekend coming, I'll spend some more time with it. Next step seems to be to try to shim it a bit.
 
JasonM said:
Checked it out a little closer. Cleaned it out, and adjusted the tension on the locking washer under the TS just a tad (it was a touch loose).

This brought the points about half of the way back into alignment. But it is still slightly off.

I couldn't find any adjustment bolts like those mentioned. Just the four that actually connect to the headstock assembly to the bed.

With the weekend coming, I'll spend some more time with it. Next step seems to be to try to shim it a bit.
Click to expand...

Those are the adjustment bolts! You shoould be able to gain slight adjustments but loosening these bolts and exerting a little pressure as you carefully tighten them back up. Your not looking to gain a lot just a slight amount.
 
ahhhh....::facepalm::.

Thanks. I did tinker with them a bit, but worried I was just loosening the whole assembly. I didn't exert any pressure. I'll do that next.
 
Try this before doing any bolts. put 2 dead centers, dead/live or what not in the tail stock but don't push it in. If you look real careful at it you will see that there is some play room as it goes in, the insertion could very well cause the offset you are experiencing.
 
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