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Medieval Crossbow
Medieval crossbow build along
by uccrossbows |
Figured i would try one of these.
This is an advanced medieval crossbow. The design is of a Swiss crossbow used in germany and Italy in the mid 1400's. The materials used are: Leopardwood, ebony, Ivory (hippo), gemsbok horn, bull horn, buffalo horn and brass.
The fittings and screws used for the bow are hand made and to spec of what the smith would have used. The light prod will pull 120lbs and the heavy prod will pull 350lbs.
The bow will be set up with a goatsfoot pin to birdy the heavy prod and can be used for added realism for the light prod that could be pulled by hand.
the stock.
This is a Leopardwood base with a madagascar ebony veneer top. The stock is not polished yet. It has about 120 coats of tung oil on it and will polish out to mirror. I was going to use a koa wood stock, but have questions as to the wood as it is developing cracks.
This stock will hold heavy poundage just fine.
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 Next shot is of the gemsbok horn and ivory thumb board. These items were used as a rear sight where the shooter puts his thumb on the board and uses the thumb knuckle as a rear sight. They are actually very crude - but VERY accurate.
This piece is solid gemsbok and ivory.
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Ivory top with gemsbok center. The brass railing are not in the pictures - i need to cut them and have to wait until i deside what thickness the stock will stay. I am thinking of leaving it at the 1.5" but might plane it to 1 3/8"
The rails will get the brass rails inbetween the horn and ivory including across the flat horn plate mid rail. From there i will sqaure it all up and clamp it then fill the under side with epoxy and let it set. This will allow me to joint the bottom to a 4 degree up slope and match the bottom to the stock top. It also gives a very strong top to handle the stresses of a heavy prod.
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below is a pic of the first of the two 1/4" thick ivory, gemsbok,brass and silver rails that the bolt rides down.
The picture is kind of blurry due to low light at the time i will take better soon.
The rail shown has the horn/brass cross piece edged upto the back. 17 total pieces go into the top rails front to back. The pieces will be cut to shape and then polished. I added the silver center rail as an after thought to the plans as i wanted to break up the darkness of the bow. I think when polished the reflection of the brass/silver with polished black gemsbok will contrast the polished ivory VERY well.
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Another of the stock and thumb board.
Am now working on finishing the board and the rails.
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Been busy making the metal pieces for the bow. Here are some more pics....
Pic of the forge at temp for making the prod for the bow. Its about 1900 degrees in there in this shot.
Side note:
This forge is the biggest non commercial forge in texas and i believe in the united states - but i know for sure in texas. It will melt iron and reach a max temp of 3000 degrees.
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 Pulling the prod out. I was running the camra.
That is the owner of the forge - good friend of mine Dan. He is a blade maker and armor smith. Does well for himself making custom and production blades and armor.
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Walking the prod for quenching. The steel is at 1550 to 1600 degrees here. steel is magnetic right? not in this picture, a magnet will not stick to it right now. Its at critical temp.
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First dunk in quench. Yes thats smoke and lots of fire coming off the steel.
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Another quench cycle after the steel is a tad cooler, still is igniting when it comes back up.
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HEre is the prod after tempering, clean up and retemper.
Altho the camra doesn't show it well the prod has a nice "temper blue" to it.
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More pics to come, last saturday i cut out the goatsfoot prongs and teeth. The bow itself is coming together this week and next.
Test firing on the prod was done - very smooth prod, am very happy with it. Will be making the heavy 400 lb for it soon. But for kicks and giggles here is a pic of the 550lb/650lb prod i have sitting here waiting to go on something.
This prod put a bolt through 3 plates of 18 gauge steel, continued through the hay bails, smashed through the 1/2" plywood back stop and shattered the bolt when it hit the ground.
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For this bow i am making two prods, a 137lb pictured and a 400 to 450lb.
The 137 will fire a 300gr bolt at about 180 fps.
The big prod will fire 700gr bolts at about 170 to 185fps
Either way it will be a fun one to shoot light or heavy 
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Q: Can't you use the light arrow on the heavy prod?? cause that would be frickin awesome?
A: No. Same reason a bow would come apart using a light arrow. It forces a "dry fire" condition. Like bows, if you dry fire a bow it produces vibrations and forces within the limbs that can take a prod apart. Firing a light missile is like dryfiring. It will do damage.
Specifically a steel prod, this will make the tempered steel shock, this shock will eventually translate into stress cracks - maybe the first time or maybe not for several times. When the micro cracks start showing up however the prod starts to become weak.
A bow RARELY breaks when at rest, you will get the break when birdying it or when it fires. This motion fragments the steel prod at the break. What translates then is what i saw.
The end loops of the string catch the end of the prod, the forward motion of the limb tips catcha dn flip the (now steel shank) around like a spinning knife. It is spinning so fast it sounds like a rock that ricochets off sound thing - you know that high pitched buzz?
The other side of the prod usually stays intact and throws the bow out of balance ripping it from the shooters hands. If it seperates it to catches the end loop and takes off spinning. Between the fragments of metal at the break and the spinning chunks of steel EVERYTHING within 10 yards side to side can get hit by the fragments and anything withing 50 yards can get a shank.
The velocity in which this happens is such that by the time you hear the crack of the prod break you have been peppered with fragments and stuck with a shank of steel.
The way to get around this is to bind the prod with a strap of leather on the back that goes over the string pins. the string keeps it from flipping in and the leather strap keeps it from flipping out. The bow kicks and fragments fly, but thats better then the shanks.
Hope that helps
Not only can this happen with firing light missiles in bows AND crossbows - it gets worse in crossbows as you are usually using two to fire times the weight of a normal sporting hand bow. When the string slams "shut" after firing you are producing 5 times the weight of the prod on the string and prod itself. So firing say 100lb crossbow - the string and prod feel 500lbs of force the instant that prod comes to brace. Its not unusal to see the string marks on a freashly waxed string travel 2.5" infront of a braced string (at rest and not birdyed). Try and push that string that far.
Now - this admittedly is worst case.... I have seen prods explode - sound like a shot gun and no one gets hurt - its part of the game. But i have also seen the very worst side.
Making a steel prod - even out of a truck spring gets even more touch and go.... make it wrong - quench it wrong - temper it wrong and you may have a brittle prod that will frag like a granade (yes tiny frags and 100's of them) due to a rockwell not in the right area of hardness OR spring de tempered from grinding or a stress crack in the spring before you ever got it.
Not trying to scare anyone - but it is very serious business and you need to know what you are dealing with and what to do before you attempt it. A 100lb prod vs a break on a 50lb bow - night and day in damage
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More info:
In a steel prod the best way to find the best bolt is to get a crony.
See the tip speed of a steel prod is fixed. It only gets to a certain speed - everytime.
How you find the bolt that matches the bow and best performance is to get bolts that are 25 grains difference from about 200gr to 700+ grain.
fire the 200gr - check fps, fire the 225gr - check crony.
What you will find happening is your getting about the same speed until you reach a point the bolt slows the average speed down by about 5 to 10fps. That is the max bolt you can fire and maintain peak fps which translates to max range, accuracy etc.
See in a heavy bow firing a 200gr bolt you will prolly see 190 to 200fps. Firing a 500gr bolt you will see about 180 to 190fps.
The tips will not come to speed any faster hence no fps difference. Is there small differences? yes - is it safe? NO....
The reason you get such a long flight on a light arrow or bolt is due to gravity, in a weapon with a short power stroke you don't see much in performance in light vs heavy until you get to punching power.
A bolt is much more aerodynamic then an arrow, they will fly farther due to that and to being able to send a missile 2 times the weight of a war arrow into the air at the same speed as the arrow. Graity reacts on the bolt the same, but the bolt doesn't shed its speed as fast (more mass) - hence longer flight times.
Anyways a break away section of a bolt - this might work but your still pushing a heavy missile off the bow - it seperates and the loss of mass will slow the bolt down faster.
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Here is a pic of the medieval two pics stirrup. this was forged and worked by hand.
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These parts i finished today at the forge.
Side pics, bow irons, trigger and roller nut block (for 200 to 450lb bows)
The plates and bow irons believe it or not are 3/16" thick brass plate that has been browned using a sulpher base - (gun bluing). Turns the brass a mellow brown/blue.
The trigger and irons are temp until the big prod goes on. The trigger still needs to be capped with a steel sear and finished.
Also today i got the goatsfoot lever close to done. Need to get 1/4" steel rivits to pin the fingers. I will post pics of that as it comes along.
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here are some of the top being put on.... |
Q: do u use a trigger or one of those little squeeze lever thingy i saw one oncebut how does that realease it
A: Really depends on the crossbow and the poundage. I use one of about 5 trigger systems that are made in the shop here. It depends on the type of bow, poundage of the bow and how real to period medieval i want to keep it. |
crossbows in the later 1500's had traditional triggers as we see them today. Did you know that the set trigger we use today in match guns and black powered guns originated from the crossbow?
The most simple lever action trigger is merely a goose neck and wedge system - aka the roller nut. Very simple but somewhat of a trick to set up right and maintain a crisp release and a light pull.
pic of the bow - long since done - pulling 450lbs
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