[capmkrk]

My company has a number of HAAS VMC's mostly 5 yrs old. I have a question about a contour toolpath that has a jerky motion, it appears to be making point to point moves. I have seen the same behavior on Fadal and Mori-Seki Mills, and the solution on the Mori was to turn on look ahead G8 P1, to turn it off its G8 P0, and on Fadal it was some G code Which escapes me at this time. How do we fix this on our HAAS?
Thanks Guys

[mattpatt]

Usually this is related to the corner rounding and/or smoothness settings.

I'm thinking that you need to check the settings 85 and 191. These are for max corner roundness and smoothness. The defaults are 0.05" and "medium".

Leaving the defaults as they are, but programming a "G187 P1" before your contour (or whatever) will see te machine move much smoother through the corners as it doesn't come to a stop at each end point.
I use this in every program depending whether I'm roughing or finishing.

You can control both the smoothness and corner roundness settings by programming say G187 P2 E0.05. This overrides the machine settings, but in this case would give the defaults anyway.

If you went to G187 P1, it would over ride the smoothness setting (to "rough"), and I believe it then multiplies the corner roundness by 4 so would whizz through the corners, with no jerking, but it will cut corners and lose accuracy as it doesn't reach it's prgrammed destination before shooting off on the next line.

To be honest, I don't know if it's an exact science as to how to set the roundness, as no one on any forum that I've searched has ever come up with the magic formula. It's more about what you can get away with it would seem, as it's all heavily affected by feedrate.

My machine is a VF2 (VF2SS on the way to accompany it) and most of the parts I make are aluminium. My roughing cuts can have a programmed feedrate in excess of 10000mm/min, but the only way that the machine will ever get even close to seeing that is by programming in a G187 P1. And even then with shorter point to point moves it won't get close to actually hitting the programmed feedrate. But....it makes a huge difference to cycle times and if I left it at the default setting, or worse still, changed setting 191 to "finish", the machine would vibrate it's way out of the door and up the road, as it would try to hit each point accurately.

For the record, I generally leave at least 1mm stock on the part for the rough cut, as using "rough" kills the accuracy, so beware!

If what I've said doesn't make enough sense, just do a google search on "Haas G187" and everything you ever wanted to know will become clear.

If that's not the problem then I'm sorry ;-)

Cheers,

Matt

[capmkrk]

Hey Matt, thanks alot! I'll give it a try

Cheers back at ya

Don