Centroid Community CNC Support Forum

Gentlemen:
I am attempting to cut a spiral using a linear move 1 inch in 8 turns. I am using a centroid factory A axis. The max speed setup is X =100, A=7900. When running each separately, they run normally at their set max speeds. when trying G1 X1 A 2880 F7800, It just crawls!!
The onscreen feed rate is between 0 and 0.1 flashing. It takes several hours to complete. I tried to do only 360 degrees, and still crawls.
I include report file, CNC code, and photos. I have a video, but I am afraid that its too big. Please tell me how to get x and A to move at reasonable rates. I am stuck!
Thanks!
Mike

Look at Parameter #2 in the manual Slaving rotary to a non rotary axis feedrate.

You also can use G93 Inverse Time

Uwe

Help! I put 40 in the parameter 2,
I prepositioned XO YO Z-0.05 A 360.
THEN I put G93 G1 X 0.9235 Y0 Z -0.05 A -2160 F12.
I included a screenshot. Note the feed rate 0 to 0,1 flashing
IT STILL CRAWLS ! No faster
THE REPORT.ZIP STILL APPLIES
Please Help, I am stuck! I can't find a Tech bulletin. I can't find where to study...

Your A-axis is set up to 4000 deg/min, so moving 2160 deg will take over 30s...

Uwe

Check the Parameters listed at the bottom of page 404 of the manual.

Uwe, how about 3 hours or more?, Mike

There is something not ok with your settings, the g-code runs 90s with A-axis on 4000

G93 F12 will not work, because the A-axis is not that fast.

Also F7800 ist to fast, F4000 is max. for your set up on A

But I can test this only on a mill with Acorn.

Uwe

G93 F2 was tried as well as 5, no difference.
The 7900 was set up by the dealer. It runs fine otherwise, it doesn’t complain about the speed. This is a servo system.
O help,
Thanks, Mike

The A axis max rate is set at 7900 degrees/minute. There is no reason it should not be able to run at F7800.

The 4000 degrees/minute figure is for the fast jog rate, which is not in play here. That only affects jogging.
The report can be a little hard to read, since there are now four fast jog rates listed before the max rate.

I recommend leaving Parameter 2 at 0. Slaving rotary moves to linear moves is only useful for offset C-A heads, where rotary movement does not contribute to the tool feeding through the material.

I am guessing that the "parameters listed at the bottom of page 404" to which dpascucci_support refers are the Smoothing parameters. According to Mike's report, he has Parameter 220 = 0 (not using Smoothing). Therefore the smoothing parameters should have no effect.

Uwe is mostly correct that "G93 F12", combined with a move that would take A from +360 to -2160, would not move at the requested speed. In inverse time mode, "F12" means to do twelve moves (G code lines) per minute: i.e. to complete the given move in five seconds. Given the max rate of 7900 degrees/minute, the movement through 2520 degrees should take a little under 20 seconds.

However, on a Centroid control there is generally no problem with programming a move at a higher feedrate than the axes can achieve. CNC12 should just clamp the speeds (scale them all down proportionally) so that the move still follows the intended path, and no axis is called upon to exceed its max rate.

All that said, I do not immediately see a reason for the problem. I recommend trying a few moves in MDI mode. Some of these questions you have already answered, but let's start at square one. All my examples will use incremental (G91) so that we do not have to worry about returning the axes to any particular starting position. Make sure your feedrate override is at or near 100%.
Does that do one revolution, in a little under three seconds?
Does that do one revolution, in about six seconds?
Does that make X move one inch, in about one second?
Does that move X one inch, and A one revolution, simultaneously, in a little under three seconds?
Does that move X one inch, and A one revolution, simultaneously, in about six seconds?

Let us know at what point in this sequence the behavior of your machine diverges from the expected behavior.

cncsnw wrote: ↑Tue Oct 03, 2023 6:46 pm The A axis max rate is set at 7900 degrees/minute. There is no reason it should not be able to run at F7800.

The 4000 degrees/minute figure is for the fast jog rate, which is not in play here. That only affects jogging.
The report can be a little hard to read, since there are now four fast jog rates listed before the max rate.

,,,,,

Ups, I stopped reading after fast jog rate

Uwe