Big old hairy glueup

[scott vroom]

Customer wants a 12' qtr sawn oak desktop. It'll have 42" of base cabs on either side with a 60" foot well. I'm looking at 5/4 milled to around 17/16 for the top. I can't get 12' boards where I live so am thinking of a running bond glueup using finished 8 and 4 footers, using biscuited butt joints for the end grain joinery. I don't have a table long enough to do this and am looking at my shop floor upon which to set my 3/4" Pony clamps. There's no way in heck that I'm going to end up with a perfectly flat 12' top, my hope is that I'll be able to pull it flat to the base cabinets with screws. I've got a 15" planer and am considering building it in 2 halves then doing a final glue up to get to the 25" finished width.

Anyone ever attempt a slab glueup of this size and have it come out reasonable flat? I'm paying $6.40 bf for the 5/4 qs oak and if I screw it up it comes out of my pocket.

[Gary Herrmann]

Try dowels or biscuits to help with alignment. Or cauls when you clamp. Let the boards acclimate to your shop for a couple weeks before you plane them. Good luck. Sounds like a fun project. I really like QSWO.

[Peter Quinn]

It doesn't have to be flat, just pick your material as carefully as possible, and maybe make a cove molding or something simple to hide any gaps between the base cabs and the top. I like to glue up with all the boards crowned the same way. If you are using 8' material it can make sense to jump up to 6/4 and flatten if the budget will allow and your joiner can do it. Its only $40 difference on that size top, so its money well spent if your yard stocks 6/4. This is one of those cases where taking it to a shop with a wide belt and paying to have it sanded makes a lot of sense if possible. Otherwise, the two piece glue up with some alignment aids or good bowed cauls will help, the belt sander can do the rest, you just have to feather it in pretty wide to avoid a big dip at that last glue line. I've done a number of tops that were too long to be flattened and too wide to go through the wide belt or planer, some over 48' wide. I start off going a bit sideways with the sander at first, treating it like a joiner plane, then straighten out to take out the cross grain scratches, then orbital.

I like to install crown down so the cabs hold the ends down once they are secured to framing. Even oak has some flexibility at that thickness. Good luck, and get help moving that thing. WO is heavy!

[Chip Lindley]

When it rains lemons, make lemonade! Since you cannot obtain 12' 5/4 WO stock to make a solid top, consider the possibility of making the top in three pieces. Make two 42" slabs for the cabinet sections, and one 60" section for the knee well. That section can rest on cleats and knock-down fittings can attach the three pieces. Breadboard ends could be incorporated on the three sections to add some visual interest, using the 2' cutoffs from 8' stock. It's just a thought...

[Stephen Cherry]

I've never done this, but it seems to me that you would be better off with random lengths, rather than the 4 and 8 foot sections. Just like in a hardwood floor, patterns in the board can be distracting, but randomness kind of blends together. One idea would be to try to get shorts, if they are cheaper, and take them as they come for length; this way you would have 2 or 3 pieces for each board. Just like a floor, this would give you a lot of flexibility in balancing color and grain throughout the top.

[Neil Bosdet]

I agree with Stephen. A random pattern would be more pleasing to my eye for your top.

[Neil Brooks]

Breadboard ends ?

Not a cure-all, but ... maybe a help.

[Karl Brogger]

What peter said, start off with 6/4 and grind it down in a widebelt.

[Mike Hollingsworth]

Macbeath Lumber in San Fran had some 12' 5/4 a week ago.

[Ted Wong]

Unless your grain matching is exquisite I would think Qtrswn White Oak w/ a bunch of butt joints would be a distraction. But thats coming from a dogmatic point of view from a design snob. Chances are your clients will probably just ooh and ahh over the fact its custom made. If it were me I'd shop the internet to find what it takes to get the job done with 12' boards. Charge the shipping back to the client.

[Larry Edgerton]

I have been doing them a whole different way for some time with zero failures.

Instead of using thick material, I use a plywood base, in this case 1 and 1/2 sheets long, but less than 24" wide to allow for edge treatment. You can build a temporary lamination table out of sawhorses and some jointed 2x material. Shim the horses using winding sticks until they are perfectly flat, and through tabs screwed to the side of the 2x screw up into the plywood to hold it in place. These screws will be removed after it is done.

Now dry fit all of your pieces to this plywood. In the center they need not be more than 3/8" thick or less, so you can split your 5/4 and bookmatch pairs, or in your case where you are not going full length, just fit. I would rethink that part, I think it looks better full length. There has to be another supplier that has 12' stock.

At the edges you can do a rabbit in a full thickness/width piece so that the plywood is buried and do the same at the ends if you want that look, or do a wide breadboard end with the same rabbit.

When you have all of your pieces dry fit, and you have rechecked your temporary setup for flat, mix up some West System and glue the pieces to the plywood. If you hav a micro pinner that can be handy to keep them in place. Depending on temp/humidity if you use a slow hardener it should be no problem to achieve this glueup in time. Chill your epoxy if conditions are not great, and spread it out to slow the reaction. The larger the volume in the container the faster it sets.

If you are doing a breadboard surround you may want to do it in two steps, your surround first and drop in your center in another step.

Once you have them all in place use bowed cauls to hold them down. It is important to do a dry glueup practice run to make sure all of your ducks are in a row.

I have done some long glueups with this method, over 18' and 4' wide for commercial applications, and there is not an open joint in any of them. Another bonus is it does not want to bow over time, and does not need to be mounted on sliding dovetails. They are very easy to sand to a flat finished surface as you have taken the stress factor out of the wood as it is so thin and the epoxy will not let it move with the seasons. Use a good finish grade plywood, birch or oak. I had problems using other materials such as Novaply. Another advantage is that you can save money, its actually cheaper as you are splitting the expensive hardwood.

If you want to try it and have any questions call me

Larry