Fluctuating feed rates?

[9 1/2]

Hey gang,

I've been making chips with my V2XT and have been increasing the feed rates as I go along. I've found that when executing X Z arcs above 30ipm the feed rates cycle up and down from 30ipm down and back rapidly. I've done lineal G01 moves at 100ipm and up (with no problems) but the X/Z arc moves seem to accelerate / decelerate (though I've not tried it on X/Y arcs yet)

I've searched through the machine settings through the PFM back end and through the BOSS front end and have come up with no solution.

There is no feed rate changes posted via my post processor, so that's not the problem. Is there an acceleration setting I'm missing?

Thanks all.

Owen

[machintek]

I remember that these machines could accel/decel feedrates when going around arcs inside/outside to keep chip loads/SFM the same.
I believe there is a way to turn it on and off by code in the program.

George

[9 1/2]

Yeah I was thinking the same sort of idea though, at this moment, I'm at a loss as to the M/G code. I'll have to look at the manual.

Thanks.

Owen

[machintek]

G44 cutter comp normal feedrate
G45 cutter comp modify feedrate
G99deceleration over ride

Per the book, constant surface feed is imposed by G45 to reduce the feed around a inside radius and increase the feed around an outside radius as a function of the cutter diameter compensation in effect. cancel with a G44.

Deceleration at the end of a motion block may be overridden by a G99 in the program line.

Yes, read the book.

George

[9 1/2]

Thanks George. I was already on that. I'll let you know if this changes my situation.

As a side note, I noticed the post processor plotted my X/Z arc in short X - Z motions. Not X-Z I/K.

Owen

[machintek]

I remember in G17 using X Y and R or X Y and I J.

George

[9 1/2]

Well gave G44 and G99 a try but no luck ........... if any one else has and suggestions Please pass them along ....

peace