whats wrong with my glue up?

[dan sherman]

I've spent the last few days preparing the stock for an end grain cutting board, and tonight I finally got around to doing the long grain glue up.

To do the glue up (6 boards) I used cauls and pipe clamps (alternating top and bottom). Almost Every time I do a glue up like this, the boards skew (see attachment) even if it's only 2 or 3 boards.

Is this because I'm using to much glue, pipe clamps, to much clamping pressure, something else?

[Tom Hintz]

Pipe clamops are not the most accurate there is in terms of their faces aligning squarely with each other. That miss-alignment can easily cause the skewing in your graphic. Also, if the edges of the blocks themselves are not perfectly square they can't be clamped up square. And, too much pressure is never a big help for alignment. I think most woodworkers use way too much pressure overall.
I was mentored by a master cabinetmaker who admonished me for trying to squeeze the wood to death rather than just clamp it up. As I discovered about everything else he told me, he was right - again and again and again.

[glenn bradley]

I can't tell from the graphic if you mean the pieces are "rolling over" or slanting to the side but, I had one of my Jorgie pipe clamps with a face that wasn't very square to the world. They cheerfully exchanged it.

I do see some discount pipe clamps (think HF) where most of them are cock-eyed; this would make it nearly impossible to keep control of your material as you apply pressure.

I have a rack of Jorgie 3/4" pipe clamps and when you need one, there's nothing like 'em. However, I don't think I've touched them in at least 2 years. K-body and Uni-klamps get used 5 to 1 over anything else. Jorgie and Bessey f-style and Irwin quick grips after that (based on frequency of use).

If the clamps are true, then alignement other than perpendicular to the material prior to applying pressure will skew the work. This is done purposly to square-up during some assembly.

[Denny Rice]

I also agree with both of the other posts...There are a lot of different things that can cause problems when gluing up multiple boards:

1. make sure your glue joints are straight and true, and try dry fitting them in the clamps before applying glue to the boards.

2. Do not over-tighten the clamps too much presssue is just as bad as not enough.

3. I don't know how your applying the glue, but too much glue can cause the project to "slip & slide" around while trying to clamp (and make a mess). I use an acid brush or something else to spead the glue on the joint and after clamping I always take a wet sponge with water to rid myself of the squeeze-out. There are some that don't like to do this because water will raise the grain of the wood, but its never been a real problem for me.

4. Check your clamps, make sure all the faces are clean and no dried glue on them and check them for squareness.

5. And if all else fails you might try using biscuits in your glue-ups, I know its an extra step but it will limit the movement of the wood. Hope this helps.

[Rick Lizek]

I've spent the last few days preparing the stock for an end grain cutting board, and tonight I finally got around to doing the long grain glue up.

To do the glue up (6 boards) I used cauls and pipe clamps (alternating top and bottom). Almost Every time I do a glue up like this, the boards skew (see attachment) even if it's only 2 or 3 boards.

Is this because I'm using to much glue, pipe clamps, to much clamping pressure, something else?

If using the proper cauls and right procedure it's difficult to mess up a glue up. Are you sure your wood is square? Cauls should have a slight crown on them and crowns should be facing each other. With cauls there is no need to alternate the clamps.

[Cody Colston]

Sounds like the wood is not square, especially if it happens on every glue-up. Check your jointer fence 90 degree stop.

[Peter Quinn]

Very simple. Pipe clamps are not square, not even good ones, the pipes are rarely straight, and before glue acts as an adhesive, it acts as a lubricant just to annoy you, pushing things in seemingly random directions. You start clamping and that thin layer of glue acts like the water between an ice skate and the ice.

So I can't tell from your graphic which direction the skewing is happening. Are you talking over the length or across the width of the glue up? Cauls and over/under clamping should solve problems across the width but neither will help much with movement along the length. Best trick I've seen for that came from David Yoshi DiChristoMoto back when he was known that way. Sprinkle a little very fine sand (I use a dredger of pumice now) along the glued edges before assembly. Just enough traction to keep things from slipping. Funny, I grew up in New England with a bucket of sand in my truck all winter, but I had to have a guy from California point out its use in wood working. It works great by the way. Oh, very fine sand, not road sand.

[John Keeton]

And if all else fails you might try using biscuits in your glue-ups, I know its an extra step but it will limit the movement of the wood.

They would limit the slip of the wood, but my bet is that when Dan does his crosscuts for the endgrain cutting board, those biscuits will invariably be right where the cuts are

I would avoid that solution, or at the least, make sure of my layout before considering it.

[george wilson]

Sand in the joints? I wouldn't want to cut those joints afterwards!!!

I recommend 2 things: Minimum pressure,and clamp up sub assemblies of less boards first,then go back and clamp the sub assemblies together.

[dan sherman]

The boards are 2-1/4" square in cross section and 22" long. I'm positive they are square and strait, as I did a dry fit up on my surface plate (it was the only horizontal surface available at the time), and all the seams where tight without applying any clamping force.

Based on everyone's responses I need to put my hand me down pipe clamps out to pasture, and invest in some new parallel jaw clamps.

I have a sneaking suspicions that I'm over tightening the clamps, because I'm applying to much glue. For years I've used junk mail credit cards to apply glue on a lay-ups like this. The credit cards usually leave a thick layer of glue, so I apply what I consider a reasonable amount of force with the clamps to squeeze out the excess. Now I have been known to snap the heads off bolts from time to time, so I might be over tightening the clamps.

What does everyone use to apply glue for large lay-ups like this?

[Kyle Iwamoto]

Are you alternating the pipe clamps, over under over under? That way they CAN compensate for out of parallel.

I too suffer from "too much glue-itus". Rub the joints together until the wood almost starts sticking. This gets rid of the excess glue and may also help with the racking problem. For a cutting board, the main idea is to get the blocks square, not much pressure would be required, just enough to squeeze the glue out. Yeah, I suffer from "too much tightening clamp-itus" too.

[Chris Tsutsui]

I guess I would call this a shortcut of an idea, but I don't know how large of a cutting board you are making, but if you can make the board into one section or two sections so that you can run the finished glued up panel(s) through your thickness planer. Then that will smooth out those jaggies.

It was super fast for me to flatten the board out using the thickness planer as opposed to sanding and scraping. haha

Being able to glue up something like that without having slight uneveness to one or two pieces is pretty difficult unless you have perfectly milled pieces, and perfect glue up tools and procedure.

If you use too much glue, the amount of moisture in the glue can even affect the wood...

[Myk Rian]

A trick I use is to put a few brads in the edges and cut the heads off. When gluing they prevent the edges from sliding around.

[Burt Waddell]

I'm always amazed at how people tend to make "glue-ups" difficult. Glue them together and then take the glued up piece to the planer. The planer does a great job of smoothing things up. This approach does take a little more wood but it also takes all lot of stress out of the process.


Burt

[dan sherman]

Burt, just taking it to the plane doesn't work in a case like this.

take a look at these 2 videos about making an end grain cutting board.
http://thewoodwhisperer.com/episode-...-above-part-1/
http://thewoodwhisperer.com/episode-...-above-part-2/

if the boards don't go together square (or at least pretty close to it), the corners won't line up when you go to make the checkerboard.