Re: [Utah-astronomy] compact parallelogram bino mount
Jim, Sorry, I was not trying to make an engineering comment, just a "user observation". Of course the legs have to have a certain spread for stability, and there is a relationship between the spread of the legs and the length of the parallelogram, along with the height at which you expect to use it. I was only trying to point out a potential drawback to saving weight by making a short parallelogram. The final choice should be based on your expected uses and needs. If you are backpacking, or have limited space in your vehicle, then size is a top priority. If you are making it to use at public star parties, then you may decide that it is more important to make the design more "idiot resistant". If the binoculars at one end and the weight at the other end define an arc that is as big or bigger than the arc of the legs, it is visually easier to avoid stumbling over the legs. Jo At 01:11 PM 5/20/2002 -0700, you wrote:
hhhmmm, I would have expected that the longer arms (crutches) would require a wider spread of the legs to prevent tipping over. If the parallelogram arms are longer, are you saying the legs can be closer together? Seems like it would be the reverse, intuitively. Jim
Thank you, Jo This is all beginning to make more sense. Who would have thought so many details, but it all makes sense. Thank you for taking the time to explain. Would love to see any pic of a so-called compact Parallel. mount just to see the geometry. I wasn't trying to be picky, just trying to see what I wasn't seeing (even without binoculars). Hope i am not a s confused with the real things in front of me. Thanks again, Jim --- "Josephine M. Grahn" <bsi@xmission.com> wrote:
Jim, Sorry, I was not trying to make an engineering comment, just a "user observation". Of course the legs have to have a certain spread for stability, and there is a relationship between the spread of the legs and the length of the parallelogram, along with the height at which you expect to use it. I was only trying to point out a potential drawback to saving weight by making a short parallelogram. The final choice should be based on your expected uses and needs. If you are backpacking, or have limited space in your vehicle, then size is a top priority. If you are making it to use at public star parties, then you may decide that it is more important to make the design more "idiot resistant". If the binoculars at one end and the weight at the other end define an arc that is as big or bigger than the arc of the legs, it is visually easier to avoid stumbling over the legs.
Jo
At 01:11 PM 5/20/2002 -0700, you wrote:
hhhmmm, I would have expected that the longer arms (crutches) would require a wider spread of the legs to prevent tipping over. If the parallelogram arms are longer, are you saying the legs can be closer together? Seems like it would be the reverse, intuitively. Jim
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--- "Josephine M. Grahn" <bsi@xmission.com> wrote:
Jim, Sorry, I was not trying to make an engineering comment, just a "user observation". Of course the legs have to have a certain spread for stability, and there is a relationship between the spread of the legs and the length of the parallelogram, along with the height at which you expect to use it.
It's not that complicated. There are limits, to be sure, but strict relationships need not be maintained. The engineering constraints on Glen's crutch mount, for example, were: 1: The length of the crutches he found at D.I. 2: The tripod he already had on-hand. (also from D.I.) The arms were too long, the tripod too short and narrow-stanced. And it worked beautifully! Now, if you want to build one to precise dimensions and arm-tripod relationships, go right ahead, but I wanted to be sure no one felt intimidated. In most cases, if it looks right, it is right. Jo and her husband are capable of beautiful, functional, meticulous work, but the crutch-and-two-by-four method will get you there, too. C. __________________________________________________ Do You Yahoo!? LAUNCH - Your Yahoo! Music Experience http://launch.yahoo.com
participants (3)
-
Chuck Hards -
Jim Stitley -
Josephine M. Grahn