In my first article in this series, I quoted Jeremy Clarkson: “How hard can it be?” Was I really that naive? I’ve been working on this project throughout the year, with three magazine deadlines to meet along the way. This last deadline was given a two-week extension by our all-wise, gracious, benevolent, and merciful editor [Nigel has always been my favourite contributor – Ed], and I was still working on the article right up until the last minute.
One crossbow tiller and stock became two, one prod became five – of which the three laminated wooden ones broke, while the remaining two were steel made from a car spring and a length of T-section fibreglass that I cut down at the cost of a bandsaw blade that was about to be replaced anyway. Apparently fibreglass is very hard on a saw blade, so be prepared to discard it once you’ve finished.
Prioritising
In the previous articles, I touched on the need for prioritising in the design and the implications of that on factors such as weight, balance, and ease of use. Introducing the prod now impacts on each of these. This is no longer the archery equivalent of a rifle; the stock, sighting, and trigger are, but now weight – and, by extension, balance – has been introduced. This also has an effect on ease of use, in terms of both firing and carrying. A rifle and a longbow are relatively two-dimensional in their profile, making them easier to sling back and carry. This is not the case with a crossbow, with the factors to consider being the overall length of the tiller – in this case, 840mm to the end of the foot stirrup – and the prod length of 680mm.
The prod
It goes without saying that the point of the prod – the bow – is to launch the bolt, or arrow. However, in order to achieve this efficiently, other factors need to be considered:
• The nature, configuration, and position of the prod;
• The resilience of the tiller, and its reaction to the considerable forces upon it once a bolt has been released;
• The travel of the bowstring after its release and forward of its static position;
• The downward direction and subsequent friction of the bowstring after its release.
I bought a book called by Rick Sapp. It was my sort of book – full of pictures of longbows, crossbows, recurves,and parts, with some text at the beginning. Some of the crossbows were single prods, some double, some with cams and pulleys, and some with fixed bowstrings. The combinations seemed endless – and these were only some of the crossbows out there; my ignorance hurdles were stalking me again. (Do hurdles stalk?)
