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1/4 -20 tap feed

gdgambler

Hot Rolled
Joined
Oct 1, 2006
Location
K. Falls, Oregon
Here is a really dumb question. Can some one or better yet would someone tell me the feed on a 1/4-20 tap. I thought is was .05 but the table runs way to fast on a dry cycle. It would break the tap. I am obviously doing something really wrong. I have tapped 10-32 holes with no trouble. Thanks
 
Lead on a 1/4-20 is .05. Thus, 1,000 RPM X .05=50 IPM. If this isn't a canned threading cycle, are you using a floating holder?

RAS
 
What control is this? I'm familiar with Fadal's g84 for rigid tapping. Both speed and feed are called out in the line invoking g84.

RAS
 
Found it. Per revolution feed... Actually, the figures are right; it will look fast. However, if your machine does not have a tapping cycle, I think the IPM might work better. You should be running in high range, to enable the spindle to reverse quickly. And, DON'T PROGRAM FOR THE ACTUAL Z DEPTH! Allow for pullout on the holder!

RAS
 
When I threaded 10-32 I programmed g95f.0313 as the feed and it ran awsome. Made 5000 parts without a glich. I thought to find the feed rate I divide 1" by 20 and it would simply give the feed rate. It just doesn't seem to work for 1/4 - 20 now.
 
I have a friend that is great with these machines that usually helps me but he is watching football and I didn't want to bother him right now. Hoping to do this without his help.
 
Yes, it does. But a 20 pitch thread is much coarser than a 32. It looks fast; at 1000 RPM (speed I run 1/4-20 in aluminum), it looks scary. Keep your finger on the big red button, and try it. Preferably on a piece of scrap first.
1" divided by pitch is always right.
RAS
 
RAS, I never thought about the pullout on the holder. That means the tap would actually feed in even more then the program allowing for the spindle to reverse right. Might be why I broke some taps in the past. Thanks a bunch.
 
Exactly. On thru holes is not usually a concern, but blind holes will getcha everytime. Measure the pullout on the holder, and program your Z depth accordingly. The best bet in blind holes are thread forming taps; no chip to worry about.

RAS
 








 
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