True, and I did consider doing that. But it turns out that the plugs
are a little too long for 3/4" material and would need to be cut down.
And as I stained the ply, they'd have to be stained as well, and
surely wouldn't quite match. All of that could be acceptable if I was
convinced that there was some need. But my sense of it is that the
glue alone will be adequate. I could be wrong; a common enough
occurrence when the topic is woodworking.
It's hard to use too many, and easy to not use enough.
Base it on the material, and the particular job ... if there is any
doubt whether you have enough by the way the job is clamping up (as in
is some of the material bowed and not making good contact?), add more to
those spots, it will rarely hurt to do so; if not, don't worry about it.
Your photos appear to be just about right for most face frame glue-ups.
Just remember, to effectively glue two wood parts together with most
modern wood glues you need both contact between the parts, and adequate
pressure (which may vary with the application).
I have no rule. Just what I feel. Sometimes I over clamp... looks like a
porcupine, sometimes not. Cauls are nice if you have them made ahead of
time. I tooks some 2x4's and ripped them in half then I planed them so
that they have a nice bow. so one side is flat and one arches.
I use either depending.
Now that I haven't given you an answer, are you finishing the face frame
first? or after?
Greg see the first two images in:
Just meant to show that cauls can be simple and also used for other
things. I turn them around at times to lightly clamp for dovetailing.
BTW what stain did you use on your inside. I like the color.
So enlighten me here. I've seen cauls (pictures of them anyway) that
have a very slight curve on the surface that will touch the work. Your
picture has a much sharper curve at each end than I would have expected,
and I can't tell if the middle is curved or not.
My understanding is that the curve on the business edge is to provide
clamping pressure in the middle even though the clamps are only applied
to the ends. What is the pronounced curvature near the ends of your
I don't want to answer for him, but... well, here I go. :-)
You are right about long cauls having a slight curve on the clamping
side, and you're correct on the reason for that curve. It would nice if
there was a formula for that curve in relation to the length of the
caul. Maybe the same guy who did the on-line shelf "sagulator" will do
one for cauls.
However, in the case of woodchucker's photo, in that application, the
curve is acting like a truss (think steel arch bridge) that keeps the
caul straight and able to clamp that distance without bending.
The difference between the two applications is in the former, you want
the caul to bend until it's touching all the boards, applying
(hopefully) equal pressure. In the latter, you don't want it to bend so
it keeps touching all the board(s) allowing it to apply equal pressure.
"Playing is not something I do at night, it's my function in life"
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
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._
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.
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
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.
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
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).
On Thu, 28 Mar 2013 10:20:34 -0400, Greg Guarino wrote:
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
When fascism comes to America, it will be wrapped in the flag and
carrying a cross.
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.
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.
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