IME = In My Experience
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| Author: | mikemcnerney [ Thu Oct 22, 2009 6:08 am ] |
| Post subject: | sides/backs laminated |
I am wondering about making laminated backs & sides,grain running parralel. Also plywood, each ply running at 90 de. And after seeing that Somogyi does a 2 ply lamination I was kind of surprised that worked but have now spoken to several folks & that seems to work well, even with softwoods for the inner layer. #1 what overall thickness are we talking here? #2 Is anyone making plywood sides, how many plys, & what thickness. Backs, a much wider piec I have noticed? Ply backs, easy to make but Is the tap tone awful. #3 Anyone out there done it & can you advise. How about a laminated back? 16" wide seems like a lot of potential expantion,contraction issues? #4 Anyone doing that, how many laminations, Can you mix quarter sawn interior with flat exterior, thickness please The last possibility that is currently on my brain is say 3 layers of sequence matched (just the way it came off the log) veneer & laminate. I'm pretty sure I will try this one for my own curiosity. #5 Has anyone tried it All this I use unibond 800 or epoxy works too. cheers Mike McNerney |
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| Author: | Laurent Brondel [ Thu Oct 22, 2009 8:10 am ] |
| Post subject: | Re: sides/backs laminated |
You don't state your purpose. I understand why laminating the sides can be an advantage, but the back? I wouldn't use commercial veneer to make laminations. It is usually knife cut and needs a good substrate (thicker than tonewood) to not warp. Unless you resaw and drum-sand your own veneer… I wouldn't exceed .100" total for side laminations, mine are usually .080". Weight is the issue. How do you know the taptone of a laminated back would be awful? I don't, never tried it. Probably never will. IME laminated sides ring like a bell with a much clearer fundamental, more sustain and more pleasant overtones than a solid one of the same wood. You can mix grain direction, it doesn't matter. Actually sides with an interior flat-sawn lam will be more resistant to splitting. |
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| Author: | mikemcnerney [ Thu Oct 22, 2009 9:19 am ] |
| Post subject: | Re: sides/backs laminated |
My purpose is to have a BRW veneer, or any other rare/expensive wood, at a fraction of the cost of solid material. Also Plywood backs/sides are more stable I don't know for sure what kind of a tap tone a ply back will have, until I do it, I have made one but not assembled or compared to a solid What is IME lam sides? In this discussion I am refering to lam as same direction & ply 90 de. I have wondered about knife checks re. strength in sliced veneer for this application. That's, in part why I am leaning toward ply, although the glue should take care of that issue I think. I had one super fussy furniture builder tell me once that knife checks can show up on a high gloss finish, so he only used his own sawn veneer. MM |
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| Author: | Peter J [ Thu Oct 22, 2009 10:21 am ] |
| Post subject: | Re: sides/backs laminated |
Mike, You might want to contact David Schramm. He has a lattice model which features laminated sides and back. http://schrammguitars.com/lattice.html This model is similar to the Greg Smallman style classical and the theory is to make the back and sides as stiff as possible to direct as much as the string energy as possible to the vibrating surface of the top. I seem to remember that David uses cross-grain laminations for each layer and then the final exposed layer is the veneer of his choice. He also uses a vacuum set-up for laminating. David is a great guy and has posted here before. I'm sure that he will give you some good advice. |
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| Author: | DYeager [ Thu Oct 22, 2009 11:00 am ] |
| Post subject: | Re: sides/backs laminated |
Mike, in my experience, laminated tops and backs ring higher, often clearer, and usually slightly shorter, than assembled solid plates. The shorter ring should be a plus for electric instruments, which is the primary use for laminated tops, although an unplugged laminated electric can make a lovely-sounding if low volume practice instrument (hey, it's an ELECTRIC). Knife checking? Never have seen it in commercially produced hardwood veneers; I have seen it in hardwood plywoods. Commercial hardwood veneers are nominally 0.024", but that's just nominal; thinner by a few thou is not uncommon. And "warping" is not a big deal when laminating layers of veneer to each other, not at all the problem you'd be courting with one layer of veneer on a tabletop. You CAN expect a small amount of distortion, "potato-chipping", but usually only 1/4" or so, nothing that can overpower the sides when it's glued down. Three-ply sides, center cross-plied, are as strong and stable as you'd want. You might want to try a three-ply back in a dish, center ply crossed, for a really stable and crack resistant plate that will be happy with minimal back bracing - it will already have a nice shape, and won't have to be bullied into place. I must say I've noticed no expasion-contraction issues, certainly no tendency for the plates to try to shrink and open seams or actual cracks. I'm still talking plywood, here, cross-plied. The last thing, sequenced layers running in the same direction. This was almost the first thing I tried, years ago, and I have to report that the parts, for an archtop, lost their arch and collapsed like old broccoli overnight. You could probably use this on a flat or domed part, but your split resistance would be down, and again, you'll lose some of the doming. Also, there's a guy out there who holds a patent for this style of assembly, and....enough said. As Laurent points out, you can mix and match flat and quarter sawn - I'm a fan of flatsawn myself. Unibond gets my vote, harder than cured epoxy. Use the Unibond blocker - vacuum pressing will squeeze the glue right through veneer without it. Dan 410 523 5419 |
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| Author: | Kevin Gallagher [ Fri Oct 23, 2009 7:30 am ] |
| Post subject: | Re: sides/backs laminated |
I'd be very careful and considerate when looking at the prospect of using laminate sides and back....especially when a veneer of any kind is involved. The veneer business is a huge industry that serves an even larger industry in furniture manufacturing. I'd be concerned about delamination and possible failure of the joints between laminate components in the future. The presses, irons, vacuum fixtures and other implements and tools used in veneer shops are very expensive and the techniques used go far beyond just clamping a few thing together. Pressure must be consistent, adequate and applied from all necessary directions to truly achieve good veneer adhesion. There's more to getting good results with integrity and the ability to present longevity in the product. Unibond with the blocked is essential in veneer press or vacuum clamping or you'll have a real mess. Just some thoughts, Kevin Gallagher/Omega Guitars |
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| Author: | Sondre [ Fri Oct 23, 2009 8:09 am ] |
| Post subject: | Re: sides/backs laminated |
IME = In My Experience
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| Author: | Link Van Cleave [ Fri Oct 23, 2009 12:25 pm ] |
| Post subject: | Re: sides/backs laminated |
There really isn't any need for blocker when using Uni-bond. There is no problem if it bleeds through. It is very easily sanded off and it doesn't effect the finish. Even Darryl Keil the guy who sells the Uni-bond and blocker thinks it is unnecessary. There are two ways to control bled through. One is to apply the right amount of glue. (A medium form roller works well. The foam looks and feels like the foam in those foam brushes.) Second is to use a card board called news board. It is like the stuff on the back of a pad of paper. This is a great thing to use as a caul and has the added advantage of catching and glue bled through. Any bleed through will be absorbed by the cardboard and only make little spots of glue/paper that are easily sanded off. Quote: I'd be concerned about delamination and possible failure of the joints between laminate components in the future. No more danger in this than in any joint in a guitar. With the huge surface area involved in veneering it may even be more forgiving. Of course one could mess this up just like any other joint. It is pretty easy to get a good dependable bonding even in a hobby environment. Vacuum bagging is easily done and this and or setting up a simple press is well within the reach of the small shop or hobbiest shop. Just like anything else you have to learn how to first but the same can be said of about any process in building a guitar if you don't know how or haven't done it yet. I have had the same thoughts as you about using BR veneers but I don't think I would do the back, just the sides. On another note I just cleaned and refinished a small table I had built that went through a house fire. My sisters house burned. Everything was destroyed. Miraculously this table had some blankets on top of it and when the roof collapsed it broke one of the legs but some how it survived. It was heavily smoke damaged and charred in a few places. I had veneered it with Tan Oak (at 1/16" ) Not the most stable of woods to say the least. After that intense heat and drying and then water from the fire hoses it was dragged outside where it sat for a day. The veneer stayed put, not the slightest opening of the seams. I was able to bring it back to near perfect condition. The only room in the house that didn't get the full brunt of the fire was the bathroom. There was only heat and smoke damage there. I had made her some furniture grade cabinets with commercial Karilian birch veneer. The finish was heat and smoke damaged, some of the drawers were full of water, but the veneer was solid and I will be able to bring them back to gallery condition. I have been using Uni-bond for a lot of years but this has cemented my faith in the techniques and viability of the product. Link |
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| Author: | DYeager [ Fri Oct 23, 2009 1:49 pm ] |
| Post subject: | Re: sides/backs laminated |
Thank you, Sondre - we should all try to speak to our experience; if we're speculating (don't have the experience) then we should point that out. Link, interesting fire story. I've tried to modify Unibond-laminated sides with a hot pipe, and it's just no go. I have a customer who bleached (two part wood bleach) a curly maple top, back, and side set to whiten the wood as much as possible before sunbursting the edges - spectacular contrast! No, the blocker isn't necessary, but you do start off with a cleaner-lookin product than without. Dan |
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| Author: | Ken McKay [ Fri Oct 23, 2009 8:03 pm ] |
| Post subject: | Re: sides/backs laminated |
Another thing relating to bleed through is that if you let the veneer sit open for a little longer the glue won't bleed through as much. Open time = veneer with wet glue before pressing. I am with Dan, I couldn't send out a product with too much glue bleed through on the face veneer even if it is easy to sand out. I do allow for a little though. Laminated sides are easy to sand through if the face is made from standard veneer. A lot of arch top makers like to bend sides from solid wood even if the top and backs are laminated. Some don't though, the preference being construction issues rather than sound, I think. Flat top guitars with laminated backs don't sound as resonant as the solid ones of similar thickness. And in most cases, I think would be not preferential to a nice jangly acoustic guitar sound. From expericence of building the same model, do I speak...IME
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| Author: | Clay S. [ Mon Oct 26, 2009 6:44 pm ] |
| Post subject: | Re: sides/backs laminated |
Hi Mike, I have built a number of instruments with laminated back and sides using flitch matched veneers reglued in the same order as they were cut. When properly done they seem to act much the same as "solid" wood. I have used the older thicker veneers (1/24th inch) as well as some of the more recent (1/42inch) veneers. As someone mentioned, orienting them in this fashion will give less crack resistance than "plywooding" them. They will act like solid wood in a completed insrtument, in extremely dry conditions they will crack. I use West system epoxy and have my veneers VERY DRY prior to laminating. I find this gives me the greatest stability in the finished product (very stabile). There is definately an economic advantage to doing this for rare and exotic woods, but no great advantage for those that can be commonly had, because of the additional time required for laminating. I like the way these instruments sound (solid spruce soundboards) as do many of the people who have played (and purchased) them. I think they compare favorably to their solidwood counterparts. |
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| Author: | CWLiu [ Mon Oct 26, 2009 8:30 pm ] |
| Post subject: | Re: sides/backs laminated |
Clay, Did you laminate the sides in a form or bend them after laminating? When did you join the back plates(or veneers)? Thanks. I have some 9mm-thick BRW veneers and I plan to glue them to solid plates. The problem is that veneers so thick are not easily pressed flat. On my first attempt, the veneer refused to be flattened in the vacuum bag and got totally ruined. Then I tried SSII, but the water in SSII took longer to completely evaporate than I excepted. The BRW layer continued to shrink after laminating. Next time I'll SSII it then press it until fully dried before laminating. |
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| Author: | Clay S. [ Tue Oct 27, 2009 9:44 am ] |
| Post subject: | Re: sides/backs laminated |
I glue up the sides in simple forms and clamp them to shape using as many clamps as will fit around the form. for the back plates I press them between flat pieces of melamine or other smooth surface. I use wax paper between the veneers and the forms. Below are two types of forms I use, a male female block form lined with formica and a thermoformed corian form that uses kerfkore as the other flexibile part. I dry out the veneers as much as practicable before laminating. Wetting out with epoxy resin allows the veneers to regain some flexibility. Moisture seems to make the wood less stabile. I allow the resin to impregnate the veneers and don't mind some bleed through as I also pore fill using epoxy. I allow the plates to cure for a week clamped in the forms. After I remove them I trim the edges and treat the parts as I would solid wood. (I glue up the book matched back halves with hyde glue or titebond, etc) The process is more work than using solid wood, but some of the veneers are quite beautiful and I think the finished product yields similar results. |
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| Author: | Dennis Leahy [ Tue Oct 27, 2009 10:57 am ] |
| Post subject: | Re: sides/backs laminated |
I'm wondering about Unibond on extremely porous veneer... With some types of veneers, there will be bleed through no matter what you do. I have thought about doing laminating with epoxy, and using epoxy as pore filler, and of course that solves any issues of the laminating glue being seen only in some pores or patches. I'm really curious about the Unibond, for several reasons: the feature that it dries extremely hard, and (even though it poses its own set of health hazards) might not be as nasty to work with as epoxy - especially in a small, indoor, poorly ventilated shop. So, let's say you have a dark veneer with open pores (Wenge? EI Rosewood?) Although I would not bother to laminate those exact species but instead would use solid wood, let's use them as examples. I do the lay-up with Unibond, and some of the pores are absolutely full of Unibond, some are partially filled, and some pores remain open. Let's say our veneer has some swirly or burly patches, so some of the Unibond forms streaks that look like the white mineral sometimes found in EI Rosewood. Some Unibond has come through and formed blotchy patches on the show surface. I'm assuming this is a realistic scenario. So, what now? I can sand the surface of my 1/42" face veneer only a tiny bit before sand-through. I still need to pore-fill the face and lightly sand. How will I hide the Unibond? Can I mix some dye into the Unibond? Has anyone done that? What type of dye is compatible? How would I grain fill the rest of the open pores that were not filled with Unibond? Will it have a different sheen than the Unibond "pore-filler"? So, those questions are for some folks with Unibond experience - even if it is just cabinet and furniture experience with Unibond. In addition, (sorry, I'm on a roll), I'm curious about making 3-ply guitar backs. I had assumed that I would go with 3 layers of veneer, with the central core veneer at 90° to the faces, for strength and stability. Those backs would probably be quite stiff, would produce very little "near field" vibrations, and the back would help the guitar to project (a la Rick Turner.) Clay is confirming my suspicions that laminates all in the same direction behave more like solid wood - at least in terms of expansion/contraction and the strength to be able to withstand a blow without cracking. Let's look at some other possibilities other than a 90° cross-ply lamination: how about a central core that is just barely off of the direction of the face core - say, 5° or maybe even 10°. Would that possibly offer the best of both worlds (or at least a compromise between extremes), and offer a back that was more acoustically responsive ("near field"), as well as providing some of the strength of a cross-ply lamination? What about the idea of using soundboard material for the core (some material that is acoustically "alive" but perhaps butt-ugly from asymmetrical staining or color patches?) The luthiers that have laminated curly Redwood to a core (or substrate) of Spruce report very good acoustic results. I'll stop here. Having asked 3,217 questions is probably enough for one post.  I'll also note that it may be good to take a look at the current method of back bracing developed by Grant Goltz: built-up vertical laminations of thin spruce, alternating crossing over junctions, forming a relatively delicate quadruple X-braced back. It might be the perfect compliment to a laminated back, and provide enough of a framework to stabilize the nearly-parallel veneers and yet allow the back to move. Grant's Monkeypod Dread Dennis |
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| Author: | WaddyThomson [ Tue Oct 27, 2009 11:35 am ] |
| Post subject: | Re: sides/backs laminated |
I'm curious! When you do laminations with epoxy or unibond, what does that do to the rest of the construction, i.e., gluing linings, tops & backs, braces, etc. Do they have to be glued with epoxy too? Do other glues work effectively after the wood has been impregnated with epoxy, which it, obviously, does when you laminate. Seems to me you'd be getting glue failure in braces and linings, since you can't really scrape back to pure wood, if you didn't use epoxy there too. Then, in that case, since epoxy tends to have more damping properties, wouldn't that effect the sound of the instrument? |
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| Author: | Link Van Cleave [ Tue Oct 27, 2009 11:46 am ] |
| Post subject: | Re: sides/backs laminated |
Quote: So, those questions are for some folks with Unibond experience - even if it is just cabinet and furniture experience with Unibond.  Dennis you make that sound like some sort of limitation.UB comes with 3 different color powders for different color woods. Dark , med, light. You can mix them if you want. In my extensive/limited  experience doing years of fine furniture of the highest level and high end cabinetry I have never had a problem with bled through. It simply isn't a issue. If you do what I have said repeatedly you won't have any issues. You can use the blocker ( I never do) or use the news board as a caul. Heavy craft paper will work as well.This will absorb the bleed through and contain it to localized blob/dots of glue paper that is sanded off with out any effort at all. If you are going to pore fill with epoxy you might want to use epoxy as a glue. If not I think UB is better than epoxy for all the reasons I have stated before. I have done hundreds of sq. ft. of veneering and laminating using UB with every type of wood you can think of from tan oak to karilean birch to crotch mahogany. No issues from bleed through. No problems with finish. I just had Exotic Woods in Oakland lay up a order for me. 5 sheets of plywood with figured Satin wood veneer and 4 sheets of satin wood backed with a cross bond. They do huge amounts of business making fancy architectural plywood with exotic veneers for large projects everywhere. Super high end stuff. What glue do they use ? Uni-bond of course. Trust me they would not use it if there was a problem with blotchiness or any incompatibilities with any finish. Why don't you get some UB and try it. If you don't like it I will buy the rest of the glue off of you. Link |
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| Author: | Barry Daniels [ Tue Oct 27, 2009 11:50 am ] |
| Post subject: | Re: sides/backs laminated |
Waddy, parts laminated with epoxy will glue well with regular wood glues. The sides that I laminate actually have a better tap tone than solid sides. Go figure. Dennis, UniBond can be bought in both a light tan color and a dark walnut color to better match your particular wood. In practice, the glue sands relatively easy so removing surface smears is not difficult. And it seems to pretty well disappear under a finish, so staining or contrasting with your filler does not seem to be a big problem. Edit- Link beat me to it as we were posting at the same time. |
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| Author: | Dennis Leahy [ Tue Oct 27, 2009 3:54 pm ] |
| Post subject: | Re: sides/backs laminated |
Thanks, Link and Barry. Link Van Cleave wrote: Quote: So, those questions are for some folks with Unibond experience - even if it is just cabinet and furniture experience with Unibond. Dennis you make that sound like some sort of limitation.Why don't you get some UB and try it. If you don't like it I will buy the rest of the glue off of you. Link Link, I just wanted to make sure I heard back from ALL woodworkers with Unibond experience - not just luthiers. Ya know, some of these dadgummed luthiers think if it is not direct lutherie experience, it ain't valid. The one cabinet/mill shop where I worked had a 4' x 8' hot press, but we used white glue, it was mostly for plastic laminate, and the few times we laid-up a veneer it was a paper-backed veneer or a 3-ply skin. So, I have no direct Unibond experience. However, probably most/all of the custom architectural panels with veneer faces that I ordered and had laid up "elsewhere" were glued with Unibond, so I probably have experienced sanding custom plywood made using Unibond, but never really knew. Guess it's time to buy some Unibond and give it a try. Dennis |
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