What Veneer for body

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Kiwicanfly
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What Veneer for body

Post by Kiwicanfly » Sat Dec 05, 2020 5:19 pm

Hi Guys
I have been interested in building an archtop for many years. I may have found a treasure load of Veneer. A real barn find cubic meters of 3mtr lengths of mahogany, walnut and maple. To me it looks ideal to laminate sides and tops.
Has any one built like this before?
I thought I could shape a former from custom wood and vacuum bag body parts.
If anyone is looking for Veneers there will be more than I will ever need in 10 lifetimes.

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nkforster
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Re: What Veneer for body

Post by nkforster » Sat Dec 05, 2020 6:22 pm

Please post some photos of the veneer if you can. Let's see what you got@

Laminating tops and backs from scratch is no simple task. Most o the European firms who do this start with a spruce core, with show veneers on the outside of maple or good quality spuce. There is a video of an American chap who does this on Youtube.


youtu.be/Nzh32jZRZl4


youtu.be/7VnOp0a7g0I

Vacuum clamping would be enough for your outside veneers but you're better off using a mechanical press for laminating the core. Do you know anyone with a CNC who can machine the male/female forms for you?

You can see the sort of process here at the Hofner factory:


youtu.be/WyFhRoi188E

Keep an eye out for a used veneer press.

Sides are easier - you need male/female formers, ideally made on a CNC. Make a press frame from steel sections, look up "skateboard press" for some ideas. I use one for laminating sides - a steel frame and 2 x 8 ton carjacks.

Even if you perfect the process of veneering, you're then going to have to work out how you bing and scrape the binding without going through. Sorry to be a "naysayer" but working with veneer is great in some ways but it also brings a whole new set of issues.

blackalex1952
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Re: What Veneer for body

Post by blackalex1952 » Sun Dec 06, 2020 10:41 am

I have been veneering with vacuum bags and formers for a while now. I asked a fellow luthier who told me that the old way in factories was to use hot sand somehow with hide glue. Metal formers, male and female with HHG and a press would work, but it's all a matter of justifying the expense re turnover and production.
A simple vacuum bag works with a carved form the shape of the top or back using West Epoxy system. Air pressure is around 14psi and a vacuum press can achieve around 11 or 12 psi...not sure how this translated comparatively to an 8 ton car jack! The method I use for sides is once again, a bag, which after depressurising to form a vacuum, is then clamped into a form before the glue hardens. The real question is "How many veneers?" So how thick are your veneers? The old ones were rotary cut, usually, to 0.9mm thickness, modern ones to 0.06mm. Veneers need to be laminated in odd numbers, ideally, eg 3 ply, 5 ply, etc...
One trick with veneers is to make a jig using a bolt and two pieces of straight timber to make a holder for the edge of the veneers then shoot them straight for edge joining, using either a plane or sanding beam, so that the veneers will butt nicely together. Clamping of individual veneer is done using stretched masking tape, then each veneer in the ply is laid up after the edges glued and the tape removed. The tape clamping is done on both sides of the sheet of veneer in question. Given the amount of time the vacuum press has to run for relative to the glue curing time, curing times can be adjusted using different speed catalysts in the glue and ambient temperature. I use bathroom heat lamps suspended on an old microphone stand...a lot cheaper than leaving them in the bathroom for people to forget to turn the damn things off!!
Cheers! Ross...ps send details of your veneer thickness ranges please!
"Everything I say on the topic is based solely upon inexperience and assumption!"

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nkforster
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Re: What Veneer for body

Post by nkforster » Sun Dec 06, 2020 3:41 pm

This thread might help too:

http://www.anzlf.com/viewtopic.php?t=7883

Basically, the more complex the shape, the more issues you will have. So an arched cutaway with a deep recurve is harder to do than a cylinder.

Kiwicanfly
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Re: What Veneer for body

Post by Kiwicanfly » Tue Dec 08, 2020 4:31 am

Thanks guys that is a big help.
I'm in the final stage of buying a very old family joinery, cabinet making business been in the same family for over 100 years. unbelievable quality of rose wood planks. Mahogany 500 x 75mm planks and so much figure grain veneer.

blackalex1952
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Re: What Veneer for body

Post by blackalex1952 » Tue Dec 08, 2020 6:30 pm

blackalex1952 wrote:
Sun Dec 06, 2020 10:41 am
I have been veneering with vacuum bags and formers for a while now. I asked a fellow luthier who told me that the old way in factories was to use hot sand somehow with hide glue. Metal formers, male and female with HHG and a press would work, but it's all a matter of justifying the expense re turnover and production.
A simple vacuum bag works with a carved form the shape of the top or back using West Epoxy system. Air pressure is around 14psi and a vacuum press can achieve around 11 or 12 psi...not sure how this translated comparatively to an 8 ton car jack! The method I use for sides is once again, a bag, which after depressurising to form a vacuum, is then clamped into a form before the glue hardens. The real question is "How many veneers?" So how thick are your veneers? The old ones were rotary cut, usually, to 0.9mm thickness, modern ones to 0.06mm. Veneers need to be laminated in odd numbers, ideally, eg 3 ply, 5 ply, etc...
One trick with veneers is to make a jig using a bolt and two pieces of straight timber to make a holder for the edge of the veneers then shoot them straight for edge joining, using either a plane or sanding beam, so that the veneers will butt nicely together. Clamping of individual veneer is done using stretched masking tape, then each veneer in the ply is laid up after the edges glued and the tape removed. The tape clamping is done on both sides of the sheet of veneer in question. Given the amount of time the vacuum press has to run for relative to the glue curing time, curing times can be adjusted using different speed catalysts in the glue and ambient temperature. I use bathroom heat lamps suspended on an old microphone stand...a lot cheaper than leaving them in the bathroom for people to forget to turn the damn things off!!
Cheers! Ross...ps send details of your veneer thickness ranges please!
I just re read this and the correction is not .06mm veneer thickness, but 0.6mm veneer thickness for modern veneers, 0.9 for the old ones, generally speaking....
"Everything I say on the topic is based solely upon inexperience and assumption!"

blackalex1952
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Re: What Veneer for body

Post by blackalex1952 » Tue Dec 08, 2020 6:34 pm

It sounds from your last post re the quality of the timbers that you have available, that you need to investigate a decent re sawing set up with an accurate bandsaw fence and blade!-R
"Everything I say on the topic is based solely upon inexperience and assumption!"

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