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I expect that using Titebond and being more careful to apply a very thin glue layer will go a long ways at making this idea work. I've noticed that using Titebond provided a MUCH less noticable glue line in all applications when compared to epoxy.

Do any of you out there this idea is inherently flawed though?

The angle of these contours is SO low in some places that perhaps the idea might never fly as is. These lines look pretty hokey to me as they are and although I expect they could be greatly improved....I'm wondering if they can ever disappear entirely.

Say they were 1/3th of what they are...and lighter to boot. Is any glue line acceptable?

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I read Emerson on the can. A foolish consistency is the hobgoblin of little minds...true...but a consistent reading of Emerson has its uses nevertheless.

StuMusic

Or go the other way and use something like resorcinol that would show off the glue line.

Or maybe a black veneer between layers would hide it.

What kind of surface prep are you using? Maybe a finer grit of surface sanding would help.

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http://www.chassonguitars.com

come on, you're just showing off.
nice!

Stuart, I know it's probably not possible for what you are doing but I almost think the layers need to be glued first and then carved. But then I don't build electrics so what do I know?

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Tim

McPherson did this with their heelcaps. They didn't want to wait for pva to dry so we used a .010 black fiber veneer between the heel and the cap. Something like that would work well for this application too as Kent suggested.

If you can't hide it, accentuate it!

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John Mayes
http://www.mayesluthier.com

I think I'm the +2 now on black veneer line. The only other thing I can think of that'll work is to use something like a hydraulic press for your gluing, along with a very thin and fast glue, to get really complete glue evacuation without leaving it time to soak in.

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Bob Garrish
Former Canonized Purveyor of Fine CNC Luthier Services

If you can't find veneer that size you might try experimenting with blackened epoxy. It's a great and unique looking design BTW. I'd like to see it finished!

Good Luck

The layers are glued prior to carving the top.

I thought of both a veneer and dying the epoxy but if you look close at the curly maple top you'll see that the REAL thin edge of the curly maple get somewhat translucent. For this reason it might actually be better to think of a white, opaque veneer between the bloodwood and the curly top. Maybe a black veneer between the bloodwood and the toasted maple. I don't know.

I decided to do a series of tests on a small scale using Titebond Extend and some other things suggested here.

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I read Emerson on the can. A foolish consistency is the hobgoblin of little minds...true...but a consistent reading of Emerson has its uses nevertheless.

StuMusic

Maybe a little....yeah.

...but I really am curious what level of control I can or need to exercise over these glue lines to have this be considered professional. I expect to improve this...maybe even a lot, but I'm afraid no matter what I do these lines won't disappear entirely....and I REALLY want them to

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I read Emerson on the can. A foolish consistency is the hobgoblin of little minds...true...but a consistent reading of Emerson has its uses nevertheless.

StuMusic

What you are trying to do is called a thick lamination. It is obvious by the varying glue line thickness that the pieces you are laminating are not flat. Any experienced pattern maker, cabinet maker, or door builder will tell you need 2 things to achieve this. First a jointer wide enough to flatten the boards, in your case a 12" or maybe 16", this cannot be done on a planer, the feed rollers flatten the stock as they go through the knives, as they exit the knives the stock returns to its cupped shape. Call around your area and ask the shops if they have a wide jointer, in my shop you would probably pay $10 to joint 3 short boards. Second you need heavy and even clamping pressure, the cheapest way to do it is a screw press frame, basically a series of press screws in a heavy maple or white oak frame whereby you can exert a great deal of force evenly. Aliphatic is the correct glue, but clamping pressure is important because the moisture from the glue will make each lamination cup or bow. You can of course achieve this occasionally other ways, but if your motive is achieving an invisible glue line reliably this is the way to go. T

I'd suspect that they were face milled, which would make them as flat or flatter than anything off a jointer. The apparent thickness differences in the glue lines are because the slope of the carve changes as it passes through various sections of the line.

I suspect Stuart's done more laminations than every cabinetmaker in the phonebook of a medium-sized city.

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Bob Garrish
Former Canonized Purveyor of Fine CNC Luthier Services

The pieces are milled flat so they are flatter than a bad bass singing soprano. And the glue jig is good I think

I think my main issues were that; 1. I used epoxy...which is aggressive and soaked in...and 2. I didn't pay enough attention to getting it thin and level before mating the parts...and 3. I laminated three panels together in one shot...so that was dumb.

I bit off a bit more than I could chew and should have studied it a little more before I went for it.

I'm still looking for an opinion on glue lines though. My real question is: Does anyone think ANY presence of a glue line between these laminates is acceptable? Right now...I'm of the opinion that it needs to be invisible or nearly so...or it's presumptuous to try to sell it.

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I read Emerson on the can. A foolish consistency is the hobgoblin of little minds...true...but a consistent reading of Emerson has its uses nevertheless.

StuMusic

Ha! Would that ANY of my laminating experience applied to this!!

Funny you should say that though. One of the things I'm pretty sure would work would be to use a 4-5 mil film prepreg film adhesive on a glass veil carrier between these layers and bake the thing at 250F for a few hours. With the ability to adjust the rheology of prepreg epoxies I KNOW a combination of viscocity and temperature would provide a 2-3 mil glue layer that would bond without seeping in.....but experimenting to figure it out, waiting for samples, freezer storage..... .....I think Titebond

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I read Emerson on the can. A foolish consistency is the hobgoblin of little minds...true...but a consistent reading of Emerson has its uses nevertheless.

StuMusic

You should be able to eliminate the glue line and yes, I think you should try.

Face milling - how smooth is the surface once you're done? What kind of cutter is used? Do you sand afterward?

I would try the gorilla glue "clear" PU formula as one of your experiments. I'd also suggest using a roller to apply it as thin as possible if you're not already. In your clamping jig, start tightening in the center and radiate out from there.

I've laminated maple strips using the standard gorilla glue (the brown stuff) and in spots, the glue line completely disappears. Using the clear formula should allow for a little bit of slop even. See attached shots. That's a lamination of two pieces of maple about 1/4" each

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http://www.birkonium.com CNC Products for Luthiers
http://banduramaker.blogspot.com

Smooth enough to where if I sanded it I'd probably do damage to it The cutter is a 2" diameter shell mill with radiused bits. The radius help prevent any ripping of the surface. There ARE tool marks but you can't feel them with your hands...and I don't think they are a problem otherwise they would show in the glue line as repeated anomolies....and they don't.



I'm tightening from center to edge. Here's the thing that worries me. There is so much surface area on these panels that I'm worried the glue is going to begin drying and lose its flowability before I get it in the clamp and get the pressure down. Maybe this whole time I've been afraid to use these glues for no reason. I used the epoxy because it remains open for hours. Those hours probably allowed it to seep into the wood too far.

Do you think that using Gorilla glue or Titebond Extend is going to present a time issue when trying to glue up two panels that are 13.5" x 19". Of course....applying it with a roller serves both functions of laying it out thin and applying it quickly.

Thanks so much for all your replies.

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I read Emerson on the can. A foolish consistency is the hobgoblin of little minds...true...but a consistent reading of Emerson has its uses nevertheless.

StuMusic

I doubt it. The white setting gorilla glue has a shorter open time than the regular stuff by about half so you might want to try the regular PU glue first.

The laminations I was doing were 3 strips about 2" wide and about 50" long. I was using a brush to spread the glue. Come to think of it, the most challenging thing about the glue up may be cleaning the roller off before it sets. Perhaps a credit card squeegee might be a better idea for spreading the glue.

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http://www.birkonium.com CNC Products for Luthiers
http://banduramaker.blogspot.com

This is cool stuff you're up to, Zlurgh! The shallow angles of your contours will accentuate the glue lines, which is some fairly simple trig, and is actually a convenient way to measure glue line thickness if you don't have a caliper handy. Pre-cure is definitely a valid concern, but I think you may just need more pressure. Considering the species of wood being used, 400 PSI in a hydraulic press would get you much closer to the sought after invisible glue lines.

A couple of other thoughts: Titebond doweling glue (white glue with viscosity of 1600 cps) or, as another poster suggested, make the lines part of the design. Water based wood glues can be colored with aniline based dyes.

PS- my introduction (perhaps this should be a separate thread?):
I'm employed as a Technical Specialist at Franklin International, which is familiar to many for the Titebond line. I started playing guitar at age 10, built my first solidbody from scratch at 16, talked Martin into taking me on as as intern while receiving high school english credits I didn't need, and studied classical guitar performance at the University of Cincinnati's College Conservatory of Music for a year and a half before getting injured and committing to Mechanical Engineering and Biochemistry. In my spare time I'm happy to do anything involving guitars. Zlurgh can attest to how happy I am to spend time talking about them while at work whenever I get a chance (one of the best aspects of my job)

If you ever want to talk glue, I'll be happy to help. My job entails working as a scientist purely in the pursuit of truth, not marketing, so there's no personal bias steering me to ever lead you astray. I look forward to contributing frequently to this diverse and knowledgeable group and am sure I'll learn a great deal from all of you.

Yo, Zlurgh

Freshly sharpened and set blades on a thickness planer with 2 longer (at least 8 inches for and aft) sacrificial scabs on the sides to eliminate any possible dips at the beginning and end of the cuts.

Do not sand!

Hot hid glue, very evenly apply on the perimeter going thinner towards the center.

Clamps first on perimeter line of the bevel cut. Then into the center.

Only clamp 2 pieces at a time....rethickness, then clamp the third.

Hide glue is the only glue that actual sucks the two wood surfaces together.

These are about the best things you can do to help avoid the glue line showing from diagonal tooling.

Try to avoid open grained woods...they accentuate the glue line as do sanding lines.

In some cases, depending on the woods being married, a thin sheet of fish paper (fiber board) helps disguises the glue line by adding a thin black (or what ever colour you choose) detail line between the woods. However, if the angle of the diagonal beveling is not consistent then even this detail line will appear to vary in its appearance.

Of course you could just live with it.


blessings
Padma

rehabilitated...ya right!

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Audiences and dispensations on Thursdays ~ by appointment only.


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I'd suspect that they were face milled, which would make them as flat or flatter than anything off a jointer. The apparent thickness differences in the glue lines are because the slope of the carve changes as it passes through various sections of the line.

I suspect Stuart's done more laminations than every cabinetmaker in the phonebook of a medium-sized city.

I appreciate your post for the best laugh of a holiday weekend. I shared it with 4 friends and we will all be shedding our pattern jointers next week, my friend Mike is telling Martin to stop making these worthless behemoths as we can all use our cnc's, mills and machining centers to do this work. Never mind that the clamping apparatus will distort the 3 dimensional integrity of what we are trying to flatten. Neophyte!

Yo, timoM

thanks for the info.

blessings

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Audiences and dispensations on Thursdays ~ by appointment only.


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Did timoM actually take umbrage with the fact that I use a cnc machine to flatten wood? Really?

These panels are held by a vacuum plate as they are milled. There is no clamping pressure.

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I read Emerson on the can. A foolish consistency is the hobgoblin of little minds...true...but a consistent reading of Emerson has its uses nevertheless.

StuMusic

It is a very odd lexicon indeed that equates "info" and derision.

Geez....do I HAVE to join a gang?

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I read Emerson on the can. A foolish consistency is the hobgoblin of little minds...true...but a consistent reading of Emerson has its uses nevertheless.

StuMusic

It sounds like you and Mike and Martin should get out more often.
Its a Holiday after all.

Glad to see you made it, Hugh. I must say...the examples I have of people going out of their way to help their customers, after almost two decades of doing R&D, is rare enough that I remember every time it happened. Thanks very much for your help the other day. I picked up some Extend the other day as you recommended.

I have a 10 ton hydraulic piston and pump that I can use for this but I'd have to fabricate the frame for it. The screw press pictured above can actually produce over 50 tons of pressure, albeit only as evenly as bolt pressure is applied. I think a 3/4" aluminum plate between the screws and the wood would even things out.

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I read Emerson on the can. A foolish consistency is the hobgoblin of little minds...true...but a consistent reading of Emerson has its uses nevertheless.

StuMusic

This is similar to one of Joe Knagg's designs:
http://www.knaggsguitars.com/index.php/ ... ennatural/

If I remember correctly he used epoxy between these layers and compressed it all with a big hydraulic press. I think there was still some evidence of the glue line though.

Trev

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http://www.PeakeGuitars.com