Atlas 10" Pic O Matic alignment question.

[Gadget]

I have an old Atlas 10" Pic O Matic lathe that cuts on a taper along the length of a shaft. I've tried correcting this by leveling the lathe but it doesn't seem to help. On a 3" long work piece there is about .006 difference from one end of the cut to the other. The larger diameter being closest to the chuck slightly tapering smaller to the other end of the piece. The far end is not supported so it isn't tailstock alignment issues.
Is there any adjustment for the headstock for alignment along the length of the lathe? I don't see anything I would consider adjustments. If there are none, what's the procedure for getting this back in alignment? This is an old lathe and isn't what I'd call great condition but it's what I have and I want to get it working as well as I can.
Thanks in advance for any help.
Dan

 

[LJP]

Tom Lipton, at OxToolCo just did a video about this on YouTube. His lathe is quite a large machine, but it may explain a few things. Hope this helps. Larry

 

[Gadget]

Tom Lipton, at OxToolCo just did a video about this on YouTube. His lathe is quite a large machine, but it may explain a few things. Hope this helps. Larry

Thanks, I looked at his feed and he has a ton of videos. I found the ones on the lathe setup very informative. Wish there was one specific to Atlas but I'll muddle through.

 

[tertiaryjim]

I can't remember a lathe I've worked on that didn't have some adjustment.
There may be a small panel to remove or you may have to reach it from underneath.
You ought to do an check with a indicator to get an idea of how the head sits in line with the ways.
At the same time you could check to see how it lines up with the tailstock and if the tailstock is true to the ways.

 

[Gadget]

I can't remember a lathe I've worked on that didn't have some adjustment.
There may be a small panel to remove or you may have to reach it from underneath.
You ought to do an check with a indicator to get an idea of how the head sits in line with the ways.
At the same time you could check to see how it lines up with the tailstock and if the tailstock is true to the ways.

I'll have to dig into it deeper. I know there is at least one saddle clamp holding the headstock to the ways. I can 't see back in far enough to see if there's a second one but I'll bet there is. As for the tailstock, it is also off with respect to the ways but not as much as the headstock. I wanted to look at it in depth today but after surviving this severe winter with no illness I managed to catch a wicked cold now that it's warming up. Spending the day resting and doing research.

 

[schor]

I just looked at a head from a th54 and there is no adjustment on the head to deal with what your describing other than adjusting for any twist in the bed as Tom described in his video. I would guess a twist to cause 6thou over 3" to be almost noticeable over 54". Do you have a machinist level that you can use to check for twist? Just move it down the bed and see if your getting differences.

Dealing with the twist is very related to how your lathe is mounted.

 

[Don B]

I'm not really familiar with this lathe but leveling can be quit tricky with a machinist level, if you have the headstock leveled to your satisfaction try a test piece like this.
You'd take a minimal cut on both raised diameters ( cut one don't move the cross slide just the saddle and cut the other ) then adjust by shimming ( or using leveling pads or feet ) the tail stock end of the lathe.

 

[Gadget]

This lathe is mounted on the long cast iron legs that I think were standard at the time. It allows some wobble when cranking the carriage by hand so it's possible they are part of the problem. I don't have a machinist's level but should be able to get close with a good standard level if I can get one that's well calibrated. I've had the back legs shimmed up enough that one of the two don't contact the floor but it didn't seem to make any difference.
It will be a couple of days before I can get back to it now but I'll keep everyone posted as to what I find.

 

[Don B]

I've had the back legs shimmed up enough that one of the two don't contact the floor but it didn't seem to make any difference.

Sounds like you'll need to anchor the lathe to the floor so you can get a little twist in the bed ways.

 

[Gadget]

Sounds like you'll need to anchor the lathe to the floor so you can get a little twist in the bed ways.

That or build a very heavy stand solid enough to withstand the torque needed to give the twist. I really don't want to drill holes in the garage floor.