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Forum topic by Cincinnati2929 posted 07-14-2019 07:03 PM 932 views 0 times favorited 56 replies Add to Favorites Watch
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Cincinnati2929

41 posts in 355 days


07-14-2019 07:03 PM

Are panel clamps a better way to go than a parallel jaw clamp for solid wood top glue up ?

I’m referring to those clamps that put pressure on edges as well as top and bottom that keep boards from buckling while edge gluing to create a panel. I prefer solid wood over plywood for countertops, tabletops, workbench tops, etc I was considering a set of panel clamps. But since they essentially a single purpose specialty clamp, perhaps it would be a better investment for my small hobby shop to put that money into more k body parallel jaw clamps that could be used for other clamping needs as well. Unless there is a benefit to the panel clamps other than keeping the boards aligned in the same plane (I could use splines or floating tenons to accomplish that), I’m inclined to go with parallel jaw clamps.


56 replies so far

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Rich

4677 posts in 1037 days


#1 posted 07-14-2019 07:24 PM

If you’re talking about the Woodpecker clamps they are advertising, they are grossly over-priced, and that style of clamp isn’t very effective at flattening the boards. You’re better off spending your money on more clamps and making your own cauls.

The advantage of real cauls is that they have a slight convex face which ensures even pressure across the panel. They’re easy to make. I cut a piece of 1/4” MDF to the right curvature and use it with a flush trim bit to shape the cauls. Be sure to put some vinyl or packing tape on the face of the caul so the glue doesn’t stick.

-- My grandfather always said that when one door closes, another one opens. He was a wonderful man, but a lousy cabinet maker

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wichman3

95 posts in 1068 days


#2 posted 07-14-2019 09:45 PM

On the other hand are the one’s sold by Rockler and Home Depot. Much less expensive and you make the cauls for them out of 2×2 material, to any length (within reason) you need. And you can cut the cauls with a convex shape to flatten the boards.

View Delete's profile

Delete

439 posts in 819 days


#3 posted 07-14-2019 10:05 PM

Panel clamps can be very inexpensive to make, but as Rich states they don’t really apply equal pressure across the full face of the panel, they can actually lift up at the center of the panel as pressure is applied. Cauls get around this. For information on both and an idea I haven’t tried out yet that combines both to make a panel clamp that costs next to nothing here’s a link.

https://hobbyworkshopprojects.blogspot.com/2019/07/panel-clamps-revisited.html

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GR8HUNTER

6319 posts in 1160 days


#4 posted 07-14-2019 11:10 PM

in the cabinet shop our cauls were rounded with formica on end they worked very nice :<))))))

-- Tony---- Reinholds,Pa.------ REMEMBER TO ALWAYS HAVE FUN

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Cincinnati2929

41 posts in 355 days


#5 posted 07-15-2019 01:39 AM


.... I cut a piece of 1/4” MDF to the right curvature and use it with a flush trim bit to shape the cauls. Be sure to put some vinyl or packing tape on the face of the caul so the glue doesn t stick.

- Rich

What is the right curvature? Is there a table somewhere that shows a particular wood and the amount of curvature as a function of caul length? Or perhaps instead of curvature, it would show the difference from a straight line tangent to the caul center to the end points at each foot from the center point?

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Rich

4677 posts in 1037 days


#6 posted 07-15-2019 01:57 AM

For a 24” long caul, if you laid a straight edge along it, there should be around 1/16 to 1/8 inch gap at each end. If you want to get technical, the radius of curvature for 1/8” at each end would be 576 inches.

-- My grandfather always said that when one door closes, another one opens. He was a wonderful man, but a lousy cabinet maker

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AlaskaGuy

5332 posts in 2756 days


#7 posted 07-15-2019 02:09 AM


in the cabinet shop our cauls were rounded with formica on end they worked very nice :<))))))

- GR8HUNTER

What does rounded mean? Does that mean curved? Formica on the left end, right end or both.

-- Alaskan's for Global warming!

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OSU55

2380 posts in 2437 days


#8 posted 07-15-2019 12:18 PM

How to make cauls

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Robert

3468 posts in 1928 days


#9 posted 07-15-2019 02:39 PM

Well, I never use cauls. My feeling is if you start right and the wood is ready, you don’t need them. If you need to use cauls to push boards flat, the panel is in trouble from the start.

In a few days after the cauls have “done their job”, the panel is going to achieve homeostasis (relax and move to its least stressed shape and position). Having acclimated wood with equal moisture balance are the factors.

IMO if the edges and clamping are done correctly, the panel will be flat when you clamp it – no need for cauls.

I do the “face in/face out” approach on the jointer that way any error off 90° is cancelled out by complimentary angles.

-- Everything is a prototype thats why its one of a kind!!

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Cincinnati2929

41 posts in 355 days


#10 posted 07-20-2019 01:06 PM



.... If you need to use cauls to push boards flat, the panel is in trouble from the start.

IMO if the edges and clamping are done correctly, the panel will be flat when you clamp it – no need for cauls.

- Robert


Robert

I agree with the importance of having straight, parallel edges that are perpendicular to the face. I was not using cauls to “spring” boards into position, just as I wouldn’t use a gang of clamps to accomplish that. I am interested in using curved cauls to distribute clamping force, to minimize the number of clamps needed for a panel glue-up, plus to get clamping force where it’s difficult if not impossible to use clamps.

View OSU55's profile

OSU55

2380 posts in 2437 days


#11 posted 07-20-2019 03:05 PM


Well, I never use cauls. My feeling is if you start right and the wood is ready, you don t need them. If you need to use cauls to push boards flat, the panel is in trouble from the start.

In a few days after the cauls have “done their job”, the panel is going to achieve homeostasis (relax and move to its least stressed shape and position). Having acclimated wood with equal moisture balance are the factors.

IMO if the edges and clamping are done correctly, the panel will be flat when you clamp it – no need for cauls.

I do the “face in/face out” approach on the jointer that way any error off 90° is cancelled out by complimentary angles.

- Robert

The purpose of the cauls is to keep flat properly prepped boards aligned as they are pushed together by clamps, not force warped boards into position. If you dont need them great. I find edge alignment significantly improved in the glued panel needing less wood removal for a flat panel.

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Rich

4677 posts in 1037 days


#12 posted 07-20-2019 03:15 PM


Well, I never use cauls. My feeling is if you start right and the wood is ready, you don t need them. If you need to use cauls to push boards flat, the panel is in trouble from the start.

In a few days after the cauls have “done their job”, the panel is going to achieve homeostasis (relax and move to its least stressed shape and position). Having acclimated wood with equal moisture balance are the factors.

IMO if the edges and clamping are done correctly, the panel will be flat when you clamp it – no need for cauls.

I do the “face in/face out” approach on the jointer that way any error off 90° is cancelled out by complimentary angles.

- Robert

Like OSU55 said, they keep the boards aligned during glue up. Even straight boards with perfect edges can slip during glue up. Even a 1/32” is a pain to deal with.

I use cauls for every glue up. Long ones for panels and little ones for things like door frames to ensure a perfectly flat joint.

-- My grandfather always said that when one door closes, another one opens. He was a wonderful man, but a lousy cabinet maker

View WoodenDreams's profile

WoodenDreams

659 posts in 358 days


#13 posted 07-20-2019 07:14 PM

I don’t use panel clamps but I do use cauls if feel they’re need on a glue-up. most of the time I don’t need the cauls. Panel clamps add extra time to the glue-ups, if your time sensitive they’re a waste off time. If you need to, glue up your panels in sections, then glue-up the sections together to finish out your width of the project.

View farmfromkansas's profile

farmfromkansas

89 posts in 61 days


#14 posted 07-21-2019 06:13 PM

I have just been using 2×4’s that I run through the jointer, and then use some clear tape to seal the clamping surface. The panels are better than just using clamps and gluing up a bunch of pieces. Less offset on boards, and flatter panels. The radius seems like a cool idea.

View Lazyman's profile

Lazyman

3661 posts in 1835 days


#15 posted 07-21-2019 08:22 PM

In the manual for the circa 1950 Delta jointer I used to have, it had instructions for using the jointer for tapering a leg for example. I use the same technique to make cauls. You basically just run though the jointer making very light cuts and lift when you hit the center. The next pass lift an inch or so sooner and repeat until you have the taper you need. Then flip it around and do the same thing with the same number of passes from the other end. I usually start with 2×2, or with a 2×4 ripped in half. I don’t do this often but it only takes a couple of minutes per caul when I need them.

-- Nathan, TX -- Hire the lazy man. He may not do as much work but that's because he will find a better way.

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