Thread: Tailstock Alignment Puzzle

Hi Bryan,

I'll leave it to others re welding moving the casting about.
Remember someone else had a go at fixing it before you, no telling what they did.
Did you check how flat the bottom of the TS was after welding?

Stuart

Stuart, yes I slapped it on the surface plate, but not till the other day. It showed 3 small areas of contact. A day and a half of scraping has increased the footprint, but made no real progress with the alignment. The shaper is the tool for that job. I just get this nagging feeling I may regret carving it up. I need to go over all my tests and measurements again. DTIs can be so confusing. And the fact I can't understand how it got that way makes me doubt my findings more.

Sounds like you have some work ahead of you.
The specs for a tailstock bore are 0.0005"inch at the front opening above the headstock spindle centre line, and 0.0005" inch per foot rise towards the headstock.
Just remember gravity affects the readings.
You may or may not get this close or even want to, but I thought I would put up those numbers for something to aim towards.

Dave

How are you testing it?
Pictures?

Thanks Dave, I'll let you know. I'd be pretty stoked to hit numbers like that, but it may be optimistic for a 50 year old machine. Way wear is going to be a party pooper. You could get it smack on in one spot, slide the TS along a bit and be out again. But I'm sure I can get it better than it is.

Edit: Stuart, documenting will be a bit of work, which I'm too bushed to contemplate right now. But it would be a good exercise. Will see if I find time/energy this week.

Maybe its in the base? Still it will give you something to work on after next weekend.

Stuart

At least you will pick up some tips on the weekend about how to check it out and what to use to measure it properly.

I do have one easy way to fix it, send the whole lathe to me and I will do it for free, it just might take me 10 or more years to do it (or so I will tell you, LOL)

Dave

Question, How do you measure the tailstock/headstock spindle height? Is it simply a matter of putting a dead centre in the tailstock and measuring the top part that is not tapered, then doing the same on the headstock?

PS I will leave any suggestions to the qualified/experienced members of this forum!

Simon

An initial test to see if the centres are aligned can be done with a centre in both spindles.

You can bring them together and visually look at them to see how well the ppoints of the centres line up horizontaly and virticaly.

You can place a thin ridgid pice of material between the centres points,if this material stays in the vertical and horizontal position with no visible tilt/angle either way you would say that the centres are aligned,if it kicks one way or the othe it indicates that more than likely the tailstock is sitting low/high or offset to the left/right,it is not often that the headstock is out of alignment.

If you wanted to check centre height you could use a parallel,vee block,inside mic,outside mic,depth mic.

Bit hard to describe easily in words but you would or could turn a piece of material in the lathe about 1"/2" long (dosent matter about dia,but a round number might be easier) with a good finish,place your parallel on the lathe bed,(preferably on the flats rather than the vees) you may need to use more than one paralle or even some pieces of tool steel or any material of a known size as long as there both the same size,(lay these along the flats but they must be higher than the vees,then bridge between these pieces with a parallel.

You would then in my case use your inside mic and measure the distance between the parallel you have across your lathe bed and the underside of the piece you have turned.

You will have to do some simple calculations to determine the centre height of the spindle from the flats of the lathe,once you have done this you can then do the same measurement with the tailstock (except in this case you will be measuring to the underside of the tailstock spindle,best to have the tailstock clamped to the bed and the spindle locked.)You can if you wish move the tailstock along the lathe bed and check centre height at numerous positions.

The calculations that you would need to take into account would be the height of total material to get you above the vee ways (this would be added to the measurement of the inside mic),the diameter of the piece of material you have turned (this would be halved and added to the inside mic measurement).

So at the end it would be PACKING + HALF DIAMETER MATERIAL TURNED+INSIDE MICROMETER MEASUREMENT= CENTRE HEIGHT OF SPINDLE,allways check the measurement of an inside mice against an outside mic unless the inside mic has been calibrated.

These checks can also be done in the reverse by working down from the material using a depth mic.

I see. So you wouldn't consider taking measurements from a DTI which is magnetically clamped to the saddle? That way you can move up and down the ways to take measurements at any point you like?

Or would this add unnecessary errors into the measurements because you are taking the readings from the saddle which sits on the ways?

Simon

It depends on what you want to measure,I thought you asked about checking centre height.

Briefly, I used 2 tests, both using a .01mm dial test indicator (DTI). For those not familiar, this is the lever type of indicator.

The height test was done with the DTI magged onto the spindle face, reading either the bore or the outside of the quill. The spindle was then rotated. This can also be used for lateral adjustment of the TS.

The slope test involved the DTI fixed to the compound so it read the top of the TS quill. The TS was then advanced along its ways and another reading taken. The carriage stayed locked and the cross slide was used to find the top of the quill for each reading. The quill stayed extended and locked.

Stuart, the base actually slopes up, but the body slopes down more.

Dave, thanks for the offer. Don't hold your breath.

I possibly didnt explain it right. I meant a means of measureing centre height purley so you can compare headstock spindle to tailstock. For the purposes of alignment does it not make any difference where the measurements are done from as long as it is repeated for both, ie the top slide or saddle?

That was more my question.

Cheers,
Simon

Bryan,

Your tests seem "okish" except the first one. The lateral test could be ok but the vertical test like that any deflection if doubled due to gravity.(I'll go test it and get back to you.)


Stuart