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Cedric Akins
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Cody would you know if anyone has ever done modifications to Cody's plans to make it into a 3A version? If so where might I find pulley wheels that would work? I believe it would be possible but I am not sure. Iam using 32.5 lbs. springs, 6" long with end loops (4.25" without).
Cody could you help, is it plausable?
Cedric
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Cody Deegan
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My book BUILDING A STABILIZER ARM is a 3A style arm using pulleys and spring plugs. However they are parts that need to be made custom by a machinist. I have not heard of anyone modifying my older arm into a 3A style. The wrists are not designed to accept such modifications. There would be no room for the pulleys.
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Cody Deegan
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I saw some 1" steel rollers at the hardware store today that are made for sliding doors. They have a bearing already encased in them, about $3 a piece. They look like great candidates for pulleys if one didn't want to have custom ones made.
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Phil Kindred
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Before I switched to drawbar springs, I had my rig set up with the same thing Cody is describing. They are very smooth, cheap, and will do the job. With the proper mounting, you will get a real bargain. The only disadvantage is they are heavy--bearing and brass.
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Cody Deegan
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I've found some steel and nylon ones. The nylons were light but I am not sure how durable. Not sure what this one is - looks like brass, but they say the bearing is steel:
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Phil Kindred
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The nylon is lighter--I went for brass because I thought metal was better. Also, the nylon ones seemed to be less tightly fit--just a personal thing.
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Cedric Akins
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Would either of you know where I might be able to find the brass and steel kind. I really would prefer to get some of the ones with the bearings already included. If I can't find them around here locally I would be happy to purchase them from either of you, Cody or Phil. I would pay you for your time as well as the cost of the 8 of them plus the S&H. This is provided that they aren't too costly. Besides it beats having them made at a machine shop.
Thanks
Cedric
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Cedric Akins
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Thanks guts I located them at a Homedepot in my area. They were a few pennies cheaper here so obviously I purchased them. I will begin testing them to see how much stress they will be able to handle. To be honest I thought they would have been much heavier. I believe these should do the trick.
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Phil Kindred
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Glad you found them You have joined "The let's find something already built that I can adapt " Brigade of which I am an enthusiastic member.  |
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Cedric Akins
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Just thought I'd let you guys know. I the pulleys work fine but I ran into clearance issues. I believe I could get around it but I think it would be better to see if I can get a real machine shop to assist me in this. Also I am unclear on the proper spring length and diameter. The springs I am using now seem a little long, but then again I haven't clipped the ends or had spring plugs made. I know that should be done after testing the unit. Oh well back to the drawing board. |
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Cedric Akins
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In case you guys want to see what I mean about clearance problems I will post some pics later today. Now take into account this is an protype attempt and I am in the testing stages. All of my wrist parts are in 1/8" aluminum. So I know that it has torsion problems. This is just to see if I got the right springs or not. I WILL NOT use this on a video shoot due to it's torsional issues.
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« Last Edit: August 01, 2005, 10:37:24 AM by Cedric Akins »
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David Delaney
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Just thinking off the top of my head - if you put a small enough pulley inside the post inbetween the bearings, could you run a 3A design with only two/three springs and wire? You would have to hollow out the bones so the spring could run in it - so you have a U channel - and use aviation wire inbetween the two/three springs (top and bottom), but would this work on the old design?
Here is a picture, the grey circles are the bearings with the pulleys inbetween. You can see the springs because they are inside the bones as a U channel. Maybe I am crazy and it won't work, but it was a thought...you would not be able to use more than 3 springs - crossing across the bones, so maybe it won't
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« Last Edit: August 31, 2005, 12:21:22 PM by David Delaney »
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Wade Francom
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You should look at Cody
s newer plans. It is a 3-A design, or check out my arm under Wade Francom's Arm in the HBS Members Systems in the Flyers Lounge. It is a 3-A design.
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:-)
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David Delaney
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Yep, saw it - it looks great. I think after I finish this one, if I still have the motivation, I will buy the new design plans and start up on a better 3A design/
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Cody Deegan
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Well, the only problem with the setup illustrated in your drawing is that the cables are running right over the pivot points. In a 3A style design, the cables run over a point that is higher and behind the pivot points. This, I believe, helps tremendously in the arm's ability to absorb shocks.
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