primitive crossbow

[backgardenbowyer]

Well, it's primitive and its a bit of fun, so I hope you'll allow it here.....

Having a couple of days free at the end of the Christmas holiday when all the relatives had gone, I finally finished my winter project - an all wood (and horn) crossbow based on the peasant "lockbows" found at Skane in Denmark.  The prod (bow) is the only usable piece of timber I could get out of a yew tree which was cut down on the university campus where I worked a couple of years ago - but what can you do with one yew billet?  ... a crossbow seemed the best solution.

The bow is about 75 # 16.5 ins which is a fairly long draw for this kind of weapon.  The tiller isn't great as I ran out of heartwood on one limb - and the string serving isn't properly centred, just ignore that mistake please!  Given that crossbows are only about 50% as efficient as long bows this means I get about the umph of a 35lbs ELB but shooting a much lighter, shorter arrow of course, the fps will fine for a bit of plinking or maybe even a field round if I get the chance - its seems plenty quick enough in the limited testing it has had so far.

Confusingly for longbow archers the stock is officially called the "tiller" and its a cheap, nasty piece of meranti from the local wood yard (they wanted a silly price for some oak), so I reinforced the "lock" area with some black buffalo horn.  The tickler (trigger lever) is a scrap piece of ipe and all the dowels are from salvaged arrows (where else!).  I was going to use hemp for the bridle (binding) but it was quicker and cheaper to pick up some jute twine from the local DIY store, and some of this was counter twisted to make a simple rope stirrup so that it can be cocked without putting my feet on the bow itself (which seems to be how the original bows of this type were used).  Its generally thought that early Norman bows has this simple notch and push pin mechanism, but some C16th examples have shown up from an excavation connected with a peasant revolt - you could make this with very simple tools indeed.  In case there is any confusion the bow is drawn and the string anchored by dropping it into the horn reinforced notch.  The pin sit below the string and is released when the pin pushes it up and out of the notch.  Simples!

I believe similar bows are used in parts of West Africa - so there is a real claim for them to be "primitive".  All natural materials apart from the usual exceptions of string and glues, and I may well make a linen string as this will faster.

I've not got the bolts right yet.  They are mostly two flights (which is typical) but are corkscrewing a bit - I quickly bodged up a couple with three flights at 90 degrees and they seemed to work better.  I suspect two 4" fletchings set on a spiral is a bit much for such a short arrow and would need a longer bolt with a heavier head to fly true.  Despite this a limited short range test suggests that the bow is quite accurate.

I've a bit more tinkering to do - maybe add a hickory spring to retain the bolts and a simple safety to wedge the string in place at full draw so the crossbow should meet NFAS safety rules, but the originals didn't bother with such refinements and it would spoil the look a little.

Sorry for crappy photos taken on phone

Enjoy

[toomanyknots]

I like it! Very simple and effective! Is the dowel that pushes the string up actually glued to the ipe, or does it slide freely?

[ionicmuffin]

TMK i believe it slides freely, i think glue would cause it to break(the glue) because of the movement involved, just a guess though

[Del the cat]

Try heavier points on the bolts too, with a short power stoke at a high poundage it's good to have some extra weight for the bow to work against.
You may only get the same speed as a 35# longbow but with a bolt 4 times the weight you will generate more power.
Del
Have a look at this post in my blog, comparing crossbow vs longbow speed vs power.
http://bowyersdiary.blogspot.co.uk/2011/10/graingram-scales.html

[richardzane]

I remember as a teen trying (and failing) to make a crossbow from a 2x4,
man..no if i had seen something like this (in the 70s) i would have flipped! "wow! I can do that!"
 thanks for sharing the details, love the simplicity.

[backgardenbowyer]

The dowel isn't fixed to the tickler as the later moves in an arc rather than directly upwards - at the moment there is nothing to stop the dowel pin falling out of the top - this is only temporary, I'll either put a base on the pin or a bolt clip on top of the bow to prevent that.

Del - thanks for advice I was of course partly copying your own lockbow which I have seen and shot.  My work will never be as good as yours!  I will indeed try heavier bolts, but want to maximise speed/trajectory rather than energy from this light bow. The bolts were just made out of broken arrow shafts and bits and pieces.  Hope there will be another primitive archery camp this spring and we can compare notes there.  Not sure if NFAS ill accept these even with a safety catch - they also require a trigger guard which isn't possible - unless you argue that there is no "trigger"