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Work Holding on a Lathe


Dec 2, 2018

I have a work-holding question I'm hoping that you can help provide a solution to, please.

The material is a length of truck leaf spring, possibly 5160, roughly 3" x 5" x .330" thick.

Is there a safe way, to either hold this in a 4 jaw chuck or hold it to a face plate for facing on the ML7?

The plan is to face it on one side, then flip it over and face the other side, machining down the thickness to .250".

Yes......there is an "arc" to the work piece as is, being a truck spring, but I will flatten it the best that I can in a 20 ton press before any facing or milling.

I've never faced material this shape nor of this size before......yep, a newbie just learning. The thought of facing this stock in an amongst protruding clamps or chuck jaws is somewhat daunting.

The other question I have, is a sharp HSS tool up to the task of facing 5160? Of course I have no way of knowing exactly what steel this truck spring cut-off is for certainty, only that it is spring steel and maybe it is 5160.

If this cannot be done on a ML7, I do have a Taig mill that I will attempt the same procedure on.

Thanks for your thots.


Mar 27, 2005
Northwest Indiana
You should be able to hold it in a 4 jaw chuck just fine. It may be pretty brutal on HSS tooling with the interrupted cut and fairly hard material. Drop your speed down pretty significantly, maybe 20-30 SFM.

If you are that new to machining, you might be better off in the mill.

jim rozen

Feb 26, 2004
peekskill, NY
A couple of comments in no particular order:

1) when facing a part like this in lathe chuck, you will be holding it by less than 1/4 inch, as that's the desired finish size. That's not a lot and if the part is rounded over at the edges (as springs often are) and the jaws have a bit of bevel at the edges or a bit of bell-mouth (ditto) you'll be flirting with a part rip-out.

2) it will take a considerable amount of work with a small milling machine to take off that much stock over that area, but this would be a more desireable approach.

3) steel is cheap. How much is your time and tooling worth? Consider buying the correct thickness stock to simplify your life.


Cast Iron
Sep 3, 2004
Wisconsin, USA
You could anneal it before machining.It would flatten easier. Get it red hot in a wood or charcoal fire, cover with more fuel, and take it out the next day when it has cooled slowly. Hammer it flat while red and return to the fire to cool. Not sure why you need spring steel. Sawing a piece of ms 1/4 plate would be easier and safer.


Dec 21, 2012
Brisbane Qld Australia
I agree ,anneal it first ....if the ML7 mentioned is around 1 hp ,I doubt you will touch spring with HSS.......a sharp pointed carbide might take a very light cut..........I would also point out ,assuming you do machine it ,the extremely hard swarf will cause havoc with your lathe bed .


Jun 4, 2016
Brooklyn NYC
for fuck sake don't waste your time fucking around with a truck spring to make a flat part. get a suitable piece of steel that's flat(ish) to start with, particularly a small piece in 1/4. why?


Hot Rolled
Jul 8, 2006
Cumberland, Maine
Unless you take many cuts at very small increments, flipping between each one, the chances of ending up with a flat piece are pretty much zero. As others have said, starting with a piece that is to size and flat to begin with makes much more sense.

And then there is the question of what you are going to do with it next. If you want just a 3 x 5 piece of flat steel, you’ll be fine. But if there is further machining to be done to it, it will likely jump around some more.