Panel glue up without clamps

**FenceFurniture** · 25th April 2018, 01:23 PM

Derek, a small sidetrack if you'll allow me please.

You have just used the one caul in a diagonal, and I can understand that working with proper cabinet grade timber of reasonable thickness (18mm) and properly jointed. However, if I were to try the same thing with my palings (most often only 12mm thick) I would end up with a first class pack of propellers!. Half the problem comes from not being able to joint them on the faces (they just taper down because they are so flexible), so I have to just do both faces through the thicky. Even thicknessing the second edge is a bit tricky when they are so thin (they like falling over), so I often have to use a very small clamp to hold >=4 palings together as they go through the thicky (and THAT was a bit nerve wracking the first time through

). You can believe that the clamp is done up tight!

So I guess I'm just throwing this out there to see if there's a solution I haven't thought of. I can replace the alum sash clamps with tape - no problem (errrr, I think). The amount of clamps I use for the cauls is the problem. My panels are similar in size to the one you are showing, around 700x300. I use 3x sash clamps, and then a short caul running above each clamp, and on top of the panel of course. The caul is clamped to the underside of the sash clamp, with which the caul is parallel. (so these are short cauls running across the panel). I can't see how I can use <3 short cauls, and then clamp them either to the bench or a granite slab (which still means 6 clamps). Using one diagonal would be excellent! Fast and less clutter.

They are generally pretty flat (enough for the intended purpose) after I run the glued panel back through the thicky. The occasional twist can often be persuaded to lie flat because they are so thin.

They've had a tough life standing in the sun for 30-odd years and that makes them tricky to deal with, but the prize is worth it.

5. Box A - first.JPG

**derekcohen** · 25th April 2018, 04:02 PM

Hi Brett

The problem is (obviously) that you are using warped boards. These need to first be unwarped ... straightened ... flattened.

I would use moisture and sunlight. Here is a great little pictorial: https://www.wikihow.com/Unwarp-Wood

Once this is done, I would leave them clamped in cauls for a week, and then remove to joint the edges - both sides - before glueing up.

If you are still dealing with warped boards, my thought is that the glue better grip well, as the tension in the glued panels will be there all the time! On the assumption that you can joint the edges, the focus with cauls is to maintain pressure across the entire length to keep it all flat and coplaner. I imagine needing several cauls spaced close to one another. The problem then is friction - downforce by the cauls will make it difficult to pull the boards together. So you are then back to parallel clamps to do this. I would first try and unwarp the boards. I have had good results with the method above.

Regards from Perth

Derek

**FenceFurniture** · 25th April 2018, 04:43 PM

Ok, thanks Derek. The palings have all been ~90% dressed beforehand and are stored in categories wrapped by bundle wrapping, which is surprisingly strong. Each packet of 6-10 boards is pretty flat when pulled out for use, but some pop back out of course.

Maybe I didn't waste my money on those sash clamps after all!

**Mnb** · 3rd May 2018, 06:11 PM

Brett,

When I was making boxes in order to learn basic stuff I had a similar problem. I was resawing with a cheap table saw to book match or sometimes I would rip a piece in strips and turn the strips so the edge grain was up and glue them into a panel - for the lids or bases. I had a flat sanding attachment on my little drill press but the pieces were still not great. I found the best way to get a decent result was to make sure to get one face of the panel flat. So with tape that has a little stretch you make sure that it is well stuck on the first piece and pull so it stretches a bit then stick it down to the next and so on. Sometimes multiple short pieces. One that is covering say the first two boards of three and another that is from the second to the third. The same number of pieces of tape on the other side of the panel so it balances. It will pull up the outside of the panel and you want the tape on the other side to pull it back to flat. Then put the best looking side down on the flat surface and push the pieces down so you get them flush. Then put something heavy on top.

**Lappa** · 4th May 2018, 11:58 AM

Derek, what is your “centre to edge” variation on your cauls please?

**derekcohen** · 4th May 2018, 04:22 PM

Hi Lappa

I check the flatness every now-and-then in a rudimentary manner (placing each on a flat surface), but otherwise it is easy to see when you place a caul on a panel.

Regards from Perth

Derek

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