thread lead?

[3axisrookie]

Just a simple question that will help my tapping issues. What is thread lead for. Thanks.

[Delw]

that tells how many inches(actually fractions of an inch) per revolution a thread goes

for example a 1/4-20 is 20 threads per inch. but in one revolution it is .050 per full turn

[3axisrookie]

Was cutting that exact thread, well trying to. Used .050 for the q value. But used f 4. Thinking it was the feed. But now see that the f is the rpm. So basically the fadal figures out it's own feed rate based off the rpm and tread lead?

[Delw]

only if you have ridgid tapping, if you dont and use compression tapping then you have to use the 10% rule.
there was a really good thread back a month or so in the fadal section(this one) that gave all kinds of examples of threading. its worth the read.

[Neal]

Delw
I disagree that you HAVE to use the 10% rule. Fadal retracts the tool 5% faster than it goes in. If your clock card is properly adjusted there is NO problem programming the correct thread lead going in. Also, it does not matter if you are rigid tapping or compression/tension tapping.

Neal

[Delw]

Neal,
Thanks I didn't know that. I hadnt compression tapped on a fadal that much since 2001, and my other machines I just used the 10% rule.

[3axisrookie]

Thanks for the replys. Not sure what the 10% rule is, but managed to get it done. First time tapping on cnc. Worked fine with the pitch for q value, rpm for f value, and g84. Was a through hole, so no issues. I'm sure once a blind hole comes up will be a different story.

[Delw]

The 10% rull for comprssion tapping is pretty much this.


When you are feeding into a hole you want to go slower on the z axis then the actual lead. this will allow the compression to draw the tap into the whole keeping it from push through and damaging the thread lead.
when coming out you want to go faster on the z axis so that the same thing doesnt happen to the thread lead.

for example a 1/4-20 is a .050 feed feed into the hole at .045 and out fo the hole at .055

compression tapping has anywhere from .100 - .250 play in it, this is helpfull when starting a thread as on compression you never know where the thread will start ( what angle of the hole)

Hope that helps, someone correct me if I am wrong.

[3axisrookie]

Definitely helps. Thanks. How can you tell it to feed faster on the way out though?

[Neal]

On your G84 line place a "P" word. That "P" word will be a percentage. I.E... P10 would be retract 10% faster than going in.

Neal

[3axisrookie]

Thanks again. Have to tap a 4-40 thru hole in aluminum tomorrow. Will try all this then.

[Delw]

use a roll tap they are stronger and dont break as easy on a 4-40.

Neal I forgot about the p word in the g84,
On the acrolocs I always used a g01 LOL