Lathe Alignment Procedure How to???

There have been several threads recently about how to align a lathe. Last night, I had a thought ricochet around my head. (It didn't hit anything) :biggrin:

I am looking for constructive criticism and brain storming ideas about how to do this without requiring a lot of EXPENSIVE equipment.

High Points:
Put a mandrel in the head stock and another in the tail stock.
Get 12" length of 7mm tube sold by several pen suppliers.
IF the tube slides on the mandrels without binding and you can turn the head stock hand wheel, the lathe is aligned correctly.

The mandrels themselves must be checked for alignment in the head stock and the tube must be straight. Roll the tube on a know flat surface like a table saw table to make sure.

You would be saving yourself a lot of time and expense, but using simply a live and dead centres on the headstock and the tailstock. If both points meet precisely, the lathe is align...!


Cheers
George

robutacion said:

You would be saving yourself a lot of time and expense, but using simply a live and dead centres on the headstock and the tailstock. If both points meet precisely, the lathe is align...!


Cheers
George

Click to expand...

Ditto

You might want to read this:

http://jlrodgers.com/pdf/lathe_alignment.pdf

robutacion said:

You would be saving yourself a lot of time and expense, but using simply a live and dead centres on the headstock and the tailstock. If both points meet precisely, the lathe is align...!


Cheers
George

Click to expand...

Unfortunately this is not necessarily true - at least not if you want to accrurately drill on the lathe. For example, you can touch the tips of your index fingers together, but the fingers don't necessarily form one straight line. You need to test at least 4 points to ensure everything is co-linear - on on the head and 2 on the tail. Assuming both mandrels are straight and true, the suggested check does this. The longer the tube used the more accurate the check. I would suggest the 10 in, tubes.

I had suggested in another thread a procedure using straight drill bits. This is more straight forward if you have 2 accurate mandrels

I purchased a double ended #2 morse taper rod to align my Jet mini. I'm not convinced it is a truely accurate way to line everything up though. One thing I notice is that it makes a huge difference how I lock down my tailstock... (with pressure forcing it forward, it seems to be accurate)
Your idea seems to have some merit. Thanks!

randyrls said:

There have been several threads recently about how to align a lathe. Last night, I had a thought ricochet around my head. (It didn't hit anything) :biggrin:

I am looking for constructive criticism and brain storming ideas about how to do this without requiring a lot of EXPENSIVE equipment.

High Points:
Put a mandrel in the head stock and another in the tail stock.
Get 12" length of 7mm tube sold by several pen suppliers.
IF the tube slides on the mandrels without binding and you can turn the head stock hand wheel, the lathe is aligned correctly.

The mandrels themselves must be checked for alignment in the head stock and the tube must be straight. Roll the tube on a know flat surface like a table saw table to make sure.

Click to expand...

This test on my Jet1014VS lathe came up negative.

With straight mandrels in both the headstock and tailstock, they are out of alignment by around 0.040".

The tailstock needs to comes sideways about .020" and up in front about .020".

The up-in-front part I can accomplish with shims.

But as to the side to side movement, I do not know of any way to move it that much side-to-side without reducing (grinding or filing) the size of the 'key' underneath the tailstock.....taking some off one corner so as to allow the tailstock to rotates slightly and come into alignment.

My warranty had just ran out when i first contacted Jet about this (i did not get to use the lathe very much until about 6 months had gone by and it took me a few more months for the problem to fully manifest itself and for me to finally figure out what was going on) and they sent me a new tailstock quill even though it was not warranteed, although the new quill did nothing to solve the problem.

I'd gladly buy a new tailstock assembly, but I am skeptical that it would be any different.

It looks to me like I either start grinding, or live with an out-of-alignment lathe.

Can you find a cheap feeler gauge to take a blades out of for a shim? Little trial and error will bring you into alignment once tailstock tighten down.

I have never been big on worrying about the head stock and tail stock being dead on. These are wood lathes, not precision machines. Slight mis-alignment does not cause very many issues, IMO. If you are trying to drill on the lathe, then I see the point, but again, these are wood lathes. Those who have success with alignment is a plus, but then again...........

Some thing I have just thought of, place a dead center in head and tail stock, check they meet with the tailstock close up. Then using a Laser line sitting on the headstock (or tail I suppose) align it with the points, then slide the tailstock away. If your lathe is corectly aligned the Laser line will still be on the point of the dead center in the tail stock. I havn't tried it (will this afternoon) can any one see why it wouldn't work ??

Alignment check that is infallible is use a dead centre in the head and tail stock bring them near to one another, lock the tail stock and wind the tail stock to the head stock using a thinnish feeler gauge when they meet the feeler gauge will stay between or deflect in the direction of the problem. This way 360 degrees are checked. Then solve your problem up until then pure speculation.

Have fun Peter.

DavidSpavin said:

Some thing I have just thought of, place a dead center in head and tail stock, check they meet with the tailstock close up. Then using a Laser line sitting on the headstock (or tail I suppose) align it with the points, then slide the tailstock away. If your lathe is corectly aligned the Laser line will still be on the point of the dead center in the tail stock. I havn't tried it (will this afternoon) can any one see why it wouldn't work ??

Click to expand...

I believe that would work, but you wood (pun intended) have to do it both ways. ie with the laser in the headstock and again in the tail stock.

Paul Huffman (Paul in OKC)has it right -- and as a master of the machinist trade he knows the gear. Close is good as it gets on a wood lathe because of the way it is built.

The alignment is a function of the inside of the ways (inside of the bed) of the lathe. Headstock and tail stock are related to the inside of the ways. Got a headstock that slides or swivels -- it is controled by the inside of the ways. Got a bed that moved - the ways are limited in alignment by the pin that holds center. Several have already noted that there is a fair amount of tolerance (slop) in the tailstock alignment against the ways.


Even if the headstock and tailstock are in very very close aligned at one point along the ways, they probably are not a few inches away. The ease of moving the tailstock is obtained by providing clearance and the clearances mean that there is some "wobble".

Where might a more effective focus of time and effort be -- getting better control of the bushing-pen blank matchup. Accept that the pentubes and bushings have to be in nearer to perfect fit. Spend more time on assuring that you are not using tools that could be sharper, and learn to let the tools cut without putting lots of pressure against the material being cut.

If you really want precise alignment get a metal lathe (been there and done that - got the tee shirt and it did not fit) but you do not need that precisions if you want to turn pens by hand controled tools. And you can pay a lot of that precision.