Expert: Jamie Yocono - 4/13/2005

Question
i understood completely as to what you were saying about if the jointer is not perfectly square. that makes perfect sense. i will actually be looking into getting a jointer very soon. one more question, are there any books or website you can reccomend for furniture plans or hobbie plans(birdhouses, etc). thank you again for your help Jamie.
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thanks again. that sounds like that is probably exactly what is happening. i cant say the boards i am using are perfectly square. what tool would you reccomend to achieve a perfect 90" angle?
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thanks for the very quick and informative reply Jamie. what you said about the straight edge is exactly right. yet the grains do alternate and DO NOT go in the same direction, which leaves me very baffled as to why i am still getting the cupping affect. i must say though, the individual boards dont seem to be cupping, it is the whole tabletop that is cupping so i am pretty sure that the movement is happening at the glue seems. but i must say humidity must play a part in all of this movement i am having, because i have seen this tabletop go from looking nice and flat one day, to cupped a couple days later, and then back straight again. i have tried reinforcing the back of the tabketop with 3/8" plywood, and it still cupped a bit. but i am going to try narrower boards the next time i try this. thanks agin for your help jamie. i
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i recently attempted for the first time to build a very simple tv stand. the top of the stand that the tv will rest on consists of (4) 6x1 pine boards that i glued and clamped together with titebond glue. i left the boards clamped for about 2 hours, at which time i took off the clamps, and let the glue cure overnight. after that i sanded the top with an orbital sander till it was nice and smooth, resembling one solid piece of wood. my problem is, every time i have done this(3 times in all) the wood bowes upward at the glue points. looking from the side, the tabletop is bowed about 1/4" - 1/2" from the center to the outer edges. have you experienced this before. i cant figure out what i am doing wrong. the only thing i can think of is the fact that i am using a soft wood like pine. any help or thoughts on this would be greatly appreciated. thanks in advance.
Answer -
Hi Mark,


You are asking one of the BIG questions that many woodworkers ask - how to deal with seasonal changes in wood. I can't tell whether you mean there is cupping on the overall width of the top, or just at the glue lines. I suspect it's the overall top, so I will answer that question.

If you place a straight edge across the two edges of your top, and there is a gap under the straightedge, that means you've got some overall cupping of the top. So I'll address that here. The reason you're experiencing that cupping is because of wood's normal movement in relationship to the humidity in the air.

With changes in humidity, wood will cup in a direction opposite of the wood's annual rings. So if the rings are facing up, the board will cup down. It's just a fact of life.  Now there are some things you can do, like add bracing underneath the top to try and minimize the cupping, but it WILL occur.

So I suspect that if your TV stand top is cupping mostly in one direction, you've probably glued up with the annual rings all going the same direction. Look at the end of your top, and try to figure out which way the rings are going. Sometimes it's hard to tell on a narrow board, where you can't see very much of the end grain pattern.

Most woodworkers use a tried and true method for making solid tops.  The top should be made up of narrower boards, say anywhere from 2" to 5" wide, and with each board, the direction of the annual rings is alternated.  So in your case, if your board is 20" wide, I would cut that into 5 pieces, each about 4" wide. Mark the direction of the annual rings on the end of the board before you cut it, as once it's cut, it's hard to figure out the direction.

When you glue the 5 pieces together, boards # 1, 3, and 5 will be in the "up" position, and boards 2 and 4 will be facing down.

Hope that's not too confusing! This topic has been discussed many times in most of the woodworking magazines and websites, so if you do a search on laminating procedures, I'm sure you'll find some artwork to help you along.

Good luck, I hope this helps. Feel free to write back with any other questions you might have after reading this.

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

Answer -
Mark-

Two things about your top cupping- wood will react odd (hence, the cupping) if you do not treat both sides equally. This means that if you do something to one side of the wood, like apply varnish or veneer it, you must do the same thing to the other side. If not, the wood will react to humidity in odd ways, and will increase the chance of cupping. When you said you applied a 3/8" backer board on one side, it made me think that maybe that's what is happening here.

Narrower boards will help, that's for sure, but another thing to check might be your edges of your boards. If you're a hair off 90 degrees, that might add up to a top that glues up with a slight cup in it to start. Clamping it might make it look nice and flat, but when it's unclamped, the board will spring back and if your angles aren't 90, you're going to end up with a cupped top. Technically, this might be called a staved top, since stave construction involves laminating boards with edges that aren't square, so that they will create a curve. Think about how barrels go together, and you'll know what I mean.

Anyway, if you're not treating the top and bottom of your board the same, that could be one area of concern. And my next guess would be the edges aren't square to begin with.

Hope this clarifies things even better for you. Good luck, you'll figure it out!

Jamie Yocono
Answer -
Hi Mark,

The best way to get a good square edge is from a properly aligned jointer. Using a square to set it up, you should be able to get it dead on. If a jointer isn't in your tool arsenal, you could try a hand plane, but you'll need to be very accurate with it. I think doing it by hand is much harder.

A tip I learned years ago- even if you can't adjust your jointer perfectly square, there are ways around it. Say it's out a quarter of a degree. When you edge all your boards, rotate the face that is against the fence. So on board #1, the top is against the fence, on board #2, the bottom is against the fence. Any variation the fence has off square will be compensated, since the 2 edged will always mate to form a 180 degree joint. I hope that made sense! It's a little hard to visualize when you're working with tiny degree fragments, but if you set your fence at a few degrees off square (say 85 degrees) and try it, you'll see what I mean.

Good luck, I hope this helps. Feel free to write back with any other questions you might have after reading this.

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


Answer
Hi Mark,

Glad you understood what I was trying to explain about the jointer technique. A jointer is a wonderful addition to a woodshop.

I am not a huge fan of using plans. When I used to teach, I always encouraged my students to come up with their own plans because frankly, most plans have errors in them. But I get many questions regarding plan sites from All-Experts, so here are some of my favorite. I like the first one the best, although the information they have regarding joints is poor and needs some clarification. But I do like the style that they use, which is often Asian or Craftsman style.

www.am-wood.com (amateur woodworker.com)
www.woodworkersworkshop.com
www.plansfordummies.com
www.woodworkingplanfinder.com
www.absolutelyfreeplans.com
www.woodzone.com

Good luck, these should keep you busy for a while. Have fun, and watch out for your fingers with those dangerous things.

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