Sorry about that, i just realized there are additional post options 

Quote from: Mirko KD on January 21, 2014, 03:38:35 PM

I increased the velocity for A axis to 18000 which is the highest value i can enter at 35k kernel speed, and total time was 10:20 - not a big difference. Then i increased the acceleration to 4725 (maximum value) and now total time dropped to 7:14. I guess i would have to increase the kernel speed in order to set higher values for velocity and acceleration?

Are talking about actual cutting time or estimated?

Most CAM programs that I have seen have an time estimation feature but also have a scaling factor that needs to be set to get that estimation somewhere near actual.  Machine acceleration and other factors are unknowns.

I was talking about actual cutting time.

In RhinoCam, to my knowledge there is no option to set scaling factor for time estimation, but from other users` experiences the actual cutting time is somewhere at 1.2 x estimated time.

I intended to run your code on my machine to see long it took.

However a quick calculation of F800 at 25mm dia. works out at approx 3700 degrees/min of the rotary axis.  

My rotary max's out at 3000 degrees/min.  So it would not give a proper comparison of time taken.


I assume that finishing toolpath is done with a ballnose cutter.   Why not run "along axis" rather than "across axis" ?  Much less demanding of rotary axis feedrate.

Greolt

Cycle time is 2:17 with  " A Rotations Enabled " unchecked in ==> Config  ==> Toolpath.
Alex

I intended to run your code on my machine to see long it took.

However a quick calculation of F800 at 25mm dia. works out at approx 3700 degrees/min of the rotary axis.   

My rotary max's out at 3000 degrees/min.  So it would not give a proper comparison of time taken.


I assume that finishing toolpath is done with a ballnose cutter.   Why not run "along axis" rather than "across axis" ?  Much less demanding of rotary axis feedrate.

Greolt

My calculation was the same as yours. In motor tuning for rotary axis i have 4000 degrees/min velocity (which should be sufficient) and 400 for acceleration, so it seems that acceleration is the limiting factor here. When milling across axis on very small objects, rotary axis makes hundreds of tiny turns, accelerates and decelerates in short intervals, so unless the acceleration/deceleration is instantaneous, the actual feed never reaches the projected value. That`s just my guess.

Why not run "along axis" rather than "across axis"? Well i was thinking the same thing, it is much less demanding of rotary axis, but unfortunately there is a downside - for finishing toolpath the total machining time is 3 to 4 times longer than with "across axis" (and i `m really trying to cut the milling time as much as possible). At least this is the case with RhinoCam, i haven`t tried any other CAM software yet.

Cycle time is 2:17 with  " A Rotations Enabled " unchecked in ==> Config  ==> Toolpath.
Alex

What do you mean by "Cycle time is 2:17"?

Hi,
forget what I said, I am stupid.   

Yes the limiting factor is the acceleration and a bit the A velocity.
With Velocity at 8000 and acceleration at 10G your attached G-Code runs in 2 minutes and 20 seconds.

You can change the acceleration by typing the value you want into the  acceleration field and klick  Save Axis Settings.
Doen't klick on the acceleration slider after that.
Alex

Hi,
forget what I said, I am stupid.   

Yes the limiting factor is the acceleration and a bit the A velocity.
With Velocity at 8000 and acceleration at 10G your attached G-Code runs in 2 minutes and 20 seconds.

You can change the acceleration by typing the value you want into the  acceleration field and klick  Save Axis Settings.
Doen't klick on the acceleration slider after that.
Alex

Hi Alex,

I entered 8000 for velocity and 10000 for acceleration as you suggested, but i get total run time of 7:14 mins. I have no idea what could be the problem.

Could you please send me your Mach profile (xml file) so i could compare all the settings to my current profile?

In addition to getting Mach set up correctly (already being addressed by others), you might take a look at using the G93 federate, provided your CAM supports Inverse Time.

It seems that if you identify A as rotary and that the steps per degree is correct, Mach will ignore everything else and calculate the correct 4th axis federate for a move using G93 (provided you have the bandwidth - rotary axis pulse rates can get very high in a hurry).  

 Mach will ignore everything else and calculate the correct 4th axis federate for a move using G93 (provided you have the bandwidth - rotary axis pulse rates can get very high in a hurry).  

I have never used G93, my CAM does not support it.

However I assume Mach will still honour the maximum velocity as set in motor tuning. (normal rapid speed)  If so, then why will pulse rates go beyond normal levels ?

Greolt