I made the mistake of ordering wood (maple) which arrived surfaced on two sides. Instead of 4/4 rough cut wood, I have 7/8 inch thick planed boards, about 6 inches wide. The boards are visually flat, without obvious cupping, twist or warping. I need to glue up two panels 48 inches long by 21 inches wide, by 3/4 inch thick. These will be the sides of a cabinet carcase, to be assembled with dovetails.
If I joint the faces of the boards dead flat on the jointer (I have a 6 in jointer) and then use the thickness planer, I’m afraid I’ll be left with less than 3/4 inch thickness (especially after handplaning smooth the glued up panels.) Would it be better to edge joint and glue up the panel from the 7/8 boards and then hand plane the panel flat with a jointer plane? This way, the thickness might not be perfectly uniform, but I thought I might be able to preserve more thickness. Any advise is welcome.
Thanks, Jay
Replies
If your boards are flat at 7/8" with no skip and you glue them up carefully, you should have flat 7/8" panels by scraping the glue line down. Really!
If i'm gluing up something that large, i like to do it one glue line at a time. I'd glue 4 pairs of 6" wide boards, joint them again, then glue up the pairs to make my sides, trim to width when done.
I lay the boards on my clamps, apply glue, and start snugging up clamps from the center out, evening up the boards with one another as i work my way toward the ends. Unfortunately, i've yet to meet my first dead flat 48" long board.
In my experieince, what looks flat isn't always flat. I mean, when I hand plane with a long jointer plane or even a jack plane, there are low areas that don't come intocontact with the sole of the plane on the first few passes, until the high spots are taken off. Usually there's a slight curvature to the panel so the center high spot is removed on one side and the other side has relative high points at the edges. This results in a loss of overall thickness, which could take it down to less than 3/4 inch.
I also like to glue them up in pairs to minimize slippage in the clamps. I'll probably use biscuits.
Well, i can eyeball flat pretty well, so if it's visually flat to me, it's flat.
I don't use biscuits for edge/edge joints, either. Richard/Sgian Dubh has explained this repeatedly...somewhere.
You realize this glue-up must be done on a dead-flat table, don't you? <G>
Edited 1/20/2003 11:21:00 AM ET by SPLINTIE
Contrary to what others have said, it's my belief that there has never been a glued up panel in the history of woodworking that didn't need some flattening after the glue dries - and I mean more than just scraping the glue line.
Your initial intuition is right - glue it up and THEN flatten the panel as a unit. Use a handplane. Familiarize yourself with the use of winding sticks. You're going to have a knife at your throat the whole time trying to preserve the required thickness. The last thing that you need to do is flatten individual boards - you'll simply lose too much thickness in that process + the process of flattening the panel as a whole. This is not to say that you can use individual boards that are way out of flat. If that is your situation then you are screwed as far as maintaining your 3/4" thickness is concerned.
I agree with you totally, about the universal need to slightly flatten a board. I think everyone except Norm on TV has to do this, but he probably doesn't own a hand plane. Anyway, I appreciate the comments, and will do the hand planing method. It actually is not critical that I maintain exactly 3/4 inch thickness, but that would be my goal.
Jay
I think Norm used a belt sander to flatten his glue-ups in the old days. Now he has a large drum sander. I think even Norm recognizes the need to flatten glued up panels. I guess the tool one uses to accomplish flatness is up to the individual woodworker.
If you have the luxury of time, let your glue-ups rest in the shop a few days before you test for flatness (cup, twist, and the rest) and begin the flattening process.
If you are making case good sides you particularly want to watch for twist in the glued up unit. If you don't, fitting your drawers and shelves will be a nightmare.
I have purposely allowed the boards to remain in the shop for a month or so to acclimate. Do you think it is still necessary to wait after the glue up, or should they already have taken on any cup or twist that they're going to?
By the way, if you discover twist in the glued up panel, is there any hope, or do you start all over again with new wood? Thanks.
Jay
I like to see what the panel is going to do, so yes I would say let them sit before you work them.
Twist is a bitch, no doubt. You attack twist in a panel the same way you would an individual board - identify the high corners and take them down. It may be a waste, but I leave stock at least 1/4" over thickness if they're going to be glued into a panel. Believe me, there have been times when it was not enough. I have the wall mounted Plano glue racks too. The jig positions the wood into a dead flat position, but believe me that is no guarantee panels will stay that way.
The easiest philosophical approach is to consider your panels as single, wide boards that you came across fortuitously and treat them as such. Single, very wide boards are never flat just as your glued up panels will not be flat.
The dirty little secret foisted on woodworkers by the machinery manufacturers is that you're going to be hunky-dory if you own a 12" portable planer and a 6" jointer. However, this level of equippage does nothing about your need to flatten either: 1) single, wide boards; or 2) glued panels.
This may cause a torrent of response from those so equipped claiming that their glue ups are flat. But the propensity to view a panel (just out of the clamps) as flat is directly proportional to one's insufficient tooling, or lack of confidence in flattening stuff with hand tools. At least I fear this is the case.
While I'm sure that occassionally somebody hits a home run and a panel may be within reasonable tolerance in regards to 'flat' (again, right out of the clamps), I find it virtually impossible to believe that this could happen on a consistent basis. Which leaves me wondering what happens at that point. Is the shoddy panel simply shrugged off with an "oh well" and put into the project? Only The Shadow knows I guess.
Trust me, you are on the right track and never need be apprehensive as you loosen your clamps and lay a straightedge across your panel for the first time.
Well, well Crunk, I think you're maybe the second person I've come across that posts in US based forums that agrees with my position that if you own a 500 mm capacity thicknesser, you really ought to own a 500 mm (20") capacity surface planer (aka jointer.) It's either that, or you must develop the necessary hand planing skills to get one face of a wide board-- glued up or not-- flat enough prior to thicknessing.
Of course, it doesn't always matter too much. Table tops held down to a stout framework with buttons and the like can be lived with if they're not just perfect, but in other applications, e.g., carcass sides, bases, and tops, it can be critical. Slainte.
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The poster formerly known as Sgian Dubh
It's amazing this mis-matched jointing and thicknessing capacity situation. Of course your right about tabletops - much less critical since they sit on top of a base.
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