Tapping lots of 1/4 x 20 blind holes in 6061

[woodchucker]

I would suggest using a "Spiral Flute" tap. they are engineered to direct the chip up the flutes and out of the hole. They work well in aluminum if kept lubricated with either a tapping fluid or a light oil. They will leave the same thread in the bottom as a bottoming tap. This eliminates the ball of chips in the bottom of the hole and the necessity of changing taps and tapping each hole twice.

I agree.

 

[JR49]

So what is the purpose of a spiral point tap?

Spiral Point = pushes the chips in front of it- best for through holes
Spiral Flute = pulls the chips out behind it much like a drill bit- best for blind hole
Happy Machining, JR49

 

[David S]

Mike Spiral point on left, Spiral flute on right. I still think a spiral flute plug tap may do your job in on shot if you are using them in a drill press.


David