How to set Rapid move ipm?

[RandyL]

"Rapid" moves, what setting determines how fast the rapid is?
Allin1 MPU11
I have max speed rate set to 150ipm, however when doing a MDI rapid move, i see the main screen display going up to ~200ipm (displayed to the right of DRO).
Does parameters 357-364 "max rpm" effect Rapid ipm?
should parameters be set at 0 or use the motor rated RPM in the parameters?

CNC11 stalls when i set move my max speed rate to 200ipm, load meter bar moves all the way across then stalls errors. calc of rpm/rev per inch*.85 gives me a value of 255 ipm estimated. I cannot come close to that value without stalling.

Thanks
RL

[cncsnw]

The Max Rate value on the Machine Configuration -> Jog Parameters table is the rapid rate for that axis.

Those are individual axis limits. The speed displayed on the status window is the combined (diagonal) speed.

If you do an X-Y rapid move on a 45° angle, so X is going 150 in/min and Y is going 150 in/min, then the combined feedrate will be about 212 in/min.

If you need to limit the combined/diagonal speed (perhaps because your servo power supply is not sufficient), you can set Machine Parameter 38 to the maximum multi-axis speed.

[RandyL]

Thank you,,
That makes sense.
Displayed ipm is a combined total from all axes moving at that time.

[Gary Campbell]

cncsnw....
Can you explain a bit more how these feeds are handled by Centroid?

In a previous life (lives actually) if I set my XY feedrate at 100ipm and executed a 45* rapid the axis (XY) feed would be 71 and of course the combined feed would be 100.

Apparently Centroid does make these speed interpolation calcs I the same manner?

[cncsnw]

Gary,

Are you asking about a feedrate (G1) move, or a rapid (G0) move.

If you "set the XY feedrate at 100 in/min" and then do a G1 move on a 45°angle, the combined speed (tool feedrate) will be 100 in/min, and X and Y will each be moving about 71 in/min.

If you do a G0 (rapid) move in the same direction there is no "set the feedrate", except in the Machine Configuration menus where you tell the control what the maximum achievable rate is for each axis. G0 means get there as fast as possible. The move will go at the fastest speed it can go that does not exceed the per-axis Max Rate value for any of the included axes.

Centroid does handle G0 moves a little differently from many controls, in that it still interpolates in a straight line. For example, assuming that the X and Y Max Rate values are equal, and you program "G91 G0 X5 Y10" then Y will end up moving at its Max Rate, but X will move half that speed, because it has half as far to go in the same amount of time. Many older controls would do a "dog leg" move, with both axes moving at max rate, and with X getting to its endpoint and stopping while Y still has half the move left to go.

[Gary Campbell]

cncsnw..
Thanks for the info. Yes I was looking at G0 and thinking G1.

Thankfully, I have never seen the dogleg version. (sheltered life)

Controls that I am used to will alway interpolate straight line, but the interpolated velocity (G1 or G0) will not exceed the max rate (G0) or the current feedrate (G1). So with your 5 to 10 example and rapids at 1000, I would of course, see a 2:1 speed ratio, but with the long movement at 890 and the short movement at 445. Which is the same as feed move are interpolated. Of course the Centroid rapid version gets there 12% quicker.

I read your calculating rotary feedrate doc that was posted a while back and it seems that there is something I don't understand ..yet. Is there a location for documentation explaining these relationships? I have been pouring over the mill manual, but in all honestly using the hunt and peck method rather than the cover to cover.

Thanks for your time