As I’m interested in cutting and engraving thin sheet metals, having a level work surface is important. But more important is having a work surface that doesn’t move, especially while pushing an engraving bit into say copper.
So using a measuring gauge in the spindle I measured the standard waste board over the surface. Highest spot was at X0, Y0, lowest at X150, Y150. In fact highest spots were the four corners. Lowest was 26 thousand inch lower than X0, Y0.
In addition, while measuring at X150, Y150, simply pressing down on the waste board added another 10 thou.
So, two problems, level (as far as the spindle is concerned) and stiffness. First is easy, just skim the waste board or a secondary, sacrificial waste board. But stiffness is different.
The 500mm doesn’t have any support under the waste board except at the edges at the front and back. So being 20mm off the table surface I cut a sheet of 12mm and 9mm MDF to size (21mm) and after cutting matching clamp down holes, slide both sheets under the X-Carve. This lifts the whole machine 1mm off the table.
I then added four bolts through the original waste board, the two new boards underneath and through the table and bolted it all down hard.
Now measuring, it’s still not level, but only in the X direction and only 15 thou from X0 to X300. But pick any X and it’s within a thou or so at any Y. So it’s now flat but not quite level. Nothing a quick secondary waste board skim won’t fix.
But measure anywhere and push down hard on the waste board and it doesn’t move. Result.
An unexpected but excellent side benefit? It’s so much quieter while cutting. I couldn’t hear my shop vac over the cutting before, now I can hardly hear anything but the vac. Not sure if that’s because it’s bolted to the table, the mass of additional boards, no fresh air under the machine, or combo of them. But really nice benefit.