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You fellas who do double sides, are you putting the two pieces to be laminated in your bending machine at the same time? Two .045 pieces seems like it would be OK, but I just want to check to be sure. Thanks in advance.

Yo darren I bend my side .075 in the bender first , then I bend the second piece .045 after that., I believe it depends on how wide your side mold/bender is , if you can get 2 similiar thickness sides on that would be ok , but I would be concerned abt the uneven clamping pressure on 2 dissimiliar pieces e.g .080and .025, ,Vy thin veneers, could be stacked together, but they may, or may not come out too well depending on the species. Practice on scrap sides first!

I think Darren wants to bend them stacked.

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Build log

I bend mine stacked just the way they would be after they are laminated.

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tim...
http://www.mcknightguitars.com

Do you put a piece of wet brown paper between the sides Tim or do you just stack them right together.

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It's not what you don't know that hurts you, it's what you do know that's wrong.

I have turnbuckles on the outside slats on my bender so I can really crank the pressure and can I use it to glue laminated sides.
Works really well.

Last time I tried this I used lower heat and fish glued and bent them in one operation. The sides are in an archtop and it worked fine. I have off-cuts sitting around to check and the glue does not seem to have been weakened by the bending heat. Sides were around 1.5mm thick each, maple on outside and rosewood inside.

Cheers
Dom

Wow, seriously? Bend and glue at the same time? That would save me so much time! Do you have pictures of your setup?

Fish glue does resist heat very well, I bend purfling laminations all the time, however there is a point where too much heat (or for too long) opens the joint up, the glue seems to flow out and dry to a whitish crust.

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Build log

Like your idea of stacking and gluing sides in one operation?? would it work using hide glue instead of fish glue ??. I would have to order fish glue ??

Ernie, No harming in trying. Coat each side with a thin layer of HG, wrap the bundle in paper so you don't get glue over your bender. I like fish glue because it has this higher working temp. HG could be weakened by too much heat so you have to get the balance right. You don't want your side coming apart down the track.
The long open time of FG also means I had plenty of time to get everything lined up carefully. With HG the heat would reactivate the glue so thats not an issue. But I would be worried about too much heat.


Something I also read was that CA glue sticks really well to protein based glues so if you get any small gaps you can squirt in some CA and it wil bond really well.
Sorry, I don't have pics at the moment but its not hard to visualise it. 3 slats are joined together at the tail end but at the head I have turnbuckles only on the top slat. I use solid forms which I think are a must for this. Forms with slats won't provide enough support. So I bend and then attach the turnbuckles and crank it down. As it cools the slats shrink a bit and it gets tighter. I can hear the bender creeking and protesting.

Hope this helps
Cheers
Dom

Dom, you are still spraying the outside surfaces with water before bending, right?

Hey Darren, yes. Once you have glue between the two sides i tape them at the tail end to keep the aligned and then just treat it as a normal side. But there is already moisture in the glue between the sides I don't wet it too much. Just a ligh spray. I don't want the glue getting wet and diluting.

I've even done it with 3 layers, maple/blackfibre/rosewood as I wanted to try a stiffer stronger side. Worked fine. Its really quite easy if your bender can appply the right pressure, either as I have done or just using clamps once it is bent. I like my system with the turnbuckles and use it on normal single sides as I get really flat beautiful bends. But what ever works for you.

Just go for it and learn. With animal glues if anything goes wrong with the gluing you can probably apply heat and get any gaps back together. But if they are bent together the two sides will fit each other perfectly so any gaps should be quite small.

Good luck
Dom

I bend my pre-glued side layup without heat in a press then press in the cutaway with a cutaway attachment and then apply heat to the silicone blanket. The glue is UF and cures rapidly. Four minutes later I have a glued up laminated side ready to use. My sides are 3 ply and the plys are 1.3 mm each, with the middle piece being cross grain. I can't imagine using sides that would be any stiffer but if needed I could make them 4 or 5 ply. The outer ply is plenty thick enough to sand without going through the ply.

I made a little video the other day. I can post if there is any interest.

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Ken

I'd like to see that video!

I don't have it on this computer so wait a day or so.
Don't expect a super slick demo like some of these around here. Just seat -of - the -pants - lutherie.

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Ken

Thanks Dom . Will try with HHG , if that doesn/t work will try fish glue.Have used brn uf glue to cold laminate 1/8in red oak pieces for a chair arm around a form. But frankly don/t like working with the stuff.I have 2 benders 1 an aluminum elec heated half form of a cl gtr and another half pattern of my many molds which goes with a silicone heating blanket. Thanks for all the tips. cheers ernie

My process is not really double sides but it might be something that can be adopted to making classical guitars with double sides. Take notice of the simple bending form.


Ken McKay Luthier - YouTube

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Ken

I just stack them together, nothing between them.

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tim...
http://www.mcknightguitars.com

Thanks Tim

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It's not what you don't know that hurts you, it's what you do know that's wrong.

Ken, thanks for taking the time to post that video!

You are welcome,
Did you notice the press that I am using. I get a lot of comments when others view my photos and videos of my process. Things like "that is a huge press" , "I wish I had one", thinks like that. It is very inexpensive and comes from Grizzly. The other parts to the press are plywood and an $10 veneer press also from Grizzly for the cutaway. so basically for $65, plus one sheet of plywood you can make a press for sides. If you need a cutaway it complicates things just a bit and you have to spend $10 more and put some more time in Notice that to raise the press so the screw is high enough, I used threaded rod (oh yea I forgot that) and blocks of plywood.
http://www.grizzly.com/products/H5510/images/1

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Ken