Acme Threading

[markba633csi]

You could do a light press fit with epoxy or loctite, it will stay put
-Mark

 

[Technical Ted]

I suggest you go for it and take a crack at threading both on your lathe! What do you have to lose? You certainly have a lot of knowledge and experience to gain. Don't be afraid to try new things. We've all been there.... the experienced guys wouldn't be experienced if they didn't try new things. It would be a great learning project for you and you have nothing to lose.

Ted

 

[SLK001]

Remember, since this is going to be a leadscrew for a vise, you're going to need LEFT HAND threaded versions of both.

Left hand would be standard, but if you can live with your vise going "the wrong way" when you try to use it, then you can use RIGHT HAND threads

 

[pacifica]

Kurt vises are not acme thread.
In use acme threads have lower friction than 60 degree threads and acme work better in the presence of debris or dust.

Russ

 

[SLK001]

Kurt vises are not acme thread.
In use acme threads have lower friction than 60 degree threads and acme work better in the presence of debris or dust.

Russ

What are they, square threaded?

ACME and square threads are used when very large forces are needed to be transmitted.

 

[Weldingrod1]

Yes, 10 pitch acme is quite deep. Lots of metal to take off. It was more than my Hardinge could retract... And 1/2" is a pretty small hole to work into.
Worth a try for fun factor! I've done them. Stub acme is a bit easier. You may want to gash the thread with an internal grooving tool before you start the threading tool.

Oh, gauging the internal thread is hard... you will do some "cut to fit" at the end.

I think you would find both a brass and a steel nut perfectly acceptable. All Bridgeports have brass nuts on the acme table screws, and they last a looong time. Lubed, the steel will hold up too.

Sent from my SM-G892A using Tapatalk

 

[devils4ever]

Remember, since this is going to be a leadscrew for a vise, you're going to need LEFT HAND threaded versions of both.

Left hand would be standard, but if you can live with your vise going "the wrong way" when you try to use it, then you can use RIGHT HAND threads

I plan on making something along these lines. I think they are right hand threads.

 

[devils4ever]

Kurt vises are not acme thread.

Yes, I was surprised to find my Kurt vise is not Acme or square threaded. It looks like a V thread to me and I think it is left handed. Maybe, it's a custom form of thread to give more precision and lots of force?

 

[addertooth]

Acme is undeniably stronger, provided you are comparing threads made out of the same material with the same heat treating process (and the same O.D.). Although it is obvious, I will still say it, a properly heat treated 60 degree thread on O1, D2, A2, 154CM steel will be very strong, certainly stronger than a similarly sized Acme thread of annealed 1018 steel. The softer steel will have the advantage of being more "chewey" or tougher to withstanding sharp shock.

 

[JohnG]

I'm confused here. My understanding is that Acme screws are designed to transmit motion, and so they develop less friction than V threads. This makes them less useful for clamping. Also, I've read that an Acme screw and nut should be dissimilar materials to minimize wear--steel screw and bronze nut is common.
I turned this left hand Acme screw to replace the worn cross feed screw on a surface grinder. I bought a pair of bronze Acme nuts and turned external threads on them to assemble a double nut with more bearing area and a slight tension between the nuts to minimize backlash.
Turning Acme threads develops much higher lateral force. If you are turning a left hand Acme screw between centers, tighten the tailstock extra tight. A single point tool for turning small diameter inside Acme threads is the hardest lathe tool to grind for my money.