How Level Does a Lathe Have to Be?

[Allan]

Good day to the Brain Trust.
I have been levelling my lathe and got it to zero along the length of the bed. I got it to zero across the bed under the chuck. Across the bed at the tailstock I have about .002" low at the front. That is, if I put a .002" feeler gauge under the level it shows zero. The problem is that the tailstock mounting bolts are in line with the lathe bed. Can't easily use them to "twist" the bed up at the front to correct it. Can I shim betwixt the under side of the bed and one side of the levelling nut? Ideas and experience would be appreciated. Or should I not worry and just chalk it up to my perfectionistic tendencies rising to the surface?

Al

 

[PurpLev]

Al,
If I'm getting it correctly, then yes, you can shim between the bed and the leveling foot- I did something similar with my 9x20 asian lathe to level it out (better that is...)

a picture might make it more obvious , or a list of what model/make lathe you are using

Sharon

 

[November X-ray]

A lathe does not necessarily have to be "level", it just needs to be aligned properly. If you have a base that is rigid enough to allow the use of a shim to correct it, why not. It is suggested on some lathes to leave the tailstock end hold down bolt(s) loose in order to not introduce any twisting.

Good Luck and please let us know how it turns out!

 

[Pacer]

The object is that when you get the lathe level to then start making some test cuts to verify that it does indeed cut true - quite often it will have to be re-tweaked out of level to get taper out or fine tune it. With yours being that close I would get it set up for a test cut and see how that comes out then work from the readings on the test bar to do your final 'tweaks'.

I could not get my get my Sheldon to indicate level across the ways, but I went ahead and made my test cuts and -- its quite close enough for me, so I havent worried about it not being 'level'

 

[george wilson]

The lathe needs to be level with itself,not necessarily level. Lathes on ships cannot be made level. They need to be setup so that they will cut true cylinders. A lathe can readily be set up without a level. In Ian Bradley's book"The Amateur's Workshop" he describes how to adjust a lathe to turn true. I used to communicate with him. His handwriting was extremely neat!!

You need to get the tailstock right up to the headstock with a sharp 60º center in both. With the centers just touching each other,look straight down on the centers with a magnifying glass. Adjust the tailstock sideways till the center points line up perfectly under magnification. Then,back the tailstock away from the headstock. Put in a fairly thick steel bar and take light cuts across it. Only necessary to do each end,really. Measure the 2 ends with a mike. Adjust the bed with shims until the test bar can be turned to a true cylinder the same diameter at both ends. Then,put on the face plate and take a light truing cut across it. They always need a little truing. Use a carbide bit and turn as slowly as possible. Cast iron will dull a HSS tool before it makes a continuous facing job,and it looks bad. If you are lucky,the facing will be only a thousanth+ hollow towards the middle. Hollow is o.k. to gov't. standards something like 1.5 thousanths in 10". That is to make flanges that don't rock around when set flat.

I prefer a lathe that will turn true AND face flat. Luckily,my present 16" lathe will do both. i don't make flanges,and like to face material flat.

 

[Allan]

Lots of experience here. Thanks!
The lathe is my Tida 10 x 36. I realize that a lathe does not have to be level with the world around it. But it seems to me it should be level with itself if one has an unmoving site on which to place it. Just seems easier to start as close to level with itself as possible.

My concern is that the tailstock end seems twisted out of..."line" let's call it, compared to the head stock end. I don't like building in variables if I don't have to. But I do like the idea of a test turn on a thickish bar to see if all the fiddling is necessary. If you will notice in the photo, the tailstock end mounting bolts are in line with the centerline of the bed rather than perpendicular to it (funny thing is that the manual shows it perpendicular but 'taint so- as the pictures prove). Thanks for the good thinking.

Al

 

[george wilson]

That is very peculiar,indeed. Didn't anyone tell the teenage Chinese girl who built the lathe to put the bolt holes on the side????

 

[Allan]

You know, George
your comment makes me wonder if the pattern for casting that foot under the tail stock got turned 90* by mistake. The manual definitely shows the bolt holes perpendicular to the lathe center line. It's the only Tida I have seen in the flesh so I can't say for sure if they were all like this.

I am wondering if I could make a "turnbuckle bolt" with one left hand and one right hand thread to Lift the front edge of that pedestal. Wouldn't have to go much to take out .002"

Al

 

[george wilson]

It is highly possible that the pattern got turned. It makes no sense made the way it is. There is a thick layer of plaster under the paint,so seams aren't necessarily visible to tell how the beds were cast. What does the foot under the headstock look like?

 

[Pacer]

An in line hole pattern is certainly done on other models, I had an Emco compact 10 (a highly respected precision lathe) and its bolt pattern was this way, on top of only being 2 holes! And, this model of the Emco was what the Chinese 'cloned' to make the popular 9x20, which has only 2 holes also.

While the holes cant be seen in this pic, (you can just make out the slots) its obvious that they arent on the sides - there was one in the left of the tail stock, and then one in the right side of the head stock. I never tried to change anything, it cut straight as it was.