Rigidity in an Atlas 10F lathe -HELP-

[Moderatemixed]

Good morning all.

I would like to pose a cumulative challenge to the group..... a “Covid 19” project. I’d like to invite you all into my shop to help me solve a problem. Due to space and pandemic limitations I will use the forum instead!

I have a 1948 Atlas 10F. I did a complete rebuild and the lathe is “as new”. The bed was reground, bearings checked, everything cleaned to bare metal and then reassembled.

I have adjusted the carriage gibs so that the carriage slides but has a bit of resistance. The cross slide has about the same resistance. The compound gibs are considerably tighter. The headstock is tightly attached, and headstock spindle bearings adjusted correctly with appropriate preload. I have an Armstrong QCTP that is tightly affixed to the compound and there is little to no overhang from centreline when using HSS or Carbide. The lathe is level and flat and is attached at the four mounting points directly to a 2 inch butcher block top. That top is attached to a 300 lb set of plywood cabinets with approximately 750 lb of tooling etc within.

I have an Edge Technologies “gadget” that helps to set the tool height exactly on the lathe centreline. I have checked with a special Edge Technologies bar that the headstock and tail stock are in line with one another. I have spent the money and done every conceivable thing that I can think of and spent significant resources to make my “turning experience” pleasant; but it REALLY IS AWEFUL!!! (That was the clean way of saying what I want to say).

When I put a piece of stock into the chuck, I look at the material, the feed, the speed, and once I start turning I have on one occasion gotten nice chips (in mild steel) but in most cases I get a surface finish rivaled by a teenagers “zit covered” face and vibrations that my wife says put ripples in her coffee 2 floors up. (I’m in the basement). Even with aluminum the lathe often vibrates like an ultrasonic cleaner!

I watch a lot of youtube and I am so “p’d” off that I cannot seem to get my lathe to “play nicely”. It isn’t from lack if trying, and certainly not from lack of investment...... it is due to a gross lack of experience, which is why I put this to you all for help. These lathes were touted by Atlas as being sufficient in shops, labs and schools, and while I don’t expect performance from it that one might get from a big Monarch, I do expect more than what a Taig, Sherline or smaller Atlas 618 would give..... and maybe that thinking is wrong. Please, I implore the group to look at the pics, call out ANY error, make any suggestion, throw out any idea no matter how ridiculous and I will check it, try it and/or adopt it.

This lathe SHOULD be able to do the light machining I ask of it without rattling my 46 year old teeth out if my head. Any and ALL input appreciated!! I apologize if this thread repeats one that has been done in the past, but I would like you (my buddies) to look at the setup and help me solve the problem..... I’m out of ideas.

Best regards,

Derek

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[Moderatemixed]

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[mattthemuppet2]

lots of possibilities here.

For one, mount the lathe directly to the bench, not on standoffs like that. If you need to level the lathe you can slip shims underneat the side/ foot that needs to be raised. To be honest, leveling your lathe is waaaaay down your list of priorities.

Second, what material are you turning? What speed? What depth of cut?

Third, you're using a relatively blunt carbide insert (CCMT by the looks of it) that needs a decent chip load to work properly. Try a test cut on a piece of Sch80 PVC pipe with a sharp HSS bit (or CCGT insert). Play around with that for a while. Then try aluminium (use WD40 or kerosene for lube). Once you've got that down, buy some nice leaded steel (eg. 12L14) and play with that. Try different speeds, feeds and depths of cut. For speed a good rule of thumb is 4 x SFM x diameter of work in inches. SFM = surface feet per minute. A conservative value for steel is 50 and for aluminium is 100, using HSS. Start there and work up. Eg. turning a 1" steel rod, speed should be 4 x 50 x 1 = 200rpm. That's pretty slow, but you can always go faster when you get used to it.

The downside with watching YT vids is that a) they assume a level of knowledge but aren't explicit about what they expect you to know and b) you're looking at years if not decades of experience, so they make things look simpler than they are. You need to get that experience your own way.

 

[benmychree]

A good start to improve finishes would be to abandon negative rake carbide tooling, it has no place on a light duty machine such as you have. The excessive overhang of the collet setup you are using would not be helpful either. As to excessive vibration, does the machine vibrate when not cutting? If so it should be easy to isolate the cause. Having the tool overhang the cross slide as it appears is not a good thing, as I have seen on my 9" Monarch, when trying to part off, when I move the tool post to the right, the problem is greatly lessened. I think your tool post is too large for the lathe.

 

[Moderatemixed]

A good start to improve finishes would be to abandon negative rake carbide tooling, it has no place on a light duty machine such as you have. The excessive overhang of the collet setup you are using would not be helpful either. As to excessive vibration, does the machine vibrate when not cutting? If so it should be easy to isolate the cause. Having the tool overhang the cross slide as it appears is not a good thing, as I have seen on my 9" Monarch, when trying to part off, when I move the tool post to the right, the problem is greatly lessened. I think your tool post is too large for the lathe.

The tool post is AXA sized, which is supposed to be good for the 10 and 12” lathes, but I will look into it. I will focus on HSS for the time being but look into other carbide. The lathe runs like a Swiss Watch when not cutting, both quite and vibration free. I have a Starrett Vibrometer and it reads zero deflection when not cutting. Additionally I measure .0002 runout at the spindle and .0005 at the collet. Thanks for the input, and will try some changes.


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[Moderatemixed]

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[Moderatemixed]

mattthemuppet2, Thank you SO much for the suggestions. I’ll try some of your suggestions and let you know what I find. The first will be to get the lathe off of the standoffs. Too I am going to look at how the butcher block is attached to the cabinet to ensure that there is rigidity there. I’m just working on installing an RPM readout so that I can accurately set feeds and speeds (I’ve been using a hand held albeit digital, RPM indicator to this point. Regarding YouTube, unfortunately they make it look SO easy, which is part of the allure. But everyone starts out a beginner.

Cheers.

Derek


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[markba633csi]

What kind of shape are the bronze sleeve bearings in in the spindle pulley? If they are worn the pulley will knock around on the spindle and add vibration. They should fit tightly within 0.001"
Also I pretty much agree with John on everything he mentioned in post #4 - Atlas lathes are happiest with HSS tool bits, you should have no trouble getting great finishes with those any day of the week
-Mark

 

[Moderatemixed]

Thanks Mark. Just checked the pulley and it is tight. Going to grind some HSS tools today. Just working on getting the lathe off of the standoffs. I really appreciate the input!


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[benmychree]

If your lathe is not equipped with a variable speed motor/control, why not just record all the speeds on a chart/plaque? I did that for my 9" Monarch