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Topic: Arm woes - what to do? (Read 1166 times)
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David Delaney
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Just curious if anyone experience this when building the arm :
When all the bolts are through and I swivel it from side to side (without the springs), it kind of sticks a little near the end. I know this is because obviously I am off on one of the posts and the bearings (really sucks!). I don't know how much of an effect it will have at the end of the project, but it hesitates slightly as I swing it one way (just the bones). What did others do when problems like this occurred (if this has happened to anyone else)?
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michael stevenson
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How, exactly, did you make the hole that the bearings and bolts go thru?
Michael
(CNC Machinist)
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David Delaney
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I used the first one as a template. I was really really trying to be careful, but I guess I slipped up somewhere. It isn't too bad, but I don't know the mechanics of how it will affect it when it is all put together, so I guess I will have to wait and see. When the arm with the bones is running perpendicular to the posts - the bolt goes through no problem, but when I boom the bones (put in on an angle), the bolt is really really tight and won't come out of the same hole. So I am off probably a couple of millimeters somewhere in the construction.
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Wade Francom
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Maybe one of your bearings hasn't been pressed in flush, the holes aren't exactly lined up, or the bones aren't quite square. At any rate, somethings is causing abnormal pressure on the bearings when they get to that range. I had a bone end-piece that wasn't milled square. It cause a slight tilt in the bearing, and resulted in binding at the end-ranges. It think this may help in your case, but that's the only thing I can think of. I remedied my problem by just filing down the piece to tue-square, reassembling the bone, and it worked fine.
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:-)
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David Delaney
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I wish it was that simple. No, they are all flush. Just must have been a small error on my part. I am really reluctant to go back and make a new post because it takes soooo long with the equipment I have. I think next time, I will use small bearings and get a metalsmith to drill all the holes for the $60.00 an hour or whatever, it costs alot, but at least it will be done quickly and accurately.
I am still guessing that it is going to be ok. I am attaching the springs today and then I can see if there is going to be any problems.
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Wade Francom
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Are you referring to the bearings in the elbow (joining the 2 sections)? If so, having the elbow professionally machined is the only way to go, unless you get extremely lucky.
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:-)
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David Delaney
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The more I play with it, I think it might just be a bone that I have a 5/16 hole a little too far out. If it cause me problem I will just turn the bone and drill some new holes, if not I will buy a whole new section. The bone is by far the easiest part to create, but the shoulders, post and elbows, they to me, are the most challenging.
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