After that rather long project I felt like a quick try with something that's been on my to-do list for years, a hinged fold up bow.
I bought a couple of stainless steel strap hinges/marine hinges off Ebay and fitted one to an odd miss matched pair of limbs from broken bows. One limb was Ash backed Yew and the other a piece of scrappy Yew, each hinge has three 3/4" countersunk head screws holding it. The purpose of the try out was to see how sloppy the hinge would be and if it would hold a 50# bow. It holds the weight ok, but will need a pin/peg or some sort of locating arrangement to take out some of the slop. The limbs are too mismatched to use as a workable bow, but I may experiment a bit more with ways to get good alignment and maybe grind the hinge down to make it less bulky.
The screws are just "general purpose" but they are twin thread and fairly coarse. I could use a longer screw or go up in diameter.
That's an interesting idea... the strain on the wood at the screw holes must be colossal - how will you stop the screws splitting the wood and tearing out under the (bow-wise) longitudinal forces?
ReplyDeleteThat was the point of the experiment, and it seemed to hold 50# fine. If it was just the one screw nearest the hinge point I'd expect it to split out. If it was the one screw furthest from the hinge point I'd expect it to be ok. The force on the screws is in a combination of pull out and shear. Seems to work, they are deep thread screws... I'll add a picture of one. Wood screw technology has moved on a lot over the last 20 years or so.
ReplyDeleteAh, yes - I look forward to seeing how it goes :)
ReplyDelete