Anyone using FANUC 18i 'Dynamic Fixture Offsets' ??

[Metal Flake (clocked in)]

Anyone, anyone....

 

We have a new Makino horizontal cell. We've been using the Dynamic Fixture Offset feature (G54.2 P1) with no problems until today when we tried it with simultaneous 4th motion. The machine was interpolating all 4axis but the location was way off what appeared to be only in X. When we got rid of the DFO it worked but we need to have the DFO working correctly with full 4th.

 

Anyone ever have to deal with this?

 

Many thanks for any comments!!

 

Dan

[mcpgmr]

Is there a "common offset" setting ? I programmed an 18i on a 5 Axis Super Abrasive grinder a few years back. We had a similar problem when the "common offset" setting got changed by mistake.I think it's on the first page when you push the offset key. It's been a while since I've messed with that control so my memory is a little fogged. HTH.

[Tom Dorgan from American Precision]

The 54.1 or External offset is the first one on the Work offset page. IT will effect all the other offsets since it is an additive offset.

[Psychomill]

Look in your Pro 3 (or Fanuc 18i) programming book on dynamic offsetting (G54.2). As I recall there was a user parameter that you set for the variance between the fixture (part) and the table rotation. It's rewritable as well with a variable in a program for different set ups.

 

Theres also a limit to the amount of correction too. I got away from doing this later though by adjusting the grid shift in the machine then building setups that were dead center to the table rotation. Haven't run into problem yet (not that there wouldn't be... one always finds a way!)

[Metal Flake (clocked in)]

The common offset is zero. I initially thought the same thing. Right now all indications point to an issue with the Dynamic Fixture Offsets not calculating the correct position change of the offset while the rotary is in motion.

 

You'd think the control would throw up an error if it wasn't meant to do 4axis interpolation. Which leads me to think that there is a variable in the parameters that needs to be adjusted....or something like that.

 

Hmmmmm....

 

Dan

[mcpgmr]

I forgot to ask what the code was doing. Is there a G93 on your x z b move ? I'm thinking the x only appears to be off because Inverse Feed rate is not turned on.

[Metal Flake (clocked in)]

Yep. G93 all the way.