I just had to tap about 40 holes. I bought a gun tap and threw it into my 1/4" impact driver and hoped for the best. They were 1/4-20 in 1/4" mild steel, and all of them came out great, and quickly.
I just had to tap about 40 holes. I bought a gun tap and threw it into my 1/4" impact driver and hoped for the best. They were 1/4-20 in 1/4" mild steel, and all of them came out great, and quickly.