Bamboo loose-laminate bow

So, amid dissertation work, complaints about marking, running student societies and all manner of other distractions, it looks like I'll finally be getting some time to work on the LARP bow a friend of mine has commissioned off me. I've got a plan, got most of the materials and progress should be made.

Now, onto my question: The prodd for this crossbow is (probably) going to be made from bamboo in loose laminates, as I haven't been able to find a reliable fibreglass or carbon fibre source in the UK. Has anyone got any pictures of loose-laminate bamboo prodds, advice or (even better) build-alongs?

Thanks!

There's this that I posted awhile back from ATARN which shows and somewhat explains Ming Dynasty non-repeating crossbows with laminate prods.

https://thearbalistguild.forumotion.com/t748-ming-dynasty-non-repeating-chinese-crossbow-build-it?highlight=ming

Read Stephen's explanations; it gives relative dimensions of each layer of lam, and a bunch of other good information.

There's not a lot written in English or even other European languages about loose laminate prods. The Chinese/Asians were masters of the concept but again little is in non-Asian languages. The Crossbow Building Wiki has some tech-talk: http://crossbow.wikia.com/wiki/Bow_design
You also get some ideas if you search Primitive Archer and Paleoplanet on "bundle bow".

Here's the very best discussion I can find on making a wooden loose laminate (they call it leaf spring) bow:
http://atarn.net/phpBB2/viewtopic.php?t=1639&highlight=crossbow

Basic idea is that you want the lams to 'free float' between the inner and outer lams. Only tie at the ends or a couple places around the outside of the stack; don't tie each lam in place. A tillering tree will let you see how the bow is bending.

Check local DIY shops or window covering shops for bamboo blind slats... Strips of bamboo flooring would also work.

My loose laminate prod is made from pieces of a 1/4" x 3/4" fiberglass chainlink fence Tension Bar.

Here in the US you can get spring steel strips of varying widths and thicknesses. Same should be true in England. Here, McMaster-Carr for example has a 10 ft length of 1" wide x 1/16" thick 1074/1075 spring steel for $44 that will be more than enough to build a 4-5 lam bow that will be the same as a solid 1/4" or 5/16" x 1" x 30" prod. Use a die grinder or dremel tool to cut pin nocks in the ends of the longest lam.

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John, I had build a Chinese repeater (chu-ke-nu) in 2011 or so, and it uses bamboo laminate prods. I purchased a piece of bamboo from an archery supplier that is intended for backing a wooden bow. It was easy to work with hand tools, and with such a short, low power bow, I didn't worry about cutting through the nodes. I just flattened both pieces (I used two loose laminates in this project, although the original 19th century weapon I based mine on used three). It was held in the stock in a mortise and with a wooden wedge. I drilled holes in the prod for stringing it.
Here are a few photos showing sequence of work. I hope this helps.

Has anyone tried cutting down a children's fibreglass practice bow to make a weak crossbow limb? I've been looking online and a children's bow is actually about the same price as archery-grade bamboo slats... Perhaps cutting the bow's riser out and then bridging the gap with a couple of steel repair plates, then wrapping the whole thing in cloth...?

I'm so indecisive about this project; I've never built a bow before and it feels like building a powerful prodd would actually be easier than a 30lb one; every test I carry out costs money, and that's a dwindling resource.

IMHO you'll spend more time, effort, money and aggro remodeling a child's bow that starting from scratch.

Loose laminate is definitely the inexpensive way to go. It doesn't need to be bamboo. A plain old red oak or maple 2x2 with reasonably straight grain from a DIY shop will work just fine as long as it's knot free.

Rip a 1 meter long 2x2 down into pieces 3-4mm thick x 25-30mm wide. You should get at least 4 pieces all the same thickness. Cut 1 piece 70cm long, 1 piece 60cm, 1 piece 50cm and 1 piece 40cm. Sand each piece medium smooth at this point. Mark the centers of each piece.

Start with the two longest laminations, stack them together on the centerlines, and use twine to tie them together at the points where the ends of shorter lam meet the longer one. Cut and glue up reinforced pin nocks on the longest lam.

Put the double lamination on a tillering tree with a reasonably tight bastard string and get it bending. Looking for about a 25-30cm draw. Test the draw weight. Not strong enough? Add the 50cm lam and try again. Repeat until you get a draw weight you like.

Yes it is that simple.

This is the kind of thing I was talking about: http://www.thecrossbowmansden.com/Build_a_Kids_Crossbow.html

This guy made a ~25lb prodd which drew around 12" out of a fibreglass kid's bow, which is tantalisingly close to my aim of 30lbs at 15", and it feels like this would last longer than a wooden or bamboo bow in the varied weather conditions that LARPs entail.

I wouldn't know where to begin ripping a 1m long board into 6mm laminations; I lack a table saw or bandsaw so I'd have to do it by hand or with my scrollsaw, neither of which are attractive options. I checked a website that sells archery-grade bamboo and it'd set me back around £50 including postage, compared to a £25, free postage petron fibreglass starter bow.

Alternatively there is the bamboo from these garden screens: http://www.diy.com/nav/garden/fencing-paving-decking/fencing/screening-wire-fencing/screening/Split-bamboo-screening-L-4m-x-W-1m-11987851?skuId=12498557 but I'm unsure about quality and width of the strips which make up the screens.

Geeze, and I thought I had limitations, living board a sailboat!

I thought you were building something for SCA, not a 30# prod. Why not just get one of those 50# replacement prods from Ebay? If you want to go with the two-piece idea, I looked on Ebay UK and saw pairs of limbs for a compound bow in the 30-35 pound class for the same money you're talking about, and less work since they're already in two pieces.

Those limbs look like they'd be great for a larger project, actually; there are padded full-length LARP arrows that'd fit that kind of draw length nicely... The LARP crossbow bolts are considerably shorter, so the resultant poundage would be lower, but you're right in that I could buy some slightly more powerful limbs and just use a shorter draw distance than what they're designed for.

This project is for a LARP in the UK, where the maximum poundage at 15" draw is 30lbs, hence my inability to just buy a replacement prodd. Were it for SCA, this build would be so much simpler!

Thanks for your comments; I'll update when I've tried something!

How about going to a place that sells hardwood flooring, ask for a sample piece choose something straight grained, and if you sweet talk them a bit, try to get a board 33 inches long plus width of your tiller.
( Formula for self bows is draw length x 2.2 plus length of non working part of center) Lay out your bow like the crossbow building wiki describes and you should end up with a sweet shooter.
Gluing a strip of rawhide to the back will make it more durable. A rawhide dog chew of the larger size will have enough rawhide but it will have to be sanded thinner after you glue it on.

A bundle bow can be made out of round sticks
https://2img.net/h/i74.photobucket.com/albums/i264/wolfsirebella/Picture-2.jpg


Paleoplanet thread about "panda bows"
http://paleoplanet69529.yuku.com/topic/33049