Est. 1998 — 27 years of woodworking knowledge
how long to clamp when gluing
eliot d
I usually glue stuff under clamp pressure and leave it over night; that's about it. But I was just wondering: is there anything positive to say about taking the clamps off after, say, half an hour and leaving it alone over night without clamping pressure? How about after two hours? You get my question: if x + y= T, where T is total gluing time and x is time under pressure, what should x and y be? Or is x always =T and y =0?
It all depends
Robert Tutsky
If you are gluing joints that perfectly match their surfaces, a shorter clamp time would be okay but you're always taking a chance by un-clamping too soon. If there is some glue squeeze out I usually wait before removing the clamps until the glue becomes brittle enough to chisel the squeeze out. Leaving the clamps on over night is unnecessary but if they are left on overnight that's okay too.
Re: It all depends
Bruce, a MN Galoot
I pretty much go along with that, but it all depends on what the next step is. If I'm doing something that stresses the glued-up part, I'll leave the clamps on a couple hours for yellow glue. If not, then a half hour might be okay.
If the part is going to be heavily stressed, then I wait overnight.
Re: It all depends
TomD
I am an overnighter guy. But I would divide stuff into several cats:
One is stuff that does not actually need clamps like dovetails, or some edge joints that are well fitted, or hammer veneering;
two is the regular stuff that needs clamps and that gets overnight, though in a production shop they may push that back to half an hour, or use RF. An example of that could be guitars when doing braces. And thermo setting glues like hide, and so forth;
Three is stuff under a lot of stress. Newbie jobs that weren't perfect but just might hold up with another turn of the screw, or laminations that have springback problems. In these cases I am looking at the specific glue and it's creep properties, and how long it takes not just to set, but reach maximum properties.
There are other situations like contact cements...
Pros are trying to maximize productivity through a day, and will have enough space and jobs to do that. For amateurs, often we have a few hours here and there, and for me often quitting time is determined by when I can get the job in the clamps, so I don't fall back another day. So overnight is just natural.
Re: how long to clamp when gluing
Bill Tindall, E.Tn.
There is no reason to remove clamps until you need the clamps or you need what is clamped in them.
The time it takes glue to cure depends on temperature and moisture content of the wood. I was told by Franklin that it may take 2 or more days to cure a joint in high moisture content lumber. Or, lumber can be worked in 30 -60 min under ideal conditions using yellow glue.
Re: how long to clamp when gluing
CStanford
Makes much sense.