Be very very careful of that $7 tap its most likely a carbon steel tap and not meant to cut threads just clean them.And a they brake in a hart beat and don't last for crap. To cut threads you need a High speed steal tap if it doesn't say HS or High Speed on it you are just throwing your money away. The way I found out about carbon steel vs high speed steel taps. I need to tap a few holes in a part I was making and I didn't have the right tap so run to the hardware store 7mi. from home 5:30 in the after noon got 2 taps I needed the real tool store is 40 mi away. Tapped one hole with the first tap got about 1/2 way truth the hole and broke the first tap got the tap out with a tap extor finished the first hole with hole tap #2 and tap #2 would not cut in hole # 2. Called a machinist friend too see if he had a tap the size I needed. I told him the story and he asked me if the the tap was Carbon steel or High Speed ? I went and looked at the tap package they where in sad carbon steel. Don't ever use a CS tap on anything that you are going to cut threads in they brake and don't last. most taps I see at the NAPA and the hardware store I see are Carbon steel so please check before you start. Ken

 

if you are just cleaning out threads, take a stock head bolt and die grinder and streak bolt in about 3 passes on bolt. this will work pretty good for cleaning. ofcourse it wont cut new threads.

 

x2

 

x3 a good quality tap will last you a very long time and cut many threads

 

i also just did A1s and thought it woudl be smaart to buy locally the tap. haha right, fastenall wanted $18 for one. and it was a 4" one. luckily i had the head off so it was no big deal. but they are holdin 55psi nicely