LARP crossbow from UK

Hey folks!

I'm John, a Biomedical sciences student from Durham in the UK. I've recently gained an interest in crossbow building after a pretty thorough foray into the modification and building of safe NERF weaponry for our university's Assassins society. I basically covered most of what can be done with that, and now I'm going for something a little prettier and more classic; the crossbow.

I'm intending to eventually build some real, high-poundage bows for target shooting, but for now my efforts will be geared towards producing replica bows with a strict poundage limit (30lbs at 15" draw) for use in live-action roleplay (LARP) and our Assassins games. These bows will need to look the part, but fit the strict safety guidelines of said societies/groups, and will need to fire soft-headed, front-heavy safety bolts (e.g. http://www.thevikingstore.co.uk/larp-crossbow-bolt-flat-headed-6115-p.asp).

At the moment I'm building my prototype bow, upon which future efforts will be based. The stock will be made from laminated sapele timber, the roller-nut made from the same, and a hand-forged (albeit with a blowtorch) tickler. The prodd will be carbon fibre, wrapped in cloth to avoid danger from limb failure.

I've ran into the issue of how to calculate the length of prodd I'll need in order to reach the desired poundage (30lbs to reiterate) at the correct draw length (15"), as I'm a little limited in terms of the material I have to hand, and so have little room to experiment. I'm planning to use two lengths of carbon fibre strip, one shorter than the other, to make a laminated prodd and even out the work done between the tips and centre of the prodd.

I'd be grateful for any suggestions anyone might have!

So I just finished roughing out the first lamination for the stock of this bow; I'm planning to use two layers of sapele like this one, followed by layers at the very front and middle, where the bow needs to be a little wider. I'll then use planes, rasps and files to get the curves I want once they're all glued together.

How does this look for a start, anyway?

[img][/img]

It is looking very nice. Welcome to the forum, too. I can't address your question about calculating the prod for a LARP weapon. Perhaps others here will chime in. Laminated tiller construction is a good way to go. I like the profile of this weapon too. I build a crossbow with a tiller that curves down fairly recently, and it really does aid in quickly aiming the weapon. In a LARP situation, that will come in handy.

Dane

Greetings
Great start, and welcome to the forum. I like the curve in the tiller!
Post pics of your progress, we like pictures here.

jds6

Thanks ^_^ I'll hopefully be able to make some more progress tomorrow, but dissertation and exams are coming up fast, so time is running out to do fun stuff =/

I'm hoping to have this done for out annual inter-university assassins game (basically paintball but with nerf guns), to give people a shock with something old-fashioned =D

I'm going to try and finish the second half of the stock tomorrow, and I think I'll attempt to thin the stock a little; it looks a little large now that I look at the photos.

I'm quite annoyed with myself for not being very careful; the sapele has interlocked grain and tears out terribly so I've got a couple of patches which need some repair (somehow). Any suggestions, or shall I just plane back the stock a little at those points?

I've actually been teaching myself woodworking for a very short period of time, and literally just now got my first truly shaving-sharp result from my sharpening station, freehand. Feels good =D Maybe I'll get less tearout with sharper tools...

The carbon fibre I've got seems a little thin in comparison to this stock now; has anyone got any ideas for a prodd material which will look a bit chunkier, last reasonably well and result in a 30lb draw? I've been hunting for ideas and frankly carbon fibre seems like the only way to go so far, perhaps backed with a wider strip of flexible material to simulate the look of a larger prodd?

You may consider using PVC piping. I know it is sort of blasphemy compared to "real" materials such as steel and wood, but I've built quicky PVC pipe bows that are easy to make and fun to shoot. You can google this subject on the net and find all sorts of websites and info on this. It will cost nearly nothing - perhaps $2 for a length of 1/2" grey or white pipe. Limited hand tools (hand saw, files and rasps) are more than suficient.You flatten and then tiller the bow using a heat gun or a burner on your rangetop, place the pipe on the floor, lay a short lenght of board on top and step on it to flatten it, then cut in pin nocks at the ends and you are close to being done. You can cover the pipe with fabric or thin leather to disguise the fact that it is plastic. A longer length of pipe and larger dimater pipe make for a heavier bow, but simple stuff to figure out with a bit of experimenting.

A way to determine draw weight at a give draw length will involve making a very simple tillering stick (tillering in this case refers to a shaping a bow, not a crossbow stock, which is called a tiller). Get a stick, perhaps 1/2" by 2" or so. Cut a socket into the top end of the stick that is wide enough to accept the wide of the prod mateiral you want to use (for instance, if your prod material is 1" wide, the socket needs to be a bit over 1" wide) , and then mark out inch marks from the bottom of the socket down further than you think your ultimate draw length will be for your crossbow. Put your strung prod in the socket, place the end of the tiller stick on a simple bathroom scale reset to zero, pull the prod string down as if it is being drawn past each mark, and observe the weight scale. Hopefully, all that that makes sense. You can then design the crossbow stock knowing where the weight you want will be at a given length of draw.

Dane

BTW, you can not underestimate how important sharp tools are! Keep them sharp and you will have far more success. And, keep them clean, too. Safety is important, but if you slip up and injure yourself, a sharp tool is better to get injured with. Case in point - I was foolishly working on a lock recess for a trade gun I am building, and was not using a vice out in the shop. The wife was at work, I didnt want to leave my pug alone in the house, so I thought I would just do a bit of inletting at the kitchen table, shaving a bit of wood away. My hand slipped and I drove the chisel about 1" into my left hand. It left a very nice chisel shaped hole there. I can tell you I felt a bit queezy and wondered just how badly I had messed up, and wondered if the wife would notice I probably should have gone to the hosptial to have it looked at. Fortunately, no nerve damage and it healed nicely. If it had been a dull or rusty chisel, the outcome would have been much worse. If you are wondering, she didn't notice for quite a while, but finally asked about all those bandages around the base of my thumb. The boys will be boys category when you mess up always seems to work.

Hi Riegis,

I was going to suggest you try a wood bow of about 30-40" in lenght with a fairly thin profile fare bit of work tillering to get it right , but what stoneagebowyer suggested using ABS or PVC pipe and hiding it under heavy linen canvas or leather would work fine.

Cheers

Thanks Dane; my dad educated me pretty thoroughly on tool use and safety, however with my recent change to exclusive hand-tool usage blade sharpening has become a big priority; it was the first thing I set out to learn, for the very reasons you laid out; I have my own share of scars from mishaps, however none of them due to a blunt tool; my worst was from a scalpel snapping and the fragment opening up the top of my wrist.

Anyway you can rest easy knowing safety is a priority for me XD

I've worked with PVC (pressure-rated and not) and ABS a lot whilst making the nerf weaponry in the past, as well as polycarbonate. My concern with these materials is the degree of string follow/set that'll develop in such materials. The carbon fibre/fibreglass basically eliminates this problem.

I've spoken to a couple of US larp bowyers, who have seperately recommended 8mm thick fibreglass rod. This would work, but it results in a round cross-section to the bow, which after talking to the folks who will be commissioning these bows, is less than ideal. I was considering perhaps taking 3 or 4 4mm fibreglass rods and making a flat bundle from them, some shorter and some longer, so that the curve is even in the prodd (so the middle doesn't do all the work) and perhaps glue/bind the flat bundle to a strip of flexible material (maybe PVC strip) before covering in cloth wrap; this might simulate a full-sized prodd without the set that a PVC prodd might take.

How much set/follow do your PVC bows take, Dane?

Thanks for the feedback so far guys; I'm wondering if I should move this thread to the LARP crossbow section of the forums?

John.

How about the flat fiber glass tension rods used in chain link fencing. Not sure about the UK, but probably avail at most fencing or hardware shops.
I`d bet they`d make a decent Prod, for LARP purposes.

Just a thought.

John, I do hope I wasn't lecturing you regarding safety. Those new to hand tools can be in for some surprises.

Not that much set, and the nice thing is you can make a new bow very quickly to replace the old one.

Never worked with fiberglass as Shiloh suggested, but it may be worth looking into.

A bundle bow, sometimes called a panda bow, may be a good idea. Ive seen those made from a number of thin bamboo or cane rods, with shorter lengths of bundles adding to the thickness of the bow as you approach the center. Also, another way is bamboo lathing. I made a Chinese repeater that way, with two pieces of bamboo cut from a very large diameter tube, then cut to width, planed and sanded to get the lathes flat and thin. I actually wenth through the seperator nodes on both sides without any issues. You don't glue those together at all, which is the same with a panda bow. You simply bind them together in a few places if needed. The lathes move against one another, so gluing them is not necessary or desirable.

Dane

So I looked into your suggestions, and the usual problem has cropped up; you guys in the states have much easier access to materials than us in the UK.

Tensioning rods in chain link are made of galvanised steel in the UK; no fibreglass ones around (looking at a US site, you can get them for a couple of dollars? No fair!).

Similarly, shcedule 40 PVC is only available in the UK from certain companies which cater to industrial applications; purchases are limited to bundles of 6 3m lengths of the stuff, for around £30 and up. The stuff you can buy for a couple of pounds in B&Q and other hardware shops are thinwall stuff for drainage purposes, not suited to bowmaking. The grey schedule 80 stuff is similarly expensive.

Tent poles are made from fibreglass, but they're hollow; I can't see them working so well because of this. I can get hold of 4mm thick fibreglass rods for roman blinds, or 8mm thick rod from some online shops, but no convenient tensioning rods this side of the pond =[

The bamboo might be an idea; I can see the precise cutting and the planing/sanding process being lengthy and difficult by hand (rather than with a thicknesser/planer); what do you think, Dane?

Working with bamboo is very easy, with simple hand tools.





If you can find large diameter piece of bamboo, you will just split it in
half and then again in halves until you get the basic width you wish for a
lathe. I have used a small hand axe for the splitting task. What may make it
much easier is to find an archery supplier in the UK who sells bamboo backing
material for wooden bows. You will have the lathe already close to the width
you want.





Bamboo is a very popular material here in the US for flooring, so you
may want to look into flooring supply companies, too.





Tools I use for working it down include a hand plane and a spoke shave,
plus hand rasps and files. My favorite type of rasp for this kind of work is a
farrier’s rasp, the kind farriers and blacksmiths use to flatten the hooves of
an animal as part of the shoeing process.




It doesn’t take much time or effort for this, so
no thickness planers are needed.
Dane

A 30# bow with 10-12" power stroke is quite trivial.

Bundled rods of anything bendy - bamboo , fiberglass , metal.
Thick piano wire - 3x3mm should do the trick - hide them inside a fake styrofoam bow wrapped with band of your choosing for looks.

Hardwood panel makes very neat looking bows.
I have made bows out of 42x11mm red oak and beech backed with sisal cord. Also denim cloth works for backing. Grocery gelatine or D3-type PVAc make best backing glue.

Flat aluminum profile. I once made one close to your specs from 80cm of 4x30mm slat.

Wooden branch, inch thick , 80-100cm long of elm, ash rowan, etc...
Ramin wood broomsticks make light bows too. Edge ringed flat back & flattened belly.

And finally. If everything else fails : a static wooden or iron prod and string with bundles of regular stationary rubber loops at the ends. A guaranteed succes.

The piano wire idea sounds interesting... have you used that before, NF?

B&Q sell 25mm x 2mm aluminium flat, maybe making lathes from that would work? I'd be worried that it'd deform or snap; how did your aluminium bow hold up to repeated firing?

I'm kind of concerned about the durability of these things when firing them often, which is why I'm being so picky about the material. I think I'll save my carbon fibre for a pistol project and try either the piano wire or aluminium.

I'm going to build the roller-nut and perhaps the second layer of the tiller today. The roller-nut is going to be made by drilling out two 38mm plugs of sapele using a hole-saw, cutting them in half and sandwiching them at alternating angles to reduce the chance of splitting.

Thanks so much for the replies, folks; they're really helping.

John.

So I just found this: http://www.ebay.co.uk/itm/BAMBOO-SLAT-GARDEN-SCREENING-ROLL-1m-x-4m-Screen-Fencing-Fence-Panel-Wooden-/230739610803?pt=LH_DefaultDomain_3&hash=item35b9270cb3

What do you guys think about a bow made from the slats in one of these screens? Bamboo is pretty strong, you get a lot of slats in a roll and I could easily replace a prodd which failed.

Opinions? Problems? Ideas?

John.

Progress!

[img][/img]

What do you think, folks?

The roller-nut pictured here is 3 layers of sapele. The 'hooks' have vertically-oriented grain for strength, and the centre is horizontally-oriented to prevent splitting. Should take 30# pretty handily, I think =D

I cut the layers out with a hole-saw, carved them separately then glued them up, filed and sanded.

Yes, that oughta work just fine. I used to make laminated nuts from maple, in a similar fashion. As a matter of fact, with a steel sear-insert, it oughta handle 100 lb. but I wouldn't go much higher! Geezer

If I were making anything chunkier than this, I'd move to delrin, but at this poundage it's not worth the extra expense (though I did offer it as an option to the friend this project is for). They were fine with the timber nut, so that's what I made.

Thanks for the feedback, Geezer!

John, regarding that bamboo fencing, I have that up on my back deck. The wire is so thin, you can cut it with a pair of scissors, so it would be easy to manage. Try it and see what happens.

Regeis wrote:The piano wire idea sounds interesting... have you used that before, NF?

I have made 100#/20"-ish foru pulley compound prod out of 20 m bundle of 2mm wire.

As a kid I also had a factory made toy bow with a single piece about yard long 4mm wire hidden inside "longbow" shaped plastic tube.
If you can find two or 3 of those - there is your prod.

You could also make the limbs from bundled metal saw blades, but then your bow needs somekind of riser secton in the middle

Regeis wrote:


B&Q sell 25mm x 2mm aluminium flat, maybe making lathes from that would work? I'd be worried that it'd deform or snap; how did your aluminium bow hold up to repeated firing?

Aluminum may "tire" and fail without warning if overstrained. I had some small Al bows fail (- they were heavily stressed and semi-intentionally destroyed for "testing" purposes ,though.)

But my first choice raw material here would be ~yard long piece of ca. 40x10mm hardwood panel tapered to 2cm wide tips and backed with thin layer of cordage (yute, sisal, manilla ) or old jeans. Red oak or beech will do fine. You might find something like that sold as "home improvement" supplies. - That would make a nice looking and efficient "real" bow and add some value to your crossbow.

Regeis wrote:So I just found this: http://www.ebay.co.uk/itm/BAMBOO-SLAT-GARDEN-SCREENING-ROLL-1m-x-4m-Screen-Fencing-Fence-Panel-Wooden-/230739610803?pt=LH_DefaultDomain_3&hash=item35b9270cb3

What do you guys think about a bow made from the slats in one of these screens?

Get that bamboo!
That will do the trick.

So I've made some progress, finally!

I've been in the lab for the last couple of months, staying with a friend because taking the bus every day takes up a lot of time. My housemates also don't appreciate the noise I make when I work wood.

Anyway, in the last couple of days I've made some progress. I wasn't getting anywhere with a steel tickler, so I've made one from sapele (it only has to hold 30lbs and if my roller-nut can be made from it I don't see why the tickler can't). I also made the second lamination for the body, and will be routing out the spaces for the tickler and nut either today or in the next few days.








Let me know what you think! (and whether I should move this thread to the LARP crossbows section of the forums...).

No reason Sapele won't work for a 30# prod. It's tough stuff. Should work for the nut and other bits as well. I'm a big fan of wood!

I get the feeling that I should make the tickler more slender... opinions?