Help with clamping pressure

[wood_newbie]

Is there such thing as a rule of thumb when it comes to clamping pressure for edge jointing?

I just did a tabletop for a "utility" table for my workshop, and for the practice I did a glue-up instead of using plywood.

Not knowing any better, I clamped the damn-fool hell out of it. (If 10 lbs. of pressure is good, then 100 lbs. is TEN times better...)

I just read an article that briefly mentioned something about clamping too tight and squeezing out too much glue, thereby weakening the joint.

So far, the table top is holding up fine, but how can I know this will always be the case???

Can someone please enlighten me on this one, or point me to a resource?

Thanks in advance for any help you all can give!

[David]

glue should squeeze out of a joint, even if the pressure is correct. Just snug the clamps down well--no need for a Herculean effort to twist the clamp handles with every ounce of strength you possess.

Ever heard of a "rub" joint? No clamping required. Having said that, you should clamp most joints for effective adhesion when using white and yellow ww glues. Trim can be held in place ala Norm, by a "few brads until the glue dries". :)

Dave

[0_Qed]

...snip...

Short 'answr' is 'no'.

"Long" gets a bit too^2 involved.

Plywood plants use 200psi +\- ... stick hse builders, using mastic, use "nails" at 16" ... ????

A SWAG would be ... when beads of the adhesive squeeze out ==> 'nuf.

You mite contact the US Forest Products Research Lab ... a tax-payer service.

:-)

[Leon]

So did I and that is basicaly the authors point of view and according to the glue companies you cannot tighten too much. There is truely a term of "starving a joint" but that is when you do not put enough glue on in the joint to start with. Clamping too tightly normally damages the wood rather than starves the joint of glue. I have never had a problem with a joint regardlsee of how tightly I tightened the clamps. That said, moderate pressure enough to close the joint and get a bit of squeese out along the joing line is plenty.

If you need further information e-mail Franklin and ask about their glues and clamping.

[woodworker88]

How much did you spend on your clamps? Mine are kinda cheap right now and if I put too much pressure on them, they have a tendency to start bending and metal fatigue, etc. I can clamp enough for anything I ever need to do, but not 100's of psi. If I need to clamp 2 small pieces together for jigs and the like, I just stick them in my vise overnight. Holds great and spreads pressure over a larger area. Much easier than trying to put 2 bar clamps on a 2x2" block.

[David]

ever tried a Bessy K body clamp? HD quit carrying them, but they are still available in other stores and of course, through the 'net. Great clamps. and you can NEVER have too many clamps...

Dave

[rickluce]

There was a great article in Fine woodworking a year or so ago regarding clamping pressure and what specific clamps are capable of. Maybe someone else remembers the issue, or you can check their website. Just a fyi, you shouldn't have to clamp out gaps. If you do your just setting yourself up for glue failure later on. Maybe someday I'll be good enough to follow that rule.

Don

[rickluce]

There was a great article in Fine woodworking a year or so ago regarding clamping pressure and what specific clamps are capable of. Maybe someone else remembers the issue, or you can check their website. Just a fyi, you shouldn't have to clamp out gaps. If you do your just setting yourself up for glue failure later on. Maybe someday I'll be good enough to follow that rule.

Don

[rickluce]

Hey!!! I didn't post twice. What gives?

[David]

I don't know. I don't know. :)

Dave

[Bruce Barnett]

There were two different message ID's, and two different dates:

Date: 23 Aug 2005 14:13:42 -0700

Date: 23 Aug 2005 14:18:13 -0700

One was 4 1/2 minutes after the other.