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| Duncan Wood... |
 Posted: Thu Oct 29, 2009 9:32 pm |
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On Fri, 30 Oct 2009 01:31:00 -0000, Atlantic Illumination Entertainment
Lighting <aiel at (no spam) chebucto.ns.ca> wrote:
[quote]David McCall wrote:
I really didn't intend to start a rag fest on Richard.
*** I didn't take it that way. It's a discussion group and participants
need not agree with one another. Followups of a dissenting or clarifying
manner, if kept civil, are for the positive.
He is a very useful member of this community.
*** Thanks, I appreciate that.
It just seemed like a bad idea to suggest such things in a public
forum where you don't know who you might be influencing.
*** I don't disagree, but as with any suggestions, the user must in the
end decide upon the suitability of those given.
You might get away with such a winch if you mounted everything
securely and safetyed it once it was in place so that you never
relied on the winch to hold any load except for while it was moving,
and then you took it out before somebody got hurt. Even then it
qualifies as bad practice.
*** Again, I am not saying that boat winches are the answer for every
lighting job, but if a correct winch is bought and is adequately
safeguarded, it may be suitable for some jobs. Certainly, safety chaining
the load in place is a good idea as is guarding the winch itself.
This discussion reminds me of years ago being in some university or
military hall where winches had been used to raise pipes with flags or
some sort of banners (or maybe they were chandeliers) high above the
floor. The winches were accessible to the public, but the handles had
been
removed. I don't remember noticing if there were locks on them or not.
I wouldn't use an eye-bolt here either because the nut has the potential
of working it's way off and dropping its load. So to speak.
*** We rent pipe and chain to a few local theatre groups for one-off
shows every year where the only option is to dead hang. The nuts have
split lockwashers and the eyebolt ends have been peened over the nuts to
prevent exactly that. Also, the longer pipes have three eyebolts.
I would prefer to wrap the cable around the pipe or perhaps use a
hitch and then swag it or use 3 wire clips to secure it. Faster and
Safer. Pipe isn't much fun to drill anyway.
David
*** We used a v-shaped rest for the pipe and a drill press to keep the
pipe and drill bit straight. A vari-speed pulley system on the drill ran
it at a slow enough speed to bite without skating.
[/quote]
This is probably a bit like the hook clamp discussion, but why do that
rather than just use a barrel clamp? |
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| TimR... |
| Posted: Fri Oct 30, 2009 6:04 am |
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On Oct 28, 9:54 pm, Lloydj <ljeffo... at (no spam) theclarientgroup.com> wrote:
.. Please don't add
[quote]to that poor reputation by using non-rated Home Depot bolts, auto
cable winches (which are 12V DC and consume a huge amount of current),
or other "cheap" solutions and having an accident.
[/quote]
A long threaded rod driven by a gear could be an elegant and safe
solution to the problem. If an 1/8 inch cable can suspend a fixture,
so can a half inch or larger solid rod.
Of course I assume you'd hire somebody to do the calculations. |
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| TimR... |
| Posted: Fri Oct 30, 2009 10:25 am |
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On Oct 30, 1:36 pm, "Duncan Wood" <nntpn... at (no spam) dmx512.co.uk> wrote:
[quote]On Fri, 30 Oct 2009 16:04:25 -0000, TimR <timothy... at (no spam) aol.com> wrote:
On Oct 28, 9:54 pm, Lloydj <ljeffo... at (no spam) theclarientgroup.com> wrote:
. Please don't add
to that poor reputation by using non-rated Home Depot bolts, auto
cable winches (which are 12V DC and consume a huge amount of current),
or other "cheap" solutions and having an accident.
A long threaded rod driven by a gear could be an elegant and safe
solution to the problem. If an 1/8 inch cable can suspend a fixture,
so can a half inch or larger solid rod.
Of course I assume you'd hire somebody to do the calculations.
It'll probably suspend it quite happily, how long before it seizes is a
rather seperate question, you don't normally use UNC/metric thread forms
for a drive thread.
[/quote]
No reason you have to use the same thread on the drive as on the
fixture. Lots of ways to skin this cat. Turn down the last inch on
either end, add ringfeder and spur gear, and a hand crank. I can
think of at least half a dozen other ways without even trying. But
with the very low forces involved, there's a good chance you could
drive it from the existing threads.
Don't be jealous because you didn't think of it first! I haven't
patented it and you are welcome to the idea. |
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| Duncan Wood... |
| Posted: Fri Oct 30, 2009 11:36 am |
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On Fri, 30 Oct 2009 16:04:25 -0000, TimR <timothy42b at (no spam) aol.com> wrote:
[quote]On Oct 28, 9:54 pm, Lloydj <ljeffo... at (no spam) theclarientgroup.com> wrote:
. Please don't add
to that poor reputation by using non-rated Home Depot bolts, auto
cable winches (which are 12V DC and consume a huge amount of current),
or other "cheap" solutions and having an accident.
A long threaded rod driven by a gear could be an elegant and safe
solution to the problem. If an 1/8 inch cable can suspend a fixture,
so can a half inch or larger solid rod.
Of course I assume you'd hire somebody to do the calculations.
[/quote]
It'll probably suspend it quite happily, how long before it seizes is a
rather seperate question, you don't normally use UNC/metric thread forms
for a drive thread. If you need to hire somebody to calculate the SWL on
1/2 inch threaded rod (which isn't the same as 1/2" solid) then you
probably want to stay away from electricity in general. |
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| Duncan Wood... |
| Posted: Fri Oct 30, 2009 8:13 pm |
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On Fri, 30 Oct 2009 20:25:10 -0000, TimR <timothy42b at (no spam) aol.com> wrote:
[quote]On Oct 30, 1:36 pm, "Duncan Wood" <nntpn... at (no spam) dmx512.co.uk> wrote:
On Fri, 30 Oct 2009 16:04:25 -0000, TimR <timothy... at (no spam) aol.com> wrote:
On Oct 28, 9:54 pm, Lloydj <ljeffo... at (no spam) theclarientgroup.com> wrote:
. Please don't add
to that poor reputation by using non-rated Home Depot bolts, auto
cable winches (which are 12V DC and consume a huge amount of
current),
or other "cheap" solutions and having an accident.
A long threaded rod driven by a gear could be an elegant and safe
solution to the problem. If an 1/8 inch cable can suspend a fixture,
so can a half inch or larger solid rod.
Of course I assume you'd hire somebody to do the calculations.
It'll probably suspend it quite happily, how long before it seizes is a
rather seperate question, you don't normally use UNC/metric thread
forms for a drive thread.
No reason you have to use the same thread on the drive as on the
fixture.
[/quote]
Err no, but if you try & buy any other thread form it gets rather expensive
[quote]Lots of ways to skin this cat. Turn down the last inch on
either end, add ringfeder and spur gear, and a hand crank. I can
think of at least half a dozen other ways without even trying. But
with the very low forces involved, there's a good chance you could
drive it from the existing threads.
Don't be jealous because you didn't think of it first! I haven't
patented it and you are welcome to the idea.
[/quote]
I've built all sorts if things driven from threads but in general winches
are far cheaper & more reliable. |
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| Sean... |
| Posted: Sat Oct 31, 2009 12:48 pm |
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Atlantic Illumination Entertainment Lighting wrote:
[quote]*** Chain hoists would be rated for that because they do suspend loads
above people - at a minimum, the workers using them.
[/quote]
Nope. For most of the chain hoists we use in our industry (the good old
model L CM Lodestar, for example) using them to lift or suspend loads above
people is directly contrary to the manufacturer's instructions. As it is
in industrial applications - lifting a load directly above people's heads
is, generally speaking, a no-no.
[quote]*** Unless some governing body tests them and comes up with a rule
book, those ratings won't appear, either.
[/quote]
Those ratings have existed for years*, and there are motors on the market
that the manufacturer specifically says are 'rated' for hanging loads above
people.
* - for example the German BGV-C1 (formerly the insurance regulation VGB-70)
and the relatively new British Standard BS-7906 Part 1 Cat A.
Columbus McKinnon have been making a BGV-C1 variant of Lodestar for ages.
They're not much used in theatre/live music, but if you think they don't
exist you're just not terribly well informed.
Sx |
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