Wednesday, 19 July 2017

New Prod, Old Prod...

Would you Adam and Eve it?
The MkII prod is actually a whisker slower than the MKI ! Am I despondent? Well just a little.
First problem is the draw weight is lower than I wanted, that's because once I got it braced (which was a nightmare) I could see one limb was stiffer, so I had to ease it off which lost some weight of course.
The good thing is that I now have two similar prods that I can experiment with.
I'm shortening the old one by an inch off each end, which will take it to the original intended length of 36" I'll see if that gains poundage and/or speed. I think I'm maybe near the limit of the materials as the prods have taken a little set (but that's to be expected). I can still heat treat the belly of the MkII if I am careful to keep the heat off the glue line.
I shot the MkI again to provide a reference and it's down to about 195fps, shooting one of my lighter bow pistol bolts takes it up to about 215fps, so that's another area for experimentation.
I'm hoping to maybe test it at a field shoot on Sunday, but we'll see how it progresses, hopefully I'll manage to avoid destroying two prods.
I glued the two 1" off cuts together as a joke and posted it on facebook as an infinite draw weight, zero draw length prod :-)

Meanwhile I bought a quick change toolpost for the lathe. It's only made of Aluminium Alloy and designed for those cheap 7"x 10" Chinese lathes. It's a tad big for my little lathe and looke oout of proportion so I jigged it up and turned 5mm off the top of it, this necessitated making a wooden plug as a steady and also filing the cam on the centre section to suit. The tool holder for a boring bar was also too high, but inverting it and drilling/tapping the holes solved that. It's got a lot of slop in it, but once locked up seems to locate the tools at a reproducible height which is the point of the whole thing.

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