Theoretically, if your joints are straight (the clamps aren't bowing the board to close the seam), all you would have to do is apply clamp pressure to compress the joint and then you could remove the clamps. Initial tack and surface tension will hold the joint together if there aren't any other stresses on the joint. However, a little bump, or even gravity could be enough to pull at the joint and if it opens even a little, it will be weakend.
You can actually test the tack/surface tension theory: make a good joint, glue it up, remove the clamps, and pick up the assembly by one board. If it's not too heavy, the other piece will stay put. If your joint is good enough, you can substitute water for the glue in this test and the pieces will hang together for several seconds!
All that being said, the clamps are there to provide the initial compression on the joint and to guard against external stresses while the glue is most vulnerable. Give it 30 minutes. I think you'd be a lot more frustrated repairing a failed joint later on than you are waiting for the glue to dry. If you really have to move faster than that, you could buy enough clamps so that by the time you ran out of clamps, the first assembly had been sitting for 30 minutes. Or check into glue systems that set up faster (RF sets up almost instantly, I think).
I am gluing squares on my chess board to the base material. My design dictates the squares be glued individually, actually I can do two at a time, allow them to set, then move to the next two. One pair is indexed off the previous two. I don't have to wait for the glue to be fully set but it has to be set enough that I can rest my indexing jig up against it and it will hold its place.
64 squares, 2 at a time, is 32 glue procedures. You can see my interest in min clamping time.
Thanks everyone. I won't start gluing until tonight so I'm open to more comments.
depending on the density of the wood and it's thickness ,
it can suck the moisture from the glue ,
and ' curl ' , lifting it from the backer .
take your time ,
no sense in rushing it now .
30 minutes is about right .
actually and generally speaking - the recommended time from the mfg. that is printed on the bottle should ALREADY have the 'extra just to be safe' time included - otherwise they would get too man complaints from people that are going by what's printed, that their glue product isn't working properly.
as Peter stated- if your joint is square and flat - and in your case it seems like it is, since there is little material and almost no stress points. you shouldn't have to keep it clamped more than 30 min.
Just my opinion, but anytime I look at thing by "what's the least I can get awy with", I'm setting myself up for failure. As others shared, if the joints are good, 30 minutes is a good rule of thumb. I have, however, tried to pull a joint apart after 1 minute clamping time, and destroyed the wood around the joint. Would I base my clamp time on that? No, but it shows me in a pinch you can "get by" sometimes. It aso depends on the joint. A cope and stick, dowled, or mortise and tenon can be unclamped sooner than a but joint, and not be a problem.
I prefer to leave things clamped overnight whenever possible. Is that overkill?--Yes, but it has certainly never created a problem.
Kent, I am with you in the camp of leaving glue ups overnight. I've done that on all my projects to date. In this case, I don't really want to spend 32 days gluing. So I'm looking for a general idea of min clamp time.
It seems as though 30min is the safe bet. So say 30min dry time, 5min setup of the next squares…I could realistically get 3-4 glue ups in an evening after work and 13-15 done on a regular weekend day. So starting tonight, and through the weekend…I could probably get all 64 squares glued by beginning of next week. A reasonable expectation. Thanks…had to talk that one out…or type it out I suppose!
Have a good weekend everyone. Any other thoughts out there I'd still love to hear them.
I did some test glue ups. Just for kicks I found that at 15min it was pretty solid! now these are small squares with not much leverage on the glue if they get bumped so 15min probably wouldn't work for something larger.
To be safe I'm giving it a long 20min. Here are the first pair of blocks glued up and clamped.
I know, I know…don't get in a hurry. I'm usually late for things anyway so they will probably get 20-30min!
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