MDF spoil boards need to be surfaced to remove the manufacturer-applied sealer to make it porous so the vacuum can operate at highest efficiency and hold down the workpiece securely.
Start with 3/4″ medium density fiberboard (MDF).
Using a 4″ fly cutter with three blades, you should be spinning at 12,000 rpm at 30 meters per minute; using a 3″ fly cutter at 12,000 rpm, run at 25 meters per minute. Overlap each cut by about 1 mm
Take at least 0.5mm off both sides to remove the sealer that comes on all MDF boards.
Seal the four edges of your spoil board by either edge banding, or using a sealer (e.g. epoxy or rubberized paint) on all four sides to seal the edges for an even and maximized vacuum. This will improve suction on a vacuum table.
What is a spoil board and a vacuum table?
A spoil board is a sacrificial board (typically 3/4” thick) placed on a vacuum table to protect the table when cutting through a substrate or workpiece. When a vacuum pump is connected to the vacuum table, air is constantly pulled through the spoil board. This creates a vacuum under the spoil board and a very low-pressure area on top of the spoil board. When a part is laid on top of the low-pressure area, the pressure on the underside is less than on top, so the part is held in place. This type of setup typically works without the need for seals between the part and spoil board. Spoil boards are commonly made of MDF, as it is a permeable sawdust and resin substrate that lets air pass through its entire surface. Since MDF is made of sawdust and resin, using different proportions or using sawdust from different wood species may affect the permeability of the material.
SUDIAO CNC rotary vane vacuum pumps with their vacuum tables, which consist of an electric direct drive motor to the vacuum pump impeller made up of self-lubricating carbon vanes. The vanes rotate in the pump housing, drawing air in the inlet and discharging the air through the exhaust to create a vacuum. The increased vacuum results in superior hold-down capability and is ideal for wood, plastic, and other nonporous sheet-like materials.