Another stupid question......accel / decel x and y

[Steambike]

So, with the exception of my thc issues (also on here) my homemade table has been cutting pretty well in its new home.i made a test file up for a series of concentric circles from 1-4” to test everything and, the results are pretty good and consistent but not perfect even though the table is dialed in nicely.....so I am wondering if y’all he relative accel and decel of x and y axis should be the same?????? It suddenly seems to make sense that they should be matching even though “counts per” are different.
Any thoughts?

[Steambike]

Sorry ‘bout the “y’all”, gotta love autocorrect

[acourtjester]

You may need to do the steps per cal on the X and Y again, the number will most likely not be the same due to the gear reduction.
If cal is done correctly the software should take care of the accel so they are even

[Steambike]

The more I think about it the more it seems like they should be matched because on a straight x or y move it would be fine, but on a curve or angled line you would introduce kind of a curved line on both accel and decel......right? Right??? Or am I the only guy who didn't figure it out in the first place? Or am I wrong

[djreiswig]

I think as long as the steps are correct, the software will figure the rest out to make it move correctly.

[beefy]

I think as long as the steps are correct, the software will figure the rest out to make it move correctly.

I'm in agreement with that.

I've never had any of my axis have the same acceleration values. As far as I'm aware, cnc software uses the principle of "weakest link" when it comes to control of the axis motors. So if one axis has less max accel than the other the faster one must match the slower one. Likewise with interpolated moves, if the commanded feedrate is faster than what the slowest axis can move, but within the capability of the faster axis, I'm pretty sure the controller slows both to the max speed of the slowest axis. Not quite that simple based on the direction and the "interpolation ratio" but I'm just explaining it that way for simplicity.

I'd guess a cnc controller would not let you punch in different acceleration values if they HAD to be the same.

I normally first enter my steps after calculating them, then I fine tune with the auto calibration feature. Had it in Mach3 and also has it in UCCNC.

[acourtjester]

If you basing you original question on sound, when moving either for an angle or circle the 2 axis do not move the same amount. You may have more X movement then Y as the table moves around and it will change depending on where on the circle it is. The slower the speed of the movement the more pronounced the sound will be. Remember steps is for the distance of movement and the accel and velocity cover the motors ability to move.
I look at velocity to be 4 times the value of acceleration (like 100 to 25) the goal is to go the fastest you can without stalling.