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Acme Tap Question

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kev74

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#1
I'm working on making a small drill press vise form a kit consisting of cast iron castings. I want to use a piece of 1/2-10 Acme threaded rod for the screw.

I'm shopping for a 1/2-10 Acme tap and see 3 types of taps available - a regular tapered single pass tap, a tandem type tap, and a two piece set consisting of roughing and finishing taps.

Is there much difference in the quality of the threads each can cut? And would the cheaper single pass tapered tap be likely to thread a hole in cast iron that would be good enough to tighten a vise? Thanks!
 

MrWhoopee

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#2
I believe it's mostly a matter of how much horsepower it takes to drive the tap. If you are a manly man, a single pass tap will be fine. It's only a vise, not a lathe.
 

mmcmdl

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#3
I have some 1/2-10 acme taps on hand ! Shoot me a pm . Dave .
 

P. Waller

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#4
A tandem tap is very long and has 2 sections on the same tool, roughing and finishing.
This will allow you to tap the parts in one set up saving a good deal of time, much like a nut tap they may accumulate parts on the shank so you do not have to back it.
 

kev74

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#5
Is it unreasonable to try and tap Acme threads through about .8 inch of cast iron? It seems like I'd be removing a lot of metal at once.

This is going to be a one-off project. If I could get it done with a single pass tap and get good results, I'd prefer to go that way. Otherwise I might try to fixture it in the lathe and single point cut the threads.
 

P. Waller

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#6
Is it unreasonable to try and tap Acme threads through about .8 inch of cast iron? It seems like I'd be removing a lot of metal at once.

This is going to be a one-off project. If I could get it done with a single pass tap and get good results, I'd prefer to go that way. Otherwise I might try to fixture it in the lathe and single point cut the threads.
If few parts are required by all means single point them, however producing such a small diameter acme thread will prove arduous with a manual machine. If there is no time constraint then have at it and you will surely learn a good deal.
 
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