Hi,
Go to X zero Y zero question:
I use a screen set that has an XYO button. If I zero the X and Y DRO’s and then jog off and click on the XY0 button the machine returns to zero for both X and Y.
My problem is when I enter adjustments for touch plate thickness and half the diameter of the bit into the X and Y DRO’s and then jog off and click on the XY0 button, the machine moves back but the DRO’s show a number like .0004 when I asked it to go to zero.

Here is my touch-off technique:
1.   I touch off of the bottom left Outside corner of X.
2.   I make the correction for the plate thickness and half the bit diameter.
3.   I select the X DRO and enter the value with a minus sign in front of the number.
4.   I repeat this for Y.

Example: I touch off using a .062 bit and a .01 thick plate.
1/2 of .062 = .031 + .01 = Total .041 DRO adjustment in the Minus X or Y direction. (-.041 Enter) I'm not sure if I'm using a bad technique or I have a setting issue with Mach3.

I was also thinking that it might not make any difference if I select Cycle Start from a point other than X and Y zero. () No matter, it still bugs me that the machine is not moving to the position requested.

I hope this makes sense. Any ideas?

Thanks,
Bill

What is the resolution (steps per unit) of your machine?
Hood

I don't know. Can you tell me where I can find the steps per unit?

Thanks for the response.
Bill

motor tuning page.

Hood

Thanks Hood,

I will drive out to the shop and find out. I'll report back in about an hour.

Bill

The Steps Per are 714 for both X and Y.
Thanks,
Bill

Also:
Velocity = 60
Acceleration = 30  
G's = .077705;
Step Pulse = 0
Dir Pulse = 4

Are you using metric or inchl?
Hood

Inch

Well I am surprised you are even getting that close to where you command.
 What I am meaning is you have 714 steps per inch, the smallest movement Mach can make is 1 step so that is 1/716 =0.0014approx.
 If you zero the dro and move off and then return to zero it will likely show that distance but if you enter a dimension into the DRO and then try to go to zero Mach can only get as close to zero as the steps will allow as moving another step would take it past the zero position.
 I am probably not explaining it very well so if you still dont know what I am meaning just post again and I will try and explain a bit better.
Hood

I think I understand. I'm not sure why I have 714 selected.

I guess if you zero the DRO's and move off and then push XY0, Mach is able to get you back to 0 but if you change the DRO and your steps per are out of a normal range, then Mach can only get you close. Is this right?

I guess what I need to know is what the steps per should be set to in inches.

Maybe even more important, will Mach be able to run G-Code correctly if you start at a position that is not at x and Y zero?

Thanks Again!
Bill