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Flash319
12-26-2005, 08:10 AM
Has anyone used these inserts or holder? They look like a great tool. I want to make a new ACME nut for my lathe cross slide but it is a 5tpi that is 3/4 inch. The smallest tool holder for the insert that Vardex sells is 1.25 inches around.

How do production places make acme nuts? I can't see them using taps for production?
I can just buy the nut but what fun would that be?

wierdscience
12-26-2005, 08:34 AM
I got a few Vardex inserts for acme thread,but I didn't buy the bars to fit,just made my own.The inserts I have are for 1-1/2x4tpi RH internal.

On a small thread like you have there a tap is about it.Any boring bar for a hole that small would chatter no end.

rkepler
12-26-2005, 08:44 AM
3/4-5 ACME is going to be pretty nasty to try and singlepoint, 1/2-8 is pretty much the same. Lots of cut and no place to put the cutting stress. You might have some luck getting a solid carbide threading tool, but I think the standards ones won't deal with that lathe a thread on that small a hole and I'd bet that the nut's length precludes the single point option.

If you have the option I'd suggest buying a bronze nut and fitting it to the existing nut - turn the new one down to .125" over the 3/4 and solder it into the old nut bored out to the same dimension. If you don't have that much room you could also consider some other way of attachment - perhaps boring through the old nut oversize and soldering (silver solder in this case, I think) the new nut alongside.

beckley23
12-26-2005, 09:09 AM
Single point it. I've been making nuts, when needed, for years. Yes, it's going to chatter, but I have found that on last few passes things tend to work out very nicely, if you take very small cuts. On the last few finishing passes, repeat the settings, you'll be surprised what difference it makes. Don't try for a large DOC.
Harry