Prototrak Plus Retrofit with Mesa 7i77 & 5i25 cards

Todd Zuercher wrote: There are a number of ways to reverse an axis. With a servo set up probably the simplest way is to change the sign of the encoder scale for that axis in your ini file. (It is possible there might be a couple of other places were you might have to change a sign to keep the correct behavior, such as homing.)

You will need to change the sign of the encoder scale and the analogue output scale.
Swapping just one will cause a runaway.

Oops, Thanks Andy for the correction. (I knew there was something else, but I just could not think of it at the time.)

Many, many thanks, andypugh & Todd for all of your spot on advise!

I have attached the most recent .ini and .hal just to keep all in one spot. The way I edited the .ini file was to click on the line, arrow to location and inserted a "-" in front of the following lines" ENCODER_SCALE = -27500" "OUTPUT_SCALE = -10" for both axes. After doing this it did not change the direction of machine cutting the sample, still mirror image. Did I use the correct method to edit, I save then closed. The only other thing that I see is in andypugh's

"" You will need to change the sign of the encoder scale and the analogue output scale. Swapping just one will cause a runaway. ""

What I edited was "OUTPUT_SCALE", but felt confidant that this is the "analogue output scale"

Thanks!!

#********************
# Axis X
#********************
[AXIS_0]
TYPE = LINEAR
HOME = 0.0
FERROR = 0.5
MIN_FERROR = 0.05
MAX_VELOCITY = 2.0
MAX_ACCELERATION = 10.0
P = 3615
I = 0
D = 65.4
FF0 = 0
FF1 = 67.25
FF2 = 0.6545
BIAS = 0
DEADBAND = 3e-05
MAX_OUTPUT = 0
ENCODER_SCALE = -27500
OUTPUT_SCALE = -10
OUTPUT_MIN_LIMIT = -10
OUTPUT_MAX_LIMIT = 10
MIN_LIMIT = -11.0
MAX_LIMIT = 11.0
HOME_OFFSET = 0.0

#********************
# Axis Y
#********************

Changing only one axis will mirror image, the part. Changing both axis will just turn the part 180 degrees.

If nothing happened, did you close and restart Linuxcnc after editing the ini? Changes to the ini file do not affect an already running Linuxcnc. (The ini file is only read when starting.)

many many thanks!!

Just changed "x" to "+" in the ini file, the cut is correct to be readable, as it cuts, facing the machine it is in correct orientation to be read. I don't think this correct yet, plan to change "x" back to "-" & "y" to "+".

If I were to put myself in the position of the machine, see the part as like you were the column of the mill looking toward the "y" axes ball screw knob, so positive "x" is when the table moves to the left, positive "y" is when the table moves away from you.

many thanks

Yeah, that would be backwards. Normally an X positive move would be table moving to the right (tool moving left on the part) and a Y positive move would be the table moving towards you. But it is your machine configure it the way you like. On a moving table machine the actual movements are opposite of the arrows on the keyboard, because they represent the movement of the tool (which isn't actually moving) relative to the table, not the movement of table. Imagine if you were watching the machine milling though a camera rigidly mounted to the table instead of standing beside it.