Biscuit Jointing

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I have read (and followed) instructions that when fitting biscuit joints, that PVA glue should be used, as this as well as gluing, due to water content , forces biscuits to swell.
I now tend to use Gorrilla Polyurethane glue on external work rather than PVA, anybody know if Polyurethane glue is suitable for use with biscuit jointing ?
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the garilla glue, even the new low expansion stuff expands so much that I no longer use it in joints I wish to flush up, sounds strange, but I use J B weld and or Goop Marine glue

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I'm really new to woodworking, but I recently saw a TV ad for Kreg Pocket Hole Joinery. It looked like it might be better than biscuit joinery. Any opinions?
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Pocket holes are great and pretty darn strong, but leave holes behind. You can plug the holes, but there's nothing to plug or hide with biscuits. Whichever works best for your application.
--

-MIKE-

"Playing is not something I do at night, it's my function in life"
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Chuck Olson wrote:

Sure! I use both.
I use biscuits to align panels. They work well for this and are hidden on all sides.
I prefer pocket screws for face frame assembly, plywood drawer box assembly, case assembly where I don't use dados and glue and one side is hidden, on the baseboard radiator covers I build that move a lot with temperature changes.
It's very difficult to hide pocket holes in visible spots.
I don't use either of them on fine furniture where joinery like mortise and tenon, sliding dovetail, or dovetails are more appropriate. I also prefer M&T or cope and stick on doors.
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Osprey wrote:

Polyurethane glue isn't necessary for that joint. Poly is good for situations in which you need a waterproof connection, gap filling, or connecting odd materials together.
And Poly isn't not nearly as strong as PVA, either.
--

-MIKE-

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Gorilla glue cures on exposure to moisture. It helps to wipe the area with moist rag before gluing. Not sure what that means for biscuits. Perhaps wet the biscuits as you insert them, to activate both the compressed wood and the glue.
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The expansion ration of Gorilla would place the biscuit pocket in danger of splitting throught the face of the board. And, like Mike said, why bother when PVA is stronger?
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Regarding Gorilla, if you have ever seen it compared in a lab test as many of the wood mags have published you will see it is about the weakest stuff you can buy for wood. If you need extreme weather exposure use expoy. Can't recall the name of that 3M stuff, system 3?
Regarding biscuits, I have always used PVA. Regarding the expansion, I thought it was a myth but then I saw it in real life. If you use biscuits for a panel, let them dry for many days before you flatten the panel. Becuase they swell the wood and if you flatten too soon then the swelling will subside later and you have some nice biscuit shaped depressions along the joint... really nice. I didn't notice it until the lacquer was laid down.

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"SonomaProducts.com" wrote:

many of the wood mags have published you will see it is about the weakest stuff you can buy for wood. If you need extreme weather exposure use expoy. Can't recall the name of that 3M stuff, system 3?
Gorila Glue is IMHO, the most over priced under peckered adhesive on the planet.
If TiteBondII doesn't cut it, time for epoxy(Raka, Systems3, West Systems, etc)

thought it was a myth but then I saw it in real life.
If you use biscuits with epoxy, they become a keying device.
Lew
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Lately. I have become a huge fan (again) of Weldbond. I wouldn't glue a finely crafted mortise and tenon joint with it, but I find it does what it does better than anything: glue strips of plywood to the bottom of a solid surface countertop.
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"Robatoy" wrote:

I wouldn't glue a finely crafted mortise and tenon joint with it, but I find it does what it does better than anything: glue strips of plywood to the bottom of a solid surface countertop.
SFWIW:
Ran some test years ago using some Corian samples, 12mmn CDX, and epoxy.
The epoxy joint didn't fail.
Lew
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The Weldbond doesn't fail either.
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On Tue, 2 Dec 2008 02:38:16 -0800 (PST), Osprey

Yes, you can use polyurethane glue with biscuits. I use water-based carpenter's glue with biscuits. The biscuits swell and lock the joint. If the biscuit is too close to the edge, it can swell a bump on the face. There are slight differences between biscuit brands.
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Interesting. (not picking a fight) I always thought glue locked the joint. And biscuits more or less just help you line up the centers of the boards.
--

-MIKE-

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Mike... you like to live dangerously, eh? LOL
If used PROPERLY, a biscuit will add strength to a butt joint.
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Robatoy wrote:

Again, not arguing here, I want opinions.....
How much strength is needed beyond what the glue provides for the average linear butt joint? Cabinet door panels for example, or a table top.
I understand that each plank of wood wants to warp in the opposite direction of the adjacent piece. Is that enough to break a glue-only joint?
Keep in mind, my middle name is overkill, so I'm usually the one using extra measures that aren't necessarily needed. :-)
--

-MIKE-

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-MIKE- wrote:

A "butt joint" is end grain jointed to long grain. It's not typically used in door panel or table top construction.
--
Jack Novak
Buffalo, NY - USA
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Nova wrote:

What do you call the joint used to connect the edges of two or more boards to make a table top?
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Dan Coby wrote:

I call it an "edge" joint.
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