Expert: Jamie Yocono - 11/28/2006

Question
Jamie,  Thanks for your answer, it covered everything and your "watch-fors" will be good to ensure a quality product.  I am planning on sanding the top with a 26" flat sander so your thoughts on ensuring a flat glue up are appropriate.  I am planning on using my flat topped workbench as a glue platform. Do you have any specific recommendations on how to minimize the possibility of an uneven glue-up?

Thanks

Marlo

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The text above is a follow-up to ...

-----Question-----
I want to make a walnut butcher block top, displaying the end grain.  I want to include a white ash strip near the edges for contrast.  Will I have problems with the top eventually separating due to the different wood species.  I plan to glue the pieces with polyurethane glue.
-----Answer-----
Hi Mario,

I've been building cutting boards for years, and never had a separation problem due to the different species moving at different rates. In fact, I used to teach a class that was specifically about making cutting boards, and we experimented quite a bit with end grain boards, using all sorts of woods. These boards were stable and great looking, so you shouldn't have any problems with competing species.

I would like to warn you about a couple of things, however. When we made our end grain boards, we ran them through a wide board sander to "plane" the surfaces flat. It's important to glue these up flat, so that they don't "rock" once they're in the sander. Occasionally, one of the boards would get glued up and not sit flat in the sander. So when it was passed through, it would start sanding, and then rock inside, and not sand the whole surface. We had to rig something to make it sit flat in the machine; we used a little duct tape and a shim on the bottom, so the cutting board sat flat and didn't move. Once one surface was flat, we could remove the shim and flatten the other side.

Another problem that can occur is glue failure if the wood gets too hot during sanding. I am not sure how you intend to flatten the surface, but if it involves a power sander, you need to be careful. Some glues will soften and fail with heat. I'm trying to remember if polyurethane is in that category, and I think it is. So when you're sanding, try to let the surface cool, rotating the areas that you sand. Don't stay in one place too long.

Another thing to be careful with is starving the joint of glue. If you tighten the clamps too tightly while clamping it up, you can starve the joint of the proper amount of glue. You want a little squeeze out, but not too much, or your joint will be starved of adhesive. Also- since polyurethane glue is moisture activated, you might want to dampen all surfaces of the wood that will be glued, thus making a better bond between wood and glue. This really helps.

OK, good luck, I hope this helps. Please feel free to write back if you have any further questions after reading this. And if this answer was helpful... please take a minute and rate my service. Thanks!

Jamie Yocono
Wood It Is! Custom Cabinetry
Las Vegas, NV
www.wooditis.com


Answer
Marlo,

There are two ways to glue that piece up and minimize slippage in the clamps.

One way is to glue up a few sections of the top at a time. It's easier to control a few pieces. Once you get it glued into these "subsections", then you can start gluing them together into larger sections again. Do this a few times, and if you're careful with each smaller section, the whole unit should glue up pretty flat.

The other way is a little dicier- it involves temporarily clamping some scrap boards on the top and bottom of your butcher block top.  Because these boards will add extra "height" to your top, they need to be thin enough to fit with the clamps and the BB top, but thick enough to keep the end grain boards aligned. A half inch piece of plywood (on both the top and bottom) would probably work.

The theory is that the top and bottom board keep the wood from slipping once you tighten the clamps. If I use this method, I do a dry run first, making sure the boards aren't too big for the clamps. Also, you need to make sure that you don't glue them to the actual top, so adding a sheet of newspaper ion between them is helpful. This method will allow you to glue the whole top up at once, but like I said, it's dicey. An extra pair of hands really helps.

Hope I made sense in writing his, this was a little tough to put into words! Good luck, write back if you need clarification.

Jamie