Need help on jointing/planing large subassembly

[Sam Shankar]

Hi folks,

I'm working on building my first laminated workbench top after reading the Schwarz books and advice on this forum. I have already glued up four 7.5" wide subassemblies of my top. The individual boards in each subassembly are pretty well aligned since I used dominos to guide the glue-up. The edges are also still pretty square to the faces, and the faces are pretty clean of glue because I scrubbed pretty hard right after the glue up.

I'm wondering how best to prep the subassemblies before gluing them to each other. Schwarz recommends jointing and planing each subassembly before the final glue up. I can see how that would be smart, but I'm a little intimidated since each subassembly is already pretty heavy and I am not eager to lose too much more thickness (they are currently just over 3" thick each). Should I:

1. Go the whole way by face-jointing, edge jointing, and planing each piece, then squaring the other edge up by running through the TS? I have a solid 8" jointer but I'm not at all sure I can keep a 50# subassembly totally square to its fence or the TS fence. (I have a 12" dewalt planer) So I'm worried I'm going to lose a lot of thickness this way. (You can just tell me that losing 3/16 of thickness is no big deal in a 3" thick maple top) Plus, if I rip one edge in an effort to get it square it will end up less clean than the jointed edge I have now.

2. Trust that the edges are still pretty square, and just face-joint what will be the top face and glue?

3. Just glue it and go?

[John TenEyck]

If the glue ups are pretty flush, which they should be if you used Dominos, then you should be able to flatten the final bench top w/o huge effort using a handplane. But if you have obvious variations or, even worse, any twist in the assemblies, then face jointing and planing are going to be a lot easier. And no, I would not worry about losing 1/4" of the top if it's 3" thick. My bench top is only 1/2" thick in the center section; only the perimeter is really thick.

FWIW, 50 lbs should not present a major problem to face joint or edge joint. Just use roller stands to help support it going into and out of the jointer. Same with planing.

John

[Paul F Franklin]

Just a few thoughts: If the what will be the top surface is already quite flat and even you can probably forgo planing the sections, but remember the only way you will have to flatten the top once glued up is by hand planing or building a huge router flattening sled. (or taking the whole top somewhere with a wide belt sander). Running a long, heavy sub-assembly through a lunchbox planer is no picnic though, you will need solid infeed and outfeed support, but in the end it may be easier than a lot of hand planing (although you'll still need to do some). I would not be concerned about sacrificing a little thickness in favor of flatness. You also don't need to worry too much about the bottom surface being perfectly flat and even, just the top.

Regarding jointing the edges: try clamping pairs of assemblies together with strips of notebook paper or the like between them, every foot or so along the length. When clamped, if you cannot easily pull out any of the strips, *and* if the top surfaces are still in line and flat across the joint, then you can forgo any further edge jointing. If the paper doesn't come out, but the top isn't flat across the joint, you can try flipping one of the sub-assemblies; you may get lucky and find that they now are flat or flatter across the joint.

Don't stress if things aren't perfect; it's a bench. You're going to have do final flattening after glue up no matter what, all this other effort is to just minimize the work involved in that step.

Having said all that, there are folks here with way more experience doing this than me, but those are my suggestions. Good luck!

[Dan Friedrichs]

Check if you live near someone who will rent time on a CNC router or widebelt sander. I recently found a "maker space" with a 36" widebelt that charges $0.50/min. So $8 later, I had a very flat bench top.

[Frank Pratt]

My hard maple top is 28.5" wide x 3.5" thick x 72" long. I first glued up 3 sections, each 9.5" wide. Those were then jointed on one face & planed on the other to the same thickness. I then squared up the glue faces by joining one with the top face registered against the jointer fence and then running through the planer with the unjointed face up. When I glued up the 3 sections I used cauls to meticulously keep them lined up. After glue up I just did a little hand planing to do a final flattening.

My jointer be is only 54" long & those sections were pretty heavy, so I build in feed & out feed bed extensions which made handling much less stressful. I made the mistake of trying to turn over the complete top myself & did a number on my shoulder. That was a dumb mistake.

[Sam Shankar]

Thanks all. I’m not eager to get outside help because, as Paul said, it’s just a bench, and because this is a skill building exercise as much as anything else. In that vein, I’m leaning towards jointing the top faces, skip planing the bottoms, dry fitting, and edge jointing only if necessary.

[Frank Pratt]

Thanks all. I’m not eager to get outside help

But please do get some help handling the complete top. When I turned my top over my thought was "I don't need any help with this" :(

[Jim Becker]

I take things like that to a local shop (one of my hardwood suppliers) and have them run them through their wide sander to level everything after final assembly. It's never cost me more than $25. And yes, that includes workbenches. "Just a bench" still has to be absolutely flat...wink, wink...nod, nod... :)

[mike stenson]

I didn't face joint mine when I assembled my workbench. I just edge jointed, and glued up with the reference face (top) down on a reasonably flat surface and cauled them to it. After that, I just planed the top flat after glue up. The bottom was flat enough that it didn't cause an issue with connection to the trestle base.

[Dave Cav]

My bench top is about 22 x 60 ash, around three inches thick. At the time I made it I only had a 15" planer so I couldn't plane the whole thing. The ash lumber was all 4/4 and I face planed everything so it was nice and flat, then glued it up into two 11" wide pieces. I used white glue for the open time. After it was dry and the glue scraped off, I ran the two pieces through the thickness planer to flatten them, then glued the two halves together using regular yellow glue, a LOT of bar clamps and a couple of cauls to keep the two halves as flush as possible. Once it was dry I did the final flattening using winding sticks and a #5 1/2 with a heavily cambered iron for the initial flattening, then a #6 and a #8 for final finishing. As I recall it took between 1 and 2 hours to get it flat, not hurrying. I didn't use dominoes, biscuits, splines, or anything else between the boards and it's held up fine for well over ten years and a major move and climate change.

[Rod Sheridan]

I would joint and plane all 4 faces then glue together.

Once glued they be so flat you'll be just using a card scraper to finish it off............Rod.

[Sam Shankar]

I would joint and plane all 4 faces then glue together.

And, to be clear, by that you mean face-joint, edge-joint, plane the other face, then run the other edge through the TS.

[H. Gregory Porter]

Don’t rush this last step. Take your time to assure you’ll have a flat work surface. I’d make sure each 7-1/2” segment is flat and the glue edges are square to the top face, sliding a square along the entire length and using a hand plane for adjustments. The better job you do here, the less thickness you’ll lose in the end.

I would definitely hand plane the entire top to flatness. You’ll have to do this to periodically reflatten it also. Unless you oriented the grain direction for each board, you may have to plane some in the opposite direction as others to avoid tear out. If that is the case, power planing is likely to create tear out. I always seem to take off more with the power planer than with hand planes.

[Dan Hahr]

Prepare each sub assembly as if it was a rough cut individual board. Don't worry about losing thickness or width too much, but don't take off any more than necessary either. Once they are dead flat, they can be glued together carefully enough that the top will be very flat and co-planar.

Dan

[Tom Trees]

I would make sure all is square, and do the dry run for sure.
Check for light between the slabs, this is definitely best done when they are standing on edge.
Two jointed battens to aid alignment for the face sides might be a good idea, just to be safe.
Good luck with the bench.



Just a bench... Them's fightin words :p

Tom

[Rod Sheridan]

And, to be clear, by that you mean face-joint, edge-joint, plane the other face, then run the other edge through the TS.

Actually I was thinking run 2 surfaces on the jointer, 2 on the planer.

If the last won't fit on the planer, then edge joint both edges and one surface...........Rod.

[Christopher Charles]

I built a bench with a 4" hard maple top as 2 12" wide sections this way without help. I glued all the sections together and flattened the bottom in the areas in contact with the base and then the top with hand planes. I probably ran the sub-assemblies over a 6" jointer and through a 12" lunchbox using roller stands. I did need help to flip the top once the two sections were glued together though!

Good luck!

[Tom Bender]

Collecting from Greg and Tom

Don't rush and use jointed cauls. Expend the extra material and effort on the cauls, the time will let you think thru the final steps.

[Patrick Walsh]

Million appropriate answers to this. Well at least a few.

But my opinion is as a few have suggested “and I have done what you are doing” a million times.

Joint two edges and plane two edges and laminate all the way up to the limits of the width of your machines. Then glue them together hopefully no more than one or two pieces.

If you do it this way as suggested a quick pass with a number seven followed by a number four and you will have a laser flat top.

There are other options but all are more work in the long run that will make getting a good result even harder.

[Sam Shankar]

Okay, got it - don't skimp on cleaning up all four subassemblies before the final glue-up. I will joint one face, plane the other parallel, and then, since I get a nice clean edge with my table saw (I think it's a Tenryu combination blade), I may use that to square up the edges before gluing rather than wrestling with the jointer (With heavy boards, I find that I have trouble keeping the face perfectly against the fence during the edge jointing. Why don't they make jointer fences much higher?)

[Sam Shankar]

427176I followed everyone's instructions, and it came out GREAT. Thank you for all the help. First, I got a friend to help. Each subassembly weighs 40 pounds, which is pretty unwieldy for a small guy like me. I jointed the flattest face, then jointed both edges with the flat face as reference. (Even with a second set of hands I've been having trouble getting my edges perfectly square, but that's another thread.). Planed them all to the same thickness.

I used four dominoes over each 6' subassembly (so 12 in all) to guide the glue-up. This is the biggest edge-glueup I've ever done and I would have botched it without the dominos to help. (Plus, once you pay for one of these things you might as well use it.) The completed top (still in clamps as I write) is currently much more flat than I thought it would be. In fact, it's totally flat as far as my 48" level is concerned. I'm sure I'll have some work to do with a hand plane but not much. I cleaned the heck out of it with wet rags to make the planing even easier.

I'm very proud of myself. That is, until I see the awful mess of the bottom side, which I'm not even trying to clean now.

P.S. Why is there ALWAYS glueup drama?!? Drama #1 - the parchment paper I used to try to keep the glue off the pipe clamps got caught between the joints as I tightened the clamps. Oh, that was a scramble, tipping up the 200 pound top to try to pick the bits out before I fully tightened the clamps. I think there's still a few slivers in the joints. Drama #2 - spilled a half gallon of Titebond III all over my shop floor just as I was getting clamps on the thing. Had to dance around that awful puddle while clamping up. They are always stressful for me.

[Sam Shankar]

Ah well, spoke too soon. It's super flat along it's length. It is gently but steadily bowed across the width, to the tune of 1/32 high in the middle. I think it has to be due to the fact that I couldn't seem to get the subassembly edges square to the face no matter what...those edges were a hair under 90 degrees. So...glue several of those edges together and you get a little bow. I don't think I'll have much trouble flattening with a big toothed plane but it's a bummer. That's what I get for being proud of myself.

I really need to figure out why I can't get a perfectly square edge off my jointer easily. (Yes, I checked my fence for square!)

[Robert Hazelwood]

1/32" over 2'...I'd say you are doing pretty good. Doesn't take much angular error to get there. One way to take angular error of your fence setting out of the equation is to alternate the faces that you are registering against the fence.

If your fence is set dead square to the outfeed, and you are still getting an out of square edge then I'd double check the knives. If one or more knives is not parallel to the outfeed then you might get that sort of result.

[Frank Drackman]

Next time for each joint, try jointing one board toward the fence and the second board away from the fence. This will cancel out any error of the fence setting.

Another cause of bowing can be too much force applied by the clamps. If the joint doesn't easily come together during dry fitting take some time to fix the issue before glue-up.

[Sam Shankar]

I went over the jointer quickly and found that the fence wobbles a teeny bit in and out of square to the table along its length. I think it may be warped a teeny bit. (Either that or my tables are twisted relative to each other, right?) The fence is dead square to the table just above the (spiral) cutterhead, which is where I've always measured and set it. But it's tipped in to a hair under 90 about six inches further along.

[Sam Shankar]

The fence seems to wobble a teeny little bit in and out of square along its length. Either it is warped or the tables are. It is dead square just above and just after the cutter head though.

The joint came together really easily but I clamped the hell out of it with 3/4" pipe clamps.