CNC routing: Using a sacrificial bed
By Ged Lodge

Placed on top of an aluminum vacuum deck, the sacrificial bed allows the machine to fully cut through material without permanently damaging the deck. When set correctly, the tool will very lightly mark the surface of the MDF, which can be skimmed regularly to keep it smooth and flat and to minimize vacuum leakage.

For routing operations, there are two ways to attach your MDF. Option one is the MDF is placed loosely upon the machine and requires the strength of the vacuum pump or blower to hold it in place. Option two is the MDF is mechanically fixed to the machine vacuum deck using the t-slots. This ensures the bed is flat and allows the surface to be regularly skimmed, improving cutting efficiently and sacrificial bed lifespan.

A mechanically fixed sacrificial bed inevitably has a longer life span. A fixed bed allows operators to re-skim the surface after which they’ll be cutting in a new, clean working area. After skimming the bed, the accuracy of the Z axis is more reliable and therefore, provides high quality cutting and precision.

If the surface is skimmed by 0.2mm on a weekly basis, we recommend the MDF bed is replaced after six months, depending on the type of work you’re completing. The core of the MDF can become “furry” making it difficult to hold smaller parts at the end of the cutting process. If the CNC router is predominately processing larger components, the hold down will be perfectly acceptable for a further six months.

Replacing your mechanically fixed sacrificial bed is relatively straight forward and should take no more than a few hours to complete, depending on the size of machine. Make sure there is no swarf or debris between the aluminum vacuum deck and your new piece of MDF.

Source: Ged Lodge is an Applications Specialist for AXYZ International, a global manufacturer of CNC router systems. For information on the company call 800-361-3408 or visit

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