Official Luthiers Forum!

Hi, I am building a uke, a practice one before I start on good wood.  I've used poplar for the tone bars and braces.  The wood is much denser than the spruce I will be using on future ukes.  My question is: can I make these pieces a lot thinner than the specs (for spruce) call for because of its density?

_________________
A higher purpose for wood.
Rich Smith
Issaquah, WA

Poplar is not a good choice. Density is not a sign of strength. Strength has to do with the ability to take stress Spruce has a higher strength to weight ratio and that is why spruce is the choice wood. To get the same strength from poplar you need more weight and thus you will add more mass .
   Density has to do with weight and hardness , 2 totally different properties.
john hall
blues creek guitars

If by "thinner" you mean that you want to change the width (the section [dimension] that will be in contact [receive glue] with the top or back), then Yes it is possible to use poplar, Shape it like an "I" beam. This will give you about the same moment of inertia and a spruce bar. The material in the center really adds very little to the over-all strength.   

But remember that wood is very susceptible to shear...

I have never been impressed with the strength of poplar compared to spruce. I would not make the braces smaller. In fact, why not do a kind of deflection test with both kinds of wood to get a feeling for how much load each can take. You might try that test long term, at least several days to see what kind of creep properties each wood may have over the long term.   I know several days will not be a certain answer to that question, but it may give some hints.

One thing poplar does seem to have is a low internal resistance to sound travel. Every log I ever dropped sounded musical.

Just realized you may be talking about true poplar rather than tulip poplar. If you are talking about true poplar, then I recommend forgetting the entire enterprise.
John

[Quote=John K]One thing poplar does seem to have is a low internal resistance to sound travel. Every log I ever dropped sounded musical.[/Quote]

That's why I use poplar for solid linings. It's easy to bend, too.

_________________
Ken Franklin
clumsy yet persistent
https://www.kenfranklinukulele.com

[QUOTE=Ken Franklin] [Quote=John K]One thing poplar does seem to have is a low internal resistance to sound travel. Every log I ever dropped sounded musical.[/Quote]

That's why I use poplar for solid linings. It's easy to bend, too.[/QUOTE]

Learn sompin' new every day.   

_________________
http://www.dickeyguitars.com

Poplar is a good tone wood but I would not use it for braces and tonebars. For linings it is very good and I have used it for one classical for a solid lining instead of basswood because it bends as easy as basswood. I no longer use solid linings for backs but I have seen historic instruments in which the linings were poplar.

Its traditional use has been for blocks in Violin family instruments. It is also found as sides and backs of violin family instruments. I built one cello from a curly set of poplar years ago that came out good. It was Italian poplar. I dont know if it is the same family as the Poplars we have in the United States.

For bracing you want light and strong and that is why spruce is used.

[QUOTE=John K] Just realized you may be talking about true poplar rather than tulip poplar. If you are talking about true poplar, then I recommend forgetting the entire enterprise.
John[/QUOTE]
So, which one is stocked at the local Home Depot? It's the stuff that seemingly can be any color at any time. Green is common, but I saw a board recently that had swirls of purple, green and brown. Another 8" X 12' board had curly figure on about a third of it, and one next to it had birdseye! Poplar would be cool for some general woodworking projects, but you just can't find two boards that are the same color or figure, so you have to paint.

Home depot is Tulip Poplar . john hall

Thank you John!