Red Cedar for Falcate Bracing?

[twopotscreamer]

Trevor, what are your thoughts on Red Cedar (Toona ciliata) for Falcate bracing? I've used some for linings and it bends easily; very light, too. Though it's not quite as stiff as spruce I reckon the epoxy lamination makes up for this. Any suggestions?

[Trevor Gore]

Never used it, but Bootle gives it a reasonable rating. Depends very much on the piece in your hands. If red cedar gets stiffer with laminating, so does spruce!

[woodrat]

Hi Twopotscreamer, welcome to the forum....I too have mused (to myself) about Red Cedar for falcates. I think that it would be good....I would like to see how it goes as I have some nice straight grained stuff.

Hi Trevor, its good to see more people are thinking about falcates and making them....

Cheers

John

[woodrat]

Hi Twopot, I did some numbers on the red cedar that I had. I cut a nice straight grained bit and tap tested it.

I did the tap test 3 times and it came out at 874, 874 and 872 Hz so I thought that was consistent enough to take as a reading. The dimensions were 0.35m x 0.025m x 0.030m and the weight was 122g giving a density of 465 kg per meter cubed and a stiffness of 5.60GPa so for the cedar I have I think it is non starter for falcate bracing.....as Trevor said in the intro to his book...at some point you have to face the facts... because the facts dont go away ....in this case anyway because I was hoping that it would be a good timber to use...

....John

[woodrat]

...as an aside, I just had a go at bending it into the secondary falcate shape and it bends so easily it is a shame it is not stiffer......It still might have merit for the secondaries though...they are the ones that are tough to bend. I just cold molded some red spruce into the Primaries with no problems and virtually no springback using Techniglue...so I will continue using that for the primaries but the Red Cedar could be employed as secondaries....
.....Trevor....any thoughts on the numbers....

John

[Trevor Gore]

Bootle has red cedar ranging between 7.9GPa and 9.4GPa for Young's modulus. John has measured 5.6GPa. So, much as I said, it depends on the wood in your hands. I've used King Billy with a YM of ~6.0GPa and at 7mm high falcates it works fine for me for 170Hz guitars. If I use spruce of ~10GPa I find that works fine for 180Hz guitars, also at 7mm high. So you can make the trade-offs between the wood species, the brace heights and how much CF you use. I don't think there are any "magic" combinations of materials and dimensions. I think it's more a case of getting your process down so that you know that you can consistently land on the frequencies you want using the materials you have.

[woodrat]

Trevor, Thats interesting. So I will not discount it as a wood for falcate bracing although I think that I will only use it for secondaries. The wood bends so easily its amazing. I am comparing that to very old brittle douglas fir that I have though that does not like to be contorted into the secondary shape although it is easier if I use 4 1.25 laminates instead of three thicker ones. I have found that the primaries need no heat bending even in spruce and the jig I built is great for that.
I have not tried 7mm high bracing yet. All mine have been 9mm high and they have been targeted at 180hz although one ended up too stiff and I needed 300g of side mass to bring it down...what I am saying is I need more practice to get the variables under control. The latest falcate laminates have all been planed to thickness instead of sanded so I hope that I have taken that out of the equation too. Also I need to be very accurate with my top dimension as 0.1mm there is important.

All in all I am having fun with this bracing and making the best guitars I have ever made.....I am happy with that!

John

BTW...my red cedar that I measured at 5.6GPa was from a fairly young tree. I got it strait off the saw at a millers nearby. It was about 750mm through so it was really only adolescent wood:) Old growth mature wood may be a lot stiffer:)

[twopotscreamer]

Thanks, Trevor and John! I think I will give it a go. I have a lot lying around from other projects and the sizes are suitable for making braces and not much else. As this will be my first falcate build I think I will build a bit oversized to play it safe.

Thanks for the awesome book!

[woodrat]

Hi Twopot, Thats great!... Do you have visual analyzer to do the tap test to find out the GPa of the cedar you have? You may have 9.something GPa cedar and that would mean that you would not have to make the braces higher at all. That is the whole thrust of the book to be able to KNOW what you have to build with instead of wishful thinking which is where I was pre the book.

BTW write your first name at the end of your posts...its a bit friendlier:)

Go for it...

John

[woodrat]

I have just found another piece of straight grained cedar in my stash and I thought that I would test it....its numbers were

0.357m x 0.052m x 0.025m
186grams
400kg/m2
tapped frequency 184Hz
Youngs Mod 7.54GPa

So you can see I have a stiffer, less dense piece than the last piece that I tested....I will use this for the secondaries:)

Cheers

John

BTW that seems like a weird coincidence that both pieces tapped out at the same frequency. I did both pieces multiple times and the peak was distinct and also registered on the the freq meter so it is just a coincidence....