The success or failure of a CNC project is very much dependent on how well an end user’s material is fixtured to their CNC table. Moving parts on a CNC table are costly, increasing lead times on production, increasing costs on materials and cutting tools. In the modern era of machining, vacuum hold down has been proven to be some of the most effective, and efficient methods for quickly and rigidly fixturing parts, allowing for fast, and aggressive cutting to be done.

Vacuum fixtures can be as simple as using a sheet of MDF for full sheet production; where the MDF acts as a buffer between your machine’s vacuum table and the substrate being cut on the CNC. A suitable vacuum pump will draw air through the MDF sheet, holding down the sheet of material on top of the CNC table to be cut out. With the substrate being held down completely, an end user can cut completely through the material, into their MDF sacrificial board, resulting in fully cut geometries, with no clean up or hand routing required.

Other fixtures can be created custom for certain, more complicated parts, or perhaps to hold down a piece of material that is much smaller than a full sheet. In this video, we created just that. We have several different “catch all” tray designs that we are going to be showing off using various tools, programming strategies, machine models, and of course, vacuum fixturing. This fixture was cut out of UHMW plastic. Its work surface and custom vacuum grid pattern was all based on small blanks we are making out of hard and soft wood. The blanks are all 11 inches in width and ranging from 7 – 11 inches in height. With this design we will be able to use a single vacuum fixture, utilizing a single x/y zero position on our CNC machine’s. This type of hold down method is not only going to save us a ton of time in machine set up prior to cutting the job but ensure we will not have any down time due to a ruined part or broken tools from poor hold down methods. Additionally, the fixture can be easily stored, ready to be used again at any given moment.

The fixture was cut out on our Atlas Series CNC Router, using a single 1/4” 2 flute straight flute cutter with a DLC coating. The cutter is the Techno CNC PL141410-2S-D. Please visit our website to order today. With this tool, we were about to cut through this material at a pretty knarly pace of 300 inches/min. Chips were coming off the cuts perfectly, resulting in a smooth zen-like edge finish.

The moral of the story is essentially to invest in your hold down method. Rotary vane vacuum pumps can seem like a hefty investment on paper. When you compare it to the amount of time spent manually fixturing a part in between runs on a CNC machine, the cost of tools lost, broken due to a loose or moving part, the cost of the same materials that caused your tooling failure; these savings through an investment in a vacuum system pays for itself forward in a very short period of time.