Light weight crossbows

So i was searching for lightweight crossbows becouse i have had a bad back since i was just a kid, and its a bit hard for me to carry very heavy stuff for a while, exercise or hold a bow with a draw of over 45 pounds for a long time (one of the reasons i like the crossbow better), and all the x-bows i found were at least 5.6 pound wich is very light, but not as light as the crossbows i make (4.5 pouds at most) wich was kind of a surprise since those x-bows have fiberglass prods and the steel ones sold by "Alchem" or "Slowbows" weigh 2 pounds at most(just the prods), but my crossbows almost always are tied with hemp and have fiberglass prods and i always make the stock pretty short and the trigger a wooden hole and peg style since i never make them over 150 pounds, anyway, i was wondering how heavy your crossbows are and maybe ideas on how to make them lighter

You can use a composite stock and add holes along the length, also reenforcing with aluminum would work. I take it you are not going for anything other than a 21st century look? Carbon fiber plates would work.

Nah, generally i always make medieval crossbows but i always use fiberglass prods becouse ive seen a lot in flea markets around here, probably salvaged from cheap walmart crossbows  , anyway i really like your idea, i hadnt though about making holes on the stock an using aluminum plates, might give it a try, my goal would be a 3.7 lb crossbow wich is just a bit more than my recurve bow, but i think its still posible with a draw of 125 lb wich is my favorite since i can span it like nothing and think its still powerful enough to take deer, or at least quail and phaesant, anyways good idea.

The majority of my builds are pretty darn heavy, though I don't think I ever weighed any of them. Now I'm curious to see what they weigh. For me balance has always been more of a factor than total weight for shooting comfort. I've got one piece with a bull-pup, thumb-hole tiller of ash wood with a fiberglass prod secured with wooden wedges and a foot stirrup that is mostly aluminum. It is one of the lightest builds I've done, but I actually added weight to the back end by drilling a half inch hole in the stock and gluing in a steel rod. It's still pretty light overall, but it balances exactly in the palm of my offhand, just  a couple inches in front of the trigger assembly.
Not using metal to secure the prod and using a strap for a stirrup are pretty big weight savers, and regardless of what material you use for a tiller or stock, wood or whatever, eliminating material from where you don't actually need it adds up. Or subtracts down, I guess.
Gnome

A while ago I put together this "Viking" crossbow, pulls about 47kg/28cm (~100#/11") - roughly comparable to 50# longbow in power. Rowan prod, birchen tiller.
Nothing special...

.. except that the whole thing weights just around 700 grams.

In fact it is so light that despite its large size- prod is 1 meter wide - it can be easily shot with one hand


With 150lbs prod , the mass would increase couple hundred grams max. Even if a rope or metal wire stirrup was added.

There really is no reason a normal 150 pound field crossbow should weight more than a kilogram.
People are just overbuilding them. If one thinks about the strain components like stirrup and lock frame need to endure, they only really need to be as heavily built as the bow string.

Hey Hullutiedemies, i just built a crossbow that pulls 75 pounds with a 13 inch draw that weighs 2 pounds, maybe less, i would say its about as powerful as a 30 or 35 pound longbow. I've also been meaning to ask you or anyone actually about steam bending wooden prods, after you bend them how long do you let them dry? and is there a formula to know how much bend your prod needs or how do you do it.

Here is a modernized version of the "viking".
Seen unfinished to show matrials


Solid fiberglass rod bow from electric cattle fence posts (*), fir tiller, lock notch and bolt table saturated with superglue. Work hardened aluminum bolt clip. Stirrup and butt from 6mm aluminum rod.
The whole thing weigths just 280 grams.

Bow pulls 35 kg at 335mm stroke (~80"/13#) roughly twice the power of those commercial pistols. Energy capacity is bit shy of 60J and the prod weigths only 90grams- so it is seriously fast. I have not had time to measure the speed properly, but this shoots allmost as flat as my wood compounds. I had no problems landing judo bolts at tree stump 70 m away.
This would be quite adequate for hunting (35-45J bolt energies are in 40-45# longbow ballpark).
Recoil is bit unpleasant because of the light weight. For target shooting I'd add more mass to the stock just to dampen recoil. But this would be nice as hikers sidearm.


(*)Here is an European substitute for chainlink tension bar. Farming suppliers and sporting stores selling horse riding equipment are places to look for these.



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steam bending wooden prods, after you bend them how long do you let them dry?

Long enough. I never paid any real attention, there is seldom hurry with these. I try to do this when the stave is green so it just goes with normal curing.

Awesome crossbow dude! thanks for sharing, and yeah i figured about steaming prods, got a couple of books about it, seems easy enough, tho i haven't tried it.

A 3 lb recurve bow?  My recurves weigh in at 15 ounces and 18 ounces!  My crossbow weigh less than 3 lb as well...

And since there is no point in light weight crossbow if it is too big to be carried, I re-tied the bridling to a flexible knot

so the whole thing folds nicely into a quivier.
Needs some care to center the string when cocking, but that is no different from shooting a hand bow. Otherwise this should actually improve the accuracy, mimicing the relaxed hold of an olympic archer.