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I've been doing double sides for several years. The guitars have been very well received and I plan to continue to use them. I've been using a clamping form which works well but I was wondering if anyone here has had success with vacuum clamping for this procedure?

Here's a picture of what I'm doing now. I've use both inside and outside forms.





Thanks much,
Terry

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

Well, that's one spikey mound of heavy clamps. I can see why you'd be interested in a new method. Why do you choose double sides?

I'd read about their use in classicals and Tim McKnight's experience and gave it a try. I liked the effect on my tone and those guitars were a big hit with the good players at the store where I sell so I kept doing them. I like them on the tight cutaway on my archtops because it's so much easier to bend the thinner wood (especially Maple) without a kink or crack. You can bend both sides of the lamination 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.

Makes sense....

What do you use as backing wood inside?

How thick is the finished side Terence? It looks close to an inch from here. Do you make your standard guitar shapes larger to account for the fact that you would loose a fair bit of interior volume and working top area?

Thanks,
Danny

I've done a bunch of these though it's been a couple years... if you do it like I do you'll need a solid form and you'll likely want a clamp on the waist (and cutaway if you have one) to get things aligned properly and flush to the form. Also note the wood shim on the inside of the vacuum bag where the air gets sucked out... without it the nipple can put a lot of pressure on the wood and dent it quite badly.

For me the setup is ugly but effective and a bit of a juggling act to get it all together, but really I can't think of too many accomplishments worth doing that aren't. By the way I've used either IRW, padauk, or maple - whatever looks best, has the best tap tone, and will be most stable- as an inner layer.

Ringo, How do you get by with out any breather material in there to insure that the vacuum is evenly distributed? A breather layer ( a porous fabric between the bag and the layup, sides in your case) will prevent the bag from chocking off on itself.
I don't do double side, but I've done a ton of vacuum bags and I'd recommend a breather fwiw.

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Jim Watts
http://jameswattsguitars.com

I've done 5, 3 ply bodies in the bag. The veneer thickness easily bent cold.
However I used a 'female' form, so the outside piece was against the form.
I do use the breather mesh, with either the unibond glue or titebond I extend.

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Mike McNerney

For the inner side I've been using a lower grade of the same wood as the outer side. LMI is now selling inexpensive low grade Rosewood sides especially for laminating. They are around .070.
I'm not sure if the type of wood matters much but I like the inside of the box to look roughly like the outside.

I have been going around .060 for the outer and .050 for the inner. Danny I think you were looking at the kerfed clamping caul that made the sides look thicker. I've tried various adhesives and have settled on Unibond 800 as the best. It dries hard and brittle like glass and gives adequate working time. Thanks for the info guys, keep it coming.

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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 never used anything like that and didn't have a problem, but it sounds like something that would be helpful. I recall that getting everything to fit together well before engaging the vacuum was key... over time everything got smushed together quite well with good glue squeeze out all around.

What do folks use as a breather layer? Some foam? Sheet/blanket material?

jamestown:

http://www.jamestowndistributors.com/us ... &page=GRID

breather fabric, bag material, release cloth, west systems epoxy, sealing putty, tutorials, etc...

we do a fair amount of bagging at the day job. i've found that a seal-a-meal (it's a hot wire bag sealer/cutter) works super for closing up the bag.


p.s: i'm not affiliated with jamestown nor do i have anything to do with boats. although i would like a zodiac someday...

I use my alum outside cl gtr overholtzer heater to both bend and glue at the same time. I have a vaku clamp system and haven/t tried vacuum clamping .But kinda doubt if any. time is saved. I use a special urea type brown glue 30 minute open time for laminations. I also like to check to make sure the laminations are secure with no voids . Which can create problems with this glue that drys so hard.

I'd like to see a picture of that rig!

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

Terence . I currently have no laminates on the overholtzer aluminum bender . Charlie hoffman in minneapolis also has one it/s just an aluminum half template of a CL gtr side with a built in heater and an outside alum shoe that clamps down the waist. Very effective . I prefer it over my 3 heating blankets . it heats up slowly, which is why I like it , gives plenty of leeway for bending all types of wood. I don/t know how to take a photo of it on my new I phone. But if you just want to see a pic of the bender . I can get my wife to post it for you. I paid $500 for it in 1990.It is worth having, as the heating element can easily be replaced I think ??

overholzer bending fixture seen here:
http://www.hoffmanguitars.com/side_bending.htm
don't know how many people realize this, but charlie's website is a virtual step by step how-to of guitar building. i've found it very useful.

for heating elements, candlestick or band type start here:
http://www.watlow.com/products/heaters/index.cfm

Thanks Ernie. Charlie has shown me around his shop and I remember that bender. Much Mojo.

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