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mcbbcn
super member
Reged: 03/10/07
Posts: 127
Loc: Portland, OR
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Hi,
I'm building my ROR with a garage door opener system, and I have cable that rolls over two drums.
The challenge I'm having is keeping tension on the cables. As the roof goes in one direction, one cable gets tension and the other gets lose, and when I bring back the roof, the cable is a bit loose and does not roll well on the drums and all kinds of havoc happens.
Has anybody come up with a solution to keep tension on the cables?
Thanks for your help,
Miquel Casas
Portland, OR
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Portland, OR
Orion Mak 150mm
Hutech Canon 40D
Orion ST-80mm
SSAG
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BCB
Undercover Saboteur
Reged: 11/24/03
Posts: 5196
Loc: Look over your shoulder
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Use tie rods at both wire ends as an anchor point. then you can tension both sides when the roof is halfway. You'll still have some flex/slack, but nowhere near as much as you would without them.
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Mark
Lost in thought. Please send search party!!!
Astro-Tech 111EDT
Orion 8" F5 Newt w/Moonlight CR-2 focuser
SVP mount w/Meade 497 Autostar GOTO mod
Treeline Observatory
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mcbbcn
super member
Reged: 03/10/07
Posts: 127
Loc: Portland, OR
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Hi Mark,
Thanks for the answer. I'm not familiar with tie rods, but is this what you are referring to?
http://www.gordosoft.com/hoptrellis1/..%5Choptrellis1%5Ccabletensioner.jpg
Thanks for your help,
M.
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Portland, OR
Orion Mak 150mm
Hutech Canon 40D
Orion ST-80mm
SSAG
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jrcrilly
Refractor wienie no more
Reged: 04/30/03
Posts: 25195
Loc: NE Ohio
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I used a single cable running from one end of the roof to the other. It is wrapped five times around a single drum in between. The diameter is constant so the cable stays taut both coming and going. You have to make sure the incoming cable doesn't wrap over the outgoing side, of course.
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John C
Urban Observatory
A&M/Astreya 76mm F/6 APO
TMB/LOMO 80mm F/7.5 APO
Tak FSQ-106N F/5 APO
Meade 178ED F/9 "APO"
Meade ETX-125AT
C14
Teeter 20" F/3.8 truss Newt w/ServoCat
CI-700, NJP, GPDX/SS2KPC, CG5-GT
ST-10XME, DSI Pro
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mcbbcn
super member
Reged: 03/10/07
Posts: 127
Loc: Portland, OR
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Hi John,
I can't picture it. Could you provide some additional description or do you have any pictures?
By the way, I provided Mark a link to try to figure out what a tie rod is. Please, could you click on the link and confirm if that is a tie rod?
Thanks again for all your help,
M.
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Portland, OR
Orion Mak 150mm
Hutech Canon 40D
Orion ST-80mm
SSAG
|
jrcrilly
Refractor wienie no more
Reged: 04/30/03
Posts: 25195
Loc: NE Ohio
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Quote:
Hi John,
I can't picture it. Could you provide some additional description or do you have any pictures?
I always meant to write something up on this. I was pretty proud of my "invention" until, a few years later, I installed a ServoCat on Dobbest and noticed that it used the same drive scheme! If you are picturing something complicated, it's not. Just a single cable from one end of the roof to the other. A hoist motor is mounted to the inside of one fixed wall and its drum is pretty much in line with the end points of the cable. The cable wraps around the drum 5 times on its way from one end to other. The ends are offset horizontally in opposite directions to keep the ingoing and outgoing cable runs separate. It's been running for about 6 years now.
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John C
Urban Observatory
A&M/Astreya 76mm F/6 APO
TMB/LOMO 80mm F/7.5 APO
Tak FSQ-106N F/5 APO
Meade 178ED F/9 "APO"
Meade ETX-125AT
C14
Teeter 20" F/3.8 truss Newt w/ServoCat
CI-700, NJP, GPDX/SS2KPC, CG5-GT
ST-10XME, DSI Pro
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mcbbcn
super member
Reged: 03/10/07
Posts: 127
Loc: Portland, OR
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Makes sense! Thanks a lot Mark!
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Portland, OR
Orion Mak 150mm
Hutech Canon 40D
Orion ST-80mm
SSAG
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