10" Atlas Trouble Turning Unknown Steel

[germaneighter]

I'm very new to machining. I'm needing to reproduce a shock mount shaft that welds to a crossmember on an older Toyota 4WD. Diameters vary along the length of 108mm. The largest diameter is approx 22mm and the smallest is 12 x 1.75 threads.
I have a piece of 1" diameter steel, used for horse shoes, that I'm trying to turn down. I've tried carbide and HSS cutters. The carbide seems to do better. My problem is I'm only able to take off a couple thousandths at a time without bogging down the lathe. I've tried all speeds but fastest works best with a very slow feed. It's taking a very long time to get anywhare.

What am I doing wrong?

Could the material be hardened? Without a hardness tester how can I tell?

thanks

[John Evans]

Hit it with the corner of a sharp file ,file marks it not hard. If file marks it put lathe in back gear at about 100-150 RPM use cutting oil and HSS should work fine. With that light weight lathe you need positive rake tools,most carbide you find is negative rake and won't work well on that lathe. Years ago I had a Atlas 12" and machined a tool from a piece of car axle no problem using HSS and lube. Try the carbide at a low speed in back gear with a heaver cut .People think carbide has to run fast ,not so will work at slower speeds. Carbide laughs at speeds and feeds that burn up HSS ,that's why it is used . It is NOT the answer to all problems.

[liveaboard]

Is your lathe motor bogging down, or just the chuck?

What I mean is, did you check the drive belt[s].
I thought I needed a bigger motor until I tightened the primary belts.

[Harold_V]

You'd be best served by describing the lathe you have, as what may work for one machine may border on the impossible for another. Also, make mention of how long the cut must be.

With a decent lathe, you should be able to remove ¼" from the diameter of that piece, and do it with one pass, with feed in the neighborhood of .010"/.012". That wouldn't be possible on a fractional hp machine, however. That's why it's important that readers understand what you're working with.

H

[earlgo]

The Atlas 12" lathe that my dad bought in 1958 was available with up to a 3/4HP motor. If the lathe is bogging down, it is either way underpowered by a replacement motor or, as mentioned, the belts are slipping or the tooling is wrong. My dad apparently was short of cash so he put on a 1/3 HP motor that was found somewhere, as it is not original. Even with that lack of hp, one can take deeper cuts than the OP has suggested. Mr. Evans is certainly right that the tooling may not be appropriate for the cut. May I suggest you look into the resource library on this site for valuable information on sharpening tools.
JMHO
--earlgo

[John Hasler]

Hit it with the corner of a sharp file ,file marks it not hard. If file marks it put lathe in back gear at about 100-150 RPM use cutting oil and HSS should work fine. With that light weight lathe you need positive rake tools,most carbide you find is negative rake and won't work well on that lathe. Years ago I had a Atlas 12" and machined a tool from a piece of car axle no problem using HSS and lube. Try the carbide at a low speed in back gear with a heaver cut .People think carbide has to run fast ,not so will work at slower speeds. Carbide laughs at speeds and feeds that burn up HSS ,that's why it is used . It is NOT the answer to all problems.

Horseshoe material is almost always A36.

Carbide inserts these days are readily available with positive rake and chip breakers. In fact, I think that most inserts available are positive rake. They are very sharp and fine grained. I agree that the reason it is normally run much faster than HSS is simply because it can be.

[Harold_V]

I should mention that I now understand the lathe is a 10" Atlas. Sorry 'bout that. For what ever reason, I didn't take note when I was reading the post.

H

[spro]

Part of the stability of the Atlas lathes is the bench it is mounted on. Take it easy, don't introduce twist. Measure with an accurate level across the flat ways, fore and back. Shims are required while tightening to keep it level in that one plane. Once it is all tight and sorta right, you will see a difference. The carriage jibs can be cleaned and adjusted for minimal play. The back one is often neglected but important because it locates the saddle two ways. You need all the rigidity available or it ain't cutting it.

[germaneighter]

Thanks for the help and advice. Am I correct in thinking that the weight of the motor sets the motor belt tension on this machine?

[spro]

I had a 12" which is similar. It had a lever cam which totally loosened the motor belt or swung it tight. The neat thing was that the lever had a fine thread, so that it could be adjusted just twisting the knob. That is, the motor weight did tension the belt somewhat but it wasn't climbing the belt. So the motor was suspended in tension within a fraction of movement.

[germaneighter]

Well, I said I was new to machining.....I had forgot to lock the bull gear pin into the pully cluster. I'm surprised I could even cut a couple thousandths. Tonight I'm making chips like crazy.

[Russ Hanscom]

Good catch, we all have days like that!