My machinist needs your help!!

I need 1/4" cut off each of the bars on my front stainless 4-bar set-up.

My machinist says he thinks he can do it without marring the bars
by wrapping a rag around each one as he puts it into the lathe chuck.
But no guarantees if it slips in the chuck.

I'm no machinist, but wouldn't a 'Screwie Louie' (rubber jar opener) be a better choice, as it's non-slip?

Or, with the vast knowledge base here on the HAMB there may be a
better solution yet.

My machinist and I welcome any ideas you may have, and we thank you in advance.

 

wrap a shit load of tape around it? like painters tape.

 

Kinda depends on the condition of the chuck jaws, how much he tightens the chuck, etc...
I would rap it with a few layers of duct tape, don't tighten the chuck too much and don't face much per pass. If you need to tap the threads deeper don't do it in the machine, that is when it's most likely to spin.

Good Luck

 

Clamp it in a mill vise in between two 2 x 4's
Mill the 1/4" off...

Personally I would mark it, then grind it off with a sanding disc or cut it with a radiac wheel. Finish with a file.

 

Use a collet chuck, it won't spin, and the ID is machined smooth so it won't mark the tube.

Holding it in something soft in a lather chuck is a guaranteed way to make it slip.

 

usually we just wrap it in some brass shim stock

 

At work I would put it in the saw between two pieces of oak, and saw it off as close to the finished length as possible, and then a quick facing to true it up. It would take a carbide blade to saw it though.

Otherwise I would try the milling like mentioned before. Also wrapping duct tape around it seems a good choice, because brake cleaner or other type of MEK/lacquer thinner will remove any glue residue without ruining the stainless. (still talking about mill here)

EDIT: we have nothing but collet chucks at work, with soft jaws and hard jaws. Didn't think otherwise.

 

I agree with Jim use a lathe with a collet set up. You can also wrap a piece of shim stock around it all so.

 

As stated in the 2 previous posts:

The collet chuck is the way to go if you MUST turn it in a lathe and this way you can round the end off if you like.... but,

The best way to cut it is held in a vise and cut in a mill as long as you don't mind a perfectly flat surface at the end of the rod.

Think about the fact that both ways you will have unprotected metal rod ends exposed to the elements, depending on your alloy it may rust. A rounded end would look cleaner protected with a dab of paint to match your body colour!

 

i second the collet chuck
best non billy bob method
may spin using tape
2 x 4s
or bubblegum for that matter

 

Agree with the collet lathe idea. If that's not a possibility, I would put it in a mill. No slippage that way. The jaws on milling vises are usually smooth and don't leave marks on the workpiece.
Justin

 

Clamp it in a chop saw a cut it. The flat cut will be perfect for the jamb nut to seat against. Remember the Kiss theory?

 

If I had collets for my lathe, that's what I would use. If no collets, and I don't have any for any of my lathes in my personal shop, I would use dead soft copper to pad the jaws. Tape and shit like that is an open invitation to a first class fuck up! And I guess since I earned a living as a machinist on everything from tractor and farm implement stuff to medical devices to aircraft parts for 40+ years then maybe I know what I'm talking about.
Dave

 

I say put some tape on it mark it and cut it with a 41/2 grinder with a thin cut off wheel. I just saved you 40 bucks with my 2 cents
later Bill

 

Send it out to NASA....this is critical

 

we dont have time for NASA they would use a teem of guys $100,000,000.00 and about 4 5 years

 

And Russia would use a pencil, lol.

 

I have a bucket of brass and stainless sheet drops that I keep next to the lathe to use as jaw pads.

Just tape them down to the jaw faces and tighten appropriately.

A collet chuck with a tight fitting collet would be the best choice (and quickest to boot).

If it's solid stainless, you're golden.

If it's plated, you're in for a life of chipping and peeling nickel or chrome if you cut it.

If it's stainless, you can polish any tiny marks out when things are all done anyway, you're just trying to avoid any big scratches and gouges.

You'll have to polish the faces you turn regardless.

 

yeah what he said,let the brass/copper take all of it!

 

I go with the brass stock wrapped around the part. If you have access to a roller, make up some sleeves from 1/32" stock and leave about a 1/8" gap.

Like others suggest, it could be easily milled in a vise especially if the bar is long, the unsupported end will tend to whip in the spindle.

Bob

 

Is your machinist capable of using soft jaws on a three jaw chuck?

 

pennies between the jaws of the chuck and the work piece works well. basically anything softer than the work piece, but im not guaranteeing it wont scratch it at all. sounds like you might need a new a machinist if he cant figure this one out on his own...

 

If everybody could figure everything out by themselves there'd be
no need for the HAMB,...............or teaching hospitals.

 

Get another machinist. Problem solved.

If he doesn't know how to do it he shouldn't be taking advice from an internet message board. He's an amature.

 

Really? With 7880 posts it's ironic that you would say that.

 

I use one layer of beer can shim stock on finished aluminum pieces.

The chucks are tightened normally and the workpiece doesn't slip.

For some pieces, depending on workpiece size, I have some alumiminum pads cut to match the face of the chuck jaw.
Roughly 1" square for a 6" chuck.

You shouldn't have any problems cutting stainless in the lathe.
Stainless is tough and carbide cutting tools work great.

A flat surface on the bar is necessary for the jam nut to lock onto.

Have the machinist use a file by hand when the workpiece is spinning and "break" the sharp edge on the cut end.

Since the end you're cutting is threaded, you'll want to cut a tiny recess so the sharp thread edges don't get you and also so the threaded eye will start easily.

Your machinist will probably do that anyway, but you ought to talk about it first.

 

A collet would be a great way to go. But if the lathe has a 3 jaw already on it who would want to remove it for that simple task? That's what soft jaws are for.

 

i understand what you are saying, but this machinist is getting paid by people to machine parts for them, he should know what he is doing. he is a skilled professional.

you wouldn't goto a doctor if he had to ask how to perform surgery on a an internet forum would you?

no offrense, that is just my $0.02.

 

only 1/4"? grind it off. lathe is way overkill. you could be done before you could get it chucked in the lathe or mill.

 

I never said he was professional. If he was I wouldn't have started this
thread. He is however cheap and with my guidance and it not being a
NASA project it might work out O.K.

None taken. Everyone that's replied has been helpful.

Thanks to all.