First Bow: Spotted Gum

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Dervish
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First Bow: Spotted Gum

#1 Post by Dervish » Mon Mar 12, 2018 11:44 am

Hello From the South Coast,


My son's turning six and I am attempting to make him his first bow. I am not a complete novice—as a child I made bows with my granddad back in Germany, mostly from hazel saplings—but given the professionalism that most people on this site exhibit, I am as good as new to bowyery. I am following steps in The Traditional Bowyer's Bible. Have cut down a fairly straight spotted gum, sealed it with fire, dried it and split it. Two questions for now:

I.) In spotted gum is the sapwood or heartwood the preferred bow-making material?

II.) What kind of bow designs lend themselves to spotted gum as well as to a six-year-old's strength?

Any other feedback about making bows from spotted gum are welcome. Thank you for your help.

Best regards,

D.

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greybeard
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Re: First Bow: Spotted Gum

#2 Post by greybeard » Fri Mar 16, 2018 12:49 pm

Hi Dervish,

If your spotted gum billet is from a small diameter tree a higher than desirable crown may cause issues with limb thickness.

If so you may have to de-crown the stave to make it suitable for a shorter light draw weight bow.

Australian hardwoods are vastly different in mechanical properties to many of the northern hemisphere timbers.

The sapwood should be suitable if it is not damaged. If it is blemished sand/scrape the length of the stave to get a clean back.

The basic flatbow plan shown below is for a 68” n to n bow. The dimensions can be modified for a shorter n to n length.

Wider thinner limbs are probably more suitable than narrower thicker limbs for such a light draw weight bow.

In a child's bow the limb width may come down to around the one inch mark.
Basic Flatbow Plan.jpg
Basic Flatbow Plan.jpg (29.09 KiB) Viewed 3548 times
I am not a fan of spotted gum but successful bows have been made from it.

Daryl.
"And you must not stick for a groat or twelvepence more than another man would give, if it be a good bow.
For a good bow twice paid for, is better than an ill bow once broken.
[Ascham]

“If a cluttered desk is a sign of a cluttered mind, of what, then, is an empty desk a sign?” [Einstein]

I am old enough to make my own decisions....Just not young enough to remember what I decided!....

Dervish
Posts: 5
Joined: Mon Mar 12, 2018 11:02 am

Re: First Bow: Spotted Gum

#3 Post by Dervish » Mon Mar 19, 2018 2:04 pm

greybeard wrote:Hi Dervish,

If your spotted gum billet is from a small diameter tree a higher than desirable crown may cause issues with limb thickness.

If so you may have to de-crown the stave to make it suitable for a shorter light draw weight bow.

Australian hardwoods are vastly different in mechanical properties to many of the northern hemisphere timbers.

The sapwood should be suitable if it is not damaged. If it is blemished sand/scrape the length of the stave to get a clean back.

The basic flatbow plan shown below is for a 68” n to n bow. The dimensions can be modified for a shorter n to n length.

Wider thinner limbs are probably more suitable than narrower thicker limbs for such a light draw weight bow.

In a child's bow the limb width may come down to around the one inch mark.
Basic Flatbow Plan.jpg
I am not a fan of spotted gum but successful bows have been made from it.

Daryl.
Dear Greybeard,

Thank you for your insighful reply. I've been working on the bow and will post you a picture once it is done.

Thank you again.

Best,

D.

Dervish
Posts: 5
Joined: Mon Mar 12, 2018 11:02 am

Re: First Bow: Spotted Gum

#4 Post by Dervish » Thu Mar 22, 2018 7:35 pm

Hello Again Greybeard,

So you’re we’re peobably right with not being a great fan of spotted gum. The bow snapped when I tried to string it. Which might of course have a lot to do with my lack of experience. Alas, I enjoyed the process. What timber would you recommend instead? There doesn’t seem to be much agreement across the web on Aussie timbers for bow-making.

RobHunter
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Location: Cranbourne Victoria

Re: First Bow: Spotted Gum

#5 Post by RobHunter » Thu Mar 22, 2018 11:01 pm

Hi Dervish

If you search "Aussie woods for bows' there are a lot of posts regarding timbers.

AS a rookie I have had a few successes and more failures. Its just the way it is.

Understand why a bow fails is pretty important. I often posted a decent photo of my bows for comment by the
kind people here.

I also learnt early on not to bend the bow too much early in the tillering process. A long string is
a must. I cracked a couple due to impatience in getting a "proper String" on it.

I don't have the equipment for harvesting timber myself - but boards are OK to use. I had a selfbow made from spotted gum last
approx 1000 shots before it failed. It developed stress fractures, which I believe is common in spotted gum bows.

Hope this helps a bit

rgds

Rob

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Re: First Bow: Spotted Gum

#6 Post by greybeard » Fri Mar 23, 2018 5:10 pm

Dervish,
Dervish wrote:..........The bow snapped when I tried to string it...........
Did you use a suitable [double pocket bow stringer] to ensure that the limbs were evenly stressed during the stringing process?

Can you post some photos of the break?

Possible causes as to why the bow broke;

Timber selection:

Bow design unsuitable for the timber species:

Poor quality timber i.e. grain runoff, drying cracks:

Not following a regimented tillering process:

The correct tillering process may seem to be tedious but you have a much better chance of success if you follow the rules.

I made two bows [one backed with pole bamboo] from a milled board of Brigalow, origin unknown. The board had a propeller twist so I had to re-mill the board until it was true. Grain runoff was quite severe which is evident in the following photograph.
3 Brigalow Grain Run-off.jpg
3 Brigalow Grain Run-off.jpg (47.38 KiB) Viewed 3463 times
Needless to say that the bamboo backed bow survived whereas the unbacked stave failed during the tillering process.

The following post shows the bamboo backed Brigalow bow.

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

My preferred local timber is [Alphitonia excelsa (Rhamnaceae) Red Ash, Soap Tree] but unfortunately I don’t have access to it any more so utilising pole bamboo as a backing material allows me use some timbers that are not suitable for selfbows.

Daryl.
"And you must not stick for a groat or twelvepence more than another man would give, if it be a good bow.
For a good bow twice paid for, is better than an ill bow once broken.
[Ascham]

“If a cluttered desk is a sign of a cluttered mind, of what, then, is an empty desk a sign?” [Einstein]

I am old enough to make my own decisions....Just not young enough to remember what I decided!....

Dervish
Posts: 5
Joined: Mon Mar 12, 2018 11:02 am

Re: First Bow: Spotted Gum

#7 Post by Dervish » Thu Mar 29, 2018 3:00 pm

Hello Rob,

Thank you for the insight and positive words. As a rookie, I certainly didn't pay enough attention to grain runoff. So that's where I am at the moment, looking for a better selected piece of wood. I'll keep you posted about my progress.

Best,

Siad

Dervish
Posts: 5
Joined: Mon Mar 12, 2018 11:02 am

Re: First Bow: Spotted Gum

#8 Post by Dervish » Thu Mar 29, 2018 3:13 pm

greybeard wrote:Dervish,
Dervish wrote:..........The bow snapped when I tried to string it...........
Did you use a suitable [double pocket bow stringer] to ensure that the limbs were evenly stressed during the stringing process?

Can you post some photos of the break?

Possible causes as to why the bow broke;

Timber selection:

Bow design unsuitable for the timber species:

Poor quality timber i.e. grain runoff, drying cracks:

Not following a regimented tillering process:

The correct tillering process may seem to be tedious but you have a much better chance of success if you follow the rules.

I made two bows [one backed with pole bamboo] from a milled board of Brigalow, origin unknown. The board had a propeller twist so I had to re-mill the board until it was true. Grain runoff was quite severe which is evident in the following photograph.
3 Brigalow Grain Run-off.jpg
Needless to say that the bamboo backed bow survived whereas the unbacked stave failed during the tillering process.

The following post shows the bamboo backed Brigalow bow.

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

My preferred local timber is [Alphitonia excelsa (Rhamnaceae) Red Ash, Soap Tree] but unfortunately I don’t have access to it any more so utilising pole bamboo as a backing material allows me use some timbers that are not suitable for selfbows.

Daryl.
Hello Daryl,

Thank you for your insight. From what I gather the problem was unsuitable wood in the first place. There was some grain runoff and while spotted gum has a tendency to have a curvy wood fibre, in the piece I used the fibre was perfectly straight. I'll give it another shot and select the wood more carefully. If that doesn't work, I will try backing it.

Thank you again for your help and guidance.

Best,

Siad

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Re: First Bow: Spotted Gum

#9 Post by greybeard » Sun Apr 01, 2018 4:53 pm

Hi Siad,

As I do not know what procedure you use when tillering selfbows I have attached a document outlining a process that works for me.

Daryl.
Tillering.doc
(128 KiB) Downloaded 233 times
"And you must not stick for a groat or twelvepence more than another man would give, if it be a good bow.
For a good bow twice paid for, is better than an ill bow once broken.
[Ascham]

“If a cluttered desk is a sign of a cluttered mind, of what, then, is an empty desk a sign?” [Einstein]

I am old enough to make my own decisions....Just not young enough to remember what I decided!....

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