Door-Frame Clamp Time with Fast-Tack Glue

A cabinetmaker's door-assembly process is so quick, he's worried that he may not be allowing glue enough time to set before removing clamps. September 5, 2006

We are trying the Door Pro by JLT clamps. The operator can cycle doors through as quickly as five minutes, meaning that a door could be in clamps for as little as 5 minutes. The doors are then set aside and left to cure for another 55 minutes. The doors are mortised and tenoned. Does this clamp time work? Does anyone have experience with this? We do not pin our doors and do not want to.

Forum Responses
(Adhesive Forum)
From contributor A:
You have the advantage of a larger surface area with the mortise and tenon style, but I think that 5 minutes is really pushing the glue time. I can only assume that you are using TiteBond II or another fast tack glue. I would wait at least a total of 10 minutes before you take them out of the clamps. There are many factors that come into play here, the temperature of the glue and the wood, such as how tight the mortises fit and what kind of glue you are using. If you make your tenons very snug that may be all you need to hold the doors together until the glue sets. If you are striving for a nice tight joint between your cope and rail I would suggest letting them stay in the clamps for longer than 5 minutes. But I would really have to see your operation to be sure. You could give more information about the type of glue the snugness of the joints the temperature etc. This would help all of us in determining how to answer your questions.

From contributor B:
Five minutes is pushing it for most wood glues. Jowat manufactures a wood glue with a 4-6 minute set time that should work nicely.It's formula number is 110.60 and is widely available at select distributors.

From the original questioner:
The glue we are using is Wood-Lok 40-0294. It has an open assembly time of 0-2 minutes and closed assembly time of 0-7 minutes. Currently our shop temperature is about 85 degrees and humidity is about 70 percent.

From contributor A:
Sounds like you should be waiting at least 7 minutes.

From Jeff Pitcher, technical advisor Adhesives Forum:
The proof is right in front of you. I'd suggest breaking some of the joints and looking at the percentage of wood failure. If the joints are difficult to break and you see considerable wood failure then the timing is right. One thing to be careful of when you use quick setting glues is the open time. I've seen some places switch to this kind of glue but then have problems because they're used to the open time they were getting with their previous glue.

From contributor C:
With a quick setting PVA it is possible to do this. The key is that the joints must be tight enough to resist any spring-back or opening up when the clamping pressure is released or the strength will be compromised and the finish poor (open joints). I have personally seen this done in at least 4 large door manufacturing operations across the country with very good results. In at least one case they are only holding pressure for a few seconds then releasing and letting the joints dry for an hour. An additional comment is that if the doors are sanded after only one hour of drying the glue joint may sink somewhat when the wood itself dries out the next day. This is something else that I have seen across the country. Allowing the doors to sit overnight fixes this problem.