MDF SUCTION TABLES

Suction table or CNC vacuum hold down table

Flow-through or suction tables are made with a sacrificial board of MDF, that is laid on top of your vacuum table's grid. The MDF is porous so the vacuum can pull right through the thickness of the sheet and hold down whatever is laid on top of it.

This style of vacuum table is used extensively in the cabinet and cabinet door industry. Full sheets of hardwood veneered material are laid directly on top of the MDF sacrificial sheet, and the CNC router cuts through the good sheet and incrementally into the MDF. When the MDF gets destroyed you throw it out and drop down a new sheet, thus preserving the vacuum table grid below.

A flow-through vacuum hold down table can also be great in applications where the material being cut needs to be fully supported, like in cutting wood veneers or plastic letters. In many cases these thin materials are affixed to a secondary waste board and then this is vacuumed down to the MDF.

So the Advantages:

• Full support for thin or weak materials
• Protects vacuum grid below
• Easy to replace working surface after abuse.
• Easy to use!

Disadvantages of Flow-through Vacuum tables:

• Requires huge volume of air flow to be effective
• Large volume vacuum blowers are noisy/expensive/consume a lot of energy = $$
• Large volume is usually at a much lower PSI so you need a fair bit of surface area for effective hold-down. It doesn't work for holding small parts/shapes.
• If only using part of the table you have a large amount of leakage, difficult to block off if it is not "zoned" in a way that matches your sheet layout.

Really vacuum hold down tables that work on the basis of suction through the MDF are really only great when you consistently cut full sheets into large nested pieces.

For thin sheet work most would suggest a 10hp vacuum pump would be the absolute minimum especially if your material is porous at all. If you intend to cut 3/4" thick sheets of plywood or hardboard with greater tool load, you'd need at least a 20hp CNC vacuum blower to be comfortable with everything staying in place. My local sign shop has a 20hp vacuum blower on EACH HALF of his table, just to give you an idea... hugely noisy but he's in production mode.

NOTE that these flat panel Flow-through Vacuum suction tables don't work for a lot of solid wood, custom shaped applications. Read on about more versatile vacuum hold down devises that use grided vacuum tables for more custom woodworking applications. >>