Calls or Cauls (?) (Re. Bow Clamp)

[John Reeves]

Dave O made a suggestion in a post regarding the "Bow Clamp" last week.

You said to use a 3/4x3/4 block to separate then clamp two pieces together. One to remain straight and the other to bend. Mark a straight line then cut on the line after removing the clamps.

What length clamp is this for? What species of wood to use? (pine OK?)

How close do I put the clamps it I am face gluing two panels together (32" grain X 24" )?



John

[DaveO]

John, actually that was a reply posted by Mike Davis. When I've made cauls, I mark the center of the board I want to use (generally pine 2x4 a little longer than the piece I'm clamping) and take a #4 plane and plane from the center to the ends removing about ¼-½", then I knock of the center peak a little.
Here's what Mike suggested using a ¾"x¾" block in the center of your caul to be.

"The computer doesn't know the particular piece of wood you are using.

To make the bow correctly without a computer:

Set a block 3/4 x 3/4 in the center of a straight solid object that won't give.

Set the board you want to cut for a clamp against that block.

Clamp the ends and pull tight against the solid object.

Mark a straight line parallel to the solid object.

Unclamp and cut along the line. No matter what kind, thickness or length of wood it will clamp tightly all along that edge" Mike Davis


HTH, Dave

[John Reeves]

Dave,

Possibly I am too much of an engineer so I have more questions. The difference between the 2/3" block to your 1/4" - 1/2" seems large to me. Am I worrying too much? How dependent on the length of the caul is this depth?

Please understand, I will accept the reply, "Just quit worrying and do it!"

John

[Travis Porter]

You can do a partial pass on each side of your jointer to do this as well. I think as you say you are over engineering. I remember reading in FWW awhile back where someone asked how much to do on cauls and Gary Rogowski replied he spent more time worrying about the national debt. If you have a 1/16 to an 1/8 of curve I would think it should be good.

[John Reeves]

Thanks guys

[DaveO]

Originally Posted by JMR2

Please understand, I will accept the reply, "Just quit worrying and do it!"

John

Dave