Cams and Grommets...

Hi again!
I had a three or four hour stint in the little corner basement workshop this week. Nothing too dramatic was achieved, but I did manage to start to add the grommets for the strings to follow - you can see them here... You can see in this photo the 'stops' built into the arms so that when the bow arm is in tension, it should straighten out completely.
Also I added the third smaller gear to the 'drive' of the doll. This has slowed the potential action of the doll when it is cranked, just in case any quick motion might have damaged the mechanisms. This has allowed me to move the handle slightly up. Might save some knuckle skin in the long run.


Tonight I've started to break down the cycle of the movements and made a primitive drawing of the possible cam shapes. I have five cams designed into the base, four are now accounted for. One for the up and down motion of the shoulders, moving both the arms up. The next one straightens the bow arm, while the other arm cam bends the forearm of the string arm forward. The fourth cam should pull the upper part of the string arm in the opposite direction as the bow is drawn.

I'm thinking now, as I type this, that the fifth cam could be used to activate the trigger hand to release the bow string - but that might be a tougher done than said.
Here's my very rough drawing of the cam designs based on breaking the time down into 360 degrees. As I've said before, this Kyudo doll won't do every movement precisely, just mimic most of them. I found a video online of a gal putting on quite a performance, and basically decided to time the motions so that the up and down movements of the arms would be the point where the doll would 'cycle' to it's beginning stance. Unfortunately my skills are not up to snuff so much to include the relaxed pose of the archer at the end of the shot. You can see the video that inspired me here.
I'll have to wait another week before I can string this doll up -- sigh. 
Before I go, one more online treat is an old black and white film of Kyudo archers in full armor practicing their combat skills. This is quite amazing, and I think that armor design has given me a few ideas on how to decorate my archer.


Here's something to make your mind buzz for now...