bamboo backed bows

[ed]

having reently purchased the Torges video on bamboo backed bows I have a few questions of the bowyers here, and Glen in particular.

best available bamboo types? I can get loads of darkish bamboo from a friend. Is this likely to be one of the useful types?

glue. I have some Selleys 308 glue which is a Urea Formaldehyde glue - any good?

What length should I be looking at for a red ironbark/bamboo bow for 32 inch draw? I gather it should be shorter than the double draw length plus 20%

I notice Torges removes the waxy rind - is this a problem for the finish? Being so hydrophylic, what sort of finish do you use to stop it taking up water, especially on rainy days!

I will have loads of other questions by the time I finish the first bow I am sure :)
thanks in advance,
Ed

[Glenn]

Ed when Dean Torges is over here he takes home with him a bamboo that is grown up this way called Madake, he said that it's the best bamboo baking he has used to date. You can make your bow much shorter with a bamboo back. For a 28" draw Dean makes them 62" long but of late he has been making backed bow as short as 56" inches. If I were you Ed I would start out with a bow length of 68" until you have made a few and then try for 66". I have a 26" draw and shoot a 62" bamboo backed bow but I could go much shorter.
Dean removes the waxy rind so he can stain them and apply a spray finish.
As far as your glue goes Ed I haven't used that one at all, I have only ever used Techniglue epoxy. Dean does use a Urea powder base glue, I will check on the name as I have some down in the shed...Glenn...

[ed]

will have to look out for that species - must be commercially available somewhere.
I split some bamboo I was given - Home Hardware stuff about six inches in diameter. Gave me six sections and then I sanded them down to a flat belly. Now that made some dust in the shed eh! I don't have a bandsaw so will look at patterning some wood and then get onto it with either a coping saw :shock: or the benchsander. Going to have to make another bench for all this stuff, especially if I buy a cheap bandsaw.
Waiting on the red ironbark to come, and then might get some other woods for the other bamboo slats. Glue one.... glue six? not much extra effort I suppose.

[Glenn]

Ed, Dean hand tapers the bamboo back down to the tip after he has cut the profile of the bow out on the bamboo back, it takes the pressure off the belly tip timber. A small electric planner is handy for this work also, in the past I have made a cradle for the planner and mount it upside down so I can use it like a small jointer, with tungsten tipped blades they are very handy...Glenn...

[ed]

well things have been moving slowly.

Chose a peice of tallow and using a hacksaw blade I roughed up the surface. I hand planed the bamboo down and then did a preparotory lay up. Then I could see that the belly of the bamboo was slightly convex. Ah well a very light sand on the belt sander and then use the end of it to put in a slight concave. Then rough that up with the hacksaw blade - watch those splinters! It was minor surgery in the shed for a bit, one then proceeded to get through a leather glove! Will be getting a convex plane blade made up.

Preparotory lay up again and I see I don't have enough clamps! Off to Bunnings to buy out their entire stock of large plastic clamps. Glenn told me that these make a good clamp because they keep constant pressure on the join.

Another lay up. All looking good. Mix up the glue, I am using Selleys 308 glue as that is the best two part glue I can get locally (Home Hardware). Mixes and washes in water but dries water resistant (i.e not as waterproof as resornicol).
Put glue on the surfaces, put them together and hold them down with tape. 26 clamps later, including a G-clamp to put in a slight reflex and I feel all funny inside! Kind of like being a virgin all over again :lol: :shock:

All edges have glue pushing out of them so figure I will be well within the 1.3mm limit for this glue.
Who said just this far into bowmaking would be so much fun. If the thing shoots it will be a bonus! I was so excited I went and did some reps with the monster woomera - 10 each side with 100# just for fun hehe.

[ed]

well I got to it again tinight. I had glued on the handle peice over the weekend. A nice peice of red ironbark to contrast the tallow.

roughed out the shape, and then took to it with a spokeshave. Starting to look good and so I decided to put in some string nocks and put a long string on it to check the alignment. Figured it was better to make sure the nocks lined the string up over the center of the handle before taking too much more wood off.
Well as I am bending the whole bow for the first time, and only trying to bend it a small amount to install a long string for maybe a half inch brace height, bang! off pops the handle peice. Really pissed off. Will let it sit alone in a corner in penance until I glue the peice on again tomorrow night.
Looking at it I think I didn't rough the surfaces up enough. So I will cut the handle peice a little shorter and make sure I get a good matching of the surfaces before clamping it again.

[jindydiver]

http://www.madmick3006.com/Gif_pics/forum_fun/useless.gif


C'mon Ed :D
Your killing us mate

[Glenn]

Ed I use a course hacksaw blade to rough up the surfaces to be glued, I do it on the belly and backing timber as well. If the handle pops off again what I have done in the past is to glue the handle on as several laminations so it can flex a bit on the fadeouts, this will relieve pressure on the glued on handle, it also helps to cut the handle laminations out to the curve of the belly timber. I had one bow that popped several handles until I did this. Would be good to see some photos...Glenn...

[ed]

handle is glued back on and I am going to let it set for a couple of days as this stuff takes a few days to get to full strength.
Talked to a bowyer at the club today and he thinks that the Selleys 308 may not have enough flex to cope, though he has never tried it for bows he knows the glue well enough. There is some better glue locally that I will look to source for the next bow (did I say that?)
here are some pics - hope they are not too big.

http://www.bujinkanadelaide.org.au/Images/Pictures/clamped_up.jpg

http://www.bujinkanadelaide.org.au/Images/Pictures/afterglueing.jpg

http://www.bujinkanadelaide.org.au/Images/Pictures/afterglueing2.jpg

the original clamp up of the handle
http://www.bujinkanadelaide.org.au/Images/Pictures/glueinghandle.jpg

the two bits seperated again grrr
http://www.bujinkanadelaide.org.au/Images/Pictures/bustedhandle.jpg

scraped good and hard with a hacksaw blade and then re-glued
http://www.bujinkanadelaide.org.au/Images/Pictures/handlereglue.jpg

[Glenn]

I've never used 308 myself but I know of other people who have used it for bows. Ed maybe if you go to a marine supplier they might have something better, I use Techniglue myself but for best results it is better to cure it with heat.
You can have a lot of trouble with glue if you wipe the timber down with acetone last as the acetone brings the oils in the timber to the surface, if acetone is used it is best to scrape the surfaces down with the hacksaw blade after the acetone, results are much better.
I don't use any acetone these days I just prepare the surfaces with the hacksaw blade just prior to gluing...Glenn...

[danceswithdingoes]

You should try to contact Alan Camp from Awaba near Newcastle, he builds bamboo backed bows almost as good as Torges. He is very approachable and knowledgeable.

[ed]

thanks for the hints Glenn and dingoes.
Glenn - wipe the surfaces down? why, if you are going to scrape all the surface off anyway...
Dingoes, thanks for the hint/contact. maybe another time as for now I have more information than I can process comfortably :?

having the first free day since I was sure the handle glue was cured I got stuck in. Bought a rasp for $2 and it is the best thing I have done. I had other rasps but either too fine or too blunt.

floor tillered it a few times until I had it a bit lighter than the 92# I was comparing it with. I put a string on it to check the nock positions.
http://www.bujinkanadelaide.org.au/Images/Pictures/strung.jpg

and then looking down the bottom limb I saw this weak spot, looking closely at the wood I saw an imperfection in the grain that I hadn't seen before.

http://www.bujinkanadelaide.org.au/Images/Pictures/bottomlimb1.jpg

top limb was way too stiff still as barely straightened out the reflex

http://www.bujinkanadelaide.org.au/Images/Pictures/toplimb1.jpg

still I was happy that the string came dead center on the handle - so no need to shift the nocks

http://www.bujinkanadelaide.org.au/Images/Pictures/stringcenter.jpg

so I got to it with the rasp and a butchers knife (works well to smooth it out) then strung it with a shorter string to check.

http://www.bujinkanadelaide.org.au/Images/Pictures/strung2.jpg

that was without taking anything off the weak area. I got stuck into the top limb again and got rid of some stiffness on either side of the weak spot on the bottom limb. exercised it a few times, checked and rechecked. Seemed to be about the right weight, though hard to tell as I was tiring a bit. So I took it to full draw. Feels a bit lighter than I wanted, maybe around 60# but I will check that later in the week when I can get to a scale.
http://www.bujinkanadelaide.org.au/Images/Pictures/fulldraw.jpg

bottom looks reasonable. Figure the top is stiff near the fade and just past mid limb. It is around 70 inches nock to nock and so I can afford to drop a bit of weight to get a better tiller and then shorten it an inch or so.
Happy with it so far, being only my second bow - the first was a shocking peice of crud made out of Aust' oak. Must thank Glenn for his help in more than a few PM's, and Dean Torges for the great explanation on his video for bamboo backed bows.

I was figuring on calling it "crisis" as I can now officially be in a mid life crisis - turned 45 today (Tuesday). Came in from the shed at 10pm, and missus had bought me a left handed Internature Viper longbow 60#@28!! Getting quite a collection here! :D

[ed]

well what a difference a nights sleep can make! I look at the bow today and where it was bending a bit much on the top has developed some chrysalling and set.

Ah well, it will make a reference peice in the corner of the shed to avoid making the same mistake next time. Basically I took too much off each time I shaved it down and didn't see the hinge until too late - i.e. today.

Off to shoot some arrows with the new viper

[Glenn]

Not to worry Ed, you can still save the bow, you could glue another thin lamination of timber on the belly, there is no reason it wont shoot for a long time, but then again it gives you a good reason to make another one, it's all good experience...Glenn...

[ed]

thanks Glenn. I have been thinking about all the little things I did wrong - and a few big things too!

What I am happy about is my biggest concern when starting it. All the selfbow advice I had received and even some of the glass bow makers had said that I would need a bow closer to 80 inches to handle my draw length. I learnt enough from this bow to see that it is well possible (with a reasonable tillering job!) to make one around 70 inches or maybe even shorter.

I looked at the bow a bit closer and think that I may have gone for too wide a profile to start off with and over powered the wood. I think I will try the next one with a thinner limb profile. herefore the bamboo thickness will be less ofthe total limb thickness.
Definitely going to make another, as soon as I get some decent glue. I used 2/3s of the Selleys packet and for $30 that is a bit of a waste when according to a glass-bowyer at the club I can get enough for ten bows for $50 of a different glue locally.

[adam]

It was looking really good too, I remember being told I didn't know how to ride a horse if I hadn't ever fallen off, pretty true I reckon.

Adam

p.s look forward to seeing the next one Ed

[Glenn]

Yes make the core a bit deeper and the width narrower. By cutting out the backing to shape and tapering the backing before gluing then the belly timber can be made slightly wider. When the bows are too wide and thin the bamboo will overpower the belly. It's all a balancing act, sometimes you have to experiment with several bows to find out what works best for the timbers you are using.
Once you get the tillering down pat you will be able to make your bows even shorter with expert tillering. Dean Torges has been making bows of late in the bamboo backed style that are as short as 56" and can be drawn 28" so at that ratio you might be able to make a bow 64" drawn to 32". That's the beauty of all wood bows compared to fibreglass composite bows you are not locked into the limitations of the fibreglass bow form...Glenn...

[ed]

64" !! :shock: Now that might take some practice hehe.

I was surprised at how nice the bamboo back came up after a scraping of the wax rind. It was a rough looking peice and all but two very small blemishes came out. The glue line was the the main annoyance, as close as I clamped it there still seemed to be a visible white line. I will see what the other glue turns out like.
I definitely made it too wide as the bamboo was 35mm accross. 30 would be more than enough, and I should have tapered it more aswell. As it was it stayed that width for 2/3s the limb length. 25mm would make for a nice slim bow not even needing thinning at the handle - something to try later maybe.

[Glenn]

Bamboo is one of the harder backing materials to work with, when you use a timber backing you can work the backing down during the tillering process but with bamboo you don't have that luxury...Glenn...

[ed]

well I did stew on the failure for a bit but then instead of starting on a new bow I started on a rescue.
First I went and got myself some techniglue CA gel. $50 will get you a litre of gel base and 500ml of hardener - do quite a few bows with that. One bowyer I know dilutes it to make it easier to spread and gets even more mileage.
then came reducing the wood belly down to a thin laminate. I kept it a bit thicker near the tips so I could make them stiffer and thinner.
I then filed the handle down to a more reasonable size and attempted to bend some bamboo so it would go along the limbs and up the fades. I say attempted because I could not get it to deform to a permanently bent shape. I tried wetting and clamping it - no luck, tried dry heat (as the asians do it), no luck, tried even hotter and all it did is turn the bamboo a light brown. In the end I reduced the length it was to go up the fades and just glued it in place. It split a little but th glue got into the split and it held.

I then noticed a slight twist and tried to tiller that out, worked a little bit. Then cleaned up all the edges and checked the tiller - good enough to 32 inches and so here it is. This is just before it shot it's first arrows, and it fling them pretty well too! Draw weight seems to be roughly around the 45 to 50 at 28, and 55 to 60 at 32.

http://www.bujinkanadelaide.org.au/Images/Pictures/bbb1.jpg

[ed]

part of the reason I took so long between stuffing the tiller and then fixing the bow was that I read Dean Torges' book "Hunting the Osage Bow". In it he has some hints on stains and finishes.
Not a traditional wood stain but this is done with Potassium Permanganate - Condese Crystals just as Scott used in this thread http://www.aussiebowhunter.com/viewtopic.php?t=5683

After that I heated in some parrafin wax as Torges says this is second only to Shellac on waterproofing a bow and much better than any varnish or oils. Here is how it comes out - well as good as I got it.

http://www.bujinkanadelaide.org.au/Images/Pictures/wholetop.jpg

http://www.bujinkanadelaide.org.au/Images/Pictures/topnock.jpg

http://www.bujinkanadelaide.org.au/Images/Pictures/handlestained.jpg

http://www.bujinkanadelaide.org.au/Images/Pictures/handleshelf.jpg

http://www.bujinkanadelaide.org.au/Images/Pictures/limbback.jpg

the missus is not impressed with the colors I chose for the tillering string though :) I think it is crass too but I like it all the same.

[HOOD]

I can't see your pics Ed :(