...sorry for the double post....
My backlash for 1" moves of 40" moves is within 0.0002" repeatability on x and Y axiz
(on a 28" x 48" working area) slaved 900oz/in motors on the Y axis single on the X axis.
But whether it's a 1" diameter circle or a 8" circle... they are all out of round by 0.030"
What I think is over tightening the bearings/slides/screws/R&P parts....then a retest.... it's always 0.028-0.030" out of round on the same axis, (11 o'clock down 5 o'clock is narrower by 0.030) regardless of climbing or normal routing directions.
This was tested with several circles inside each other, each running in the opposite directions.
ALL are out of round. so I even rotated the MDF test board just to validate it was not material stress related.
There is no (zero) racking (twin 900 oz/in motors) which might have made sense if backlash on one side were greater than the other
(trapazoidal resultant motion or reversal along the X axis is the Y axis racked)
hhhmmmm... should my dual motor Y axis acceleration setting be twice the single motor X axis?
or perhaps half the X axis to compensate for power to weight of the gantry vs just the head on the X....
(or am I over thinking all this)
Now I know I read somewhere on these forums there is a difference possibly in absolute stop vs continuous speed....circle interp etc
An example visible to anyone is while making my dust shoe, one circle seemed to start and stop a lot, while others were a continuous motion/sound
This is visible at
https://www.youtube.com/watch?v=gr6VAfZCQloat the 1:54 mark you can here it starting and stopping cutting hard i nthe material, yet later circles are smooth and conitnuous.
I did not do anything different.... straight conversion from VCarve Pro to g-code, yet this one circle cut with the start/stop sound.
The MDF circle tests done a couple months ago now still bugs me as I've not been able to formulate any real logistics to hunt down, other than settings for the way MACH3 should/can be config'ed to cut circles.
for reference...the whole machine...
https://www.youtube.com/watch?v=KklafqyZpSY&list=UUNTCxkF_0pxnMa-g9HTVgxAAny clues here as to where I should start testing to re-config this machine for clean round circles?
tia
ptegler