Another Headstock/spindle alignent problem

[kvt]

Ok, Have been working my old Taiwan made 10x24 lathe over. All new bearings in the head things cleaned up and the spindle set up taking all the slack out with the indicator etc. Now trying to get it back in alignment with the ways. since I do not have a known good test bar, in fact I know it is not as can see bend in it on a sheet of glass.
Have been trying a method I saw on here called. Rollie's Dad's Method of Lathe Alignment
But having problems with the alignment. Set up on center line with wide flat tip so movement off ceter just a little does not affect it.
close to the chuck reads 0 and 3, and other end reads plus 25, and minus 32, (told you the bar was not straight)
thus 0+3 = 3 divided by 2 =1.5
25 +32 = 57 divided by 2 =26.5
1.5 - 26.5 =25 25 thou out on the outer end.
watching the gauge on the on the end of the shaft Moved it 12.5 thou or 1/2 of the amount.
problem was once went back and did all the measurements and calculations again
it was still a diff of 25 thou on the outer end.

Am I doing something wrong,

any help please

 

[Dave Paine]

I am not familiar with the Rollies Dads method. I watched this video by Keith Rucker which I thought was a good way to align the lathe. He turns a short piece of scrap to the same diameter as the quill, then uses a dial indicator to get things aligned. Interesting.

 

[Bamban]

Ken,

I have a 1x12 inch test bar from Pacific Tool and Gauge, do you want me to stick in a flat rate box and send it to to you? O also have a MT5 test bar from Miller Machine and Fabrication, I think it is 2 1/2 or 3 inches in diameter. If you can chuck this up on your 4J, you may borrow it as well.

nez

 

[ddickey]

Ok, Have been working my old Taiwan made 10x24 lathe over. All new bearings in the head things cleaned up and the spindle set up taking all the slack out with the indicator etc. Now trying to get it back in alignment with the ways. since I do not have a known good test bar, in fact I know it is not as can see bend in it on a sheet of glass.
Have been trying a method I saw on here called. Rollie's Dad's Method of Lathe Alignment
But having problems with the alignment. Set up on center line with wide flat tip so movement off ceter just a little does not affect it.
close to the chuck reads 0 and 3, and other end reads plus 25, and minus 32, (told you the bar was not straight)
thus 0+3 = 3 divided by 2 =1.5
25 +32 = 57 divided by 2 =26.5
1.5 - 26.5 =25 25 thou out on the outer end.
watching the gauge on the on the end of the shaft Moved it 12.5 thou or 1/2 of the amount.
problem was once went back and did all the measurements and calculations again
it was still a diff of 25 thou on the outer end.

Am I doing something wrong,

any help please

Wouldn't 25+-32=-7?

 

[kvt]

BAMBAM, I may just come up and see you one weekend if I do not get this figured out, I do not trust the post office not to mess it up. I ordered a ground and finished bar, but by the time I got it, It was bent.
Will send you an email.
finally able to get back in the shop a bit now that my certification for my other job is complete. A pain but it pays the bills.

ddickey, that my be part of it, but still I swung the head stock where the end of the bar moved more than that and it did not seam to make much difference. Will be giving it another try this week.

 

[kvt]

Ok, have been working on it some more. Here is what I have now
close to the chuck
0 to 0.0025
outer end
0.025 to -0.028

results
0 + 0.0025 =0.0025 divided by 2 = 0.00125
0.025 + -0.028 = -0.003 divided by 2 = -0.0015
0.00125 - - 0.0015 = 0.00275
that is over 10 inches. I guess I will try getting a nice sized AL rod and do some quick turns close to the chuck and the end, then measure and see what I have.
have to put the gears back on first.

 

[kvt]

ok gave up on that one and went to doing a cut on a bar, Alum bar, held in a 4jaw and indicated, finally got it down to what I think is a respectable alignment.
one end Miced to
0.78655
the other end miced to
0.78645
over about 7 1/2 inches.
I think that is pretty good on a 77 version of an old lathe.

Let me know.

Ken

 

[ddickey]

What did you give up on?
These were full length cuts?
.0001" is not good enough. That'll give you just over a thou taper over 8'. Lol
But seriously that is a pretty narrow bar for that length. Did you take a spring cut?
No reason to use a four jaw unless you wanted to reduce run-out. I use the four jaw too though as my three jaw has a ton-o-run-out.

 

[Rustrp]

Here's a tubalcain 2 part video on alignment. I think you could just skip the aluminum foundry work and use larger round stock of your choice. I think he like to add as many processes as possible sometimes. Like he says, you can save the bar for tune ups at a later date when it's needed.

 

[kvt]

Trying to do it the Rollie'a Dad method . is what I gave up on,

Yes that was a final cur that was full length spring cut.

That is the biggest stock I had so it is what I used.

The reason it was a 4 jaw is that I have not got a 3 jaw set up at the moment, have to find or make a backing plate for my 3 jaw
I