Vacuum Veneer Press Project (long, with pics)

Roger Myers

Member
Messages
23
Location
Stratham NH
I just completed building and testing my vacuum veneering set-up and thought I'd post a few pics and tips for those that might be interested in a similar set-up. I've done a fair amount of veneer work in the past using hide glue, and that will still be my choice for certain tasks, but the vacuum set-up combined with the Unibond 800 is going to see a lot of use from now on.

The press I built was the "Joe Woodworker" EVS kit and his rebuilt Thomas 110V pump. I already had a 220V Gast vacuum pump which I have used with vacuum bags but when I used it I left it running continuously as I did not have the vacuum sensing and control system to cycle it on and off... That pump is now dedicated to the lathe. I'm not affiliated with Joe Woodworker in any way, but have been very very satisfied with all my transactions with him... tools, veneers, and the vacuum parts. The Unibond 800 I get from Vacupress.

So first some pics of the EVS kit parts, the pump, and the PVC components..
 

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Vacuum Press Cont.

Directions given with the kit are pretty straightforward...
First assembly is the main manifold that will connect to the two 4" PVC chambers (which allows the system to "empty" the vacuum bag quickly).
First tip is that it is difficult to thread two large 4"PVC chambers onto the manifold... be sure to run the fittings onto the PVC caps at least once in advance to make sure you did a nice job threading the caps, and that they thread on easy.
Second tip is to not be stingy with the cement when you assemble these manifolds...when you test the system and have a leak, it will likely be here...and that leads to the third tip (which I wish I had thought of in advance)
After assembling the pipe and caps, and letting the cement cure, test them with compressed air (low pressure is all you want or need) and using soapy water find the leaks...and mark the spots on the pipe...don't worry about sealing them yet, but mark where they are leaking. Same deal on the small PVC chamber.

Teflon tape is the only sealant you need on the brass fittings... On my first assembly run, I worried too much about aligning the fittings as shown in the directions, and not enough about getting them good and tight..If you compare my sub-assembly pics to the final test pics, you will see that the alignment is different...and that is fine...

OK - for some sub-assembly pics...
 

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Vacuum Press cont.

I built the carrier assembly pretty much as shown in the plans, although any set-up will work. I did make it a little larger to help protect fittings and gauges, and I made a cut-out in the vertical panel to accommodate the runs from one side to the other...added some holders for the power cord and so on...secured the capacitor so that the terminals are out of direct touch...and added casters for mobility... A couple of light coats of shellac on the plywood to help keep it looking better...

Now, for some more tips....
Before you secure the 4" PVC manifolds, and the pump, etc. to the carrier... test the system... The leaks in the system will be much easier to find and fix if you have 360 degree access to all the parts. This was the most frustrating part of my assembly. I secured everything first, then tested it, and then searched for leaks... finding and fixing them is very hard when they are on the backside or bottom of the PVC, hidden by the carrier...
Remember I said to pressurize (at low pressure) the system and mark the leaks? The reason will be apparent now....when you test the system and it leaks (and it likely will) you can apply some clear silicone to the places that leak (while the system is drawing vacuum) and it will pull the silicone into the voids..then shutdown the system and let the silicone cure overnight. By having marked the leaky spots before, you know where to put the silicone, and by not fastening all the parts together, you can reach all parts of the PVC to apply the silicone... this would have saved me a lot of time...
assembly pics...
 

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Vacuum Press Cont.

Best part of course is testing...and using the system.

After finishing the system and sealing all leaks (really just one good sized one in the 4"PVC) I tested the system...with no bag connected, and the valve closed, the system drew 22" of mercury vacuum and held it steady (without the pump ever turning on) for over two hours! Not too bad!

I built a top and bottom caul assembly out of MDF...with frame on the bottom assembly to help guide the top caul into position. These have a network of grooves cut into the sides of the cauls that face the bag, to allow for all of the air to be drawn out. All edges and corners of the cauls are rounded...bags are expensive, and under high vacuum the edges can and will tear holes in the bag...

Tested the system with a bag on it... system cycles on about every 30 minutes for about a minute to maintain a vacuum between 18 and 22" of mercury... not too bad and more than enough. You can see that I simply clamp the bag to the end of my assembly bench... makes for quick and easy bag closure.

So finally...mix up a little Unibond 800 (shop was right at 65degrees, the lower limit for Unibond 800) and apply it to some scrap MDF and veneer.... (I use a foam roller) leave it in the press for about 5 hours... shut the press down and then let the part cure completley overnight...
Results meet my expectations... very flat panel, easy assembly, good adhesive cure!

A good weekends work which will save lots of time going forward and open up new possibilities for me...

Old hat for the veneer & vacuum press pros... but a satisfying result and learning experience for me! Could build a second unit in 1/2 the time knowing some of the tips I know now, so if these help someone else :)

Any questions, feel free to ask!!

Roger
 

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Roger, I've had my JWW setup for over a year now and it really opens up other uses. I find I use it more for vacuum chucking than veneering, and am looking forward to making a vac. clamp and frame.
 
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