Radio-Frequency Glue Curing

Cabinetmakers report varying experiences with RF glue-welding equipment. August 8, 2006

Have any of you used a wood welder to zap your doors in the squaring clamp? I have been using a high tack white PVA glue and then putting them in our JLT clamps after about 5 minutes. I'm trying to kill that lag time between. I figure that the time it takes to zap the corners will be offset because of the time to take it from the pneumatic squaring clamp and set it in the JLT clamps. Our wood welder (Woodrite) says 5 seconds but no longer than 10 seconds per joint. I've tried to tune it in and get the millimeter to arch right, but it seems that I either do not get the joint enough or I cook the glue. Instead of wasting my time, I'm asking the pros. Even if I get it right, is the joint going to be as strong?

Forum Responses
(Cabinetmaking Forum)
From contributor D:
I purchased a woodwelder with high hopes about 5 years ago. We tried every type of glue under every conceivable set of circumstances, and never got any type of adhesion whatsoever. They don't work, period. Even if they did, you can't zap a door as it lays against a metal clamp or a metal clamping table, thus ruling out the idea of zapping in the JLT.

From contributor T:
I have been using one for 15 years with great success. It's important to use a glue compatible with rf welders. I use type 1 or 2 Titebond. My glue joint failure is next to nil. I can't comment on the door clamp, as I use bar clamps. You do need to keep the electrodes from getting nearer than about 1/2" from the clamps. If necessary, use wood spacer blocks.

From contributor X:
Woodrite's woodwelders do a great job. They're fast and efficient. My only concern is the safety issues. Make sure you wear gloves, goggles and long sleeve shirts to avoid the hazards of glue spitting back at your body. Glue does get mighty hot and can burn holes in your clothing and can burn the body when hit directly. Use caution.

From contributor D:
I am very curious how you got yours to work, and what you consider successful. Does that fact that the welder dries the glue constitute success? Please describe the application where you are having this success. It's not as if I would consider our results only marginally acceptable. They were total failures. In fact, if I were to edge glue a board and hold it into the air, the pieces would simply fall apart. We tried Titebond, Titebond 2, white glues, and resin glues with varying amounts of glue, in various species of wood of various thicknesses and applied heat for various periods of time. Never one successful piece. I've hung onto the machine with hopes of getting to their booth at a trade show, but have not done so yet. I would love to see a demonstration with positive results.

From contributor R:
Your description does not sound like a product that does not work as advertised. It sounds like a defective product. Did you not contact the company with your experience? Or try to exchange it? Does it not have a warranty?

From the original questioner:
I'm with contributor D, except I got mine to cook leaving the glue tacky on the perimeter and toasty in the center. Guess I was hoping on a trick. We clamp our doors on a Ritter squaring table and then put them into the JLT for further cure. That is the procedure with a high tack glue, but I'm trying to avoid the second step and offset it with the woodwelder.

Using Titebond II and various amounts and various curing times (anywhere from 3 sec to 30 sec). It seems that combo works. On my first attempts, the door was on the metal squaring table and the millimeter wasn't tacking up but about half, so for test purposes, I besse clamped them on a wood table and the millimeter tacked full load, but it seemed to either cook the glue or leave it with nothing at all.

Just to clarify, I used different times, different amounts of glue and all of these with different tuning on the millimeter from the hand unit. Seems like I've exhausted all the combos. By the way, I spread the coil to different widths.

From contributor T:
I like to run the meter about 2/3 or higher, count off 5 seconds, and I'm done. The hand unit on these units is critical. If they get bumped, they may need adjustment or to be rebuilt. I spot weld every 8" on edge glue ups and go directly to machining, with no failures. Contributor D, it sounds like you have a unit that is not working. I'd give the factory a call. They've been very helpful to me and I bought my unit secondhand.

From contributor X:
I first used the trial and error system. We were doing tongue and groove on a forty five degree angle. Taking scraps, we assembled various pieces using the hand held units set at various settings. We then disassembled what we created and found that the joints held and would tear at other parts of the wood rather than at the joints. We watch the wood and glue cook and found that some pieces conducted current better than others, thus the variance. From that, we learned to run the unit by the seat of our pants. Pull the trigger and watch the glue cook. Release the trigger when cooked. We worried about glue lines showing and tried various types of glue. We settled on hide glue for the type of wood we were using. We had glue splatter (hurts when hit with) but we learned to judge when the joint was done. Assembly is a slow process - 4 joints per door, but clamping the old fashion method was even slower. The welder allows one to create faster where time is money. You're working with an external microwave, which is dangerous, so use caution.