Darryl Keil Last Activity 2025-09-09 11:09 AM
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Paul Kierstead

Posts: 39

Joined: 2008-01-24
Location: Ottawa, ON

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Subject : Two-ply, backing veneer and torsion boxes.
Posted : 2008-01-24 4:35 PM
Post #34321
Background:
So, I just received my Vacupress equipment and am keen to embark on a project. Beyond the first one (a simple cabinet), the next up is a desk which has considerable span; on the order of 5 or 6 feet. A torsion box seems like a very good option; I have made smaller versions previously to my satisfaction. Naturally, it will be veneered. The plan is a bullnose type front. I was quite happy when I viewed the videos and seen the veneer being pulled right around the front.

Questions:
1) I really like the idea of using the press to glue the skins to the inner lattice structure. Clamping up such a beast would be very painful otherwise. What, if any, problems might I encounter doing that?

2) Torsion boxes create "interesting" questions w.r.t. backing veneers; specifically where is it located. In the video with the bull-nose, Darryl uses a two-ply veneer and doesn't appear to use a backing. Does the two-ply method stabilize the veneer to such an extent a backing veneer is unneeded?

3) The desk will probably be at least 2" thick. The "bullnose" will be more like two round-overs with a flat area between them. When I bend the veneer around it, should I stop the first glue right at the top, or should I do the first glue around the first bend, and the second glue around the second bend?

Thanks for taking time to read this!


 
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Don Stephan

Posts: 825

Joined: 2003-07-18
Location: Cincinnati, Ohio

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Subject : RE: Two-ply, backing veneer and torsion boxes.
Posted : 2008-01-24 8:02 PM
Post #34323 - In reply to #34321
Paul:

I can comment on the torsion box itself, but not the bullnose.

I've pressed a couple torsion boxes, and used the resin coated honeycomb paper available at www.vacupress.com. The only caution is to dial back the maximum vacuum to I think about 15" when pressing the torion box itself. I used urea formaldehyde glue and 1/4" plywood skins, with a poplar frame around the honeycomb paper. Include more solid wood wherever you anticipate needing screw holding capability. After the glue is sufficiently cured, remove the torsion box, stand on edge, and let cure overnight. After that, the assembly is strong enough to withstand 25" of vacuum when pressing the face veneer. My two were only experiments, so I didn't veneer them, but if I had, I would have veneered both surfaces.

The honeycomb paper is relatively inexpensive - I'd suggest purchasing enough to make a test, perhaps 3' x 3', with your bullnose and try rolling the veneer down over the edge.

Good luck!


 
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Paul Kierstead

Posts: 39

Joined: 2008-01-24
Location: Ottawa, ON

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Subject : RE: Two-ply, backing veneer and torsion boxes.
Posted : 2008-01-28 3:32 PM
Post #34337 - In reply to #34323
Thanks Don. In response to your message, I spend a couple of days poking around, finding a couple of articles in FWW that were particularly useful. It would look like the honeycomb is a pretty good idea; I seen examples of quite large tables made using it and it seemed to work well.

It would seem, though, that the skins should be veneered before the torsion box lamination in order to be able to draw enough vacuum to ensure good adhesion of the veneer, whether it is a wood or honeycomb interior. This seems to call into question whether it is possible to put the bullnose on, since it would definitely seem to need veneering after box construction.

I'll have to revisit my angle on this. I'd really like to have a very good match between the top and the bullnose; maybe separately veneer the bullnose and apply it afterwards. I'll have to post a separate one to ask about skin thickness, etc. since I think I asked too much in this one


 
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Darryl Keil

Posts: 1455

Joined: 2003-05-22
Location: Maine

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Subject : RE: Two-ply, backing veneer and torsion boxes.
Posted : 2008-01-28 8:38 PM
Post #34341 - In reply to #34337
Paul,

A two ply veneer is really just the backer glued to the face veneer instead of the substrate. There are times when its more useful to do it this way.

As far as putting the veneer on the skin first, I would recommend doing it after you put the skins on the honeycomb. Its the way I have always done it.

Although its a bit complicated, you could veneer the top and wrap the veneer around the bullnose without seams but you would have to do it in two steps. Veneer the top face down on the platen with a caul underneath. You would stop the glue about 1/2" back from the start of the bullnose. Once the top is glued then you would block up your top on a 2" piece of rigid Styrofoam and wrap you bullnose is the second pressing. The Styrofoam elevates you panel so you can tuck the bag underneath easily. You can also skip the Styrofoam and hang your bullnose off the edge of your platen.

I would suggest a test run on a sample as the "two stage" pressing is a little tricky and you would need to get the feel of it before you tried it on your actual top.

Another option is to veneer your bullnose separately and attach it after the top has been veneered. Yes, the veneer wont match perfectly between the top and bullnose but you may have much better success doing it this way.

Darryl



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