Hello Guest it is April 13, 2021, 12:09:35 PM

Author Topic: Rotary axis feed rate?  (Read 2395 times)

0 Members and 1 Guest are viewing this topic.

Rotary axis feed rate?
« on: June 01, 2018, 05:04:44 PM »
Hi,

I'm in the process to setup the 4th axis in my machine with Mach4. In Mach3 there was an option under the tool path configuration where you could set "use radius for rotation" and then enter the radius on the settings tab. How do I do this in Mach4? I'm unable to find an answer to that in the forum or on the net.

If it not possible to do it in Mach4, has anybody solved it in some other way? I'm cutting with the X, Z and A moving at the same time, so therefore it would be nice to be able to translate the degrees/min to mm/min on the A-axis.
Kjell       

Offline Mauri

*
  •  321 321
    • View Profile
Re: Rotary axis feed rate?
« Reply #1 on: June 02, 2018, 04:40:35 PM »
Kjell,
This is not possible in Mach4 with any settings, it was never implemented.
The only way you can do it is if your G-Code has G93, this would require your G-Code Processor program to be able to generate G93 code.
The other alternative is to use the program from this website.
https://www.ganotechnologies.com/cnc/rapidrotary/
To use this in mm units use "Inch settings" as the mm will incorrectly calculate (Unit settings should not have been included in the formulae).
To make it more accurate (optimal) if your G-Code that you wish to convert has the A Axis on a seperate line for X/Y/Z then all axis with produce all the correct tool surface speed in line with your selected F Speed in the original G-Code prior to its conversion.
Do not be concerned about any big F numbers under G93 all are the correct surface speed.
Regards,
Mauri.
Re: Rotary axis feed rate?
« Reply #2 on: June 05, 2018, 04:36:32 PM »
Mauri,
Thanks’ for pointing me in the right direction. Been thinking about this a couple of days and have look into what my post is capable of. I assume that when you calculate the time for an operation you will use the A axis (the rotary)?
I took a bit different approach and assumed that tat the (commanded) Z is the is the radius of the circle. This is of course only true when X, Y, Z = 0 are in the middle of the axis. I then calculated the surface speed on the rotary to be the same as the commanded one and set the F to that value. I guess that would do the same as calculate how long time the operation will take?
Not sure if I’m thinking wrong here, but if this is true then this implementation would be easier (for me) compared with to calculate the time every operation would take. I have so far just performed a couple of “dry” runs, but it seems to work ok.
My worry is that when you go to a very small radius the speed of the X and Z will end up at max, which means I break the mill. But that would be the same if using G93?
Kjell           

Offline Mauri

*
  •  321 321
    • View Profile
Re: Rotary axis feed rate?
« Reply #3 on: June 05, 2018, 05:05:06 PM »
KJell,
In the program the Z (Radius) is used everytime it changes to calculate a new F Speed for the A Axis to maintain the correct surface speed.
The Maximum speed that the A axis can go is what you have set in your Motor Settings so you should have no concern.
On simple step cuts on a rotary you can calculate it, however if you are cutting up to a 4 Axis Simulataneus object the this program is the only way to do it.
Otherwise you need a program to generate G93 Code.
I have all the formulaes, however I cannot program lost a lot of my programming skills it just getting to old.
Regards,
Mauri.

Re: Rotary axis feed rate?
« Reply #4 on: June 05, 2018, 05:41:45 PM »
Mauri,

As I do it now, I use the Z as the radius, means, that every time Z is changing the post will generate a different feed i.e. a different degree per minute that corresponds to the programmed mm/min on the surface of the stock (I know most of you are inch guys

Offline Mauri

*
  •  321 321
    • View Profile
Re: Rotary axis feed rate?
« Reply #5 on: June 05, 2018, 07:26:06 PM »
Kjell,
If you are concerned about your A Axis speed then just go to the Mach4 Config/Control/Motors/Motor3 and reduce the Velocity to a max that you will be happy to use.
That will be the maximum the Machine will run the A Axis.
Regards,
Mauri.
Re: Rotary axis feed rate?
« Reply #6 on: June 16, 2018, 02:06:36 PM »
Mauri,
Thanks for pointing me in the right direction. After a lot of digging around, I think I have my post to generate time inverse feed (G93). Remains to test it live, looks ok in the “air”. “Just” need to get the macro for taking out the 0 in the stock with the probe to work for Mach4 as well.
Converting from Mach3 to Mach4 is not just that easy