tapping

[cncshawn]

Having problems with tapping a hole. Using a 1-14 3 flute bottoming tap. trying to tap a casting about an 1 1/4. Problem is the machine is thrown into alarm almost to the bottom of the hole. When I get the tap out, it is packed with shavings. I thought maybe a spiral flute might help so I ordered one today. Should be here tommorow. If this don't work, does anybody got anymore suggestions? Maybe tap halfway, pull out and then finish tapping?


Thanks,

Shawn

[HuFlungDung]

Shawn,

What material is it? If it's cast iron, then a straight flute tap would be okay, maybe a plug version instead of bottoming, though.

What kind of machine? Does it do repeat rigid tapping?
I would think that it would be good to take a couple of passes to do the hole, so that you could get some new lube on the tap as it progresses farther down.

Have you considered thread milling? This is what I would recommend for the cleanest looking threads, and far less brute force is required to drive a thread mill than a tap.

If its a blind hole, a spiral flute is generally the correct choice for normal tapping.