New Medieval Finished

Howdy fellow Arbalest builders,

Just wanted to say hi, and share a few pics of my newly finished crossbow. After a couple failed experiments last year with forging steel prods, I got frustrated and (after a break ) went back to a prod material I had plenty of experience making bows from: wood. After only a few more failed prods I decided to start adding sinew backings to them as well...and hey, one actually worked!

The rest of the build was done in a simple, mostly-medieval style; I figured I should go as traditional as possible, since the old timers had likely worked out most of the kinks already .

So, here's the whole thing all built up:









Specs:
Osage Orange prod, heavily backed with elk sinew and covered with a bullsnake skin. 35" nock to nock, 9" powerstroke, and pulls appx. 160#. (I still need to take it to the bow shop for proper weighing and a chrony measurement)

Oak tiller, made in two pieces...no socket reinforcements or the like, just wood. Sourced from an old, broken table owned by my great-grandmother.

Roller nut made of ziricote wood...9 plies glued up with epoxy, with a steel sear added. Bound into the tiller with hemp twine.

Hemp string; loops reinforced with spectra fishing line, and covered in leather.

Hemp prod binding; stirrup binding is rawhide, in that cool 'basket weave' medieval style (one of my favorite details!). I coated all the hemp with a beeswax/pine pitch mix, which makes the whole crossbow smell great .

Hand forged steel bits, including tickler, bolt clip, stirrup, cross-pin for a rope cocker, and removable sight.

Not shown are the bastard string and rope cocker...picture ugly blue mountaneer cord and pulleys from the hardware store...but they do work OK. I may make less ugly, natural cordage versions eventually. Some proper bolts (medieval type, probably ash wood, and fletched in real feathers, not duct tape!) are on the agenda, too.

It shoots very nicely! Good range and power, with a little practice I was able to (mostly ) keep my shots on a paper plate at 40 yards. I think it would have enough 'oomph' to take large game, with appropriate bolts and broadheads.

Thanks for looking! Once again, a big "thanks!" to the whole forum; all your posts, pics, and info were what made this build possible.

Cheers,
-Orien

Looks Awesome! I really like the snakeskin, nice touch!

Excellent work!

Love the detail in the prod binding, snake skin, string and tickler.

The whole family let out a collective "Daaaannnggg!" That is a mighty handsome bow.

Thanks gentlemen!   I appreciate the nice words. I ended up spending an awful lot of research time, and doing many failed experiments during this project, so it feels very gratifying to finally get a working, decently-powered crossbow made.

As I said above, I highly doubt it would have worked out without the help of this forum...so thanks again! Many (indeed, most) of the details were directly adapted from info I found here. Best crossbow forum on the 'net...

It is really encouraging to see a working crossbow with a wood prod (with "decent power"); can you estimate what the poundage was before you added the sinew? and did you tiller the prod fully before you added the sinew?

Like you, practically everything I know is from what I have learned from people of The Guild and YouTube - and my own experience.  Someone advised me to make long bows before trying a crossbow prod which is probably very good advise, but I'm too old with too little time to start making long bows when what I really want is a crossbow (and maybe a little stubborn).

One thing I am doing and would suggest to anyone wanting to stay more or less authentic (I believe) is using linen string well waxed for the bow string; it doesn't seem to stretch and is nice to work with.  Do you pre-stretch the hemp? I would like to know as I plan to use it for binding on the prod.

Your did a sweet job with your bow and thanks again for the much needed encouragement

That's a unique and handsome weapon! Love the snakeskin, and wood salvaged from a family table. Very nice. Would like to see more detail on the nut, I assumed it was Delrin based on the photos.
Gnome

He said the nut was a 9 layer epoxy glue up of Zircote wood (tough stuff), with a steel sear.

GodricSwin wrote:It is really encouraging to see a working crossbow with a wood prod (with "decent power"); can you estimate what the poundage was before you added the sinew? and did you tiller the prod fully before you added the sinew?

Like you, practically everything I know is from what I have learned from people of The Guild and YouTube - and my own experience.  Someone advised me to make long bows before trying a crossbow prod which is probably very good advise, but I'm too old with too little time to start making long bows when what I really want is a crossbow (and maybe a little stubborn).

One thing I am doing and would suggest to anyone wanting to stay more or less authentic (I believe) is using linen string well waxed for the bow string; it doesn't seem to stretch and is nice to work with.  Do you pre-stretch the hemp? I would like to know as I plan to use it for binding on the prod.

Your did a sweet job with your bow and thanks again for the much needed encouragement

 
Thank you!

I actually did very little pre-tillering to the prod before backing; I figured it was risky to try for much bend without the sinew on. It was very stiff! I was able to flex it just enough by hand to see that the bend was fairly symmetrical. After backing I tied it temporaily into the tiller ('tiller' and 'tillering', that's confusing! ) and used the rope cocker to bend it the rest of the way. I got lucky eyeballing the symmetry, and not much final adjustment was really needed.

As I said above, I have quite a bit of experience making wooden bows already (I even taught the skill to a group of high-schoolers over the winter). It is certainly good practice...the longer the bow, the less stressed the materials are, which makes breakage less likely. That said, if you're stubborn (and who on here isn't ) and careful to follow general bowmaking principles, I don't see why you couldn't succeed at making a wooden prod without doing a bunch of preliminary work. (I'll type a bit more about my thoughts on wooden prods below, since there seems to be interest...)

I have often heard that linen is a superior fiber, but the hemp cord was available locally (walmart!) and seems to be working out fine. I didn't pre-stretch, just pulled everything as tightly as I could; the string itself stretched very minimally, but nothing else moved as far as I can tell. The string was easy to shorten back up by twisting it a little.

Gnome wrote:Would like to see more detail on the nut, I assumed it was Delrin based on the photos.

Yes, as Ken says, the nut is made of wood...plywood really, 6 plies running in one direction, and 3 turned at 90*. Ziricote is extremely hard, about like ebony or the like. The sear is dovetailed in from the side, and glued as well. I was not absolutely sure if the nut would deal with the forces I was putting on it, but it's been 100% fine so far. I'll try to get some close-up pics to show it better.

Thanks for the comments!

Orien

Man sometimes a post comes and hits me at just the perfect time. Yours is one of those. I too have suffered a number of failures on the learning curve. Going from stick bows to prods is a whole new experience. There simply isn't much room for error. As for the fiberglass, I just dislike working with the stuff. I dearly want to go to more natural less ugggg inducing materials. I was even considering trying out making a horn composite bow, but here you've done it with just sinew. So naturally I have a few questions. How thick did you layer on your sinew and how many pounds of draw weight do you think it added? What kind of reflex did it add and did you need to do any deflexing to compensate? Have you experimented with keeping it spanned for any length of time? If so have you encountered much set because of it?

One of the ideas I had was to do a fiberglass belly with a sinewed back. My logic is that the unidirectional fiberglass will pull the neutral plane close to the belly and take most all the strain off of it. This will put almost all the strain onto the back which would be protected by nice stretchy sinew. Theoretically (communism works, theoretically) if I do it right I will be taking advantage of the sinews ability to stretch (thus storing more energy) while protecting the belly from taking any set. Of course I am sure reality will probably be splintered sinew and a face full of fiberglass. It is similar to a composite horn bow without the awesome compressibility of horn.

Godric

You got some seriously good advice there. But realistically, if I were given the same advice I would probably stubbornly ignore it as well!

As promised, I've tried to write up a little bit more on wood/sinew prods.

First, a disclaimer: I've never been a very scientific type of bow builder. I don't take notes, and I lack the math and physics background to anaylyze this stuff very intelligibly. My methods tend toward "research traditional practice, then build it and find out"...not a super efficient way to go about it. Any conclusions I reach below should be taken for what they are, one guy's (semi-)educated opinion on what works, but not the only way to go about it.

So...It's an obvious fact that wooden bows break. (Lol...As a beginning bowyer, I blew up 14 longbows in row before producing a shooter!) Short, powerful hand bows are particularly highly stressed, and prone to explode...a crossbow prod is even shorter, and generally much stronger than any hand-held bow. What can the maker do to prevent failure?

I ended up with a fairly simple solution of just a few elements: A) deflexing the prod to keep brace tension and compression stress low, and B) a heavy-duty, tension-resistant backing, in this case sinew. A third important factor, C) was wood selection; I deliberately chose Osage, the strongest, most compression-resistant wood I had available.

Design wise, the prod is 36" total length, 35" nock to nock; dimensions at center (backed) are 2" X 1" thick; at the tips, 1 1/4" X 19/32". It is heavily asymmetrical (the upper edge of the prod is essentially flat), and is deflexed by about 3".

The deflex was produced by steaming the prod, and then hand-bending it over a round piece of wood. The deflexed prod is under only minimal stress at brace height; string tension starts out relatively low, but the draw weight ramps up quickly as the string is pulled back.

The sinew layer is about 1/4" thick at the center of the prod, tapering down to more like 1/8" at the tips. Proportionally, it stays at about 1/5 of the limb thickness throughout. It's kind of hard to guess how much of the draw weight is the sinew working; I didn't really tiller before adding it. The way I see it, it's an integral part of a composite bow, enabling the back to handle the stress...draw it far without the tension-strong element, and you're asking for a blowup. 

It was just a guess as to how thick the layer should be, but I figured too much sinew was as bad as too little, and would would overpower the belly wood. I applied the sinew the traditional way, using hide glue (knox gelatin). There was no sign of reflex occurring, or of any motion at all, after adding the backing...my guess is that the wooden core was simply too stiff for the sinew to bend.

The snakeskin is mostly decorative, but it also makes a more water-resistant cover for the sinew back...sinew hates water. Both skin and wood are heavily shellacked and waxed, as well.

The prod seems particularly stable, which is nice. I've left it braced for several days a time or two, and also left it spanned for several hours at a time; I couldn't detect any set, or difference in the way it shot, after doing so.

(I have to admit, I am curious just how high a draw weight this construction can handle, or to put it another way, when it will become obvious that a horn belly needs to be added! Wooden bellies will no doubt start failing eventually, but I would not be surprised at all if a wood/sinew prod could be made that exceeded 200-250#.)

-O

twedzel wrote:
One of the ideas I had was to do a fiberglass belly with a sinewed back. My logic is that the unidirectional fiberglass will pull the neutral plane close to the belly and take most all the strain off of it. This will put almost all the strain onto the back which would be protected by nice stretchy sinew. Theoretically (communism works, theoretically) if I do it right I will be taking advantage of the sinews ability to stretch (thus storing more energy) while protecting the belly from taking any set. Of course I am sure reality will probably be splintered sinew and a face full of fiberglass. It is similar to a composite horn bow without the awesome compressibility of horn.

Interesting! Thanks for posting. I haven't ever really fooled with fiberglass...I have worked with carbon fiber fairly extensively, but not for bow making (I worked at a bike frame factory some years ago...modern composites are indeed kind of nasty! Needle-sharp, irritating dust and toxic glue fumes...good times. I've deliberately avoided such materials ever since. )

Actually, CF might make a good belly...fairly strong in compression, if I remember correctly.  IMO something like this would totally be worth trying; you can always soak, remove, and re-use the sinew if the core fails.

Like you I generally prefer natural materials, both for historical interest and because they are usually less toxic...they also often have unique properties that modern materials haven't quite matched yet.

I have never used sinew so this past week I have been playing with sinew backing an ipe stickbow. My hope is to apply this to making a sinew backed ipe prod. But laying on sinew is not as simple as it looks. I've already done 3 courses of sinew that I have needed to strip off for one reason or another.

OrienM wrote:It was just a guess as to how thick the layer should be, but I figured too much sinew was as bad as too little, and would would overpower the belly wood.

My understanding is sinew will never overpower the wood belly like fiberglass or bamboo will. It has very little stiffness compared to the wood. The neutral plane shifts towards the stiffer material. Heavy courses of sinew should push the neutral plane towards the belly therefore taking compression forces off the belly and exerting more tension force onto the sinewed back (which it can take). Stiffer materials like bamboo backing will shift the neutral plane towards the back and therefore force the belly into greater compression. The biggest problem with thicker layers of sinew is the added weight and that the backing is more hydrophillic and less stable in wet climates. Of course this is only my understanding of the subject, I have not played with sinew until now so I could be wrong! According to the traditional Bowyers bible a course of 30% sinew should make the bows backing virtually unbreakable (assuming a good tiller). Then it is a matter of the belly being able to withstand the forces being exerted on it.

Hey there Orion, I haven't seen you on Paleoplanet for some time!
Very nice cross bow! How fast is it shooting and how heavy are the bolts? I built a hickory prod x bow last year that was 60 ntn and 80 lbs  
at 27" . The cool thing about it is you can shoot regular arrows with it.
cheers fiddler49

Hi Fiddler, nice to see you here! Thanks for the nice words...I still need to get this thing measured as to speed, etc, but will post when I do. I have made a set of ash bolts for it now, and I'm finding it a very fun weapon to shoot. (It took its first game, a cottontail rabbit, over the weekend too...I made a very nice head shot at 30ft or so )

For various reasons, I kind of dropped off the 'net for a few years; I really should pop in and say hello to everyone at Paleoplanet sometime soon. I'm actually just about to start teaching a group of high-schoolers some primitive-technology type stuff this semester, so I've had primitive skills on the brain a lot recently.

I think the "full sized" xbow sounds really cool (if a bit bulky )...in researching my own xbow project, I came across some SE Asian bows made similarly; they were described as crossbows for warfare or large, dangerous game. Being able to shoot regular arrows would be a nice feature.

A few close ups of my wooden nut, for Gnome or anyone else who's interested. Hard to see the laminates, unfortunately, since the wood is so dark in color. (Also, my "looks good at arms length" workmanship looks pretty raw up this close! ). This worked out well, though, and I wouldn't hesitate to recommend something similar for under-200# crossbows.





My use of JB weld to glue in the sear doesn't help the appearance either, lol, but it sticks much better to metal than epoxy, imo. Wish I'd added a little charcoal dust to the glue.

As an aside, I came up with a possibly new way of notching a nut for the tickler. The hardwood plywood was extremely hard to work with cutting tools, so I ended up using a red-hot piece of metal, the same size as the working end of the tickler, to burn the notch in. Very fast and easy method, it turned out.

Orien, I made a delrin nut ,same as you show. I found out one thing for sure. I could not cut the fingers at 90 degrees to the axle. The stuff is so slippery that it would dry fire .I'm not riding the table real hard though. I luckily caught it before  it went off. I had to angle my fingers so that it kinda became a mild hook of sorts.I'd be interested to know if any one else has had problems similar. I done all the cutting in a mill  and set up right on. By the way nice work my friend. It looks a treat.

Thanks for the nice words! The fingers are tipped backwards by a degree or two, but it's hard to see in the photo. (I had made that mistake already too, on an earlier, aluminum nut ). I agree, a little bit of hook makes for a much more secure grip on the string. Dryfires are scary...

I sort of wish I would have made the area behind the fingers curved (like on original medieval nuts) instead of flat; a detail to remember for next time. This one does reset itself when cocked, but only just barely rotates back far enough. The curved version would probably work better.