[lseguine]

i converted a grizzle 8086 manual mill to cnc, i'm using mach3 mill and a bob to drive the steppers. i cut a box figure and several other staright cuts involving both x and y axis with no problems, including angular cuts.

then i set up to cut a circular hole and when it cut i got a strange result. the x axis movement appeared to function as expected but the y axis cut fine till it approached the point where the changes in position became small as the max move going positive and about to change to going negitive. at this point the y axis stoped moving untill the change of direction and the changes expected became large.

the end results were a circle wit flat sides in the y directions.

the circle was a 5/8 hole mesuring i got .624 in the x axis direction but in the y sides i got .594 ish

i'm trying to figure out what is going on. i am intrested in how the x and value are calculated for movement in g-code? also how are the points calculated ? is it in degrees, x or y movement, ????

i'm wandering if i have a bad motor or is it something in the c-11 board orthe drivers, or is it mac3??

[ger21]

Pictures would help, but it sounds like it might be backlash?

[lseguine]

i have set the backlash to be in efect...

i did a test to try and figure out what was going on.
i set up a dial on the y axis, run the table in several large steps to rule out backlash. did a couple .001 steps via keyboard, then i thought i had zeroed out everything set single step value to .001 then walked the table in recording values in the mach3 DRO and the dial readings got the following:

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

this was enough to let me think something funny was going on but no idea what????

anybody got any thoughts?