My CNC spoil board is aluminium. 5mm thick with 4mm threaded holes drilled at a pitch of 20mm. However, the table on the Genmitsu 3018-pro is not quite flat. Hence my need to machine this to create a flat working area.
Material for a Spoil Board
The spoil board can be made from a number of materials. A lot of times they are made from MDF and these work fine for a lot of engraving applications.
However, if you want to machine a metal part accurately you want to fix it and reduce the compliance. This includes any compliance in the spoil board and hence my decision to make an aluminium one.
Flattening the Spoil Board
I created a rectangular machining programme in Carbide 3D, a single cutting operation with a depth of 0.1mm that I could then repeat to step down through the board.
I used a 6mm aluminium cutter from milling cutter stores, but told the software it was a 5mm diameter cutting bit to increase the overlap.
As you can see the spoil board has countersunk holes to allow it to be bolted down to the CNC table.
The working area is 150mm x 100mm with a Z-axis travel of 50mm. This is significantly reduced from the original Sainsmart Genmitsu 3018-pro, but this working area was reduced to allow me to increase the machine stiffness.