Re: [CAD_CAM_EDM_DRO] EMC setup questions

awallin25 wrote:

>Hi All,
>
>Thanks for all the answers to my previous questions. I have now got my
>system up and running with EMC.
>I am still looking for the right settings to get my units correct:
>Now EMC works in mm and shows mm on the screen, but my table moves
>lots more than 1mm when commanded to move 1mm. This is when I have
>input_scale=1000 and the emc-gui shows a feedrate of around 20-60
>units?/s
>

Well, what units are the input scale set to? Do you have 1000 steps/mm?
Or, 1000 steps/inch?

The definition of units and the steps/unit must be consistent.

What is your units mode in the RS-274 interpreter? You can select G20
or G21.

>I am using steppermod.o
>
>I have linear_units =1
>
>I have tried to calculate input_scale as follows:
>my steppers are 200step/rev driven with halfs steps => 400steps/rev
>my ballscrews give me 5mm movement for every rev.
>=> input_scale should be 80 ??
>

Yes, that sounds right.

>
>
>when I set input_scale to 80 on one axis for testing it, it seems to
>work when jogging in the + direction, but I immediately get a
>following error when pressing the - button.
>The FAQ tells me to reduce feedrate when this happens. I have
>max_velocity set to 20 on all axes.
>If I understand correctly the parallell port whould be able to do
>around 5 kHz which would be equivalent to a feedrate of over 60mm/sec
>on my system (5000steps/s / 400 steps/rev * 5 mm /rev > 60 mm/s)
>even with a very low feredrate I get the following error when trying
>to move in the - direction.
>
>

Well, if max velocity is 20 mm/sec, that should come out to 1600 steps/sec.
If mac velocity is 20 Inches/sec, that should be 40640 steps/sec, shich is
certainly a problem for software step generation. Definitely check the
G20/G21
selection. Should linear units be specified as =1.0 , or does that make any
difference?

Jon