In order to get jobs cut evenly on your Industrial CNC Router, it's important to make sure your tabletop is even with your spindle. Even if you've made sure your routers legs are level, there can still be high and low points on the top surface. The best way to do this is using the spindle itself to plane the surface below.
Step 1: Planing or Fly Cutting Bit
The first thing you'll need is a planing bit designed to skim the surface of material. The bigger the diameter of your bit the quicker the job will be done. You can either run the bit up and down the table manually, or you can just use a post processor program to make a "pocket" the size of your table.
Step 2: Making a Pocket
In your Vectric Program, make a rectangle the dimensions of your tabletop (48" x 96" for a 4' x 8' table)
Set your origin positon as the bottom left corner.
With your rectangle shape selected (highlighted in pink) choose "Create a pocket" from your toolpath options.
Enter your bit information. Assuming you fly cutting bit has a 3" diameter, you can call your bit an end mill with a 3" diameter.
Set your "stepover" at 40%. This is the overlap between passes back and forth and 40% should leave a fairly smooth finish. If you're seeing lines between cuts, you can increase the percentage to make it cleaner. (Keep in mind this also takes longer, so aim for a good balance.)
Set your depth at .0625 or 1/16th inch. We're only skimming not cutting.
Calculate the tool path and save the g-code and you're ready to send it to the machine.
Step 3: Getting Your Machine Ready
Bring your spindle to the front left corner of the table surface to match the home position you set in the Vectric software. Zero your X and Y there. Zero your Z about a 1/16" above the table. This will show you the high spots on your table. Let the program run and when it's finished, zero your Z 1/16" lower and run it again. Repeat until the bit barely skims the entire surface.
Note: If you're planning your sacrificial board, make sure that you have it secured all around the edgesas some materials will lift when they're planed and material gets lighter.