Machsupport Forum
Mach Discussion => General Mach Discussion => Topic started by: Fastest1 on November 10, 2009, 08:14:00 PM
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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?
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Hi, Fastest1
Are you entering a Value in Settings Page ? and using G01 with F "feed speed" set to a value ?.
Chip
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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?
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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
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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.
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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
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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?
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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
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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
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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?
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An 1/8 step is a nice comprimise. Going to 1/16 may not do much for you. So it would be
40 steps / degree x 8 microsteps = 320 steps / degree
Then fool with velocity and accel some to see what works.
RICH
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I went 1/4 160 etc. I will try higher resolution. Accel and velocity are a little high for a Sherline. Thanks again going in to change jumpers. My next controller will have a hinged top and a dzus fastener!
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Never mind I set the A axis to 1/8th step and 320 steps per unit, 2400 velocity and 200 on the accel. I also changed my setting in gen config regarding a axis, unchecked it to make it linear. Why ? I dont see a change in anything? What does that refer to? Angular or linear, though I thought I understood the words just not the context apparently. Any tips there?
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There are a number of configuration settings that affect the A axis. In general config angular is measured in degrees and not affected by a whether you are working in inch / mm units and if inchecked it will be measured in linear units just like the other axis. Do a search , type in , ROTARY TABLE AS LINEAR , and you will find a number of posting s worth reading. There are a whole bunch of things associated with a rotary table. I have just used mine as an indexer
but you can program moves in ipm instead of degress , etc.
RICH
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Will look iinto it more, especially now the table moves! Thanks Again