AlienFirstClass
professor emeritus
Reged: 02/13/09
Posts: 738
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I am thinking about building some "crutch tripods".
How stable are they compared to other commercial tripods and other ATM buildable tripods?
Thanks for any info.
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AV in CMH
sage
Reged: 11/07/05
Posts: 461
Loc: Columbus Ohio
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Hi,
I have made one of these and can say that for a C80HD it was fine.
A brace between the legs makes a big difference. I would not use this type of tripod for a long scope or a heavy scope.
Relative to more traditional tripods I have made I would say that the crutch tripod is not as stable. But then, for a low weight scope how much do you really need for average viewing?
The cost and time required to make a tripod from cructhes is very attractive.
Here is a picture of a crutch tripod I made.
Good luck,
Anthony
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ed_turco
member
Reged: 08/29/09
Posts: 27
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As the guy who got this design in S&T (Jan,1996), I can attest to the fact that these are very very stable. In fact, at the minimal coast involved with getting 3 used crutches, it is more stable, dollar for dollar than anything else. As I was quoted in S&T article, "I SAT on it!" At 200 lbs at the time, I sensed no weakness or instability to the unit as I sat there! The pictures show my 4" f/10 scope which is like a rock on a pipe fitting mount. Another picture shows a close up of the tripod head on another scope.
I attach this second picture as there is an issue with how the legs are attached to the tripod head. On many tripods I have seen, the shoulder parts of the crutches are somehow attached to the head by various means, in some cases, the builder even leaves the rubber pieces on the crutches.
My method of construction has always been to remove these shoulder pieces and redrill the holes on the crutch for long screws which go through the head. True, without tooling, this is a somewhat difficult job, but I have done this by hand and by eyeball and come reasonably close.
ANY attachment other than this, such as screwing or nailing the shoulder piece to the side of the tripod head is definitely not stable., and I would have never dared to sit on the top of my tripod and escape injury.
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ed_turco
member
Reged: 08/29/09
Posts: 27
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Aw heck, I forgot the second picture!
Edited by ed_turco (11/05/09 02:51 PM)
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AlienFirstClass
professor emeritus
Reged: 02/13/09
Posts: 738
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Thanks for the info.
So when building a "Crutch Tripod", should one use wood or metal crutches?
And how tall of a tripod have others built...crutches come in different heights?
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StarStuff1
scholastic sledgehammer
Reged: 04/01/07
Posts: 977
Loc: South of the Mason-Dixon Line
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Wood dampens better than metal so....
2nd question: all the crutches I have seen come with adjustments for various heights for the different victims needing them.
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Tools that make objects very far away appear much closer than they actually are.
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ed_turco
member
Reged: 08/29/09
Posts: 27
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Most of my crutch tripods have a length between 30 and 36". And of course, they are adjustable within this range.
I see no reason why one cannot make a 50" one for a refractor platform.
I always use wooden crutches; I think they do dampen vibrations better and they look better too.
Wooden crutches can be had for free out of the weekly trash. Or they might be found on Craig's list or at the Salvation army. How can you go wrong with a mount that can hold a tremendous weight which costs under $20 TOPS? In addition, my 30-36" tripods have always weighed less than 10 pounds.
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AlienFirstClass
professor emeritus
Reged: 02/13/09
Posts: 738
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Quote:
Wood dampens better than metal so....
2nd question: all the crutches I have seen come with adjustments for various heights for the different victims needing them.
True crutches have adjustments but they also come in different sizes...some for shorter people and some for taller people...so if one wants a short or long tripod it makes a difference.
Thanks for the info.
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dpwoos
sage
Reged: 10/18/06
Posts: 218
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I bought one from T&T, and then built my own. I use one for my 20x80 binos with a Universal Astronomics UniMount, and another with my 6" Mak-Newt and a Universal Astronomics UniStar. I made mine from wooden crutches that were given to me by the local VFW, and they are extremely strong/stable/functional. I love them.
Edited by dpwoos (11/10/09 08:29 PM)
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ColoHank
professor emeritus
Reged: 06/07/07
Posts: 513
Loc: western Colorado
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Tightly bonding a thin skin of high-grade plywood to both sides of each crutch would transform them into torsion boxes, similar in construction to an airplane wing. Thus modified, the crutches would resist twisting and bending forces more effectively and would thus yield a more rigid, stable tripod. Even 1/8" thickness plywood would suffice for this application.
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Questar 3.5 standard - pyrex and BB coatings
Powerguide II
8mm, 12mm, 16mm, 24mm and 32mm Brandons
modified Bogen 3030 w/ homebuilt wedge
Homebuilt Galileo scope and very large and ugly homemade tripod
other odds and ends, including iPod Touch with StarMap Pro (what a marvelous combo)...
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"Nothing exists but atoms and empty space. Everything else is opinion."
Titus Lucretius Carus 99-55 B.C.
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ed_turco
member
Reged: 08/29/09
Posts: 27
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I am so pleased to see how well you did with the design. Thanks for the treat!
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dpwoos
sage
Reged: 10/18/06
Posts: 218
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The design is very good, but I have to give most of the credit to T&T as my crutch tripod is a pretty close copy of theirs. I think that the torsion box idea is great, but for my uses the design is much more than sufficient as it is. My sons and I have built a lot of astro stuff - mirrors, scopes, eyepieces, accessories, etc. and I consider the pedagogical opportunities at least as important as the cost savings. There is a lot of learning and teaching that can happen in the building of something as simple as a tripod, including talking to the old guy who gave us the crutches!
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AV in CMH
sage
Reged: 11/07/05
Posts: 461
Loc: Columbus Ohio
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Talking to the "OLD GUY" who gave you the crutches might just be the best and most overlooked part of a project like this.
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dpwoos
sage
Reged: 10/18/06
Posts: 218
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Certainly not overlooked or unappreciated! He took us to an old semi trailer that was full of wooden crutches, and said that nobody wanted the wooden ones anymore. He also said that WWII vets were dying at a rate that would have been totally unacceptable during the war. It got my sons and me talking about my dad's experiences as a B-24 waist gunner. My dad, who was comfortable with violence and was a bona fide "tough guy", was not a big fan of the war or war in general, and was in many ways a non-violent person. He/we never bought anything that we could make or fix, and I like to think that I have passed on at least some of those skills to my sons, including through ATM projects.
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AV in CMH
sage
Reged: 11/07/05
Posts: 461
Loc: Columbus Ohio
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dpwoos
Your comments are interesting to read. Have you ever shown this man the final product made from the crutches? I'll bet he would be happy to see them used.
I have remind myself not to get swept up in the "mission" of building something like an ATM project. It's easy lose perspective when this happens.
Regards,
Anthony
Edited by AV in CMH (11/12/09 01:17 PM)
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dpwoos
sage
Reged: 10/18/06
Posts: 218
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Your idea to go back and show the fellow how we used the crutches is a good one, and I will try to make it happen. We do a lot of observing stuff for schools, scouts, camps, etc. and in fact a friend and I spent a couple of hours yesterday evening at a (relatively) local elementary school showing 5-6th graders Jupiter, M31, M15, etc. Maybe I need to find a way to do some general public observing - "sidewalk astronomy", and let this guy know when and where. BTW, the kids were great - enthusiastic and very knowledgeable and we all had a fantastic time.
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AlienFirstClass
professor emeritus
Reged: 02/13/09
Posts: 738
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Quote:
The design is very good, but I have to give most of the credit to T&T as my crutch tripod is a pretty close copy of theirs. I think that the torsion box idea is great, but for my uses the design is much more than sufficient as it is. My sons and I have built a lot of astro stuff - mirrors, scopes, eyepieces, accessories, etc. and I consider the pedagogical opportunities at least as important as the cost savings. There is a lot of learning and teaching that can happen in the building of something as simple as a tripod, including talking to the old guy who gave us the crutches!
Anyody have a link to T&T?
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