Had a little play with Maple, ended up with a ripper

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yeoman
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Had a little play with Maple, ended up with a ripper

#1 Post by yeoman » Tue Sep 10, 2019 8:39 am

Aloha,

It's been quite a while since I posted anything I've made. Truth is I haven't made many bows over the last few years. One or two here and there. Mostly I've been teaching bowmaking which has been every bit, if not more fulfilling, than making my own. Especialy two young bowmakers in particular, but that's for another post.

A few months ago I was in the local fancy timber place and happened across a 50 x 150 mm board of Hard Maple, about 2500 mm long. The grain, visible only through the rough-sawn surface, looked reasonable so I grabbed it.

A couple of weeks ago I sawed a stave off it and sanded two sides clean. My heart dropped to start with, as it seemed the grain was too violated to be a viable bow's back.
ring lines highlighted.jpg
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In reality it turned out to be fine. But to be on the safe side I skewed the centre line of the bow to be slightly diagonal on the board.

I took some bend test data and calculated the dimensions for a 64" longbow pulling 60 lb @ 28". I draw 26, but I have my program calculate everything to 28, except for the warbows which are designed to draw to 30 or 32.

Anyhoo. Out were spat the dimensions. I was a little skeptical actually. The program said it only needed to be 32 mm wide. I was unsure this would be sufficient, and I had used average figures from a range of previous bend tests of other samples. Regardless, I marked and cut out to the dimensions thinking I would be happy with whatever draw weight I could get as long as the tiller shape was good. Here are the dimensions:
Maple longbow dimensions.JPG
Maple longbow dimensions.JPG (39.48 KiB) Viewed 194 times
When I cut it out I put a short string straight on it, as I was sufficiently confident in my cutting. I didn't take a picture but one limb was a touch stiffer than the other. I didn't do any weight reduction tillering - only tillering to correct the shape of the bending limbs. I didn't take any pictures of the tillering until just over half way through, which we see here:
part tillered.jpg
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The tips were still a touch stiff at this point but I knew they'd come around as the draw progressed, and they only needed a tiny whisp taken off at the grinder.

Not long after this I got to my full draw of 26", where it pulled 53#.
full draw rotated.jpg
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I only thought of this just now, but here it is with an overlay of the intended draw shape (which is drawn to 28"):
maple longbow superimposition.JPG
maple longbow superimposition.JPG (74.07 KiB) Viewed 194 times
As it turns out the bow is a touch short at one end, but otherwise the shape is pretty close to the design.

I was quite surprised how close to the calculated draw weight the bow ended up. Below, I've plotted a gross generalisation of a force-draw curve (I know they're not straight lines, thanks) and plotted where this bow sits. It wouldn't quite reach 60 lb at 28", but it's pretty close.
maple longbow projection.JPG
maple longbow projection.JPG (38.67 KiB) Viewed 194 times
I've never worked Maple before. It was a joy to work with. it grinds much the same as Ironbark or Spotted Gum (on my grinder anyway), and sands easily. It was a funny mind-trick. Historically in my workshop, light-coloured woods are light mass (radiata pine, white cypress, celery-top) and dark woods are heavy (Spotted Gum, Ironbark, Massarabundah). This wood is light coloured and also reasonably dense (haven't calculated it but is probably in the realm of 800 kg/m^3).

When I sanded and waxed it I found this amazing orange horizontal fleck across just one of the limbs. I've no idea what that's about but it looks cool. I don't know if you'll be able to make it out in this picture:
cool grain.jpg
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Because it's designed to work, and experience an even stress all along its length, it has absolutely no discernible handle section. I filed in a tiny groove to mark the arrow pass.
braced on table.jpg
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braced handheld.jpg
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Still to do is make the tips outside the nocks look purdy, and make a string to test how well it shoots. I did fling some arrows, but I used the heavy tillering string which still had the vinyl tube I installed to protect it from wear on the tiller stick.

Once unstrung the tips had 1 5/8" and 1 3/8" set, which I think is reasonable and is what I had anticipated from the original calculations. It weighs just a hair under 14 oz. It took me perhaps 3 1/2 hours from faffing about with the initial layout to shooting it.

That's all, folks.
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Outbackdad
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Re: Had a little play with Maple, ended up with a ripper

#2 Post by Outbackdad » Tue Sep 10, 2019 8:59 am

Looks great, be good to see it all finish.

Eddie

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Re: Had a little play with Maple, ended up with a ripper

#3 Post by Stickbow Hunter » Tue Sep 10, 2019 10:49 am

Things have been pretty quiet on here of late Dave so it is good to see you post this up. The limbs have a nice bend to them. I too look forward to seeing the bow finished.

Jeff

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yeoman
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Re: Had a little play with Maple, ended up with a ripper

#4 Post by yeoman » Wed Sep 11, 2019 12:09 pm

Thanks gents.

I've finished it up good & proper now.

I've shot a couple dozen more arrows through it, and it's lost a pound, so now it's 52# at 26". Fortuitously, the arrows I had to test it are around 520 gr, a convenient 10 grains per pound.

I set up the chronograph and let fly. The lowest was 144 fps, but I also got 159 (!). More commonly was 148-153 fps. Not bad for a simply-tapered bit of timber.
Chrony results.jpg
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I finished up the tips and made a dacron string. Nothing special in either case, but simple enough for the amount of effort that went into making it.

nock 3.jpg
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nock 2.jpg
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nock 1.jpg
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The set has increased a little.

set.jpg
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But all in all I'm very happy with it. Will definitely keep my eye out for more Maple in the future, and looking forward to what else I can get from the rest of the current board.

standing proud.jpg
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greybeard
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Re: Had a little play with Maple, ended up with a ripper

#5 Post by greybeard » Fri Sep 13, 2019 4:30 pm

Dave,

For a quick foray into the plank of maple the bow turned out well and the chrony numbers are acceptable.

Hard rock maple was my favoured timber for flat bows. In the early days I used to back the bows with jockey silk to help stop fibres lifting on the back of the bow.

Now days I back the maple in reflex with pole bamboo to virtually eliminate string follow or giving integrity to recurved tips. The bamboo backing also helps to negate the effects of awkward grain.

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!....

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yeoman
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Re: Had a little play with Maple, ended up with a ripper

#6 Post by yeoman » Fri Sep 13, 2019 7:38 pm

Thanks Daryl. If I'd spent a bit more time caring for the design and the tiller process, I might've been able to squeeze another few FPS out of this one.

I've made perhaps 100+ bamboo backed bows, and almost all my students for the past eight years have also made bamboo backed bows (another 100+). I can certainly attest to the durability and reliability of backing with bamboo.

But selfbows are my first love and any chance I get to pick just the right board, I find it hard to beat the simplicity of a selfbow. I can live with a bit of string follow as a trade off for ease of manufacture.

I figured that in the US Maple is used as a backing timber, so with the right board it should be more than adequate as a self-backed bow. But now I have a dilemma - the rest of this board - will make a few bows or a lot of backings. I think, on balance, I will go 1:1 staves and backings.

I'll also head back to the timber yard to see if there's any more suitable Maple. Or Hickory.
https://www.instagram.com/armworks_australia/

Bow making courses, knife making courses, armour making courses and more:
http://www.tharwavalleyforge.com/

Articles to start making bows:
http://www.tharwavalleyforge.com/index. ... /tutorials

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