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Author Topic: Slave axis problem  (Read 2760 times)

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Slave axis problem
« on: October 31, 2010, 09:59:22 PM »
I am converting an old pantograph burning machine to a cnc router/plasma. I originally was driven by a rack gear on one side of the gantry. I added a rack on the other side so it would not rack when using the router. The problem is i couldnt get the same diameter pinion gear as the original so it is slightly bigger on the one side so the gear ratio is slightly different. i thought that when you set up each drive it would work as long as the perimeters was right for each drive, but when slaved it only gives the number of pulses for the x drive. Is there any way to fix this or am i going to have redesign my whole rack setup to match both sides?   

Offline Hood

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Re: Slave axis problem
« Reply #1 on: November 01, 2010, 03:22:31 AM »
As far as  I know a slaved axis has to be the same steps per unit as the master and there is no way to change that.
Re: Slave axis problem
« Reply #2 on: November 01, 2010, 07:48:35 AM »
I was really hoping that wasnt the case. lol  Guess if I cant get the right ratio thru my timing belt gear reduction im gonna have to order another rack/pinion.

Offline Tweakie.CNC

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Re: Slave axis problem
« Reply #3 on: November 01, 2010, 09:24:47 AM »
What is the ratio of one to the other as far as steps are concerned, is it a whole number ?

Re: Slave axis problem
« Reply #4 on: November 01, 2010, 12:56:25 PM »
I dont think its a whole number. One side is 5092 the other is 4244 steps per inch. The one pinion has a pitch dia.of 1.25 the other is 1.5 , then it goes thru a 25:1 belt reduction. Then 1000 count encoder in quadrature to make 4000 count per rev. ,then a x5 step multiplier on the gecko servo drive. lol Making my brain hurt just thinkin about it, Im guessing maybe ill have a order for mcmaster carr for another rack in my near future.
Re: Slave axis problem
« Reply #5 on: November 01, 2010, 01:32:08 PM »
I have found a gear that will work. When i ordered the rack/gear from mcmaster carr they didnt carry the gear size I needed but I thought it didnt matter because i thought you could just enter the the different counts into mach, which works on an individual axis but not a slaved i guess. Anyway i have found the right gear thru msc so it will b an easy fix. Thanks for the help