Excited about Kerfed Linings!

[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.