[dustin1706]

Hey guys,

I come across home projects on occasion where I need to tap a lot of holes and I have always done so with cheapo Sears / Canadian tire hand taps. I now need to drill and tap a lot of holes in aluminum for my current CNC build. I have decided that I will pick up a procunier 2E or 3E on ebay.

My question is, where can I actually buy good machine taps online? I keep searching, but I only come up with commercial distributors that have no online pricing or purchasing. Right now I only need to do some 1/4-20 blind and through holes in aluminum, but it would be nice to pick up a few different common sizes for projects in the future.

Also, I understand that I want to use spiral flute taps for blind holes and spiral points for through holes. Would you experienced machinists recommend conventional taps or form taps?

Oh, and all of the tapping will be done on my 3/4 HP Drill press. (Craftex brand, same as Grizzly tools) It has almost 4 thousandths of runout, but that should be sufficient for tapping 1/4-20 holes, right?

Thanks!

[djr76]

MSC - http://metalworking.mscdirect.com/

the drill press in question should be sufficient to tap those holes

[dustin1706]

MSC - http://metalworking.mscdirect.com/

the drill press in question should be sufficient to tap those holes

Thanks man, I didn't even browse MSC for taps and google never came up with it.

Would you guys go cutting or forming taps for aluminum?

[djr76]

Depends, forming taps are a stronger thread and generally used in thinner materials, for deep material, I used cutting taps. FYI - cutting taps and forming taps use different size drills. 13/64 drill for cutting, #1 for forming on 1/4-20, use a lube and preferably uncoated tap for aluminum.

[Chrliev]

I like forming or roll taps the threads are stronger, tighter and there are no chips to clog up the tap.

For 1/4-20 threads, use a #1 (bigger) drill for forming and a #7 for cutting, when forming also be sure to chamfer the hole opening unless you don't mind that the thread ends stick up and out of the hole a little bit. Because of its metal on metal pressure, Roll Forming threads also works well using a lubricant such as motor oil or 3in1 oil...

[Chrliev]

I almost forgot, I buy taps from Mc Master Carr. They have a large selection of standard taps, ordered from their website, I get same day delivery...

[dustin1706]

Thanks a lot for the info guys!