Cross slide not square to spindle

Update,
I took a .025” cut across my work piece and measured the step with a micrometer.
It was only about .003”. It just felt like more when measuring with my fingernail :)
I then took a .005” cut and there was no step at all.
After some head scratching I concluded the cross slide (and work piece) is moving away from the tool towards the latter part of the cut and therefore the front of the work piece is swinging inwards torwards the tool causing the trailing cut.

It actually doesn’t sound too bad (no clackity clack) and the finish is reasonable.

From this I conclude the problem is simply a worn cross slide.
For the accuracy I require for my small hobby jobs I’ll probably work with it.

Thanks for all your comments.
David
 
David,
I know in an earlier post you said that the ways had been cleaned and then the gibs tightened down.
One technique that might help for worn cross slide ways while milling:

I am assuming you have the gibs set loose enough that the power cross feed is useable.
If that is the case, you could consider tightening the gibs further and just turn the very snug lead screw by hand during milling operations. The success of this is certainly dependant on the amount of 'saddle' shaped wear you have on the dovetail and of course your finished part expectations. Its possible this could alleviate a .003" shift.

EDIT. Please excuse. I'm sittin' here at 0 dark thirty with coffee before heading off to work. David, I'm curious if you have done any maintenance on the carriage to bed ways interface. I ask because when I got my Atlas, while relatively clean, it was adjusted very loose. For example, the carriage had factory shims under the way 'clamps' that hold the carriage to the ways on the bed. There was 0.006" of shim. More shim, the looser the fit. I removed it all and checked the carriage fit. It was fine without the shims even though the bed ways measured dead on 0.375" with a micrometer. Not sure why the factory shims were there. Adjusted the gib on the backside of the carriage too. Nice and solid due to a bed with little wear. Maybe yours is a similar situation? Possibly the carriage is jumping around a bit if it has room to move on the bed ways?
 
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chips&more said:
I have now talked to four people in the industry and none of them say the cross is made/set-up to be minutely out of square. It should be 90°. If your/a lathe does not cut flat and square then it’s worn, made wrong or flexed or something. Maybe a manufacture(s) back decades ago used that practice. And then the saying has stuck to the wall and folks today say it like it’s done today…Dave
Click to expand...

It's impossible to make the crosslide exactly 90deg ( +/- nothing !) to the spindle. there always has to be a tolerance . All quality lathes are designed and made to face concave. Your 4 friends need some education !
 
Dinosaur Engineer said:
It's impossible to make the crosslide exactly 90deg ( +/- nothing !) to the spindle. there always has to be a tolerance . All quality lathes are designed and made to face concave. Your 4 friends need some education !
Click to expand...
In "Machine Tool Reconditioning", Page 306, Figure 26.64, the tolerances for cross slide movement are 0 to .0005" for tool room lathes, 0 to .001" for 12" to 18" engine lathes, and also 0 to .001" for 20" to 36" lathes "(To face hollow or concave only on 12" diameter)". I agree with you, Dinosaur Engineer, tolerances have to give pragmatic results, and Ed Connelly agrees as well.
 
I have had the carriage off as mentioned previously when I got the machine I couldn't move along the entire length of the bed.
I think PO had tightened it up as much as he could while down at the head stock end. The little bracket that holds the carriage slide handwheel gears in place had been smashed at some stage and was all "bodgied" up. I have since replaced that with a new one. That may say something about how tight it was.

I have cleaned and set the gib so I get reasonable movement right along the bed.

I have had a look at the video posted above where the guy gets a dial indicator and a jimmy bar to measure the movement along each of the slides.
I was of course making my milling cuts with the cartridge locked but I had not clamped the gibs up tight.

Another thing to mention is parting off is nearly impossible for everything except thin walled stuff.
While doing this I can see a tiny bit of "oil movement" on the slides both on the cross and compound slide right in the joint where the two surfaces meet. I have completed the milling job at hand so now any adjustments I make will simply be to improve things in general.

I do remember seeing a shim under the carriage clamps when I had it apart. I'm 99% sure I put them all back.
I might just get onto the flat bed with a micrometer and see how worn they are.

I don't think anything is going to help much if I do actually have saddle shapped dovetails on the cross slide.

Getting slightly off my own topic :)
I bought a face plate for this machine a while back. That is to say it is the right part for the machine but it has not been trued up on this machine.

One thing I'd like to do is true it up but now that we have cast doubt on my cross slide I'm reluctant to try it.
It is about 8" or 9" dia. Just enough room to fit your hand between the bed and the face plate.
When I put a dial on the OD in runs out about .005 not that this reading really matters.
When i put a dial on the face it runs out about .003
For my hobby jobs this is going to be adequate so I might just leave well enough alone.
I'm only thinking of this as I said before. I'd like to get it as good as it can be.

BTW I trimmed up the backing plate on the 3 Jaw chuck a while back and cleaned it right out. That runs < .001 now which is great.

Thanks again for all your thoughts and comments.
 
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