Rotary Axis Feedrates

[donmul]

How can i stop mastercam from inputting various feed rates when i do a rotary axis substitution? Is there an option in mastercam or do i have to modify the post?

[HEED]

Are you talking about inverse time feed rates ? They are on every line, and that's actually the preferred method on rotary work, however it's a GIANT pain in the @$$ to try and figure what it's really feeding at. You can change it in your mach def. if you want to be in upm rather than inverse time

[donmul]

Thanks Jesse. We got it figured out. We edited the post to eliminate rotary feed.

 

Donnie

[Zoober]

Could be dangerous if you are doing a combination of rotary/linear feeding. 1/T is designed to control rotary and linear feeds at the same time.

Consider this:

You are moving X3.0 F50. - pretty easy. 50ipm.

And, A30. F50. - still easy. 50dpm.

Now, X3.0A30.0F50. - ipm or dpm? will that helical move be correct? nope.

 

Better than I can explain.

 

 

HTH

[HEED]

That's why they use DPM feedrates in inverse time, Donmul. Especially when your diameter changes on rotary you can really have feed rate issues if you are trying to feed in IPM on a part that is much bigger than your programmed for.

[Storkman]

quote:

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however it's a GIANT pain in the @$$ to try and figure what it's really feeding at.

---

Not really. From the Fanuc manual:

 

60/programmed feed = seconds to complete

 

60/10 ipm = 6 seconds

 

60/6 ipm = 10 seconds

[HEED]

When I post using the inverse time feedrates, it posts feedrate on every line, is there a easy way to compound all these feedrates ? That's a slick little formula for figuring it out, though. Much simpler than I have seen in the past.

[Zoober]

Inverse time feedrates must be on every line for most controls - ie:Fanuc

The reason for this is because the feed describes the time for a given move to be executed, and if the move length is different, then so is the feed value.

 

HTH

[Storkman]

I did change a post once to use a single feedrate. But you will get a real irratic movement. It will feed slow as heck around corners (rotary moves) and go wild on linear moves.