Official Luthiers Forum!

Gluing End Grain to tops or backs, anybody doing it? I know or have been taught gluing to end grain is a no no not just in instrument making but also other wood working, so I’ve never really done it. I admit I’m tempted sometimes because it seems in an area like a tail block with face grain running vertically with instruments sides running horizontally it might be a good thing and if your worried about joint strength on the end grain ends put a slice of kerfing or lining on the face grain side ends. This would slightly rob some soundboard space but overall is this crazy thinking? I know guys are doing ply tail block and spliced joints but that’s not what I’m asking about.

Interesting you should bring this up - http://www.luthiersforum.com/forum/viewtopic.php?f=10101&t=54505&hilit=+end+grain
It's worth watching the video woth the conclusions and reading the whole thread in the post.

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The name catgut is confusing. There are two explanations for the mix up.

Catgut is an abbreviation of the word cattle gut. Gut strings are made from sheep or goat intestines, in the past even from horse, mule or donkey intestines.

Otherwise it could be from the word kitgut or kitstring. Kit meant fiddle, not kitten.

Kevin Ryan's new kerfing utilizes end-grain gluing. At first I was a bit surprised but I did several tests and always get complete wood breakage. Spruce glues very well to the endgrain in the kerfing. When gluing the top and back, I apply Titebond and let it soak in a bit and then add some more. Titebond Extend is good to use in this particular case -- apparently it is better than the regular formulation anyway - so just use the extend version regardless.

Thanks Colin that’s interesting. I may break the rules and try gluing tail block end grain to tops & backs. I don’t build to sale so it’s not like I’m experimenting on paying customers. Don’t get me wrong I want my stuff to hold up but I’m curious. I do understand sometimes cracks can start at end grain and possibly split a top or something but it could also do it to the sides if the face grain is running parallel to the instrument rim grain and I believe this is how Martin & Gibson do it.

Maybe it’s turned into a tradition thing in regards to tail block and head block methods. End grain gluing might not be the strongest but does it supply adequate strength in certain situations like those mentioned above, I guess it might particularly if steps are taken to keep the end grain from glue starvation. I guess we shall see.

My question is why do it?
FYI, Prewar Guitars uses vertical grain orientation on their neck and tail blocks. For someone marketing guitars as replicas of 1930's models, the decision seems a bit curious, to say the least.
Wood shrinks over time, but there is virtually no shrinkage along the grain. This means as the sides get narrower, the vertically oriented blocks don't get shorter, producing a hump on the top and back.

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John

Well I can’t say I disagree just didn’t think about it. I guess I just see a perfectly good scraps of cutt off neck blanks and stuff and just think boy that would make a nice tail block if wasn’t for that end grain orientation issue .

You could always edge glue a couple of pieces together to make the block tall enough. I have made tail blocks from many different medium density hardwoods, including cherry, walnut, sassafras, and sycamore.

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John

Thanks John! Yeah it’s funny you mention that I just did that last night before bed. I glued 2 pieces of cherry side grain to side grain after cutting them down form 3” wide to 2 3/8” to get my 4 3/4” height. Easy enough and makes feel better about being scrap efficient & thrifty.