Basic clamping question

[Kevin Villas]

I have been reading back posts for a while now trying to learn all I can. Must say I have learned a lot since recently discovering this place.

I just wondered what the general thoughts were on clamp time.. I have read to leave things clamped for 24/12/6/2 hours.. Heard its even bad to leave things clamped for 24 hours from some places and others say its best..

Curious as to what you guys do? Also wondering about veneer clamp time when using cauls.. Since I am about to do that, I was going to at least leave it clamped up over night.

Thanks for the input!

[Chris Padilla]

Kevin,

Overnight can't possibly hurt. If you aren't hurting to get the clamps back, overnight is usually what I do but a lot of products (read the label) can let you get away with as little as 2 hours in the clamps. PVA (yellow/white) are like this I think but poly's tend to need much longer clamping times and epoxy is well, whatever the label says and might depend on how you mix the two parts together.

[Todd Burch]

Kevin, I do it based on need. If I don't need the clamps, I'll let the glue-up sit in the clamps until I need them next, or until I'm tired or walking around it or moving it. (Read: > 4 hours).

If I'm in a hurry for clamp-reuse, and the weather has been warm enough, I'll take the clamps off after 10-15 minutes and let the assembly dry on its own. (yellow glue).

Generally speaking, with yellow glue, after an hour I consider it done cooking in the clamps.

[John Miliunas]

In a production shop I used to work at PT many, many moons ago, I can't remember leaving anything clamped up for more than four hours, tops! That said, I'm kind of like Todd in that, if they're not in the way and I don't need them right away, they can stay clamped. That IS a rarity, though! In practice, it's usually overnight.

[Don Abele]

Kevin, I typically keep my stuff in the clamps at least 2 hours. Most of the time, like I'm sure most will say, I leave it in there over night. I use Tightbond II glue and a quick check of the label - it suggests clamping "for at least an hour." As for veneering, I use UniBond 800 and depending on how I mix it and the temp, it can be as short as a hour to as long as 8 hours.

The best solution is just to read the label. Leaving it in over night won't hurt (there's too much data to prove otherwise). Just don't apply so much clamping pressure that you squeeze all the glue out. Just enough to bring the joint together. I think this is the most common cause for joint failures.

Be well,

Doc

[Dan Gill]

It all depends on when I need the clamps. I learned while making raised panel doors that I could put a single 5/8 inch brad into the back of the door at each joint and then get my clamps back for the next door.

I know, some of you will shudder at the thought, but it works. Set them a little deep and do a little touch-up, and nobody will ever see them. And I only have 4 Besseys!

[Keith Christopher]

I use min 4 hours on yellow PVA's, but on the polys I almost always let them sit overnight. alot depends on temp and humidity also, and as we've all just about said, if you don't need the clamps, leave them there, you won't be disappointed that way.