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Hi guys, I have been gone awhile on travel but I am home now and back to crossbow stuff and still on my mission to develop and produce low cost drop in triggers to aid the DIY Xbow builders. Especially the first time builders who may not have a shop full tools at their disposal.
So I thought I would post my latest build with with some ideas on how someone can build a fun crossbow suitable for hunting and target shooting without investing in a ton of tools and material. Keep mind that I am no expert like some on this site. So use what is useful and toss the rest!
To me the first design consideration is the bow. The rest of the design flows around it. Weight of course, but most important is draw length.
So here are some bow options that I know. First, the crossbow store (online- google it) can supply ready made bows (prods). I have used Barnett 150 lb prods from that site and they worked very well. They come with a string and ship already strung for $65. I have tested them on my bow testing rack and they pull a true 150 LB at 17" of draw. They shoot 22" 460 grain arrows at and average speed of 223 FPS. (51 Foot LB of energy) Not super speed for a crossbow but way faster than any of my homemade recurve hand bows and those recurves shot completely through deer, pigs, and elk over the years. So I am sure it will take any kind of game. They also have lower cost ($29.95) Chinese bows but they don't have a string and I have heard that they are actually much lower poundage than the advertised 150 lb, like 120# or so, but I have never used one myself.
There are many other options, including steel bows made from car springs and ready made crossbows prods provided by artisans talked about on this site.
But back to the CHEAP option. This bow is based on ideas posted by KenH on this site. (Thanks Ken!) The bow shown below cost me a whole $10! Now that is my kind of price !
As Ken described in his post it is made of fiberglass fence tensioner rod material and is a loose stack design. I found a local supplier here in Orlando and picked up a 8 foot section for $10. I wanted to have the same draw length as the Barnett bows (17") so I made the outer leaf 35" and the nocks are 34" apart. The other three leafs are 28", 18", and 10". I wrapped the center with strong cord and also added short wraps at each section as seen below. For the nocks, I epoxied on a short piece of walnut about a quarter inch thick at the tip and tapering down to about 1/8. I filed and sanded the shapes and then added deep nocks for the main string and a shllow inboard nock for the bastard string as seen here:
This bow came in at 145 Lb at the 17" and gives an arrow speed with the same heavy 460 grain arrow of 208 FPS. (44 Foot Lb of energy) The difference from the Barnett being due I suspect mainly to the increased efficiency of the Barnett recurve design and the slightly lower draw weight on this one.
The disadvantages of this bow are, 1) Width - Barnett is 28" tip to tip strung and this one is 32" tip to tip for the same draw length. 2) Slightly lower speed. (208 FPS ver 223 FPS) 3) You have to make the string.
Advantages: 1) Fun of making your own. 2) CHEAP! 3) Having something different than the crowd.
And here is the finished (OK near finished) cheap Xbow;
Well this is getting long winded and I have only covered bow ideas so far so I will stop here for now and follow up with cheap easy stock and trigger thoughts soon.
John
Hi guys, I have been gone awhile on travel but I am home now and back to crossbow stuff and still on my mission to develop and produce low cost drop in triggers to aid the DIY Xbow builders. Especially the first time builders who may not have a shop full tools at their disposal.
So I thought I would post my latest build with with some ideas on how someone can build a fun crossbow suitable for hunting and target shooting without investing in a ton of tools and material. Keep mind that I am no expert like some on this site. So use what is useful and toss the rest!
To me the first design consideration is the bow. The rest of the design flows around it. Weight of course, but most important is draw length.
So here are some bow options that I know. First, the crossbow store (online- google it) can supply ready made bows (prods). I have used Barnett 150 lb prods from that site and they worked very well. They come with a string and ship already strung for $65. I have tested them on my bow testing rack and they pull a true 150 LB at 17" of draw. They shoot 22" 460 grain arrows at and average speed of 223 FPS. (51 Foot LB of energy) Not super speed for a crossbow but way faster than any of my homemade recurve hand bows and those recurves shot completely through deer, pigs, and elk over the years. So I am sure it will take any kind of game. They also have lower cost ($29.95) Chinese bows but they don't have a string and I have heard that they are actually much lower poundage than the advertised 150 lb, like 120# or so, but I have never used one myself.
There are many other options, including steel bows made from car springs and ready made crossbows prods provided by artisans talked about on this site.
But back to the CHEAP option. This bow is based on ideas posted by KenH on this site. (Thanks Ken!) The bow shown below cost me a whole $10! Now that is my kind of price !
As Ken described in his post it is made of fiberglass fence tensioner rod material and is a loose stack design. I found a local supplier here in Orlando and picked up a 8 foot section for $10. I wanted to have the same draw length as the Barnett bows (17") so I made the outer leaf 35" and the nocks are 34" apart. The other three leafs are 28", 18", and 10". I wrapped the center with strong cord and also added short wraps at each section as seen below. For the nocks, I epoxied on a short piece of walnut about a quarter inch thick at the tip and tapering down to about 1/8. I filed and sanded the shapes and then added deep nocks for the main string and a shllow inboard nock for the bastard string as seen here:
This bow came in at 145 Lb at the 17" and gives an arrow speed with the same heavy 460 grain arrow of 208 FPS. (44 Foot Lb of energy) The difference from the Barnett being due I suspect mainly to the increased efficiency of the Barnett recurve design and the slightly lower draw weight on this one.
The disadvantages of this bow are, 1) Width - Barnett is 28" tip to tip strung and this one is 32" tip to tip for the same draw length. 2) Slightly lower speed. (208 FPS ver 223 FPS) 3) You have to make the string.
Advantages: 1) Fun of making your own. 2) CHEAP! 3) Having something different than the crowd.
And here is the finished (OK near finished) cheap Xbow;
Well this is getting long winded and I have only covered bow ideas so far so I will stop here for now and follow up with cheap easy stock and trigger thoughts soon.
John
(This is fill in work for them.) But they hope to get to it this week if no more high $ interruptions come in.
LOL
I slowed things down this week because I requested a small change. 
Now at some point it WILL go off if you hit it hard enough, as will ANY trigger, due to the inertia of the trigger mass holding it back as the stock rapidly moves forward. But it should not fire with a light to medium hit. It was not bad and it took a hard hit to make it go off. Not unsafe at all but could I make it better? 
I realized that if I reduced the mass of the trigger, it would make it much harder to make it go off with a hit to the stock. I hand machined out material from the middle of my test trigger to lighten it and repeated the test. Now it takes a much harder hit to make it go off. I could not hit it hard enough with just my hand to make it fire but can still get it to fire if I hit it with the hammer very hard. But as I say, any trigger on any cocked gun or xbow WILL fire if you hit the rear hard with a big hammer. Unless you have a safety and it is on. 
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