Second Spotted Gum bow

[AngusB]

Hi all,

I've had another go at a spotted gum bow since the last one worked. I haven't fixed it up yet. I wanted to leave one working bow as at least a partial success.

This one is a little shorter at 63" nock to nock. I extended it slightly with blackwood tips to fit a string I had and used a blackwood handle. I do like blackwood. When strung it has a 5 3/4" inch brace. It's currently 40# at 24" and as I would like it slightly lighter I have room to move.

The second photo below shows the bow. The first photo shows the bow lying flat on a table. I has developed a significant permanent bend (?set) after tillering so far and firing a few arrows to test. It's about an inch at each nock. Is this an acceptable or normal amount or do I have a problem? What can one do to minimise this developing?

I balanced it on the bird for good lighting.....

[AngusB]

Reading more about this I find that this question has of course been asked a thousand times on various forums.

Stress on the wood, stress close to the handle, moisture content, width vs thickness ratio etc.....

I thought I was well behaved on the first, perhaps the wood is too thick near the handle and perhaps the handle is too wide, moisture ratio should be fine as it's a board and sat in my garage for over a month in summer.....

I gather that some woods just are more inclined to take set. The question really probably is whether Spotted Gum is in that camp. The newer bow has already taken more set with one limb being close to two inches.

If I lower the poundage by either scraping more from the belly or narrow the width will I decrease the tendency to set?

[greybeard]

Hi Angus,

String follow / set is inevitable with selfbows. Steps such as pulling the limbs into reflex using heat can help minimise the amount of set. I prefer to use wet heat [steam] rather than a heat gun.

http://www.primitivearcher.com/smf/inde ... ic=33079.0

https://www.tradgang.com/tgsmf/index.php?topic=170954.0

Alternatively backing the stave with pole bamboo and gluing in reflex is probably a better long term solution.

The image below is my moveable form the posts being set for a deflex / reflex bamboo backed bow. Simply re arrange the posts to create different limb profiles.
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Moveable Form.jpg (24.01 KiB) Viewed 5219 times

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The link below is basically a bend through the grip bamboo backed Brigalow bow.

http://www.ozbow.net/phpBB3/viewtopic.php?f=34&t=13037

Daryl.

[AngusB]

Clever gadget. Where do you find pole bamboo of reasonable sizes. I bought the biggest pole I could find in Bunnings a couple of months ago but it wasn't big enough.

[AngusB]

and that Brigalow bow is a pretty one. I thought at first that there were three layers but it's just shadow is one of the side on photos.

[greybeard]

Angus,

I was fortunate to get a good pole from my local Bunning’s store. I was told the stores have a certain amount of autonomy as to the depth of products they stock.

I was able to get six strips out of this 10 cm pole using my cordless circular saw.

Daryl.
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Bamboo.jpg (83.97 KiB) Viewed 5188 times

[AngusB]

Currently Bunnings appears to only have

https://www.bunnings.com.au/lattice-mak ... e_p3041186

which is black and narrower meaning harder to get flat strips of sufficient width.

I think I got a 60mm one last time which I split into 4. Each piece made quite a narrow strip when I trimmed it flat.

[DankyKay]

Nice looking bow Angus, I purchased a spotted gum shovel handle from bunnings but am having trouble chasing a growth ring due the the small radius of the timber. Where did you source your timber from?
Cheers, Dan.