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Offline Fastest1

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Sherline cnc rotary table
« on: November 10, 2009, 08:14:00 PM »
After much playing around and reading about how to configure the rotary table
stepper combo nothing was really clear. My experiences with the 23-305-DS8A and
a Sherline cnc ready rotary table with a 72:1 ratio are as follows. Steps per ?
I wanted per degree so after 400 steps per rev X 72 rpms of the rotary's shaft =
28800/360= 80 steps per degree. I see no difference whether dia. is checked or
not. Velocity is at 806.4 and accleration is at 407.8125. All is spinning anyway
at a speed faster than I can really use while cutting. If I hit G0 A90 she does
90 degrees. I cant figure feedrates yet as this must be dependent on diameter of
the part I am cutting, right? Anyway any tips would be greatly appreciated. BTW
I could never get my vref over .21 (should be .294vdc I think @70% of .42 volts)
on the a axis? Seems to work well though. Does this sound like the right way to go?



I want to die in my sleep like my grandfather, not like the passengers in the car! :-)

Offline Chip

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Re: Sherline cnc rotary table
« Reply #1 on: November 10, 2009, 08:27:58 PM »
Hi, Fastest1

Are you entering a Value in Settings Page ? and using G01 with F "feed speed" set to a value ?.

Chip

Offline Fastest1

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Re: Sherline cnc rotary table
« Reply #2 on: November 10, 2009, 08:42:23 PM »
No, I was entering G0 A90 and getting a 90 degree movement. I am not sure how to really configure it. If I go with IPM then doesnt it depend on how far away the work is from the center of the rotary table? I dont really have a plan with it. maybe some lithopane cylinders of the kids and such. Am I going about it the wrong way as usual? Have you tried to set 1 up?
I want to die in my sleep like my grandfather, not like the passengers in the car! :-)

Offline RICH

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Re: Sherline cnc rotary table
« Reply #3 on: November 10, 2009, 08:45:37 PM »
Stepper is 200 steps / rev
Sherline Table is 72 rev / 360 deg in one rev

200 steps/rev x 72 rev/ 360 deg= 14400 steps / 360 degrees
So that's 40 steps  / degree   and if microstepping -10
40 steps / deg  x 10 = 400 steps / degree  


Then for velocity try 2400 and an accel of 200 and see if it skips, if it does lower them.

RICH                      

Offline Fastest1

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Re: Sherline cnc rotary table
« Reply #4 on: November 10, 2009, 09:01:07 PM »
Rich
Originally I tried 40, due to  my mathematical formula but movement didnt match anything I could understand
Right now, if I move 1 unit I go  1 degree. I must be half stepping I think. My real concern is more with what is the norm? Should I figure in degrees or inches? If in inches, where would you measure the travel? near the center or at the outer edges? My control of the stepper seems to be very good. I tried quite a few (read many) configurations before settling on these speeds. Is there a potential problem you see arising or just a difference in approaches? Thanks for the response.
I want to die in my sleep like my grandfather, not like the passengers in the car! :-)

Offline RICH

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Re: Sherline cnc rotary table
« Reply #5 on: November 10, 2009, 09:13:17 PM »
You have a choice in how you want to work. I think it's in the general config, A axis can be degrees or linear, and i have only used mine in degrees. If in linear then is based on the circumference of the circle your doing. Check your drive and see if you can change form 1/2 step to something better as you will get a finer resolution.( smaller part of a degree that you can turn the table to) No bragging here, but the one table i have will do 3.5 ARC seconds and I actualy use it with a callimator to check optical stuff.
RICH

Offline Fastest1

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Re: Sherline cnc rotary table
« Reply #6 on: November 10, 2009, 09:32:25 PM »
It is just a jumper change in my controller to change steps but do I want to 1/1 and set my tuning to the 40 steps per degree you alluded before? Btw I did try that setting just to confirm it after I read your post but it did only go half the distance/degree I wanted. Is better 1/4 step or 1/1 step?
I want to die in my sleep like my grandfather, not like the passengers in the car! :-)

Offline Fastest1

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Re: Sherline cnc rotary table
« Reply #7 on: November 10, 2009, 09:34:21 PM »
Now that I responded, if I am half stepping now and go to 1/4 stepping wouldnt I need a setting of 160 not 40? It seemed much clearer BEFORE I started thinking about it! LOL
I want to die in my sleep like my grandfather, not like the passengers in the car! :-)

Offline RICH

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Re: Sherline cnc rotary table
« Reply #8 on: November 10, 2009, 09:45:15 PM »
I don't know what settings you have available such as full step , 1/2, 1/4 1/8/ 1/16. If can change to 1/4   that will improve things and yes, you would change the steps /unit by aa factor of 4 ( four times as many steps to go the same angle ).
RICH

Offline Fastest1

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Re: Sherline cnc rotary table
« Reply #9 on: November 10, 2009, 10:09:38 PM »
Rich
I have all of the above available. I am set at 1/ 2 stepping now, you think I should set it to 1/4 step and change the step per unit to 40 with the other accel velocity figures?
I want to die in my sleep like my grandfather, not like the passengers in the car! :-)