Thought I would ask out of curiosity, when I set X0Y0 at the corner of the spoilboard and set the machine to go to absolute point X10, Y10 it did Yright on but the X was 3/8 of an inch short. Just curious why it didn’t go to absolute 10 on the X axis.
I should have done this from the beginning, I measured the grid for the Y axis- dead on, but the grid for X is off, so much for assuming. Anyone have a better idea on how to cut an accurate grid, Asking for a friend 
If running g-sender, did you run the calibrate program?
I have a grid on my spoil boards that I burnt with my laser but a shallow cut with a V-bit works fine as well. As far as the placement I centered mine. The problem, as I see it, with basing the grid on the front left corner is that you can’t clamp anything at [X0, Y0] and have room to use a touch block.
If you go with it centered just measure the work area to find the center, you can use gSender and measure with the mill, and start the carve from the center. If you do go with the front left I would leave room for at least using a touch block and would think about starting it far enough from the edge to make a removable corner fence to make mounting work easier. With a nice fence and some toe clamps you can mill the whole top of a board at once with no clamps in the way.
I have posted a couple of spoil board grids in my Dovetail Guide, the last half of the thread, if that helps at all. The pics are svg, right click->save as, I also posted crv files if you have Vectric.
I also wonder what you mean by absolute point? Do you mean measuring or the small machine coordinates in gSender. If your talking about the machine coordinates, it depends on whether you home the machine or not. It’s been awhile since I ran without sensors for homing but I think machine [0, 0, 0] is wherever the machine was when it was turned on without homing.
This other post of mine explains how I use my centered grid for double sided work if your interested.
You gave me a lot of information, thank you. By absolute point, I was curious how accurate my grid was so I hit the " go to" button on gsender and the next window asked for “X and Y” points to go to. I put in X10 and Y10 to see what happened. My grid is 2" and the Y hit dead center but X was off by 3/8 so I knew I screwed up somewhere. I checked my set up using vcarve pro and the problem was there, vectors were at 2.07 and not 2.0. I’ll check out your info and re-do the grid. Thanks again.
Hi oz, I checked the calibration and it said I was close enough so I didn’t mess with it, but I found the problem== my vectors were off when I set the gcode. I’ll go back to vcarve and re-do it and try again. Thanks for the response.
Great. Glad you found out the problem.
@1mike1 Pls post back when you have tried a new vcarve file, Mike.
I just ran a new vcarve gcode based on Michaels post about starting in the center of the spoilboard and it seems to be a lot more accurate. As he mentioned, I set P59 at the center of the board and the difference between the old and new grid at board center is 1/2 inch. Appreciate the helpful feedback and one day I will get the Longmill figured out
@1mike1 Tks much for reporting back, Mike. Have fun with your Long Mill.
I’m closing this topic as resolved.