Kostal Guitars Project and build Thread

[Beau Hannam]

Jason,

With standard sides and kerfing, when you route the binding channel which usually exposes some kerfing- you temporarily lose that drum boooooing sound when the tap is tapped until all bindings are in place.

Does this still happen with laminated sides (or not because you never reveal the kerfing)?

Thanks

[iim7V7IM7]

Jason, in the event you are interested in seeing/hearing about other luthier's lamination fixturing, here is luthier Peter Oberg's (who learned from Robert Ruck). It looks quite similar to yours. His laminated sides use a different wood for the inner layers. In the example shown, the outer laminate is Black Cherry and the inner is Port Orford Cedar. The result is lightweight, stiff and it smells great to boot. Peter uses solid linings.

Good luck with you project!

Originally Posted by jkostal

John,

I really am a big fan of laminating sides. Twice a year I have the students at the Roberto-Venn School of Luthiery come out to my shop for an afternoon visit. One of the things that I always do when I am talking about laminating sides (which at that point is a foreign concept to them) is that I pass around a kerfed OM rim that is built in the standard method (one side, kerfing and vertical braces) and a blocked up, laminated rim that I have not yet kerfed. The laminated rim is probably 25-30% more stiff without the kerfed linings being added yet. In my opinion, this creates an incredibly rigid rim, like a snare drum, that allows the top and back to vibrate more without as much loss of energy in the sides due to flexion. The added benefit of having a huge glue joint and one side glued to another is that you mitigate the need for vertical braces, and greatly reduce creep should a crack form. Theoretically, the grain lines of the two laminated pieces would not line up, and as long as the glue joint holds, the crack has nowhere to go. One other benefit in the construction process is that clean up and flat sanding the sides is really easy as they don't really dip or move as you are sanding them.

It's a bit tricky to decide how to laminate. I have seen people that have great success using vacuum, others use clamping jigs like mine with a million clamps and some have done it far more simply. Like anything, once you find a method that works for you, I recommend sticking with it.

The downside to laminating is time, materials, and weight. Laminating takes time, so building a rim suddenly became a little longer then before. Material wise, you can decide what to laminate with. In the beginning, I was laminating BRW sides with BRW inner sides. While this looked amazing and sounded really sexy, the cost associated with this method was ridiculous, and I started having backs with no sides, so I have recently stopped doing that. I currently laminate with Wenge, EIR, Honduran Rosewood or Ebony depending on what I am trying to achieve sonically and visually. If it is non-BRW sides that I am laminating, I will often use the same material as well, meaning a mahogany sided guitar may have mahogany inner laminates as well since the cost is not as great as when I was doing that with BRW.

Adding a huge glue joint adds significant weight, as does the thickness of the two sets being laminated. I have seen people thin the two sets down so that, once glued together, they equal a pretty standard set with an overall thickness of about .08-.085". The nice thing about two sides about .040-.050" thick is that bending them is a breeze and laminating them makes them strong. I have seen some people do a variation of wood sides and wood veneers (think a .060" outer side with one .020" inner veneer or two .010" veneers), and I have seen people go over in thickness. Its all up to you, and every option has pros and cons to stability, sound, and construction. If you decide to go this route, take your time and think about what you are trying to achieve and accomplish and then have fun with it.

I use TAP plastics epoxy resin. I know Tim McKnight and some others use a laminating glue made for woodworking, and some others use things like tight bond, and other more standard glues. Again, it's up to you which route you take as they all work pretty well once you understand them.

Good luck and let me know if I can help when the time comes.

[jkostal]

Originally Posted by quentinjazz

Great posts Jason, very inspiring!
According to you, the weight of a rim with laminated sides the way you do it is almost doubled compared to a standard rim with single sides?

Thanks

q.

Quentin,

I don't know that it is twice the weight, but it is heavier with my building style which entails building over normal thickness compared to a regular set of sides. With my rims, I also use a large neck block which adds to the weight, so my heavier rim is a result of a lot more than just the laminated sides themselves. I don't view this as a problem though. We are talking about a few ounces at most. Most of my clients play sitting down, so the added weight allows the guitar to rest easily in their lap when they play. The weight in the body helps to counterbalance the weight of the headstock and tuning machines, and to me, the result is a guitar that balances well in your lap and doesn't require you to fight the weight of the headstock as much with your fretting hand. Like I said, the sides are only one aspect of that weight in my rims...most of it is neck block related for me.

I guess the proper way to convey this thought is that if I had a single side of East Indian Rosewood measuring .080" thick, and then had two sets of sides of EIR each measuring .040" thick, and I glued them together, the glue has mass, and permeates into the pores, so theoretically, even though they would be the same thickness, the laminated side would weight more given the glue saturation. Obviously there are different densities and such at play here, so there is no absolute with this, but that is my thought process. I would say in this example, the laminated sides would be more stiff as well. To me, that added stiffness outweighs the weight factor given that its nominal at best.

Gustav Fredell used to build using a solid outer side, and two inner veneers. The overall affect was that his rim was incredibly stiff, but weighed less than a single side, so it is possible to build more lightly given your wood choices. In this example, Using an outer laminate of EIR with an middle laminate of holly and an inner one of dyed maple for instance would probably yield a lower weight than just EIR by itself to full thickness.

I could be wrong with all of this, because I haven't played around with different options, but these are my overall thoughts.

[jkostal]

Originally Posted by Beau Hannam

Jason,

With standard sides and kerfing, when you route the binding channel which usually exposes some kerfing- you temporarily lose that drum boooooing sound when the tap is tapped until all bindings are in place.

Does this still happen with laminated sides (or not because you never reveal the kerfing)?

Thanks

Beau,

I still find that you get that same effect, although maybe not as much. I notice it when I glue the top and back on and get a certain tap tone, and then I route for the binding and that tone becomes muddled and not that exciting as we reduce the surface area and decrease the stiffness of the glue joint. Once the binding is glued in, I gain that response back, so it is pretty much the same as a standard kerfed back. One thing that I like about it though is that I am gluing my binding to a solid wood surface (no gaps between the binding) which makes for a more solid glue joint, and because I don't have the gaps in the binding, I don't get glue dripping into the body so there is no surprise cleanup like I used to get with a regular rim.

[rogthefrog]

Interesting discussion of laminated sides.

Do you know if anyone has tried using thin carbon fiber or kevlar for the inner lamination? It might add strength with less weight.

[Julian Gaffney]

Originally Posted by rogthefrog

Interesting discussion of laminated sides.

Do you know if anyone has tried using thin carbon fiber or kevlar for the inner lamination? It might add strength with less weight.

Hey Roger,

I've tried that and I imagine that I'm not alone there. Inner and outer laminates in East Indian Rosewood with a few sheets of carbon fiber in-between. The result was a marginally lighter and "tougher" side. Combining that with slightly lighter woods for the blocks (Spanish cedar in my case) shaved a little under a pound off the final weight of the guitar. A nice weight savings but ultimately I went back to a similar style to Jason. Carbon fiber is really tough on tools and nasty to work with - even with the right protections I have adverse reactions to the dust.

Enjoying the progress Jason, very cool!

[rogthefrog]

Originally Posted by Julian Gaffney

Hey Roger,

I've tried that and I imagine that I'm not alone there. Inner and outer laminates in East Indian Rosewood with a few sheets of carbon fiber in-between. The result was a marginally lighter and "tougher" side. Combining that with slightly lighter woods for the blocks (Spanish cedar in my case) shaved a little under a pound off the final weight of the guitar. A nice weight savings but ultimately I went back to a similar style to Jason. Carbon fiber is really tough on tools and nasty to work with - even with the right protections I have adverse reactions to the dust.

Enjoying the progress Jason, very cool!

Hi Julian! Thanks for the input on this.

The caliber of builders participating in the Custom Shop is staggering. We're lucky.

[jkostal]

Originally Posted by rogthefrog

Interesting discussion of laminated sides.

Do you know if anyone has tried using thin carbon fiber or kevlar for the inner lamination? It might add strength with less weight.

Roger,

Julian, my brother from another luthier, is spot on in his assessment. There are some benefits but to me, I try to minimize the amount of time I spend working with carbon fiber. Currently I only use it for neck reinforcements and I find that if I do any sanding on it, it gets on my skin, and I have to go take a shower as I almost immediately start to itch and end up with irritated skin. I would prefer to not have to use it any more than necessary.

The second thing is that carbon fiber isn't very good at adhering to a particular shape unless it is glued to something. Once you glue it to another bent side I guess it would be ok, but that carbon fiber sheet is going to most likely always want to be flat, which in my mind, induces some level of stress into the joint. By pre-bending the sides before laminating with wood sides, we have a more relaxed joint to work with.

When I first started guitar building my attitude was much more of a "make it work" mentality. If the fit wasn't perfect, I used more glue or more clamps and got it to work. When I apprenticed with Ervin our attitude was more that every glue joint should go together without effort. I should be able to hold two things together with minimal pressure and there should be no gaps of any kind. The clamps are merely there to hold something in place so that I don't have to. A huge amount of clamping pressure should not be needed on a good fitting joint. In my opinion, this is just good woodworking and craftsmanship. As such, I feel like using a CF inner laminate would cause me to fight the natural desire of the sheet to be flat, allowing it to be curved only by clamping and gluing it really well. I have also had issues with wood and carbon fiber gluing together well when stress or shearing forces are placed on the joint. It is dependent on the glue and what is being done, but I just don't know that I would feel super comfortable with this laminate after the guitar is built. If something is going to go wrong, I would prefer that it happen during the build process and not later on down the road. In this case, I would feel pretty confident that the guitar would go together ok, but I would probably worry many nights after shipping the guitar out the door. Just my 2 cents, but thanks to Julian for sharing!

[Beau Hannam]

I've heard of people laminating silk (which is actually an extremely tough material and very hard to rip) between a wooden inner and outer layer. But as 99% of those who laminate attest, a simple two ply wood laminate is completely structurally sound- why over think it. (says he who has never done it

[rogthefrog]

Originally Posted by jkostal

Roger,

Julian, my brother from another luthier, is spot on in his assessment. There are some benefits but to me, I try to minimize the amount of time I spend working with carbon fiber. Currently I only use it for neck reinforcements and I find that if I do any sanding on it, it gets on my skin, and I have to go take a shower as I almost immediately start to itch and end up with irritated skin. I would prefer to not have to use it any more than necessary.

The second thing is that carbon fiber isn't very good at adhering to a particular shape unless it is glued to something. Once you glue it to another bent side I guess it would be ok, but that carbon fiber sheet is going to most likely always want to be flat, which in my mind, induces some level of stress into the joint. By pre-bending the sides before laminating with wood sides, we have a more relaxed joint to work with.

When I first started guitar building my attitude was much more of a "make it work" mentality. If the fit wasn't perfect, I used more glue or more clamps and got it to work. When I apprenticed with Ervin our attitude was more that every glue joint should go together without effort. I should be able to hold two things together with minimal pressure and there should be no gaps of any kind. The clamps are merely there to hold something in place so that I don't have to. A huge amount of clamping pressure should not be needed on a good fitting joint. In my opinion, this is just good woodworking and craftsmanship. As such, I feel like using a CF inner laminate would cause me to fight the natural desire of the sheet to be flat, allowing it to be curved only by clamping and gluing it really well. I have also had issues with wood and carbon fiber gluing together well when stress or shearing forces are placed on the joint. It is dependent on the glue and what is being done, but I just don't know that I would feel super comfortable with this laminate after the guitar is built. If something is going to go wrong, I would prefer that it happen during the build process and not later on down the road. In this case, I would feel pretty confident that the guitar would go together ok, but I would probably worry many nights after shipping the guitar out the door. Just my 2 cents, but thanks to Julian for sharing!

That's great to know as well. Thanks! I didn't know carbon fiber was so nasty.

[jkostal]

Busy day today but all of the sides have been laminated, and cleaned up. Next these beauties will get fit into the rim. I will then make some neck blocks, tail blocks and cutaway blocks and begin blocking up the rims.

[justonwo]

Looking awesome. That arsenal of chisels looks fearsome.

That is some wonderful looking mahogany!

[jkostal]

Originally Posted by justonwo

Looking awesome. That arsenal of chisels looks fearsome.

That is some wonderful looking mahogany!

Thanks Juston,

I always enjoy your sense of humor! The truth is that the chisels are for decoration purposes only! I would really hurt myself if I was allowed to use anything that sharp. They are just movie props made out of rubber, and I take these shots in a room in my house set up just for this type of picture!

The wood is not mahogany, but rather master grade Balsa wood that a local artist painted to resemble Brazilian Rosewood, but now that I know you don't know the difference I will really enjoy surprising you with your upcoming 12 string, and the wood I choose to use! "No really Juston, pallets make the best guitars"!

While I shouldn't need to say this, for the rest of you out there...the chisels are real, the photo is in my shop, and the sides are Brazilian Rosewood! Just clarifying so that tomorrow there is not a new AGF post about how Jason Kostal uses Balsa wood on his guitars, and his mommy prohibits him from using a chisel because they are sharp and he is accident prone. End of disclaimer!

[JamesO]

Hey Jason, what is the grey thing hanging on the wall?

[Beau Hannam]

Originally Posted by JamesO

Hey Jason, what is the grey thing hanging on the wall?

Im guessing its a Peterson strobe tuner?