Chinese tap and dies?....

T Bredehoft

T Bredehoft

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I'm interested in a set of Acme tap and dies from China,

1set ACME 1/2-8 right-hand high quality trapezoidal HSS thread tap & die TR1/2×8

The illustaration shows an acme tap and a regular 60 deg die. All / both for about $36.00 including shipping.

Does anyone here have any GOOD words about these, I'm quite hesitant, but they are all I can find in 1/2" 8 diameter pitch.
 
I can't speak for this specific set but I bought a set of 2 metric taps not long ago for a project, they were not very good and beyond dull right out of the box.
 
Acme taps are generally very expensive any where from $100.00 to 400.00 your not going to get much for 36$
 
I paid about $90 for an import 1/2-10 Acme tap in 2019. Worked well but was a bit freaky to use as I could see the shank twisting as I tapped the hole.
The forces involved in tapping Acme threads seem to be much higher than 'normal' threads. Because I was concerned with snapping the 1/2-10 tap I bought a 7/16-10 Acme tap to run through the hole first as a sort of 'roughing' pass then followed up with the 1/2-10.
 
Thanks, guys, I was mostly interested in the 1/2 -8 die, for wood working threads, but I don't know if the die is normal threads (as illustrated) or acme as mentioned. End of that search.
 
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For what it’s worth, McMaster doesn’t list a 1/2-8 tap.
 
I wouldn't chance it. I wouldn't want to ruin the work / time it took to get to that point if something went wrong.
 
I don't see a link in your post, but I would be concerned with them calling them trapezoidal threads since metric threads are trapezoidal and have a different angle than ACME.

This company sells 1/2-8 leadscrews and also says they sell taps, you might find what you need from them.

www.roton.com

Taps for Lead Screw Thread Forms - Roton Products Inc.

Along with these Taps for Lead Screw Thread Forms - General Information, Roton offers a large variety of screws and nuts. Find your size and put your order in today.
www.roton.com

A 1/2-8 ACME thread is not very common, are you sure it is not 12mm x 3?
 
On another hand it's not a big financial risk. If you buy the pair, I'd first run the tap through a few pieces of the same material/thickness as your project. It'd really stink to see a thread from you titled "How do I extract my broken Chinese 1/2" - 8 tap from my part with 10 hours work into it".

Bruce
 
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