[Newbie] What Exactly Is Part 0,0,0 - All My Y Cuts Are Shifted In +y

[countryguy]

Yep.... Me again. Wow- tons of respect for you guys that do this everyday!

Issue: I'm onto my next CNC generated part and I've determined that my Y cuts seem off over .125? in the Y+ space (I think I have that right). I cut two parts w/o really noticing. bummer. I'm learning fast there.
From the pic, it cut in too far towards -Y and left a large offset then to the Y+ edge of the part.

I did part zero as:
Find X edge w/ my edge finder. (.2 wobbler) used .1 to get to wobbler center.
Find -Y edge. Went .1 back into -Y to center.
The 5/16 cutter sure looked centered to me.

I ran the dial indicator along the long edge of the part.... 0.0 +/- a thou. It was square.

after- I ran several Y direction tests w/ the magnet base and 1" dial indicator. It's dead on. 1.000 is recorded as 1.000

Could there be something wrong in the CAM post processor - even though it looks fine on the simulator? Or am I unsure where 0.0.0 should be when I do the wobbler and then put in the cutter in. I've included the two pics. 1 from the sim, 1 of the part. 0.0.0 of the sim cutter is where my physical cutter was too.

The dxf drawings were dead on square on both sides. CAD and then CAM all look OK?

I'm just wondering where to dig now? I'll try a few circles and a few test holes later or tomorrow.

 

[countryguy]

Ohhhh.. I've used 2 different post processors- Each do the same thing. I use DolphinCam. I am trying a DXF test by saving as R12 rather than a newer dxf type. Redo of the Cam and cad .... I hope you guys have some clue. this cannot be something new and I imagine is a simple fix.

 

[coolidge]

Are you off 1/2 the diameter of your cutting tool?

 

[countryguy]

It's close. .3125 cutter. Sorry. Meant to put that in. Would that .5 * a sixteenth then? Anyway it is sort of close It's a very solid 30taper YMC supermax.

 

[countryguy]

I had been using a cam rotate feature to get it correct to the mounting on the mill. I did find a bug there last week but not in the calcs. It was minor.
But All my error parts used this cam based rotate function. I have cut several other projects w/o and did not have this issue. Hmmm I am pulling that out for my next tests. Learning learning learning. .

 

[RJSakowski]

Your CAM model looks like it is showing a machining pass around the perimeter of the part. Your coordinate system appears to be zeroed on the upper left corner of the workpiece in the CAM picture. If the controller thinks the zero is actually the finished part, it would machine a part like you have. Are you offset in the x direction as well?

I always use the finished part for the zero reference and enter an offset for any machining to the workpiece when I find my edges.

 

[gr8legs]

I did part zero as:
Find X edge w/ my edge finder. (.2 wobbler) used .1 to get to wobbler center.
Find -Y edge. Went .1 back into -Y to center.
The 5/16 cutter sure looked centered to me.

If you are finding part zero by moving to the upper left corner of the part as shown in your drawing then you need to compensate for Y by adding the y-offset of the wiggler (half it's diameter) to the y value.

It sounds like you're going the wrong way with the Y zero offset.

Or maybe I'm misunderstanding what you're doing...

Stu

 

[coolidge]

Yeah there's a 'DOH!' in the setup here.

 

[Silverbullet]

I started going Dah when he said hes going dolphin fishing or some such thing.

 

[backgear2]

Do you use work offsets? G54 for start position from home?
Does your machine move to the corner when it first starts ?
My machine uses G53o(1-99) for work offset so what does the first few lines of you Gcode look like???