Excited about Kerfed Linings!

[John Coloccia]

I was instructed by my guitar sensei to make my own kerfed linings. There's nothing at all special about them other than I was very careful to make them all precisely the same thickness, and consequently they all had an extremely consistent and precise web thickness. This sort of lets you make all the webs a just a little thinner because everything takes stress equally.

The results:

My linings are in front. Luthier supply in back. The store bought one is actually just a little longer than the particular piece of mine I choose, so I'm actually at a disadvantage here. Still, there's a very clear difference in flexibility.

http://i913.photobucket.com/albums/ac335/jcoloccia/kerfed%20linings/DSC02050.jpg

Ah, but the proof of the pudding is in the eating, so let's eat some linings. Does that little bit of extra flexibility really matter? See for yourself.

Theirs (look familiar? It's actually cracked in two place, but my fingers covering one up):

http://i913.photobucket.com/albums/ac335/jcoloccia/kerfed%20linings/DSC02052.jpg

Mine:

http://i913.photobucket.com/albums/ac335/jcoloccia/kerfed%20linings/DSC02053.jpg

These things go around curves like butter. Yeah, they took a long time to make and it was very tedious and exacting work, but it's worth it, IMHO. And anyhow, now I have enough linings for a while :)

http://i913.photobucket.com/albums/ac335/jcoloccia/kerfed%20linings/DSC02051.jpg

So I learned something rather surprising about myself. I can actually get excited over kerfed linings :D

[Mike OMelia]

OK, so what about yours makes them better than "store bought"? Also, I never apply them dry. I always wet them, expecially in tight curves. Just an aside, I prefer reversed kerfed linings.

Mike

[Chris Fournier]

Why are you applying them on the wrong face John? Neither would have broken if the kerfed face was facing outward would they?

There's a fellow in the US Tom ... (California I think) that sells kerfing and the quality was very good and very reasonably priced. Kerfed, solid, mahog, basswood etc.. I'll see if I can look up his contact info and post it. I bought from Tom for a reseller that I used to work for.

I make my own kerfing for my instruments too. It's a simple tedious but rewarding job for that afternoon when you aren't that sharp (I could make a lot of kerfing given that reasoning).

I felt like I had discovered how to make gold when I ran my first batch! My wife was less impressed and truthfully our financial fortunes did reflect her opinion more than mine. Feels good to have a stock pile though!

Can you tell us more about this student teacher relationship that you have going? I bet you bring an apple evey time and leave it on his/her bench...

[John Coloccia]

Re: wrong face

I could have flipped them over and gone to a different curve. These particular ones crack at the waist everyone, doesn't matter how they're installed. Not a big deal if they do break anyway. Just using it as a comparison.

Re: is it better, why make your own, etc
I'm not really sure how to answer that. Other than hardware, electronics, truss rods (which I have made but don't anymore) and bone bridge pins, the linings were the only piece I didn't make myself. I like that I now make 100% ofthe guitar myself, other than the metal bits.

There's no real point to this thread other than share what I'm up to. I guess I prefer the boring nuts and bolts threads. :D

[Chris Fournier]

Re: wrong face

I could have flipped them over and gone to a different curve. These particular ones crack at the waist everyone, doesn't matter how they're installed. Not a big deal if they do break anyway. Just using it as a comparison.

Re: is it better, why make your own, etc
I'm not really sure how to answer that. Other than hardware, electronics, truss rods (which I have made but don't anymore) and bone bridge pins, the linings were the only piece I didn't make myself. I like that I now make 100% ofthe guitar myself, other than the metal bits.

There's no real point to this thread other than share what I'm up to. I guess I prefer the boring nuts and bolts threads. :D

While I am north of the border and therefore no expert on the condition I think that you have a serious case of "Yankee Ingenuity!"

Did you use a gang saw set up or have at it one kerf at at time?

[Mike OMelia]

Any kerfed lining is subject to breaking if the radius is tight enough or the kerf is not deep enough (I think). There might be an exception, though I have not tried it: ZipFlex folks make laser cut lining. Way more kerfs than any I have ever seen. But its too expensive for one-offs like I do. Their stuff is really aimed at mass producers where labor & waste costs are a big variables. Cool stuff though! Anyways, spritz the non-glue side with warm water, let it soak a bit, and flexibility increases, breakage decreases. Not a boring thread... some stuff to be learned, right? My favorite lining is Spanish Cedar. In fact, I use Spanish cedar anywhere I can get away with it. I love the smell... its the only reason.

I am going to offer another unsupported theory suggesting reversed kerfed lining is better than the usual stuff. If you bind your edges (most do) then the routed channel only cuts the little blocks of the lining. I guess some will say you should never touch the lining... but I do. Since the I am using reverse kerfed lining, the "backing" stays intact and adds more support to the "little blocks". Plus, IMHO, the look is cleaner.

Mike

[John Coloccia]

While I am north of the border and therefore no expert on the condition I think that you have a serious case of "Yankee Ingenuity!"

Did you use a gang saw set up or have at it one kerf at at time?

One kerf at a time, with a little pin to index the next kerf, similar to a fret slotting setup. I did a wide board, and then ripped them to size. I can't take credit for it. It was shown to me, and I also saw a YouTube video doing the same thing though I can't find it anymore. It seemed like it took forever while I was working the kinks out (it's one thing to see it done, and quite another to actually do it), but it really only took a few hours total starting from a rough plank of 5/4 cedar. That includes setting up and testing my SawStop to actually run with this blade, setting up a new zero clearance insert, test cuts, making the fence with indexing pin, figuring out how to make the miter (I ended up using my bandsaw with the "back" side of the fence to the right of the blade so gravity is helping me out), etc. The next run will be a larger batch and will take far less time.

LMII sells their Spanish Cedar linings for almost $5.50 each! I'm pretty sure I don't have $100 worth of Spanish Cedar sitting on my workbench. LOL. My second run will probably finish paying for the custom blade I ordered for this. The only question is what do I do with all of my old kerfed linings? If someone wants them, let me know and they're yours.

[Pat Barry]

I'm here to learn something new so please tell me what these dohickeys are for? What is their purpose in the world of guitar making? I don't recall ever seeing them on anything Hendrix was playing. Can you show a picture with a little more context? Thanks.

[John Coloccia]

I'm here to learn something new so please tell me what these dohickeys are for? What is their purpose in the world of guitar making? I don't recall ever seeing them on anything Hendrix was playing. Can you show a picture with a little more context? Thanks.

They go around the sides like this to give the top and back more gluing area, primarily.

http://i913.photobucket.com/albums/ac335/jcoloccia/reverse%20kerfed%20linings/DSC02031.jpg

They also add a little bit of stiffness. When you route for the binding channels, it's not uncommon to completely cut through the top/side or back/side joint, so you need them for that too. Sides and tops are very thin.

[Pat Barry]

I see - very interesting! Thanks for the picture John. I kinda thought they were for stiffening things up around the curves. Didn't realize they were used to help attach the top and bottom too.

[Mike OMelia]

Oh! I see you are using them as reversed. Good for you. But why did notch out for the vertical pieces? Are you going to overlay with lining? (thinner)

How do you plan to do the tennon or dovetail with the neck block attached? And, I think I see something in your blocks.... for sure the tail block and that is vertical grain. I realize from a "strenth" point of view that might make sense. But there are two things that you will bump into. One is the shaping or doming that you do for radiused tops and backs. End grain is very difficult to shape (ask me how I know). Second, end grain makes a poor glue joint. All of my neck and tail blocks have the grain in the same direction as the sides.

Mike

Edit: On closer inspection, I see you have indeed covered those side pieces. Me personally, I'm not that big a fan of going thru the trouble. The main reason for them is to prevent side cracks, or to prevent side cracks from spreading. Until I see eaxamples of cracks happening under the lining, I will not notch the lining.

[Cary Falk]

That's a cool way to make them. I never thought about slotting a board and ripping them to size. When I made mine I used a miter gauge on the bandsaw. I put a block behind the blade so that I could only push the strips in so far and still keep the depth of cut uniform. A pencil line on the table gave me my spacing. Mine was pretty low tech. I only made one guitar so i couldn't justify a special blade. I thought I would post to give a alternative solution for people making a guitar or two. John's solution is clearly better if you intend to make many guitars. Either way it is time consuming but rewarding when you can say I made all of the wood parts.

[John Coloccia]

Oh! I see you are using them as reversed. Good for you. But why did notch out for the vertical pieces? Are you going to overlay with lining? (thinner)

How do you plan to do the tennon or dovetail with the neck block attached? And, I think I see something in your blocks.... for sure the tail block and that is vertical grain. I realize from a "strenth" point of view that might make sense. But there are two things that you will bump into. One is the shaping or doming that you do for radiused tops and backs. End grain is very difficult to shape (ask me how I know). Second, end grain makes a poor glue joint. All of my neck and tail blocks have the grain in the same direction as the sides.

Mike

Edit: On closer inspection, I see you have indeed covered those side pieces. Me personally, I'm not that big a fan of going thru the trouble. The main reason for them is to prevent side cracks, or to prevent side cracks from spreading. Until I see eaxamples of cracks happening under the lining, I will not notch the lining.

re: notching out

Because that's how Benedetto does it, and it seemed like a nice touch. Having done it both ways, it seems like it makes the sides a little stiffer, but it's a heck of a lot of extra work coming back to cover the braces and then trim all those little liners flush with their neighbors. I have some tape George Wilson sent me that I'll try on my next build. I go back and forth, and I don't think it really matters that much other than to say George mentioned the cross grained side/brace joint possibly causing problems down the road, hence the fabric tape that George very generously gave me a bit of to try out.

re: neck mortise
I've traditionally done it by hand with a saw and chisels, but on this one I have a mortising & tenon jig that I'm going to try. On future builds, I will probably pre-slot the neck block. I will then turn my mortise jig into a end graft jig, I suppose.

re: neck block/tail block grain direction

Look closer :) They're laminated blocks. The lamination at the sides runs horizontal, and presents long grain to the sides and the top. The inner lamination is vertical, and will prevent a split should the guitar ever be dropped on it's tail pin (a common repair). I don't see many do this, even on high end offerings, but I see some people doing this and I think it's a nice touch. Honestly, I'm starting to wonder if it wouldn't just be best to use a piece of some quality plywood, like Baltic Birch. I know that's sacrilege, but the only way these things improve is by trying unconventional things.

[Mike OMelia]

Sounds like you have it covered. As for Plywood in handmade guitar? Nah. I like your idea better. I have seen folks use Baltic Birch for this purpose. This will sound silly, but I like the isnside of my guitars to look great. And smell good. So tell me more about this mortise & tennon jig. I am very interested in what you have to say here.

Mike

[george wilson]

I put in neck and tail blocks with grain horizontal to the top and back. This makes it more possible for them to shrink and swell with the sides,which also have horizontal grain,of course. Though the sides and neck/tail blocks are not of the same species most of the time,I at least want to give them a chance of keeping up with the movement of the sides.

Violins are a lot smaller,and not very deep. Plus,the tops and backs are thicker than on guitars,so do not telegraph dips or swells in their blocks like guitars can. Everyone has traditionally,including Strad,made their blocks vertical grain. To make their end grain glue better,the old trick is to impregnate the end surfaces with glue. Let it dry,then file it off some. Then,apply final glue to glue the top and back on.

I use individual blocks in my guitars. The best Spanish makers have used them for a long time under their tops. Often,they use a solid,bent strip in the backs. I just go whole hog and use individual blocks all around. At the least,since each block is glued down,separation of adjacent blocks as can happen in glued strips of kerfed lining(with solid side towards the sides) is avoided.

There is no need to clamp the individual blocks. Just setting them in place,the tack of the glue holds them in place.

[Chris Fournier]

I apply these on a case by case basis. My last acoustic used some very figured Brazialian rosewood for the sides and back. The grain in the sides was pretty crazy and the side braces kept things in check. No failure in use yet.

The guitar is so full of cross grained construction that it boggles the mind. Try to alleviate one cross grained faux pas and you're sure to introduce another or maybe two! Oddly enough, a careful build seems to allow them all to work with their own inherent deficiancies.

Amazing. I'm putting my picture of Torres back up in the shop. Guarnari needs company.

[george wilson]

Martin uses blocks with grain parallel to the sides. They are trying to avoid warranty work. Yes,the guitar is full of cross grain woods,but we can only do our best where we are able to.

In 57 years of building,believe me,I have made plenty of mistakes,and I still don't have all the answers.

[Mike OMelia]

George, you made mention of glue impregnating the end grain, then regluing. I could be wrong here, but my guess is you are referring to hide glue (not PVA, etc). That would make sense with hide glue because it will melt into the first layer... not so with PVA (Tite Bond), right?

Also, I did not understand your comment about Martin end blocks. With their orientation, does the end grain come into contact with the tops and bottoms?

Mike

[george wilson]

I was talking about hide glue as used by traditional violin makers,and myself. I use it where ever things like tops or backs might have to be taken off for repair.

On Martin guitars,the neck and tail blocks only have side grain coming in contact with the top and back. I also orient my end blocks that way,so that with changes in humidity,the end blocks have a chance of swelling or shrinking with the sides. This helps keep bumps or depressions from appearing in the top and back. Nothing is really perfect if the sides are made of different wood from the blocks,but we can only do our best.

[John Coloccia]

Maybe if I end up fooling around with laminating block some more, I will chamfer them so that they don't contact the top and back. Probably make a step so there's no danger of ever developing a buzz from where the top gets close, but not contacting, the block.

[george wilson]

But John,you might lose the strengthening that the blocks give to the top. I have seen that very thing done on some guitar. Goya???? Can't recall. If the block touches the top at all,it can still cause a swell or shrink in it.

I think that laminating the block will still cause trouble,because the sides will still grow or shrink. If the block can't ??? I really think the best compromise is to make the blocks with horizontal grain. The whole guitar is basically a compromise any way. All kinds of vastly different woods glued together.

[John Coloccia]

LOL... No No. I meant just the cross grain grain part, and leave the horizontal grain as is. I spoke with Cumpiano about this recently and he just uses a block with no lamination. His reasoning was, "If you buy fine crystal, do you construct it so it can be dropped on the floor?", and he's absolutely right. Generally, he doesn't even use side braces of any kind except the feet you see on Classical that reinforce the braces and extend a bit up the sides.

Then I think about it some more and I decide I also wouldn't let most guitarists use my crystal :) I'm learning. It will be interesting to see what I'm doing in 10 years compared to today.

[george wilson]

I'm still confused at what you mean. I'm not too sharp today,anyway.

[Mike OMelia]

Burying side braces in the lining is overkill and way too much fuss (IMHO). The point of the brace is to minimize cracks and to limit propagation. Cheap insurance. My linings are curved at their tops. I cut my braces to "wedge" in place. The look is clean. And easy to accomplish. I do not like any breaks in the reverse lining. I use a square block (thin) to set the 90 deg angle with respect to the top lining (profiling is on the backs, right?). Takes about an hour to do a harp guitar. While we are on the "burrying" of stuff, I also do not bury my top braces in the lining anymore, just the bottom. I want the top to have a nice even thickness edge all the way around. No damping of the top into the sides via the braces. There are some who purposely thin this part of the top, or cut a gouge all the way around.

Mike

[george wilson]

I do bury my top braces in the lining,and also thin out the top around the edges. The edge of the top is the hinge line that the top vibrates up and down upon. Burying the braces,while they are quite well thinned at their ends,helps them not eventually vibrate loose.

I choose a good strong fabric that does not rot for side braces. They glue much more securely,are not subject from popping loose from the sides shrinking or swelling,and stop crack propagation better than wood braces.

I also glue a little piece of fabric over the ends of braces that cannot be buried,and along the edges of bridge plates as well. They are small pieces,and serve as insurance to help prevent buzzing from loose brace ends.

Back in the 30's and 40's,Gibson seems to have not buried the top braces on their cheapest models,to save time.

What is your thought or logic in choosing to not thin the edges of your tops?

[Mike OMelia]

I do bury my top braces in the lining,and also thin out the top around the edges. The edge of the top is the hinge line that the top vibrates up and down upon. Burying the braces,while they are quite well thinned at their ends,helps them not eventually vibrate loose.


OK, I have done it that way. I have not made them long enough to have one vibrate loose... that is good advice. Since I glue my tops on last, I've always wondered how the pros locate the slots to cut. I do get what you mean by thinning them out.

THanks George.

Mike

[John Coloccia]

You're going to laugh when I tell you the "secret". Inlet both the back AND the top before you glue either of the plates. It seems so natural to inlet, then glue, that this escaped me the first time too :) It doesn't have to be perfect, either. Once you've taken out enough to let the plate drop, you can always add back some lining if you're taken away too much.

On classicals they have a little foot that they glue over the brace that serves to keep the brace from coming loose. From reading through Cumpiano's book, he does something interesting. He removes the lining entirely at that point, and then glues an additional piece of lining right on top of the brace, like a miniature foot.

[george wilson]

I just get the finished but not braced top and camp it in place oner the sides which have the liners in place,and the neck and tail blocks. Then trace the sides onto the top from the inside. This without the back on. This will show you where to terminate the braces. Then put on all the braces. put the top back in place. Mark the liners where they need to be cut away,and also draw a line on the end of each brace where it goes under the liner. Also on each liner,draw a line showing how deep the mortise needs to be,just by eye. If any brace is too tall where it meets the liner,cut it down some.. Then,it is easy to turn the sides over without the top on it. Take a long steel rule,and draw the angles that the mortises need to be cut,by connecting them with the location of their opposite numbers on the other side of the sides. Cut the edges of the mortises with a fine saw and chisel away the liners between the cuts to the depth you have drawn for each one. Then,trim down the ends of the struts as needed. The top should just fit in place. Make sure it will go down to the sides ALL the way.

After the top is finished,you can do the same procedure to the back, Make certain it is held perfectly centered before committing to mark the liners,etc.. Obviously,the sides need to be perfectly out against the form,too,or you may end up with the guitar having cockeyed waists.

I don't like the way Cumpiano proceeds. Haven't perused his book in decades,but I leave the body in the mold until the top and back are glued onto the sides. I think he doesn't,and that is asking for trouble. Maybe I'm not remembering it right. My eyes are messed up right now,and I don't feel like trying to re read his book.

[Mike OMelia]

Your right, I am laughing. It NEVER occured to me to mark off both sides. What dufus I am. In part, though, to be fair to myself, I am dealing with harp guitar bodies. These can be beasts to mark up. Part of the problem is the size of the panels that you need to do 2 part sets. Three piece sets are common to accomodate the harp arm, but I don't like going there. Two piece sets mean you have to be very careful getting the centerline correct AND aligning with the harp arm. With typical two piece sets, because of cost and availability, there typically is not a lot of room for adjustment. But it is doable. But by leaving them in the mold, I should be able to accomplish the same thing.

Thank you both.

EDIT: Still, I will keep my buried ends on the tops very thin. Feathered.