Hi,
Your suggestion is to reduce the jog increment down so few steps are in the buffer. OK, the jog increment was 0.001" - I guess I could go to 0.0001" if you think that would help. As far as knowing how many steps are in the buffer, how do I determine that?
That is a good question. In my case, as I use an MPG and do not use on-screen buttons, the solution and result are much plainer.
Lets say for example your machine has a max velocity of 1200mm/min. I choose this number as it suits my mini-mill which because of axis gearing
has relatively low G0 speeds.
1200/60= 20mm/sec.
If I set the max jog increment to 1mm, then if I spin the MPG (100 pulse/rev), at any greater than 20 clicks per second then movement is going to accumulate
in the buffer. Its entirely possible to spin the MPG at 1 rev, or 100 pulse per second, and thus I would have significant accumulated motion in the buffer.
If however I reduce the increment to 0.1mm then that same 100 pulse per second input results in 10mm/sec movement which is within my machine velocity
and therefore no accumulated movement.
The trick here is that I know how many steps per second I am applying by virtue of me spinning the MPG.
In your case using Mach's jog buttons is issuing a certain rate of steps....and exactly what they are I don't know. Lets guess and say that Mach is issuing 1000 pulses
per second, then at 0.1mm jog increment that would indicate a movement of 100mm/sec which exceeds my machine velocity and therefore get motion
accumulation. If I selected a jog increment of 0.01mm then the same 1000 pulse/sec input would result in 10mm/sec movement which is suitably within my machine limits.
I'm not sure off-hand how Mach determines the pulse rate. On the jog screen there is a slider at the bottom which is a percentage of max, whatever max is. Using that slider
you can slow the pulse rate down until you approach the balance point necessary to avoid accumulated motion.
I'm hoping that smurph sees this post and he will surely know how to set the rate. My guess is that once you make an appropriate setting you will then never touch it
again for the life of the machine. Such has been the case with my max jog increment, once I found the 'sweet spot' of 0.1mm it gets left there for months at a time.
I will sometimes drop down to 0.01mm if I have a fine touch off to complete, but even that does not happen that often.
Craig