Finger joints in glulam beans - Woodworking Talk - Woodworkers Forum
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post #1 of 7 Old 09-25-2020, 06:58 PM Thread Starter
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Finger joints in glulam beans

I was watching this video about the construction of glulam beans. Check out the finger joint gluing operation starting at about 1:30 in the video. Note that they heat the glue joint to cure it. Does anyone know what glue is being used?
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post #2 of 7 Old 09-25-2020, 07:23 PM
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specifically, no.

radiant/conduction heat cured,
UV cured,
microwave cured,
radio frequency cured,
electron beam cured.....

are all methods of getting an "adhesive" to do its thing "instantly" in an industrial setting where gluing it up and letting it sit for 24 hours is less than acceptable to the MBA types.

each technology requires a glue that is specifically intended for that use.

most of the equipment/processes used are not suitable for a home shop.
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post #3 of 7 Old 09-25-2020, 07:29 PM
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It's probably Phenolic resin glue.

I don't believe they could get heat through wood that quick. It was probably a wood welder.
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post #4 of 7 Old 09-25-2020, 09:24 PM
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from the video - most likely RF cure.
and yes - RF can penetrate/heat/fry wood at 4-5-6 inch depth with no problem.
don't get too close - it'll heat your molecules just as quick as the glue.....
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post #5 of 7 Old 09-26-2020, 02:16 PM
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i'm gonna go with steve and say wood welder. though i didn't see any filler rods
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post #6 of 7 Old 09-28-2020, 12:15 AM
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at the plywood mill we use heated press plates. the time for pressing is usually around the 4 minute mark for a load i belive, depends what we are making(3/8, 3/4, etc). and how fast they try and run the lay up line.

our glue gets made in the mill. we get a 53' tanker or resin delivered every day. and mix the soda ash and other great **** in house. they test for viscosity. and it changes accordingly. i cant speak for the lvl. i can speak for the industry i guess. i would assume that glue is most likely made there. and adjusted accordingly.

i guess i could ask the glue mixer at work what exactly is in the glue. haha. i never cared enough.

so ya, our press does sheets of 3/4" SPF in around 4 minutes ish(like i said, dont pay attention much to that, i work on the drying the veneer side, not glueing it into panels). thats 32 or 34 sheets at a time though. 2 presses

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post #7 of 7 Old 09-28-2020, 09:08 AM
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Looks like an rf cure on the fingerjoints to me. Phenolic resin is much more conductive than wood, so the rf energy mainly heats the glue line with little energy heating the wood. Factories like to use a single glue chemistry, although some will split business between two suppliers. I'd say they are using phenolic resin for everything and catalyzing it one way for a cold press cure and another way for an rf cure.

I enjoyed the video. Thanks for sharing.
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