Thursday, 6 July 2017

Crossbow Shoots Cleanly

I've got it shooting cleanly now, I twisted up the string to increase the brace height by about 1/4", but I think the stiffer prod mount is also a factor, it was probably moving a fair bit on each shot, that's to say if it put in 2 or 3mm of permanent bend, it must have been moving at least twice that dynamically and that may have been what was throwing off the string. My guess is that I could probably take off the inner string catchers.
I'll probably do more experimentation and development before finishing the MkII prod, after all I want to try to get all the mistakes out of the way on this one.
Now I can take more than one shot I've paid more attention to the feel of the bow and trigger pull, getting lined up for the shot and almost shutting my eyes to concentrate on the feel, the trigger pull is quite hard, but some of that is just feeling the raw edges of the steel, it's also not quite at the right angle to the finger. The bow feel to kick slightly, but again its all nasty corners and an unfinished grip.
It's a good time to strip down the trigger mechanism and examine it. I've been working on it this afternoon as it was rather stiff and is a long pull, I'm ok with the long pull, but some adjustment of the bent (that's the step on the tumbler that the sear engages in) was needed. I jigged it up in the vice so I could use a fine slip stone to just ease it a tad. Trigger mechanisms will wear, some can be adjusted but they will all need some maintenance at some point. A trigger mechanism than can slip could be lethal. A little while back I saw one on a crossbow which had the tumbler made of Aluminium alloy with no steel insert, as I rotated it I could see considerable wear, I mentioned it but was told it was fine and had been round a couple of NFAS courses (I was pretty horrified). We really do need to understand the equipment we use. There was a thread on one of the archery forums about release aids for compound bows. To be frank it was scary and IMO just wrong... here's a quote:-

The problem I had was drawing and getting early misfires. The arrows fly high and long!!!! very scary. Some archers have sorted their draws to the point where they do not expect misfires. I gave up as I could not take the risk... when was the next one going to happen??

To give the guy his due he gave up on that type of release aid and decided not to risk any more misfires, but I find it worrying that there may be others out there who are using triggers and not fully aware of the risks they may be taking. Risks that could be greatly reduced with a better understanding of the need to maintain the equipment and the risks of not doing so.
Over the afternoon I've done more testing and even clamped the crossbow on the bench and measured the trigger pull, it is indeed too heavy at 12 lb !!!! I'll rework it a bit more.

I had a visit last night from a guy with big Yew stave from Salzburg which he'd got from Gunther one of the Austrian contingent at the ILAA Mary Rose shoot the other week. It was a very scruffy bit of wood with some serious damage at one end, one ring that seemed to have turned to black dust for a good few feet and numerous checks and cracks. On the plus side it was big! After much thought, mumbling and head scratching we ran it through the bandsaw to produce a couple of staves. Not quite sure what poundage of bow I'll get from them but hopefully in the 75-110# range. The staves are a "think about it" sort of project, I'll take 'em down further by degrees as the whim takes me.

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