Wonky Machine Origin

Hi. I’ve purchased a used pcnc 770 series 3 mill. It is my first venture into cnc milling. I’ve already discovered the y axis limit switch wasn’t wired properly. That is now fixed. When I reference the x and y axis the table moves right and towards the operator. X andSo the spindle ends up over the top left corner of the table.

Q1: Is this the correct location for the machine origin? Just want to make sure.

Reading the manual I see the table should move to the left (from the operator’s point of view) when the right arrow on the keyboard is pressed - which it does.

The manual states the Y axis should move away from the operator, i.e. towards the z column when the up arrow is pushed. And the manual also states the down arrow should make the table move towards the operator.

When I push the up arrow the table doesn’t move.
When I push the down arrow the table moves toward the z column.
Looking at the y axis dro the value starts at zero and increases in a negative direction. When the table reaches the y limit the DRO reads a negative number - something around -7.xxx inches. I’m thinking this isn’t correct. Should it be a positive value?

My machine was built in 2012 and the limit switch wiring does not match the diagram in the pcnc 770 manual. Was this machine perhaps originally wired for Mach3 and Path Pilot was installed by the owner at a later date? Did they get the wiring messed up somewhere? Or is this normal behavior? I’m thinking it isn’t right.

I can live with the backwards y axis but I really would like the the y axis dro to increase in a positive direction when the table moves toward the column.

Q1: Isn’t this the normal behavior for the machine or am I not understanding something?
Q2: If the machine’s y axis is indeed not behaving properly, is there a simple way to “flip” the axis so the table moves from zero to a positive value as the table towards the column when the up arrow is pressed?

I am open to sage advice.

(lol, I really hope I have the directions right.)


@Dan_Beeker I think you are struggling with something that took me a little while to get the hang of when I first started:
When you are commanding PathPilot up, left, right, down you are actually commanding the spindle to move relative to the work piece. However, since the spindle only moves in Z the table has to move the opposite direction in X and Y. If you think about Y from the perspective of the work piece, Y+ would be at the top of the work piece which would put the table closest to the operator and Y- would move the table away from the operator in order to get the spindle to the bottom of the work piece.

Yes, the machine references with the table close to the operator and to the left.


Yes, it is going to take a while to get my head around the coordinate system. But after spending a while just figuring out X+ Y- Z- etc I’m confident I’ve got things right. Baby steps but I’ve made my first part! Woohoo!

Thank you for your help.

first part

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Wahoo! She’s beautiful!