[Bdi4emc-help] bdi 4.51

[Paul]

On Thursday 16 November 2006 00:08, David Szakovits wrote:
>    after looking over the documentation on the cd.  i am still a little
>    confused or disoriented and the task seems nearly impossible.
>    starting with the setup for the sherline mill maybe it is not so bad.

Agreed, the documentation could be improved, but it is unlikely to get 
overhauled any time soon..

>    if i start with the sherline software that appears on the bdi desktop,
>    what files, variables and documentation should i concentrate on first.

Using a config that is known to work as a starting point is probably best. 
The /usr/local/emc/mill_inch_freq.ini is as good a choice as any with the 
added advantage of being linked to a desktop icon. The first set of 
parameters that will need changing will be OUTPUT_SCALE and INPUT_SCALE to 
match the stepper motors & feedscrews. Assuming a 1:1 gearing, no step 
multipliers in the Gecko drives, and standard 200 steps/rev motors, the 
correct number would be: TPI * 200

Once the scales have been set, you can play around with the velocity and 
acceleration parameters - A general rule of thumb here is the max velocity 
can be found by taking 1/([EMCMOT]PERIOD * OUTPUT_SCALE) divide by five so 
that you don't trigger following errors at high speed..

Once you have found the maximum accelerations and velocities, turn them down 
to the lowest values that are acceptable - You are tuning for longevity not 
the fastest way to wear out a machine.


If you wish to sidestep tuning of PID parameters, change the EMCMOT driver 
from freqmod to quickstep.


Regards, Paul.