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Starting out.

Posted: Tue Mar 21, 2023 6:12 pm
by Teraniabow
Iv decided to start my first bow using spotted gum. It seams Luke a good choice for a beginner. Someone mentioned ruining their bow by chasing performance and incorrect stringing. Can someone tell me what this means.
Cheers.

Re: Starting out.

Posted: Tue Sep 19, 2023 11:34 am
by Feral
performance would be squeezing as much out of it as you can. The unbacked spotted gum bows I've made maxxed out at about 20 pounds. This was about 1800 long and a basic pyramid shape from about 50mm at the fades and 20mm at the nock. Incorrect stringing could misaligning the nocks, or using the wrong string type maybe.
Some people say to try the Holemguard design for Australian bows. I've never tried it.
You could try backing it with bamboo. Bunnings sell long wide pieces which I used with minor success to start with.

Re: Starting out.

Posted: Thu Sep 21, 2023 2:53 pm
by greybeard
Common Name(s): Spotted Gum
Scientific Name: Corymbia maculata (syn. Eucalyptus maculata)
Distribution: Australia (coastal regions of New South Wales)
Tree Size: 100-165 ft (30-50 m) tall, 3-5 ft (1-1.5 m) trunk diameter
Average Dried Weight: 59 lbs/ft3 (940 kg/m3)
Specific Gravity (Basic, 12% MC): .71, .94
Janka Hardness: 2,330 lbf (10,360 N)
Modulus of Rupture: 20,550 lbf/in2 (141.8 MPa)
Elastic Modulus: 2,867,000 lbf/in2 (19.77 GPa)
Crushing Strength: 10,410 lbf/in2 (71.8 MPa)
Shrinkage: Radial: 6.3%, Tangential: 9.9%, Volumetric: 16.3%, T/R Ratio: 1.6


Firstly, are you going to use a milled board or a split bush billet?
When using a bush billet I carefully remove the bark and clean up with a wire brush as I don’t want to violate the fibers on what will be the back of the bow.

viewtopic.php?f=34&t=17237

If using a milled board you could try backing it with dry wall tape.
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Jointing Tape.jpg
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https://www.youtube.com/watch?v=iVCMsbF_OD0 Kramer Ammons Dry Wall Tape Backing

[I don’t like the way the handle and abrupt fadeouts are done.]

Below is a basic plan I used when making hard rock maple flat bows backed with jockey silk.
I believe wider and thinner limbs would be better than narrower and thicker limbs.
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Flatbow Plan.jpg
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The plan is only a suggestion which you can modify where needed.

Daryl.