Newbie- Rigid Tapping

[StalkDaddy]

I have never really had the need to tap before using our Haas TM1 mill, but we have a job in right now that had 25 tapped holes and I do not want to do all of them by hand. Since the machine had spindle orientation and rigid tapping appears fairly simple with our programming software, I thought I would have a try at it. My only question is if I can use a standard straight fluted tap for this operation or if I need something different. Seems to me they could break easily. Any advise?

[yoshi900]

material? thru hole or blind hole? how deep?

[StalkDaddy]

The material is 304 stainless, 1/4-20 thread tapped 1/2" deep. We also do a lot of aluminum stuff as well. If I start doing this, i might as well apply it to other stuff we do as well.

[christinandavid]

Would be inclined to add .2mm to the core hole diameter as stainless tends to close up on the tap.

A spiral flute may be better for blind holes but you will still need to keep tap and holes free from stray swarf and I have found them to be less reliable on tight tolerance threads.

There is also the option of roll tapping, which due to the larger core size required, is probably safer breakage-wise (and no swarf to rip up aly threads) but again, not that great if you need a tight tolerance thread.

DP

[Jawno]

You might consider a tapmatic too.
If your going into a blind whole you'll probably want to give yourself a couple tenths of hole beyond the end of the threads so the machine has time to slow down and reverse.
I second the previous info.
Exotaps work well for us.
Good luck.

Jawno

[underthetire]

Some coolants don't like tapping in 304 either. You might have to mix heavy, or apply tapping fluid by hand.

[Shane123]

i hate tapping in 304, and the 1/4-20 tap is usually weak and snaps easily in it. drill oversized by .003 or .004 if possible, and try peck tapping. if your controller don't support peck tapping, just program it to tap the same hole at different z depths. by the way, i hate tapping 304.

[Cruiser]

We had a series of parts to thread that had an unforgiving tight thread tollerance. The matr'l was stnls & inconel. After much head ache it was finally decided to mill the threads and throw the cutter away and replace it after x number of holes. It became very reliable once we knew how many holes was safe to do before changing cutter. When cutting tool was selected, we opted for the best tool that was available, period !

[5axisguy]

Do not use a floating holder for rigid tapping. Tap must be in a collet or milling chuck, tight!