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Ducksoup
02-11-2018, 04:54 AM
I'll be making some ukuleles for my grandkids and the backs and tops will be book matched walnut and redwood. Should i join those book matched pieces together before or after I plane to my final thickness? I was figuring a final thickness of approximately 2.5mm, is that to thick?
Thanks for suggestions.
Tom

Kevs-the-name
02-11-2018, 05:12 AM
Personally, I thickness my backs to 1.9 to 2.2mm depending on the wood and ukulele size.

I tend to get them to about 3-3.5 for joining before I get them to final thickness.
Im not stating this is the only way but I find it easier to get a clean and consistent join.

Dusepo
02-11-2018, 08:52 AM
About 2mm is what I use.

Allen
02-11-2018, 09:37 AM
There are two types of backs. Active or reflective. You need to decide what you are wanting to use.

Active backs will be thin and braced lightly. They will work well if the instruments isn't held against the body and dampen the sound being produced from it. No advantage at all if the playing style doenst allow that. In fact could be detrimental.

Refelctive with be thicker and braced a little more. They work well when the back is held against against the body. As they aren't desinged to produce sound, any dampening that may happen isn't a concern. In fact they work much better as the sound created inside the body is reinforced by reflecting back to the soundboard and helping drive it more.

I make all my backs reflective after noticing this effect by listening to my ukes played by different artists over several years while refining my design.

Do your bookmatching first, then final thickness afterwards.

sequoia
02-12-2018, 05:59 PM
I'll be making some ukuleles for my grandkids and the backs and tops will be book matched walnut and redwood. Should i join those book matched pieces together before or after I plane to my final thickness? I was figuring a final thickness of approximately 2.5mm, is that to thick?
Thanks for suggestions.
Tom

You don't really specify if your thickness of 2.5mm is for the backs or for the top. Seems a bit thick for a top... will be too thick if you are bending sides. And yes, join the plates before planing to thickness not after.

As for Allen's comments on reflective or active backs: In my admitted limited experience, I've noticed that a robust, hard, relatively thick back seems to give the best sound, so I go for "reflective". The thin "active" lightly braced back seems to come out a bit... thinner sounding maybe? Nice fingerpickers, but can't stand up to hard strumming. This is still an area where I scratch my head. So many variables, so little time.

ksquine
02-13-2018, 07:59 AM
I join my plates thick...3-4mm. It's easier for me to work with thicker plates when gluing and clamping together. I also usually get a slight mismatch somewhere along the joint where one side is higher than the other. The glue squeeze-out and mismatch get planed away after.

Wildestcat
02-13-2018, 08:04 AM
I join my plates thick...3-4mm. It's easier for me to work with thicker plates when gluing and clamping together.

I do the same. Much easier to work with the thicker plates.

Graham Greenbag
02-14-2018, 10:48 PM
Allen and Sequoia make what I find to be a very interesting point about the build of backs which I was totally unaware of. Gents, please will you expand on that for me?

I also now wonder whether arched backs have merit due to the stiffness created by the arch, the focusing of sound or what?

I normally use a strap so aren’t too concerned about Uke weight, if a stiffer (so more reflective) back needs thicker material then the small associated extra weight wouldn’t be an issue to me.

Apologies if I divert the thread, but it’s also an interesting input on how much planning is actually required. Easier to leave the wood thicker and then somehow get advantage from that?

Kevs-the-name
02-15-2018, 09:42 AM
I join my plates thick...3-4mm. It's easier for me to work with thicker plates when gluing and clamping together. I also usually get a slight mismatch somewhere along the joint where one side is higher than the other. The glue squeeze-out and mismatch get planed away after.

Exactly the same for me too!

sequoia
02-15-2018, 08:20 PM
Allen and Sequoia make what I find to be a very interesting point about the build of backs which I was totally unaware of. Gents, please will you expand on that for me?

I also now wonder whether arched backs have merit due to the stiffness created by the arch, the focusing of sound or what?

I normally use a strap so aren’t too concerned about Uke weight, if a stiffer (so more reflective) back needs thicker material then the small associated extra weight wouldn’t be an issue to me.

Apologies if I divert the thread, but it’s also an interesting input on how much planning is actually required. Easier to leave the wood thicker and then somehow get advantage from that?

Sides and backs still baffle me. The one thing I do know is that the sides need to be tapered and the back rdioused. Neither of these two things are that difficult to do and it makes a big difference. Gotta do that. As to bracing, type of wood,, thickness, etc. I'm baffled. Currently I'm a big thick back and sides guy out of dense hard wood. But who knows. Not me. I think the back and side construction is still a big black box when it come to lutherie. Torres said it didn't count for s- - - t and he made some of the best instruments ever made. Go figure.