Tips on leveling a lathe.

[Phil_C]

An old former Navy guy told me years ago level didn't have anything to do with it, you want the spindle parallel to the bed. Surprised this only has a few comments on it. I think this gets you to what Firstram mentioned above "Rollie's Dad", I think though this over simplifies it, it would be really nice to get the bed level with no twist, I think Rollie's Dad method would add twist to the bed when the issue is head to bed alignment . But I guess there is the Correct way and many "that works for this" ways. One could get a headache, for my little 12x36t I chose to get it level as I could with what I had then true the bed to the spindle with the test cuts. I believe this method is also in the old SB small lathe manuals, I think i have one downloaded that covers it. But i probably added twist to the bed...... or took it out, see now i have a headache.

Phil

 

[D.sebens]

Holy cow is it twisted. I have no clue what happened to it in it's life. I currently have about .200" under the rear tailstock end mounting bolt. I have decreased it from .027" at 16" to .009" at 16". I think the cabinet is absorbing a LOT of the shim obviously. I am thinking I will have to bolt down the front of the cabinet to be able to pull the lathe down. As I put a shim in it pulls pressure up from that leg. I can change my readings if I push on that leg.

 

[D.sebens]

I edited my post above to fix my averaging error at 16". the 7.75" distance in the picture would also be incorrect so disregard that.

 

[RJSakowski]

An old former Navy guy told me years ago level didn't have anything to do with it, you want the spindle parallel to the bed. Surprised this only has a few comments on it. I think this gets you to what Firstram mentioned above "Rollie's Dad", I think though this over simplifies it, it would be really nice to get the bed level with no twist, I think Rollie's Dad method would add twist to the bed when the issue is head to bed alignment . But I guess there is the Correct way and many "that works for this" ways. One could get a headache, for my little 12x36t I chose to get it level as I could with what I had then true the bed to the spindle with the test cuts. I believe this method is also in the old SB small lathe manuals, I think i have one downloaded that covers it. But i probably added twist to the bed...... or took it out, see now i have a headache.

Phil

Level has nothing to do with lathe alignment. But what leveling does is give you a convenient reference against which to measure bed twist.

For various reasons, a lathe bed can be perfectly level and still cut a taper. One can reduce the taper by twisting the bed slightly. The only other way that one can reduce or eliminate cutting a taper that I am aware of is to rotate the headstock. While this works, be aware that it also directly affects the ability to cut a flat face and therefor isn't a good idea unless you know that you have a misaligned headstock.

Years ago, I was cutting a .004" taper over 6" and I rotated to headstock to correct the issue. It worked but now when I faced a part, I had introduced a ..004"/6" domed cut on the face. The real issue was the lathe was fastened to a steel table the twisted the tailstock. The correct solution was to remove the bed twist.

I leveled the lathe and realigned the headstock so it no longer cut a domed face. Then I rechecked the level and measured the amount of taper using the RDM test and shimmed to remove the taper. The final operation was to use the two collar test to confirm that the lathe no longer cut a taper.

 

[Firstram]

Level has nothing to do with lathe alignment. But what leveling does is give you a convenient reference against which to measure bed twist.

For various reasons, a lathe bed can be perfectly level and still cut a taper. One can reduce the taper by twisting the bed slightly. The only other way that one can reduce or eliminate cutting a taper that I am aware of is to rotate the headstock. While this works, be aware that it also directly affects the ability to cut a flat face and therefor isn't a good idea unless you know that you have a misaligned headstock.

Years ago, I was cutting a .004" taper over 6" and I rotated to headstock to correct the issue. It worked but now when I faced a part, I had introduced a ..004"/6" domed cut on the face. The real issue was the lathe was fastened to a steel table the twisted the tailstock. The correct solution was to remove the bed twist.

I leveled the lathe and realigned the headstock so it no longer cut a domed face. Then I rechecked the level and measured the amount of taper using the RDM test and shimmed to remove the taper. The final operation was to use the two collar test to confirm that the lathe no longer cut a taper.

This!

 

[Firstram]

Holy cow is it twisted. I have no clue what happened to it in it's life. I currently have about .200" under the rear tailstock end mounting bolt. I have decreased it from .027" at 16" to .009" at 16". I think the cabinet is absorbing a LOT of the shim obviously. I am thinking I will have to bolt down the front of the cabinet to be able to pull the lathe down. As I put a shim in it pulls pressure up from that leg. I can change my readings if I push on that leg.

Are you just sweeping that bar or rotating it to find the average (RDM)?

 

[D.sebens]

Are you just sweeping that bar or rotating it to find the average (RDM)?

That’s rotating and averaging the high and low.

 

[chatter chatter cut cut]

with 2 4ft straight edge clamp ed to the lathe bed at head and tail stock a construction level at the ends [almost 4 tf. away] the twist is magnified and switching the level from end to end to veryfy the reading should give you a good reading. i used this method on my minilathe . a .007 shim got it right on. its easy and probably free.

 

[D.sebens]

After bolting down the two low corners I was able to get it down to 13.5 thou of taper over 16". The desk doesnt look like it will take much more. I will let it sit overnight and check measurements once it has equalized. Does any body have any other options of how to go about this?

 

[D.sebens]

Also how do you align a headstock? It seems like that could be the problem but it sits on a vway? Seems like it would lock it in?