Greetings all;

Axis LINUXCNC - 2.8.0-pre1-3476-g03ffa4b

I have disconnected the joint.n.vel.derivitives from the 
pid.velocity-deriv pins because of the huge spike that was subjecting 
the stepper drivers to. Jogging the machine around before homeing is IMO 
how the machine should move full time.

Because one thing I just noted, is about a 100/1 difference in the 
acceleration times, controlled by whether or not its been homed.

If I keyboard jog it before its homed, the accel/decel times are in 
milliseconds to default speeds in the 54 ipm range. I can make it dance 
from the keyboard.

Once homed, that same jog has an accel/decel time of a very slightly fat 
full second up to the same speed and the stepper soubdz resemble the 
rise and fall of a motor driven fire siren only somewhat faster. And 
this lag shows in the halmeter looking at the joint.n.vel command. Z if 
homed, takes most of an inch to get up to top speed, and most of an inch 
to get stopped. And a full second of flashing numbers between 0 and 
the .9 vel limits, eg 54 ipm.

This effects all 4 axis's, and in not effected by changes in the TRAJ 
section DEFAULTS or MAX's of the ini file. I just put values there 
copied from the machine units/minute values from one on the axis's.

Doubleing the MAX_ACCEL of an axis, and redoubleing that for 
STEPGEN_MAX_ACCEL also does not have a visible effect after homing.
Before homing, it sharpens the accel bumps noticeably, but despite that I 
have not triggered a following error in half an hours putzing with this.

What can cause this extremely slow accel responses to the jog keys once 
homed?, and which I assume apply to running code, because running code 
and cutting air its obvious the machine is suffering. Running down at a 
G38.2 F10 z-4 expecting a contact stop at -1, would make contact ok, but 
the machine might coast another 1/4" before it got stopped, smashing the 
pcb contact pad and likely breaking the $20 tool.

Thanks all.

Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page <http://geneslinuxbox.net:6309/gene>

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