Need help tap drill sizr

[Mike8623]

What size drill do you use for a 5/8-30 tap, cant find it anywhere

 

[jcp]

19/32" should give you about 72% thread. Look at this calculator...https://www.newmantools.com/tapdrill.htm

 

[Mike8623]

Yah, i tried that drill.

I am trying to get a ideal 310 die to screw into a 7/8-14 adapter so that i could use those dies in my dillon 550 reloader and not have to buy new dies. The ideal 310 adapter inside thread is supposed to be 5/8-30. Well i have a 5/8-30 tap and i redrilled the hole with a 19/32 drill bit...then retapped for 5/8-30 and the inside diam is still too small. I dont get it.

 

[jcp]

What does the od of the factory 310 die 5/8-30 male thread measure? What does the od of the 5-8-30 tap measure?

 

[Mike8623]

The od is 7/8-14 on the adapter and works just fine with the dillon head. It is the inside diameter that has me confused. It is supposed to be 5/8-30. The id on the adapter mics at .590" the tap od mics at .625" the od on the die mics at .645"

My head is just swimming

 

[Mike8623]

I could make a larger diam. Tap at 30 threads but my lathe wont cut 30 tpi

 

[jcp]

Then the thread is not 5/8-30....it's .645-30. You will need to find someone who can do a .0333 lead.

 

[jcp]

What lathe do you have?

 

[Mike8623]

Yah, you are right. I have 9 of those dies in 3 different calibers and was hoping i could just make 9 adapters on my lathe and save 300 dollars by not having to buy 3 different sets of dies at 7/8-14 .

 

[Mike8623]

The lathe is a grizzly g0709.