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Union Graduate tailstock alignment

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minilathe22

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My Union graduate tailstock appears to be pointing about 3mm off centre, if I put two centres in the headstock and tailstock. This has not been an issue until now, I am trying to create a collet chuck by drilling a hole accurately through the centre of a piece of wood held in a chuck in the headstock. However the drill wanders and appears to not drill an accurate hole due to the alignment issues. I can see the end of the drill wandering in a circular motion as it drills the wood.

Is the only way to put some small strips of metal under each side of the tailstock slides until it is correct? and then super glue them? I don't see any adjustment is possible. I have also considering slackening the bolts that hold the lathe bed to the main casting, but these are already pinned, so probably wont move very much if at all.
 

CHJ

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Don't forget to check direction of any offset before you try to adjust.
Is it parallel to headstock centre and just offset to one side, or is it in line with the headstock but pointing off axis.
Ashampoo_Snap_2019.07.08_21h33m11s_001_.jpg
 

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minilathe22

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From above I can rotate the tailstock by 2mm or so, meaning it won't be pointing straight either.

In terms off offset I think it is out both horizontally and left/right. Probably quite a lot of effort to resolve, perhaps by adding metal with a welder and the grinding down to correct shape.

I believe there is a device for holding drill bits which can negate the effect of the offset but not the incorrect angle.
 

Trevanion

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Not to sound daft but are you locking the tail stock in place when you’re checking it? A lot of lathes can seem quite far off when they’re unlocked and able to slide freely, but once locked in place they’re fine.

A graduate shouldn’t be that far out unless it’s been absolutely abused and thrashed.
 

minilathe22

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A good question, I believe I can move it left or right and then lock it in that position, I don't think it moves to the "correct" position when I lock the tailstock. But I will check.

I don't see any signs of previous abuse but it could well be 40 years old, and I believe came from a school, so will have been subjected to many impatient beginners learning the ropes!
 

minilathe22

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I have had another look and can see that horizontally the alignment is actually quite accurate. It is from above which shows that the tailstock points maybe 2mm towards the front of the lathe. I am not sure how to assess whether its pointing straight or not.

I have tried slackening the bolts between the lathe and the headstock, but it returns to its original alignment when the bolts are retightened, due to the dowel pins. I wonder if I remove the dowel pins, and tap the bed until it lines up and retighten then I would get a better point to point alignment.

How might I measure the angle the headstock is pointing at?

lathe-tailstock2.jpg


This is the view from above.
 

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Trevanion

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minilathe22":1ggdekmy said:
I have tried slackening the bolts between the lathe and the headstock, but it returns to its original alignment when the bolts are retightened, due to the dowel pins. I wonder if I remove the dowel pins, and tap the bed until it lines up and retighten then I would get a better point to point alignment.
I suspect if you did that it would only fix the problem right at where the points touch, and once you move the tailstock back down the bed it would be out at that end, not a massive inconvenience for centre turning, but it will still be out.

Is the machine leveled properly and sitting firmly on flat ground?
 

CHJ

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To check the alignment of the headstock in relation to the bed place a reasonably long (straight) bar or dowel in the chuck and look along its length to see if it aligns with the bed.

To accentuate the tailstock alignment direction place the largest straight drill or bar you can in a Morse taper 'jacobs' chuck as you would when drilling, again look for its alignment with the bed.


Dependant upon whether both appear to be parallel or otherwise with the bed you should have a better handle of which needs adjusting.

Trevanion makes a valid point about lathe levelling and mounting, it is easy to twist a lathe bed.
 

leisurefix

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Is it possible that one or both of your bearings is out of alignment, not sure if this is possible, but read your other post about having replaced the bearings and the spindle is stiff to turn which does not sound right.
With the drive belt loose the spindle should be free to turn with barely perceptible friction.
 

Phil Pascoe

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minilathe22":3m60d39d said:
I have tried slackening the bolts between the lathe and the headstock, but it returns to its original alignment when the bolts are retightened, due to the dowel pins. I wonder if I remove the dowel pins, and tap the bed until it lines up and retighten then I would get a better point to point alignment.
How might I measure the angle the headstock is pointing at?
I can't speak for the peculiarities of your lathe, but don't presume factory settings perfect. If I insert the aligning pin on my old 28 - 40 it is way out of line. If your tailstock is out but still parallel the difference between the two centres will be exactly the same at both extremes of travel of the quill -if the gap increases as you wind it out, obviously the tailstock is angled.
 

minilathe22

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output2.jpg


Success :D I slackened the bolts between the bed and the headstock, and put a small wedge under the far end leg piece on one side. After some careful jiggling and slow retightening I have managed to make the two points meet much better. I don't know whether its pointing straight, I have a 400mm drill bit somewhere so when I find that I will put it in the tailstock and see if its pointing straight.

As for the bearings, It might be possible that they are mounted slightly skew in the headstock, they do seem to get hot when running so I am running it at low speeds to run them in, and monitor the temperature. Then up the rpm a bit. I only noticed I had a bearing issue when I tried some small diameter work and had to do higher rpm. If they stay hot even after a fair time of running in I will investigate whether they are not fitted properly.
 

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