Z axis direction

I have a vmc mill to which I am fitting a DRO. At the moment I am only fitting a scale on the knee and not the quill which I usually keep locked. I think the usual convention for the Z positive movement is when the cutter moves away from the work so I would interpret this to be when I lower the table, I think I should set the DRO to register a positive movement when lowering the table. Does the forum agree?

Mike

That is how it would be done on a CNC machine.

Nigel B.

I agree too. Z minus will remove material, therefore as you have said, knee up = minus.

Andy.

It seems we all think the same way so Z plus will be knee down. Thanks chaps for your input.

Mike

So on the X axis, what would left and right be? and for the sake of completeness the Y axis?

I have my Y axis - going away and + coming towards me. X axis left is + and right is -ve

I just made it up as I went along but I have turned one of my DRO's upside down so it sits lower. So maybe I did it wrong now?

Edited By Oompa Lumpa on 04/02/2014 22:17:41

X + direction is with the tool moving to the right (table moves to left).

Y+ direction is with the tool moving towards the back of the table.

Martin.

Hi
When i used to set the cnc machines I Know its old hat now But i used a 5mm setting peice not my best slips . using electronic hand Wheel wind the quill down carefully take a light touch . go to controller Datum set z + 5 . As martin says
Always s think in terms which direction the cutter is moving z- x+ y- etc . drifting away a bit wire eroders you can program the bottom different to the top say for backing of dies
  I would have thought the knee up on a milling machine would enable the slot drill / cutter  to take another 
peck/cut  therefor Z minus .  I have my flack jacket on ready for replies 

Nobby

Edited By Nobby on 04/02/2014 23:09:42

Well I got one of them right anyway!

Thanks for that. I will put that "right" in the morning and more likely get the next job ready for the scrap bin

graham.