Phenolic Base Board and Plenum Q

I had posted a few pics of my vacuum table a few months ago. I made a couple of minor mistakes when I built the vacuum plenum and I have found the jigs I have needed to build various parts take too long to setup. I decided to replace the base board and vacuum plenum with phenolic and correct my errors. I am trying to decide how to attached the vacuum plenum to the base board. With the UHMW table the only option was screws, but now I could use an adhesive to bond the plenum to the base board. My preference is to use an adhesive, but I am concerned about the difficulty milling off the plenum later to access the base board bolts should I need to. I am looking for suggestions.

Hey Brad,

Clicked on your profile and not seeing any old post to view pictures - If you can add a few that will be helpful. Also providing the vacuum system specs your using will help as well. My current routers have the spoil board floating on the vacuum table and a rubber gasket along the edges and zones. This work great because once its finished its a easy swap but this requires alot of suction.

Gluing the spoil board to the base works but its a pain in the @!! to plan off

Screwing the spoil Board down works great but you have to make sure you seal all the edges very well - We normally use wood glue because we have gallons of it on hand and it rolls on well.

One of the most important factors is how powerful your vacuum pump is and your table size.

I have a single phase vacuum. The original vacuum and plenum design work perfectly fine (pic below). Each of the squares is 3/4" square and the space between works for 1/4" wide gasket material. To make pods efficiently I will be adding a radius to each corner of the grid squares and a small chamfer around the perimeter of the squares. There are a couple of other minor changes I am going to make as well. With my system I can generate up to 9" of vacuum and that is about par with what most get with home built systems. That level of vacuum has proven adequate for the cut speeds the entry level machines are capable of. I will have to upgrade my electrical service for the machine and vacuum I want eventually.

The reason I am re-building the plenum is so I can use pods to hold down parts. I have been building jigs or tee squares until now to hold down parts for secondary processes. Those methods are a bit too time consuming, and a few simple pods should work better. I do not have enough vacuum power for pods (plus small scale vacuum pump too loud), so I will be using a venturi pump for the pods. The error I made with the UHMW plenum was making all four at once and then stacking them poorly for a few weeks. In that time the UHMW pieces curled. When I finally installed the plenum parts on my table the grids do not all line up as well as I want to use pods. I also milled the surface of the plenum after the grids were made instead of before. That too was a mistake because now some of grooves around the grids are not the correct depth. This second error has led to some problems achieving a seal with the perimeter gasket. I have gotten around the second problem by bolting down the spoil boards when they are in use. With the spoil boards bolted down I can achieve full vacuum without a gasket.

The reason I am using phenolic for both the base board and the vacuum plenum is for stability. It is expensive, but Gary's discussion at camheads convinced me it is worthwhile.

I think I will glue down the phenolic plenum. I was looking at options last night and screwing the base board from the underside does not seem to be a lot more work. I am making a test plenum and some pods to test my design with MDF before I cut the phenolics. The cutters arrive today and all the phenolic is carefully stacked in the shop already.

Attachment 366233

Well, I finally finished the plenum top. The adhesive worked fine after I figured out which trowel to use. I used an epoxy from Smooth on, but if I were to do it again I would use a West product. I was having difficulty with the first sheets, and when I called West tech services he said I could have easily used a few of their products to bond sheets of phenolic provided the top surface was removed. That would have been much easier because the smooth on product was quite thick.

I am not sure I would suggest to others to mill phenolic with the smaller machines that are not as stiff as the industrial models. That step of the project turned out to be quite challenging. I have cut aluminum, and that has worked fine on my machine, but the phenolic was worse to cut.

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