How many clamps?

[-MIKE-]

Those articles are correct. And honestly, if the wood breaks before the glue joint, isn't that stronger than it ever needs to be?

[woodchucker]

Different caulse for different purposes.

I can bend these puppies very well, all the way flat. That's why they taper so much.

Yes the middle gets a lot of pressure. There is a slight flat in the middle, I started with a smooth radius. They were too thick in the middle. As I played with them, I got them so that I can use most or all of the caul. I have cauls that are less pronounced, but these are my favorite. They haven't split, and do many different tasks. They are super light, they work well on dovetails since they will imprint a little. They don't mar.

My maple cauls are heavy less radiused.. lift about 1/8 from center to end .

One of the great things about making things is being willing to experiment. When the cost is not high try it. Try different things. Sometimes what you hear is not always true. Sometimes there is good reason that everyone does it one way. Cauls can be totally flat and just spread the clamping pressure out. I chose to try something that would fit many uses. As you can see, I use it for my dovetailing. I started using it the opposite way, but it required a lot more turning of the clamps. turning it over required less (why because of the large crown that you asked about). But in an instant i can turn it over and squeeze the living snot out of that board and have it so rigid I could drive a chisel into the end if I wanted to.

So much for my book on a little question. _So what stain did you use on your Shelves.. I like it and want the same._

[Larry W]

Absolutely! It's your call! :)

[Amy Guarino]

Funny thing, that. I experimented with various combinations of MinWax (Wood Finish) stains and came up with a small sample that I liked. Then I tried to recreate it in a larger batch. Needless to say, it never came out quite the same. I came up with a pretty decent mix, but in the end decided to go with Gunstock, right out of the can. This is partly because I knew I'd be able to recreate it anytime. I left it on for just about the maximum recommended time before wiping.

I'm pleased with the results, although I'm not sure the combination of my camera, a mix of fluorescent and incandescent lights and the monitor on your computer adds up to faithful reproduction.

[dadiOH]

Given the usefulness of plywood and the ugliness of the edges, the ability to glue solid wood to the edges should be cultivated. It isn't hard either; all you need is...

1. smooth, square edges on both ply and wood
2. sufficient glue
3. sufficient pressure to hold them together until the glue dries.

Your previous failure may have been due to any or all of the above but I'm thinking the most likely is insufficient glue. You don't want so much that gobs squeeze out but enough to get a line of roughly pin head sized globules.

All in all, much easier to apply than to trim flush.

[Lew Hodgett]

-------------------------------------------------------------- IMHO, exposed raw plywood edges are like ugly on an ape.

I prefer to band plywood visible edges with an interlocked tongue and groove glued joint as follows:

(Think of tongue and groove construction used with wooden siding of years ago.)

Assume a 3/4" plywood and a visible 3/4" solid wood edge.

Run a 1/4" x 9/32" deep dado centered on the 3/4" plywood edge.

Starting with a 1" x 3/4" solid wood piece, cut a 1/4" thick x 1/4" long tenon centered on the 3/4" solid wood piece.

(This yields a 3/4" x 3/4" solid wood band when assembled.)

The assembled edge banding yield a 33% increase in the gluing area of the final joint (3/4"^2 vs, 1"^2) as well as creating a 3/4" vertical interlock of solid wood.

Quick, low cost, and strong like bull.

The biggest PITA of the whole process is making sure the wood is flush with the plywood after assembly, IMHO.

BTW, have used rubber bands and a dowel pin as clamps while the glue dries. Surgical tubing also works.

Lew

[-MIKE-]

I'm not saying the OP did this, but it bears mentioning, because who knows what might have happened or what he may have been told to do, technique wise....

I was sort of mentoring a young man in the shop who was building a gift for his wife. When we were in the process of gluing something, he asked why I didn't let the glue "set-up" first before joining the parts.

Apparently, at some point in his life, he was building something with someone else and from what I could surmise, they were using contact cement. Well, he obviously had taken what he learned about contact cement and falsely applied it to all gluing, in general.

It makes me wonder about the current condition of anything this young man has ever glued before. :-)

There *are* techniques many of us have used where you apply glue to a surfaces, especially porous ones like plywood, let it soak in a little, then join together... or even add a bit more glue to the surface, and join and clamp.

But that's not what I got from my experience with this gentleman. This was more waiting so long that the glue was setting already. In any case, those things always make me wonder what's "not' being said when subjects like this come up.

[-MIKE-]

I gave up spending the time and effort to even try to make them flush when gluing and setting up. Now I simply make install them a bit proud on purpose and then trim them flush with a pattern bit in the router.

I have a jig for running them vertically. I can do that in less time than it would take to try to glue them flush.... plus, I never get it perfect and end up going to the router, anyway, so why not cut to the chase.

[Lew Hodgett]

------------------------------------------ Be carefull.

I've used this technique and had a bit that cleaned up the wood but also left cutter marks on the plywood.

After that ran test cuts with a different bit.

No problems.

Lew

[-MIKE-]

You are correct, not all bits are the same. I prefer a to start with a quality bit that is more likely to have an exact match between the cutter and the bearing.

This isn't to say that a cheap bit will be off, but testing on some scrap is recommended. We talking thou's here, so it's not something you can see by looking at the edge of the bit or even using a straight edge to check.

ALSO... if you're not perfectly square to the table, meaning there will be a slight angle to the pattern bit, you can end up cutting into the plywood surface. DAMHIKT. :-)

You can also guard against this by raising your bit *only* high enough to cut the solid wood and not the plywood. It's tricky, but I've gotten pretty good and fast at it.

[woodchucker]

Thanks, was that a gel or oil based solvent stain?

[Amy Guarino]

Oil based.

[woodchucker]

Thanks I like that Gunstock... never worked with it. A friend that is moving just unloaded all of his stains on me.. I'll have to see if there's any in there.

I added a few more pics to show how much I can bend these cauls. I can get them flat, but with different clamps . Not enough travel with those.

A woodworker can never have too many clamps, or enough clamp helpers.

They are quick to make, can be changed easily with a handplane. you can cut v notches if you had to hold a bunch of dowels... Cauls can be anything flat, round to hold staves for a barrel. etc.. They can save you when you run out of clamps. I have over 200 clamps, but sometimes that is not enough, not the right kind or enough of the right length. These can help get you through.

I also have what I call squaring corners. Another type of caul that has facets on it. I can pull an out of square box into square and hold it while the glue sets. It also pulls the joint tight. Not like the wire spring clamps, but these do the trick.

[dadiOH]

For those less experienced, one can also leave a sliver of wood which is then easily removed with a chisel. Or file.

It can also be done other ways; by hand, eg. I've also done it with planer blades in a molding head on a radial arm saw.

[Greg Guarino]

I used a rabbet plane to trim down the solid oak edging around a desktop I made. The picture quality is lacking, but these photos illustrate the concept:

It was easy to set the plane's fence to cut only the edging. I think I may even have set the depth stop to be flush with the bottom of the plane iron at first, but I may have been afraid it would leave scratches; I don't see it in the pictures I took.

[Greg Guarino]

Thanks for the added pictures. That was very helpful of you.

How did you determine the curvature for the long cauls, trial and error? Cauls like that could have simplified my bookcase glue-up, and I have 3 more to do. I also might not have bought 8 of The World's Cheapest Bar Clamps (tm). They were of some use - I put them on last to fill in between other clamps - but I have half a mind to cut six inches off them. They are 24" long, but it's hard to imagine them being of any use at that length. They bowed quite "gracefully" at the 13" or so I had them open.

I like your corner cauls too, but I wonder if a curve on the outside corner might be an improvement over the "flat". With anything other than a square box, the clamp will only contact one corner of your cauls anyway. With a slight curve, the clamp could make the same amount of contact, but more "centered" (or so it seems to my untutored eye).

[Larry Blanchard]

I can tell you what I did. I set a hand plane to take off a fairly thin shaving, but not a see-through. Leaving about 10% of the middle of the caul flat, I took one or two passes out to each end, then moved out about

1/3 of the planed distance and did it again. A final pass or two over the last 1/3 and a couple of short swipes to round the transitions and I was done.

[woodchucker]

Yep you are right a curve would improve it. I was thinking the same thing. They are easy to make, 2x4's make excellent corners.

As far as the curve, it's trial and error, you want the pressure to keep from picking up in the middle. When you have too much flat, you will see the middle rise and not offer pressure. Then you have to think, did I tighten the clamps too much, or are the cauls just defective. Me I'd rather put more pressure on, and have full contact in the contact area. Then if I Put less pressure on, I have a smaller contact area (edges recede). But I never want to have alot of pressure and a void in the middle.... just play with it. it's cheap wood and you can use them for something else if they don't come out right.

[Greg Guarino]

[e-mail]:

Mostly jewelry boxes then?

[Greg Guarino]

I just remembered something. I was putting an edge around a desktop a couple of years ago, back before I had all of my current woodworking savvy. :) The desktop is pretty large; 72" by 30" if memory serves. I had not yet discovered pocket screws (along with many other useful techniques). I decided to use glue, dowels and clamps.

I had only two clamps long enough for the long dimension. Adding to the problem, the piece of oak 1x2 I used for one end piece was bowed a bit. When I applied the two clamps I still had a small gap in the middle. I decided to take another piece of 1x2 oak and put it in as a "caul", a word and concept I had not yet heard of.

I have a reasonably intuitive grasp of physics, but somehow it didn't occur to me to put the "caul" on edge for greater rigidity. Or to use something thicker. In the heat of the (glue drying) moment, I grabbed for the first thing at hand.

The thin pseudo-caul helped a little, but there still wasn't enough pressure in the middle. I grabbed a small piece of very thin plywood, maybe 3/16", and inserted it between my "caul" and the middle section of the edging. Then I cranked down the clamps tight, bending the "caul". That did it.

I didn't occur to me until now that I had in effect made a crude "stepped" version of your curved caul; a piece that protruded more in the middle than at the ends.

I have since been advised that there were any number of better and easier ways to accomplish the whole task, but it's funny that I ended up reinventing the wheel to solve a problem in a time-sensitive moment.