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Author Topic: strange circle cutting  (Read 2036 times)

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strange circle cutting
« on: August 09, 2012, 08:36:34 PM »
hello, i'm kind of new to this machinning with cnc.

i recently converted my grizzle 8086 mill to cnc using hass plans, using a c11 driver and stepper motors.

i have cut a few simpple things with good results, they were basicly straight cuts in both x and y direction.  did 2 text cuts as well that had some curved lines.

i am using solid works cad with the HSMXpress for poast code.

i loaded the code cut the part and it came out the correct demintion in the general x axis direction. and as it got close to the max y direction things stoped moving???

i'm cutting a 5/8 hole.  in the x direction it measures 0.624 aproxamatly but yis 0.598 aprox. see the pic. 
any idea on what is happening???

Offline Tweakie.CNC

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Re: strange circle cutting
« Reply #1 on: August 10, 2012, 02:33:53 AM »
It could be backlash in one or both leadscrews or it could be a loose motor coupling / pulley etc.

Tweakie.
PEACE
Re: strange circle cutting
« Reply #2 on: August 10, 2012, 03:41:46 PM »
motors are direct coupled the coupling is tight backlash is on. it appears as if the y axis is not responding to smaller movement steps??

i set up a dial on the y axis and set jogg to step at 0.001 then wwalked the table getting this results

   DRO            Dial
0.0000           0.0000
0.0133           0.0000
0.0143           0.0000
0.0153           0.00098
0.0163           0.0012
0.0174           0.0022
0.0184           0.003
0.0194           0.0041
0.0204           0.005

i ran the table in for 1 inch befor starting so it would be well out of any backlash .

also while running these i noticed tha for some strnge reason the DRO for the x axis started gumping up by about 0.100" but no movement on the machine just the DRO?????? then it stopedand i havent been able to reproduce that ..