During my move, my vacuum table was damaged. All was not lost though, I’ve decided to show you how to make one while I remake mine. Since I’m just copying my old one, some of the photos will be different from the written instructions you’ll need to do to create your own from scratch.
What is a Vacuum Table?
Vacuum tables are devices that use suction to securely hold work pieces during machining. They are most commonly used during CNC cutting, whether with a mill or router, or with a drag knife. They can be various sizes, and they are comprised of a perforated table top connected to the vacuum chamber, and a vacuum pump that continuously applies suction.
Why Would You Use One?
Vacuum tables are commonly used as a method of holding down a workpiece during machining. They are safer than having clamps in the work space because there is nothing for the machine to accidentally run over or into. A vacuum table also allows access to all sides of the piece being machined, so it is better suited than traditional clamps. I use one to hold my boards in place while cutting out my dollhouse furniture pieces. Since my finished parts are so small, there is no other way to hold them in place.
How to Build Your Own Vacuum Table
To build a vacuum table, you’ll need some wood, some MDF, screws, glue, and a means of drilling hundreds of small holes. You can use a hand held drill, or set up your CNC router to perform the task for you. I try to use MDF as infrequently as possible because I’m allergic to it, but for the top of our vacuum board, there really isn’t anything better. MDF is porous, so it is great for the air holes and suction, yet the top and bottom surfaces are treated, so the air doesn’t pass through them leaking air. MDF is also engineered, so it is extremely flat, and having something perfectly flat is just what we need for the vacuum table. If there were waves in the table, it couldn’t hold down our work piece well at all.
First, you’ll need to decide on how large you’d like your vacuum surface to be. I typically work with boards that are 8″ wide, so I’ll make my vacuum table about 8.25″ wide. Sometimes boards are a little wider, and I don’t want the board to not fit. Take this width measurement and add in the width of your side support boards. You’ll also need to decide on the length. This will be the top surface with all the holes.
You will need a second piece of wood that is the same size for the bottom, but it does not need to be MDF. Then, you’ll need side pieces to box in the vacuum table. Go ahead and build up the bottom and sides of your box. You don’t need to do any fancy joinery, just a simple butt joint at each corner will suffice, but do heavily coat all the seams in glue. I predrilled screw holes in my board, but you can skip that step if you plan on using only glue.
Next, you need to cut the hole for the vacuum hose. Measure the diameter of your vacuum hose and draw a circle the same size. You can use a large bit in a drill or a jigsaw or a bandsaw. I took the hard way out and did it by hand with a small hack saw. I don’t recommend that, but it was all I had at the time and it did work. I’ve since added a small jigsaw to my Christmas list.
If you are using a hose port like I do (it makes it easy to reconnect the shopvac’s hose), go ahead and attach that now. You can use screws, but I used bolts here. Bolts allow for a tighter seal between the port and the surface, as I can tighten them up without fear of them ripping out of the MDF.
If you don’t have a specialized port piece, I recommend you make your own collar. The extra length will keep the hose more secure and that will give you better suction. I created a collar for my first small vacuum table and it worked quite well. I took a small block of wood, cut a hole the same size as my vacuum hose, and then rounded all the top corners to make it look nice. Don’t round the bottom, you’ll want that perfectly flat to attach to the table. This extra inch or so of wood helps the hose stay in place when the vacuum is running and gives it a slightly tighter seal.
If you are making a large vacuum table and spanning a large area, you can include supports inside. Some people use a wall system, I’ve used pins that act as columns. As long as you do not obstruct the airflow to any part of the box, it will work. Even with my relatively thin table of 8 inches wide, the vacuum will still pull the table top surface down, so you should probably include some method of keeping that from happening in your own table. If a bow is created in the table, your machined work won’t be as precise.
Once you have all the pieces measured and cut, liberally apply glue to all the seams. The glue will seal up any air leaks you might have, so make sure everything is well coated. You can also use screws to secure the table top and bottoms to the sides, and again, coat everything in glue. While you have the glue out, brush a coating of glue on all of the MDF edges. The edges of MDF can leak a small amount of air, and this will seal them up completely. You could also use polyurethane or wall spackling. Use clamps to hold the boards tightly in place while the glue dries. Vacuum tables only work because the box is air tight, so the better job you do making sure it can’t leak, the better suction you’ll have for your work.
When the glue has dried, it is time to place your vacuum table on your mill table. If you happen to have rails on your mill table to help you place your work parallel to the mill, use those, but if not, clamp one corner of the vacuum table and then run the mill in each direction along the table’s edge to line it up properly. You will want to get this as lined up as you can, but you don’t need to spend an hour perfecting it. Once you are happy with the position, clamp the vacuum table down like its life depends on it.
Next it’s time to drill holes! There are various software programs out there that let you create 3D models, and almost as many that run CAM software. Choose your favorite and create a pattern of holes, then run the file. The size of the holes and how far apart to space them depends on what the vacuum table will be used for. If you are doing a large table, larger holes are fine.
I work in tiny scales, so I make the tiniest holes possible, and I space them very close together so I don’t have to worry about my small parts flying loose because there wasn’t any suction below them. I do recommend an alternating pattern for your holes, so that any thin vertical or horizontal elements you cut won’t accidentally fall between your hole pattern.
If you are interested in milling both sides of your work piece, you might also consider a registration pinhole system. By having pin holes in definite known locations in your table, you can cut holes for them in your workpiece on one side, then flip the workpiece over and place it back over the pins, ensuring that the alignment is perfect.
And that’s it! Attach your vacuum hose, place your workpiece on the table, cover any remaining exposed holes with something not porous (like a sheet of vinyl), turn on the power, and get to work!