Acme threads 1

[MachinistMike]

I am wondering if anyone has used the acme taps that have the rougher tap in front of the finish tap. I am tapping a .625-8 acme thread in a brass bushing. Any info. on the subject would be great. ie drill size to use.

 

[bigj2]

This is an acme tandem tap and works very well. The tap size can be calculated by taking the reciprical of the pitch (8) and subtracting it from the diameter. 1/8 = .125 or Diamerter 625-.125= .5 or tap drill. This calculation works for most English threads.

 

[MachinistMike]

Thank you for the tip. I used the tap and it did work very well. Thanks again.