Thicknessing Veneer
Thoughts on belt-sanding or planing sawn veneer sheets to thickness. November 14, 2009
Question
I've been resawing my own veneer for decades. My standard process is to resaw to just over 1/8", then use sleds to plane it down to just under 1/8" so that I can ensure the veneer does not act like solid wood and try to move. Needless to say, using the sleds is a pain. All of a sudden it hit me... Why not take the resawn pieces (always jointed on one side), then do the lay-up, then run the entire sandwich through the wide belt to drop the veneer thickness? This seems to be too simple to be right!
Forum Responses
(Veneer Forum)
From contributor J:
It may seem too simple, but it's not. Your off-the-saw thicknesses need to be fairly consistent so that the piece isn't canted one way or the other going through the sander with an unsanded surface on the table.
From the original questioner:
Excellent point. The only way to avoid that would be to do two setups in the bag. Press one face, sand, then press the other face and sand. I think even with the two pressings there might still be time savings in process.
From contributor J:
You've got to be careful with the two separate pressings; with unstable veneer species or thinner substrates, there's a high potential for curling.
From the original questioner:
Yep, I'm aware of the unbalance issue. But I think if you did the second pressing right after the first and did not let the sheet sit around, that this could be mitigated...?
From contributor J:
You can get away with it in some cases, but it's best if the veneers are cut nicely enough that you can do it all at once. Like I said, thinner substrates and especially moisture-sensitive veneers can be problematic.
Another thing you'll run into is if you're doing bookmatching; though you joint the plank before slicing the veneer, that jointed side will be against the substrate on only one side of the bookmatch. You can glue the sawn surface down, but it does need to be fairly smooth and non-lumpy, and may require a little more glue. This is just another reason to fine-tune your bandsaw.
From contributor N:
Here's a different thought: maybe your sled is too complicated. Mine is a piece of 3/4" MDF the width of the planer bed, with a cleat nailed on the bottom on the feed side to keep it in place. No hassle at all, just feed the stuff through just like lumber. The other option, get yourself an old Inca jointer/planer. I can plane 1/8" veneer without using a backer sled. If you want to run it through the widebelt, just make a sled with a small cleat on the back to keep it from shooting back at you. Sand it just like you'd plane it, before you press it to the substrate.
From contributor L:
I do a lot of sawn veneer and can offer a couple of suggestions. First, all the other comments are good ones.
Second, there are times when you *have to* glue the surfaced face down leaving the sawn face up. The best example is when resawing curly woods. Thin curly maple, for example, seems to chip out even worse than thicker. So to avoid trying to sand out chipouts in very thin stock, you have to glue surfaced face down. The nice thing about this is that any chipouts on the surface face get buried.
Here's the rub, you should be gluing both sides of the core stock at the same time to avoid warp. Doing this, I've never had a problem with 3/16" veneers glued to 1/2" Baltic birch core. The problem with doing this is contributor J's point - you give up book matching, unless the grain is extremely consistent.
The key is doing a very good job of keeping the thickness even during resawing. Then you can use a widebelt sander to finish off the thickness.
From contributor K:
We use the wide belt to thickness the individual leaves of veneer prior to laying them up; it's much safer and more predictable than running them through the planer, and they are of equal thickness, so no difficulties in pressing. I sometimes edge glue the leaves into a sheet and then sand the sheet prior to pressing, to make handling easier and keep the epoxy from wicking up through the joints. I find thick veneer is usually too strong to keep together with veneer tape or stitching thread. Another way is to tape the leaves together during layup with packing tape or blue masking tape. I think laying up the resawn veneer without thicknessing would be problematic unless you have a virtually perfect result off the saw. That said, I have seen articles by Krenov disciples who do it that way (though they no doubt do their final surfacing with homemade hand planes).
From contributor C:
I also make some veneer, and resaw it with a thin kerf saw blade on the table saw. The bottom line is a particleboard sled with a thin strip on wood glued on the end, then run it through the widebelt sander. Also can cut it on the bandsaw.
