I’m working on a vacuum table for my PRO 4896. I have a Black Box Hurricane pump.
I was planning on doing a base layer of MDF that attaches to the CNC, a middle layer of MDF for the plenum, and a top layer of ultralight MDF as the spoil board.
I’ve been hearing MDF is a poor choice for the plenum due to its porosity even with sealing.
I’m looking at some alternatives. Would love input from others with more experience.
HDPE:
- Pros: inherently air tight
- Cons: not stable with heat - can tend to grow/warp in hot weather. Can’t glue it to the base layer.
Baltic Birch:
- Pros: more air tight than MDF. More stable against environmental changes. Could seal it. Can glue to base layer.
- Cons: Less air tight than HDPE
“fancy” MDF - moisture resistant: a little better than regular MDF.
Curious what everyone here thinks? Any recs?
I have a hurricane like vacuum table on by 60120. I have the center 4’ of X as vacuum.
The base layer is melamine. I surfaced off one side and cut the air channels. I sealed those and the sides, I believe with polyurethane though next time I would probably use table top epoxy. A layer of 3/4” MDF (surfaced on both sides) is glued on top. I resurface it occasionally and have gotten a lot of use before needing to replace.
If you plan to glue the top layer I see no need to use plastic.
On my next incarnation I will probably use baltic birch because I can get it in 5’ widths to match my machine better. I would also include threaded brass inserts in known locations so I can easily attach fixture plates or other hold down mechanisms on top of the vacuum table. I don’t do sheet goods nearly as much as I used to and hurricane style vacuum tables aren’t good for small parts.
One thing to consider is that most HDPE will warp when you cut a bunch out of it unless you specifically get the cast and stress relieved type. It can be a bit spendy.
Another option for the bottom layers could be a closed cell rigid foam board. The specific type depends on what you an source. PVC, Polystyrene and a few others could work. You would have to test it. Probably cheaper than HDPE.
With a bunch of work you could make MDF airtight but I think there are better options. A thick edge banded melamine could work well. I think you can get 49”x97”x1” sheets in most places. Could put the plenum directly in one sheet with threaded inserts to hold the top sheet down. I use nylon 1/4-20 large Phillips head screws to hold ours.