Primitive Archer
Main Discussion Area => Bows => Topic started by: Del the cat on July 21, 2011, 02:37:20 pm
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Inspired by a picture of a 'Bow Weighing Machine' made by Clarence N Hickman in 1938 I've made this machine :).
His one used rack and pinion gearing, but I don't have any real metal working facilities so I've geared it with pulleys.
It needs some fine tuning, return springs and such like. It also needs calibrating for length and weight.
I shall try and fit a nice black felt pen so the curve shows better and do a video once I've finished the detail (Hopefully tomorrow). The great thing is it works!
(http://i411.photobucket.com/albums/pp195/Del_the_Cat/Website%20stills/100_1297.jpg)
It's a treat to watch it work, the bow sting is hooked onto the back of the machine and the bow is pulled up by the handle, a thread is also hooked over handle and this is geared to pull the graph plate horizontally. A big spring from a spring balance is incorporated into the base and the stretch of this is geared onto the vertical slide where the pencil is spring mounted using a bit of hacksaw blade.
It's just 'designed' on the fly using stuff I had lying about, I've been thinking about this project for a few years and I've built it over the last few weeks.
http://s411.photobucket.com/albums/pp195/Del_the_Cat/websitevideos/?action=view¤t=fddemo-1.mp4 (http://s411.photobucket.com/albums/pp195/Del_the_Cat/websitevideos/?action=view¤t=fddemo-1.mp4)
Dunno if this is really the place to post it, but just wait for the video, it will make you smile.
Del
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It's gonna take the video for me to get it. Looks cool though. :D
George
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yep video would do, more pics would help too
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That's just cool! I can't wait to check out the video.
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I've removed the old video, this is the new one.
http://s411.photobucket.com/albums/pp195/Del_the_Cat/websitevideos/?action=view¤t=fddemo-1.mp4 (http://s411.photobucket.com/albums/pp195/Del_the_Cat/websitevideos/?action=view¤t=fddemo-1.mp4)
I've cropped it a bit tight at the end to save download time.
You have to ignore the line it plots on the way back down as the pen only returns slowly, I need to adjust the return elastic!
Del
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That't nuts! In a kind of brilliant way!
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Sweet! :) :) :) :) :) :) :) :) :) :) :) :) :) :) :) :) :) :) :)
Love it! Great thinking
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Great videos there!
This one is doesn't work so fine, but could see for a moment how it working. It is great! Congrats!
Looking forward for this project shure!
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That is way cool, how accurate is it?
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So cool!
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That is way cool, how accurate is it?
Not very accurate yet, I'm still working on taking the slop out of the mechanism, adding return springs (elastic cord) and calibrating it.
It's getting smoother and better all the time.
Dunno how much I'll use it, I just made it for the challenge of it really.
It would be handy if I was building Asiatic recurves with siyahs for testing differnt arrangements.
Dunno how much difference I'll see in my longbows and primitives, but I'll find out pretty soon.
Del
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All I can say to that is WOW!!!
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Seriously cool contraption!
Hope you get it to work properly.
/Mikael
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Here's another video explaining how the two movements, horizontal and vertical work.
http://s411.photobucket.com/albums/pp195/Del_the_Cat/websitevideos/?action=view¤t=FDdemo.mp4 (http://s411.photobucket.com/albums/pp195/Del_the_Cat/websitevideos/?action=view¤t=FDdemo.mp4)
Del
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well that was fast, ask for a video and we gett two. nicely done. and thanks
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You've got quite the contraption there Del! So does this graph the poundage per inch pulled?
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You've got quite the contraption there Del! So does this graph the poundage per inch pulled?
Exactly, once I've calibrated it, I'll draw up some graph paper to suit and photocopy it, the vertical scale will be marked in pounds and the horizontal scale in inches.
Del
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Now all you need to build is a wooden robot arm to pull it at a steady pace :)
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Amazing.
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Like it!
Isn't the correct fd curve an average between when you go up and down. When you pull up the friction in the machine is working against you and when you go down it's working for you.
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::) :-\tec.over load but quite interesting all in the same machine. Cool 8)
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I couldn't understand how when I calibrate the machine I get a lovely big vertical deflection, but when I do it with a bow the graph is about half as high as it should be ???.
Eventually after some extra tests it dawned on me..... I was a factor of 2.2 out, have you worked it out yet?
Yup, I was reading my dial in Kg not Pounds ::).
Yeah but I figure that now I'm twice as strong as I though ;D
Del
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LOL, gotta love it. Hate to tell you, but as you get older those kinds of mistakes get a lot more common. :'(
Did you make the cool bow you put on the machine in your video? Looked real nice.
George
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LOL, gotta love it. Hate to tell you, but as you get older those kinds of mistakes get a lot more common. :'(
Did you make the cool bow you put on the machine in your video? Looked real nice.
George
Cheers George, yeah, I made that in 2009 using up some old f/glass lams I had from my crossbow making days, I glued them up unto a Maple core made from a bow I made which came in underweight. Here's a couple of pics.
(http://i411.photobucket.com/albums/pp195/Del_the_Cat/AR_Bow-1.jpg)
(http://i411.photobucket.com/albums/pp195/Del_the_Cat/ARBow.jpg)
Del
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Nice, I'll bet it spits out an arrow.
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Nice, I'll bet it spits out an arrow.
Yup it does but I don't shoot it much, the club where I shoot is theoretically a Longbow (ELB) club... but since I joined they allow primitive too ;D.
Just gotta finish tweaking the FD machine, then I can tidy the garage and makes some Yellow shavings ;D ;).
Del
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I understand, it's nice they've compromised for you. Of course, your ELBs are gorgeous so they must like you for that I'd think. ;) I wondered if you'd started. Have you practiced a splice yet?
George
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Nope, but I'll get all done and tidied up, then I'll be ready to splice on Monday (when Mrs Cat goes out to choir, I can have some quality time with my wood ;D. Whoops, maybe I should rephrase that? :-[)
Del
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Cool contraption Del! :o
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Still having fun with your wood...at Your Age....way to go Del........... :laugh: