Minor update 1-Jan-15
It has a 5 shot magazine and the bow is cocked via an integral toggle mechanism. The draw weight is 50 Lbs.
It was essentially finished May 2005. (See below for August 2011 update). Construction work started early 2001, after performing the design work in 2000. This period includes 2 years when I could not do any work on it.
Time on the ‘back of an envelope’ enabled most of the problems to be seen and designed out. If I had 3D CAD I would of found most of the ‘clashes’ and enabled the precise timing of the rotating magazine, bolt loading mechanism and cocking mechanism to be achieved without having to visualise it all in my head.
With the exception of the limb materials, all else was made from scrap materials. The design had to be changed / compromised to utilise such materials. The idea was to use high tensile aluminium but suppliers wanted £100 plus delivery plus VAT for a 6ft by 4ft sheet. As I only needed a few square feet, I used bits of low tensile aluminium left over from the conservatory. Component sizes had to be made larger to take the loads.
I had a lot of trouble getting true bolt flight. They were hitting something and stripping fletchings as well as damaging components.
As this is a ‘one off’ it constitutes a working prototype. If I did the job again, the lessons learnt would result in a much better job.
I would defiantly add an 1/8in or 1/4in to some of the dimensions. The extra would allow improved strength / clearances. An example component being the bows centre that attaches the limbs. I laminated this to minimise splitting of the wood, but still had to reinforce with high tensile aluminium rods.
I would consider increasing the size to shoot bolts 5in long, not 4in. Although the effect on the balance due to the extra weight and consequential shift in the centre of gravity would be detrimental.
Anyway its done, now for something else.
Update in 2011.
I finally ditched the wooden riser section that holds the limbs in place. This was the piece that required reinforcing with aluminium rods to prevent cracking. The new steel piece allowed more room such that I could reinforce the mid section of the stock by adding strong wood held with epoxy resin.
The above major changes plus some minor ones make it usable now.
Its only taken a total of 10 years !!
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|Prototype Electric Bow|
|Automatic Cross Bow|
|.45 Cal Ball Bow|
|Self Cocking Electric Cross Bow|
|Chinese Repeating Cross Bow|
|Cross Bow Videos|
|Bow Pistol Photos|
|Prototype Electric Bow Photos|
|Automatic Bow Photos|
|45 Cal Ball Bow Photos|
|Self Cocking Bow Photos|
|Chinese Repeating Bow Photos|
|Break Bow Photos|
|Toggle Bow Photos|