LinuxCNC S-Curve Accelerations

So it's a way to tame down the machine when jogging? Is there a user-accessible setting for this anywhere?

Edit: Seems like a bad idea in that case since it also greatly increases stopping distance.

Changing the overall acceleration, yes in the ini file.
Changing the jog acceleration to full value set in the ini, i do not know.
Sorry, i just bumped into that a while back testing some very fast cnc plasma machines i am building here:
forum.linuxcnc.org/show-your-stuff/38547...plasma-build?start=0
RodW also bumped into it at the same time as i did, so we compared some notes and came to the same conclusion you did.

arvidb wrote:
Edit: Seems like a bad idea in that case since it also greatly increases stopping distance.

Well yes and no.
Yes it will change the distance required to stop, but it will stop at the soft limits properly.
No, as it is very easy to repeatedly press a button and cause the machine to jerk badly, especially the bigger machines with a lot of weight to move, if full acceleration is used.

IIRC separate jogging acceleration was added after the fact - I assume because someone required lower acceleration for jogging then machining.

If you want to experiment there is also a HAL component called simple_tp.
It is used by PnCcnf to simulate jogging control. it was a direct copy of motion's jogging planner (at one time anyways)

Chris

So... do you think it's a way to reduce jerk, or does someone actually need lower acceleration when jogging?

My guess is acceleration was lowered to compensate for a problem and that jerk control would help a lot.

Jogging on a powerful machine is a difficult process - as you said it is constantly resets it's end point and must be able to stop by the end of the last planned move.
Add in that turning a jog handle constantly is not a consistent speed, means the axis speed is constantly accelerating, so constantly jerking.

The part that makes it easier to code would be that only one axis must be calculated at a time.