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The first vacuum veneered panel – results

The results? It worked! I think I will keep this vacuum press.

I did the following using new shop-resawn veneers; previously resawn panels will be used for the doors (i.e, the “wing”, and “Don Quixote”). Before doing any serious work with the vacuum press I wanted to assure myself it worked properly, and that I was indeed familiar with the process. The system did the job well. But not all was perfect, as you will learn toward the end.

Now, some details of the first veneer panel done with the vacuum press:

1-glueline.png

 Notice the glue line. This is the show side of the glued-up veneer panel; no blue tape, no tape of any kind on this side. I scraped off the “gooey” glue after 45 minutes.

1-brickclamps.png
Bricks become clamps. They are needed strictly to hold down the glued edges of the veneer pieces. The tape pulling the panels together is underneath.

1-mapleside.png		 The spalted maple veneer panel, after coming out of the vacuum press. It might become the inside face of the back, visible when the doors are opened.

1-cherryside.png		 The cherry veneer panel, following vacuum pressing. This will be the back face of the cabinet.

As I did the quality control of this first veneered panel I noticed a slight bow as I sighted down the top and bottom edges. To measure the amount of the bow, I placed the panel flat, with the concave spalted maple side up. With a straight edge placed across the surface I measured 0.030″ concavity (this is 30 mils, or 30 thousands of an inch).

I was puzzled about this amount of distortion, as I expected the veneered panel to be perfectly flat. One obvious area to look was the platen I fabricated, and showed earlier:

1-firstpressrun1.png

In retrospect, I now feel that the platen should not extend too far beyond the edges of the package being pressed. This is especially true if the “sandwich” is thick, as this one was (about 4 inches). I now believe what happened was that the outer edges of the platen lifted slightly during the time that vacuum was on, lifting them and causing the slight deflection I measured.

I must run one additional test, to determine if my thinking is correct. That is, unless anyone reading this can confirm my theory in the next 16 hours or so. I would appreciate your feedback, especially if it will save me doing another test glue-up.

The bottom line of this test: I achieved absolutely perfect adhesion, with no gaps anywhere along the visible glue line between the veneer panels and the substrate. In addition, the entire surface of the veneers is perfectly flat, totally free of bubbles or areas of poor adhesion.

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First vacuum press run – finally!

Edit to add: The glue-up of the 1/16-inch thick veneer panels went flawlessly! I must credit John Fry for the success. He recommended I use a variation of the veneer panel glue up. This technique does not use any tape on the show side of the panel during the glue up procedure, as tape would smear glue that squeezes out. Instead, he suggested I use strips of wood close to the seams, one on each side, using bricks to hold the seam areas flat. Thanks, John!

Also added (for those who don’t know John Fry): In his latest episode of the Carlo Mollino’s curvy table, Furnitologist Neil Lamens highlighted John Fry as one of two woodworkers pushing the envelope of our craft. I could not agree more! You can see the step-by-step procedures John has used in many of his outstanding pieces, at his web site, Chisel and Bit. Simply click on the Details button below each of the items in his Gallery to see the wonderful pictorial essays.

What follows is a comedy of errors.

Yesterday (Monday) I trimmed the veneer panels such that both pieces were of identical size – tried a few different things, and finally settled on simply placing them under two pieces of MDF, exposing to the cut mark line, and cut them to size at the same time using a climb cut. It worked great!

Then I had to “troubleshoot” my heating blankets – totally forgot that these models have an 11-hour timeout. Of course, it took me a while to figure this out .

I realized at one point I did not have enough of the 1/2-inch MDF substrate I needed, so I ordered some and it was delivered to a cabinet shop five minutes from the house. I picked up the MDF this morning, and started work. Things went well, to get me ready and moving along!

For later today, I must remember: Go back in about 30 minutes to shut off and turn on the blankets again, as doing this resets the 11-hour time limit. I need the blankets to remain ON for the entire night, to get full cure of the adhesive.

It is an exciting time, waiting for that panel to come out of the vacuum bag tomorrow morning…

One thing I did NOT do, but it is suggested for shop-sawn veneers: I did not apply glue to the backs of the veneers; this is normally done for shop-sawn veneers, not for the very thin, commercial veneers. I hope I did not screw up; I totally forgot to do it! But I DID apply a generous amount of glue to the MDF. Hopefully, not an excess. I must get a better feel for it the new glue, Unibond 800, compared to the DAP plastic resin glue I have used in the past.

Up to now I have applied veneers only to small pieces no larger than jewelry boxes, and had never used a vacuum veneer bag. If I did not screw up things too badly, and the results are good, I will share with you. If not, I know exactly which pile this veneered panel will go into – and you will not find out where this pile is.

Now to share the job finally underway: On the left, the 19″ X 24″ panel just after firing up the vacuum pump; on the right, the heating blankets providing sufficient heat to allow proper curing of the glue (I keep the shop at 60°F to 62°F in the Winter):

1-firstpressrun1.png 1-vacpressblankets1.png

Relevant links:
John Fry, Chisel and Bit
Neil Lamens, Furnitologist
Unibond 800

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Setting up the vacuum veneering press

The VacuPress vacuum veneering press arrived yesterday; I had a chance to run a quick test, to make sure everything was working as expected. It was! The total time from unpacking, to making the 2′ X 4′ platen, to taking the photos below: 75 minutes.

Now the fun can start with the application of cherry and spalted maple veneers, to continue work with the Krenov-inspired cabinet:

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As you can see, the pump pulled 24.5 inches of mercury, which is great at our 1,150-foot elevation. It took 38 seconds to reach this vacuum level, using this 2′ X 4′ platen with the 4′ X 8′ bag shortened by simply moving the C-Clamp tubular clamp near the back of the platen. I am quite pleased!

Since I normally keep the shop around 60° to 62°F in the Winter, I will be using the heating blanket to preheat the bag contents overnight, to ensure that everything in the bag stays above 70°F during clamping – typically 12 hours. This will allow proper curing of the veneering adhesive (Unibond 800).

I will keep you posted on my veneer projects using this vacuum veneering system. In the meantime, today I am headed to the Open House being held by Metro Hardwoods, the newest supplier of hardwoods and exotics in the Kansas City area. I might take pictures, or even shoot some video to share with you.