The Hybrid Compound Crossbow

How to build a hybrid compound crossbow by combining medieval and modern technologies into this weapon, the article includes crossbow parts diagrams and general building instructions.


| March/April 1987



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To get the best of compound bow technology and crossbow ease of use without complex construction, we’ve married a stock-and-trigger system to a store-bought compound bow—in this case a Bear Whitetail Hunter.


PHOTO: KEN FORSGREN

Build your own hybrid compound crossbow using these building instructions and detailed diagrams. 

The Hybrid Compound Crossbow

It’s a common myth that the crossbow of the Middle Ages was a far superior weapon to the bows of the time. In fact, in the hands of a skilled archer, the medieval longbow was more accurate, had longer range, and could deliver more arrows in a given period of time. The crossbow was popular largely because it stayed in the cocked position without strain on the archer. Because arrow (or bolt, in crossbow parlance) release was always the same, accuracy was easier, too. In short, the crossbow required less skill to shoot.

As a result, when firearms replaced bows as weapons of war, the all-wood longbow became the mainstay of sport archers and hunters, and the crossbow became a sinister weapon non grata. 

Recently, interest in the crossbow has rekindled because of improvements in performance made possible by blending composite materials and compound (aided by pulleys or cams) bow technology. In our September/October 1984 issue, we told you how to build a simple crossbow (one that differs little in basic design from those used nearly a millennium ago) and related that the performance of even commercial versions of this design was mediocre. By contrast, this compound crossbow has very high arrow speed, reasonable range, and accuracy comparable to that of a modern bow. It's also sophisticated and complicated.

To get the best of compound crossbow technology and compound crossbow ease of use without complex construction, we’ve married a stock-and-trigger system to a store-bought compound bow—in this case a Bear Whitetail Hunter. The system bolts to existing holes on the bow, so it can be attached and removed easily without modifying the bow itself. Many bows, including most in the Bear and PSE lines (and others), have threaded holes (or a series of slots) 9-3/4 inches apart for mounting the stock. Some, however, such as Browning bows, can't be fitted.

To keep the assembly’s weight within reason, it’s essential that you use aluminum for most of the hybrid crossbow’s parts. Tubing available from hardware stores works well, because it can be cold-formed. Though more sophisticated alloys would be stronger, the heating procedure used to bend the harder material is beyond most tinkerers' capabilities. With the added support of the side strut, this tubing is strong enough to handle the stress exerted by the 65-pound-draw compound bow (probably less than 45 pounds at full draw). If you plan to attach the mechanism to a more powerful bow, you should consider using a more rigid material. We used 6061 T6 aluminum plate for the flat parts, but 2024 T3 would also work well.

todd reece
2/16/2010 11:58:51 AM

Wow... a serious weapon. I wonder, seeing how the article said some bows were compatible and some are not, I wonder which bows built in the past 20 after this article would fit the requirements? Has the author kept up with the possibilities, can he give a list of what to look for, or is this just another nice "the way it was" articles? Either way.. fearsome weapon, and despite no "range" report, looks like it could really do the job.






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