Takedown Project Part II

[looseplucker]

Hello

Since I last posted the bamboo backing lams have gone on the limbs - am not entirely happy with it as I made an error an glued a lam on that was not finished in terms of thicknessing - way too thick at the inner limb. Premature Senior Moment.

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Hopefully I can get it down a little thinner so the bow is not overbuilt and goes snap.

I got a hold of some brass tubing from a dealer and made the inner sleeve to fit.

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Last night I fitted the outer sleeve

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. I placed position markers in the centre which is a help while fitting the sleeve to the tenon.

There is a sleeve seat all the way around which does recess into the bamboo backing over the riser. There the boo is about 6mm thick, so cutting a mm or so was not an issue.

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The other pics show the respective limbs in various stages - and the tip overlays, which I put on before the bamboo backing and which has a nice effect.

[longbow steve]

Starting to take shape LP, I think the bamboo reduction will be safe considering it is not in the working section of the limb.
You should be able to tiller the belly for the senior issue.
What was the belly timber again?
Looking great. Steve

[looseplucker]

thanks Steve - I did PM you with some stuff

Some may have to come out of the working section - but not overly much.

The belly at the moment is an outside lam of the core of spotted gum. There is still a belly of bamboo to go on - going for the interlocking nodes idea on the shortlongbows that Greybeard makes so expertly and that I am trying to get to work

[jape]

Very impressive, looking better all the time. What working weight were you going for? Looks like quite a heavy shooting bow with opposing lams of bamboo if I understood it right.

How will you lock it together, stop it coming apart - just tight fit or will you have a catch of some sort like a sprung button?

[looseplucker]

Thanks Jape

I am going for 45-50# @ 26.5" (which is my draw length). There is scope for tillering of the belly with boo there.

The bracing of the bow will keep it together. I fitted the brass ferrule last night

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and because it was not form fit when a tube with the outer sleeve

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I will need to shim it - thin leather or rawhide soaked in supaglue will do the trick - and then sand to fit. So a combination of snug fit and bow brace.

I also checked the floor tiller (without the final belly lams on just to see how it was faring given the Senior Moment and the need to thin the back lams a tad) - and its doing quite well - didn't have to use much effort to do what would be an acceptable floor tiller.

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It will need some final tillering to get to the draw weight I want - but its reasonably light weight and nicely balanced thus far. So far so good.

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[jape]

Actually mate you aren't old enough to have a 'senior moment'! You've still got your hair and it isn't grey! It is an excuse some of us truly senior folks need so you can't pinch it, sorry, you will have to think of another. In fact I had my senior moment when I didn't realise the stringing of the bow would hold it all in place ...

I am a bit confused about the boo. I thought on another thread here somewhere it was decided that bamboo is actually best in the belly not the back. I remembered that because it was opposite to traditional suggestions. Then again, I am probably back to front and upside down. I can't believe it is only 16 degrees here today and I am cutting firewood.

[ichiban]

im pritty darn sure you shouldnt touch the bamboo back as the outer most layer of bamboo has ALL the power fibers, if possable reduce from the sides and belly.
please someone correct me if im wrong, i wanna learn 2

Dave

[Stickbow Hunter]

Coming along nicely John - great build-a-long.

Jeff

[otis.drum]

perhaps instead of shimming it with leather you could build it up with a soft metal or alloy. solder or lead perhaps. then you could shape it to fit snug.

[looseplucker]

I have reduced bamboo backs without breakage - although it is advisable not to. it was only a mm or so. Plenty left.

In this case I had to reduce it or it would do in the core - have to get an economy of scale somewhere.

I reduced it at inner to midlimb, and will trap the rest.

And Jape - I said it was a premature Senior moment. I am actually 43 - but forever 15.

Otis - not a bad idea - fella across the road has a welding kit - it has potential. I'll try the shimming first, test the result and then if no go try the other technique. I'll report back either way.

Course, I could cease being a tightarse and buy the components - but that it no fun is it.

Thanks Jeff - plenty of time to bust it yet

[longbow steve]

Looking forward to seeing it bend, you are a very patient man building a bow this way as most lay up the layers in one go.
Thanks for documenting the process. Steve

[looseplucker]

Cheers Steve. I actually did the inner and outside lams for each limb together in the sense of two on the back side of the upper limb. Then did the lower limb, and then did the belly sides. Then put on the boo for the back.

I'm an early riser anyway - I can get up, take the kelpie for a run, come back, wrangle the kids and missis - and then sneak out to the workshop - do a glueup on a form and then clean up and go to work.

[ichiban]

she will have a nice profile when done, i did a simmilar self bow (which blew up) but i did get about 2 doz shots out of it. im guessin it will still count as a long bow as long as that string dosent touch.
cant wate to see her finished.

Dave

[Brumbies Country]

I second what Steve said about you being a patient man John. I've been watching the progress and been impressed with the steady progress. New fellas like me can learn alot from the way you've gone about this.

Simon

[looseplucker]

A historian, Thomas Carlyle, wrote The History of the French Revolution. Took him ages. When he'd finished this life's work he thought he could go for a constitutional, maybe sneak in a pint or two. When he returned home, the cook had used all of the manscripts for pie bottoms. Burned. Ruined.

Apparently, he uttered a deep sigh, and then started from the beginning.

Which, after swearing a lot, then laughing, and then phoning Yeoman and a couple of others, is what I did when the lower limb went on Sunday morning - I had floor tillered it and got a string 1" shorter than the ntn lenght (TBB recommends 2"). Limbs OK - so started in to exercise and tiller the baby. Maybe got to 15" of draw and pulling about 50#. Bang.

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- I might go for a lower draw weight as the bow is only 59ntn. As I pull 26.5" it should hold together if tillered right.

So I remade the laminations and a new riser part for the lower limb and new bamboo back and belly lams.

To soothe my bruised ego I also did some work on a shelf and squared up the arrow pass for the upper limb- bit more maybe needs to come out there

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There is the silver lining with this - if you bust a take-down, you only have to rebuild a limb. I suppose if you bust a one piece, keep the bits for the next one you bust and make a takedown

I am still a novice with this - very much so - but I am learning patience in spades. To tell the truth, I did think that if it was going to go, it would at the point it did. Just a feeling.

In the meantime I mounted a set of fallow deer antlers that a mate gave me (was going to make knife handles and stuff but the missus suggested they would look nice on the wall).

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- bit limited on what I can get done as my young bloke has been in for surgery (myringoplasty to fix an eardrum) so have to hang in the house with the lad.

The bamboo lams go on tonight and then the outer sleeve has to be refitted.

Then we'll have another go at tillering it into a shooter. If you do hear a loud crack followed by a series of swear words (some of which you may never have heard before) - it'll be me. Fingers crossed.

[longbow steve]

Thats a shame LP, Do you know why it failed? What bamboo are you using? Are you adjusting the taper for the assymetry when grinding the lams or relying on evening it up later? Steve

[Stickbow Hunter]

That is disappointing John for sure. Where did it break actually, I find it hard to tell by the photo - was it at a node out near a fade out?

Jeff

[looseplucker]

Gday Jeff - it broke just up from the fade - about an inch or so - probably just about where the thing gets dead flat after coming out of the fade.

Steve the bamboo is from a pole I got at bunnings - and no - I did not allow the 2" assymmetry thing in terms of the taper. I have now done so with the rebuilt limb and the bamboo is a shade thinner at the inner and mid limb on the lower limb (which is the shorter one) than previously. The boo is yet to go on - the core is parallel lams of spotted gum 4x1.4mm - anything I should do with that?

I don't know why it broke - but I did have a feeling that this point was vulnerable - based on the length of the limb (29" in total) and what I am asking it to do.

[longbow steve]

Hi Lp, Probably not enough taper as it is a narrow design so you dont get much benefit from the width taper therefore putting stress down at the handle.
With the assymetric design you need to add more taper to the shorter limb other wise you have to adjust the width dimension disproportionally to get the tiller right.
Bunnings bamboo can be a bit mouldy but I dont think thats your problem, it should be Moso. Steve

[looseplucker]

Thanks Steve

At the moment ithe boo on the back and the belly tapers from about just under 3.5mm at the fades to 1mm at the tip. Probably have a bit more wiggle room but should I put a taper in the cores?

[pdccr]

Sorry to hear mate, it was looking like it would be a nice bow.

[longbow steve]

Hi John, 11mm - 6mm core stack with a bit of width taper should be plenty provided you are getting the full benefit of the taper on the bamboo and not being ripped of by the bamboo curvature (i dont know if this occurs, Daryl may have struck it). Steve

[ichiban]

it is my understanding that bamboo backs are "generaly" (im gonna cop it for that) about 1/8 down to 1/16 is this correct, it could be that the bamboo just crushed the belly, bamboo backs are generally safest with bamboo bellys IMHO.

[longbow steve]

Hi Ichiban, John has a bamboo belly on his bow. Steve

[looseplucker]

Yes that's right - back and belly with a spotted gum core.

lower limb # 2 came off the this morning and re-did the tip overlay. Bamboo back goes on next then I refit the sleeve. Probably do the belly tomorrow. Hopefully it will be on the tiller stick by Sunday afternoon.

[yeoman]

John, seeing your own project fail, sighing, then starting again is what seperates the bowyer that shoots from the archer that makes bows. It's really diheartening to see a whole bunch of work go out the window (if you're tillering inside have the windows open ), but it's important not to let it get you down for too long.

Ichiban, I'll contest your claim that the best belly match for a boo back is boo. To support myself, I'll state that while the stiffness of bamboo is great for it's mass, and it has a tension strength which excels steel for the same mass, the modulus of rupture is simply too low to make it the best match for a boo backing. The fibres which run through the surface of the boo are long, strong and mean, and can take tension really well, but they take set earlier than many other woods.

For me, the best belly for boo is a really hard, dense timber, like hickory, osage, ironbark, spotted gum, sydney blue gum etc.

This isn't to say that bamboo can't make a good belly, there are many great bows which have boo on back and belly. It's just that if you want to start playing the figures, engineering and mathsy game...there are superior choices.

Dave

[otis.drum]

it looks similar to the limbs of some of my later selfbows....broken

[Graeme K]

I am with Dave -- bamboo is less than the ideal material for a belly, its just not that strong in compression. Still you obviously made it wide enough to make it work since you have not experienced heaps of set.
In the end it is a great looking bow and very well done.

Graeme

[looseplucker]

Howdy

I have made a couple of bows with bamboo on the back and the belly - one was not perfect, but is still shooting.

In respect of this one, I took a couple of weeks off and last night only just refitted the sleeve for the lower limb. I have roughed out the belly lam and will get it on this week sometime. I am not entirely happy with it in terms of node placement on the back (right on the end of the fade) but will push on with it.

Part III of the buildalong will be the tillering - for which I hope to have audience participation

And Dave - I did more than sigh - I swore a lot, and then laughed, and then called you on the blower asking if you heard the bang as the lower limb went off.

To aid the morale I finished tillering a board bow that looks as rough as guts, but a nice shooter - notwithstanding a bit of limb twist at one end - its the one made from a spotted gum floorboard and backed with calico that I had the kids colour in. Going to give it a trial on some bunnies this weekend.

[ichiban]

i was just stating my experiance i have found that bamboo resists compression from bamboo very very well (maby its in my mind) this is how dogma starts i guess.
besides generally people use raw boo for the back and boo flooring for the belly but there is a much higher concentration of power fibers in a raw boo back then there are in a boo flooring belly. but it would be a task doing a raw boo back and belly.