Hello Guest it is September 28, 2020, 05:46:26 AM

Author Topic: "A" Axis Help Needed  (Read 2855 times)

0 Members and 1 Guest are viewing this topic.

"A" Axis Help Needed
« on: December 03, 2013, 05:28:02 PM »
recently added a cnc rotary table to my mini mill. Having a problem with my settings. I've made most of the config. settings I've found here. When I move the table with a G01 code or code from a wizard, the table rotates beyond the desired stop point, and continues to rotate. I'll try and post the .xml file. Any help and suggestions will be appreciated. 

Offline RICH

*
  • *
  •  7,412 7,412
    • View Profile
Re: "A" Axis Help Needed
« Reply #1 on: December 03, 2013, 07:03:20 PM »
Usualy the rotary table is configured in degrees.
Thus,
G01 A 360 F1 would have the table rotate 360 degree's at a feedrate of 1.

Not sure what motor is driving your roatary table,ie; you need to tune the A axis just like the other axis's calculating the appropriate number of steps per degree, enabling it, and tuning for acceleration and velocity.
All in the manual.....

RICH
Re: "A" Axis Help Needed
« Reply #2 on: December 03, 2013, 07:31:14 PM »
Rich,

The rotary table has stepper motor. "A" axis is configured for angular not linear. I used mach 3 to set the steps per and when told to "go to zero", it does. I have the manual printed and I've read and had all the checks that I believe are applicable. What else could it possibly be?

Offline RICH

*
  • *
  •  7,412 7,412
    • View Profile
Re: "A" Axis Help Needed
« Reply #3 on: December 03, 2013, 08:44:13 PM »
Allen,
Your steps per unit for the A axis are 10000.
You would have a gear ratio of 1800:1 which dosen't seem correct.......
ie;
200 steps per rev for motor x 10 micro steps x 1/360 degrees per rev x 1800 gear ratio = 10000 steps per degree

What is your gear ratio for the rotary table?

I know my Sherline is 72:1 ( 400 steps per degree) and for my Klinger it's 180:1 ( 1000 steps per degree).
 

RICH
« Last Edit: December 03, 2013, 08:58:10 PM by RICH »
Re: "A" Axis Help Needed
« Reply #4 on: December 03, 2013, 08:58:39 PM »
Rich,

Admittedly that whole calculation thing is confusing. Here's the data I got for the table.

36:1 worm wheel (gear, I guess)
max angular velocity 30 deg/sec
max angular accel. 250 deg/sec
rapids over 180 deg/sec
nema 23 stepper w/ 1.8 deg steps
7200 full steps per revolution
backlash within 15 arc minutes
1 amp winding current or .5 amp full winding current.

So, you're saying the answer is in here somewhere?

Offline RICH

*
  • *
  •  7,412 7,412
    • View Profile
Re: "A" Axis Help Needed
« Reply #5 on: December 03, 2013, 09:11:00 PM »
BTW,
Rotary Resolution is 1/ steps per degree.

Linear conversion:
1 second per inch of distance = 0.000004848"
1 minute per inch of distance = 0.00029888"

So the Klinger at 1000 steps per degree has a resolution 3.6 seconds and at 1 foot that equates to a linear change of 0.00021".

Just some stuff, ;)

RICH

Offline RICH

*
  • *
  •  7,412 7,412
    • View Profile
Re: "A" Axis Help Needed
« Reply #6 on: December 03, 2013, 09:17:46 PM »
Quote
So, you're saying the answer is in here somewhere?
Your steps per unit:
200x10 ( i assume your are microstepping )x (1/360) x 36= 200 steps per unit.

For tuning ( same as the yo tuned the other steppers...)
Start with a low velocity say 5 and accel of 1, then just double the velocity until it skips. Then reduce the velocity at skipping by 40%.
Now start increasing the accel until it skips .  
That should get you in the ballpark quickly and you can refine later.

RICH
Re: "A" Axis Help Needed
« Reply #7 on: December 04, 2013, 12:59:30 PM »
Rich,

Problem solved. Adjusted velocity and acceleration, now I'm in business. Thank you for your help.