View Full Version : tapping 303 stainless

03-09-2005, 09:20 PM
having trouble tapping 1/4-20 blind holes in 303 stainless Using flood water based coolant floating tap holder. can anyone help speeds ? Oil?


03-09-2005, 09:40 PM
Can you use form (roll) taps? They're stonger, and make stronger threads.

If not, try running the hole up to like .204ish (if it's for you, and not critical, you could go up a bit more on the hole dia and reduce stress on the tap), and yes, use tapping oil.

03-09-2005, 10:23 PM
You need to use a tin coated bottoming tap and try around 20sfm.
I would use a #5 drill ,put tap free oil in the hole. If thats to slow and you have a lot of holes to do then put twice as much oil in you water. Another thing are you using ridged tapping on machine? If your not and you have it use it. Try these speeds and feeds Speed 305 rpm's Feed 15.25 IPM and dwell in the bottom of the hole(G04 P300). If your still breaking taps then go up to around .208-.21 on your hole size. I tap stainless a good bit and i allways do pretty good on it.


03-09-2005, 11:02 PM
Thanks for the quick help Ridgid tapping with a floating holder or a fixed holder? Just wondering if you meant just the gcode setting. I don't have a seperate cooling pump just fill the holes? leave cooling off? thanks

03-09-2005, 11:15 PM
Well i meant use a M29S305(thats the machine code for riged tapping on my machine). I tap in a riged holder using riged tap on machine cycle. You can use your coolant pump you just need a lot of solubale oil mixed with water. But i have to say the tapping oil works best its just slow to do. I run Mori Seiki machines and they have Fanuc controls on them and the tapping code is writin like this


Thanks and i hope this helps

03-10-2005, 12:59 AM
Tapping 303 shouldn't be any real hassle... even with coolant. I think you need to ditch the floating holder though and go rigid ( ER collet or similar ). Unless your machine requires the use of a floating holder for tapping.

Like mentioned before, a good coated tap will work wonders. If you're doing a blind hole, make sure you have good drill depth for chip clearance when using a gun tap (regular tap ). Otherwise, go with a roll tap or a spiral fluted tap.

I tap a lot of SS and I tend to use Vegataps alot. I tap 300 series at 120sf with coolant and 400 series at 120sf with some moly dee. Your question was a bit vague on the details so I hope this helps.

Hey Rekd... I'm feeling a sense of deja-vu here... :D :rolleyes:

03-10-2005, 01:04 AM

Hey Rekd... I'm feeling a sense of deja-vu here...

http://img.photobucket.com/albums/v240/FukNRekd/Smile/grinyes.gif http://img.photobucket.com/albums/v240/FukNRekd/Smile/grinyes.gif http://img.photobucket.com/albums/v240/FukNRekd/Smile/grinyes.gif

03-27-2005, 01:14 PM
I've found using cutting oil from pipe thread machines, also works great on chewy material. When I tap SS/chewy material I use a straight bottom tap, Spiral taps
don't work very well
I stop the cycle and apply oil with a hand sprayer on the tap and in the hole before taping the hole

03-28-2005, 05:58 PM
I have a little trick for applying oil to my tap before tapping the hole.

I just put a cup of oil somewhere on my table, and tape it down so it doesn't tip over during rapid moves.

Then I write a sub that moves the tool to my cup, and dips the tap in it.

I call the sub. Then tap a hole (or more if I can get away with it).

Saves me from having to stand in front of the machine with tapping oil.