Sources for cast iron, round acme nuts?

tobnpr · May 19, 2019

Disassembling/cleaning up an old horizontal knee mill that was converted to a vertical with a Tree head.

The roind acme nut for the table lead screw had split at some point and was repaired with screws, but I'd like to replace while it's apart.

3/4",5 tpi, 2" long x 1.5" diameter. Can't find any that long at McMaster, any other sources for this?

Rob F. · May 19, 2019

Buy an acme tap, preferably a used one.

tobnpr · May 19, 2019

Nah...
Not worth the effort and expense to.go that route.
The repaired nut is serviceable, but figured if I can replace it with minimal expense and effort I would.

tobnpr · May 19, 2019

Not sure how parts replacement is "shop management" and not machine reconditioning, but...
Found McMaster does have cast iron in 1-1/2" length by 2-15/64" dia.
Should be able to use the slightly shorter length and can turn down the OD to 1-1/2" .

Hbjj · May 20, 2019

Is it possible the screws are there to adjust the lash ?
Or is there some other way

sfriedberg · May 20, 2019

I was going to direct you to Roton for Acme nuts. However, they carry bronze, not cast iron, and their round "sleeve" nuts are a bit shorter than your original part. Still, a possibly useful source.

Mark Rand · May 20, 2019

Depending on what your time is worth to you and whether you've got a lathe, making new nuts from cast iron bar is a fairly simple exercise. If the originals were split with a screw adjusting the spacing between the two ends, that can be replicated. If not, it's worth making a carrier with (for instance) a 20tpi female thread and a matching thread on one of the nut halves, with a lock nut, so you can adjust the clearance as time goes on. The system of a partially split nut with a clamping screw that is used on some machines is not to be recommended.

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Sources for cast iron, round acme nuts?

tobnpr

Hot Rolled

Rob F.

Diamond

tobnpr

Hot Rolled

tobnpr

Hot Rolled

Hbjj

Cast Iron

sfriedberg

Diamond

Mark Rand

Diamond

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