ICEINSPACE
Moon Phase
CURRENT MOON
Waning Gibbous 72.9%
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13-09-2021, 03:41 PM
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Registered User
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Join Date: May 2011
Location: Hobart
Posts: 134
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Motor for Roll Off Roof
Looking at automation for the backyard observatory as a summer project. First step will be an electric motor to open and close a roof. Seen a few options with a bit of research such as eBike motors (promising) and garage door motors (overpriced).
There are also some companies that make these items specifically for observatories but they too, are way overpriced.
The roof itself, including rolling resistance, would be less than 30kg.
Apart from the obvious functionality, it would also need to be capable of being controlled down the track by software such as Voyager or SGP.
Also, the observatory has 240v mains running to it.
Any advice most welcome.
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13-09-2021, 09:56 PM
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Registered User
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Join Date: May 2009
Location: Para Hills, South Australia
Posts: 3,620
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You would need to calculate the Friction to overcome the initial work done. Once you have the initial resistance, that will be the power rating of the motor that you would need to look at.
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14-09-2021, 07:13 AM
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Gravity does not Suck
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Join Date: Mar 2005
Location: Tabulam
Posts: 16,993
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Go to Supacheap Auto or similar look at cheap 4wd winches..$200 on a good day, maybe less, pulls 2000 lbs but the big feature is you get all your cables, controls etc which saves you heaps.
I have two which pull a 3.8 x 3.8 mt roof ...needed two because actually makes cabling easier plus there was no way I could get a "drum" system to be reliable...it ended up slipping no matter what...so now they both pull on each corner..have to rewind and reset but the advantages are worth the extra mucking about...as I said think what is in your package...you get......the following:-
Winch, electrical cable to hand controller, power leads to battery ( or 240 to 12 vlt unit ..plus why not leave a battery in the system ..for heater or a light ..whatever) stainless steel cable to drag the roof ... its the cost of all the little things that get to you plus usually compromising on this or that...
Good luck and get started.
Alex
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28-09-2021, 03:17 PM
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Registered User
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Join Date: Jul 2005
Location: Melbourne
Posts: 46
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Maybe a bit expensive $398 from Bunnings but a sliding gate motor works excellent on my obs. All you need to get is a box of toothed rail that is also available. On the inside of the control unit you can access the digital control signals for open/close. I've designed a cct that you could use to externally control via SGP (but not tested) but I find that using the remote control is just as easy.
John
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28-09-2021, 04:18 PM
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Registered User
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Join Date: Oct 2005
Location: Junortoun Vic
Posts: 8,913
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Alternative...
A small geared motor and a length of bicycle chain. A couple of sprockets and the chain connected to the roof at both ends.
There are many amateur observatories using this system.
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29-09-2021, 05:18 AM
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Gravity does not Suck
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Join Date: Mar 2005
Location: Tabulam
Posts: 16,993
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29-09-2021, 06:07 AM
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SpeakingB4Thinking
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Join Date: Apr 2019
Location: Canberra
Posts: 829
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Hello,
I'd get a weight test on the roof, rig up a cable line at the mounting points your going to use. Then use some weights to work out how much force you'll need to get the roof moving.
If your going to use chains(non-bike ones), watch the length and slack or its going to be very hard to keep the rig quite.
Steve
Last edited by mura_gadi; 29-09-2021 at 06:25 AM.
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29-09-2021, 07:21 AM
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Gravity does not Suck
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Join Date: Mar 2005
Location: Tabulam
Posts: 16,993
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The big disadvantage of my set up, which uses two 4wd winches is the noise...it is unbelievable and such that I asked my neighbour near half a klm away if it annoyed them..they said after they go to bed they hear nothing fortunately.
Alex
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29-09-2021, 04:11 PM
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Registered User
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Join Date: Jul 2005
Location: Melbourne
Posts: 46
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Bunnings - Gorrila 240v 100kg electric hoist. $130 bucks.
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01-10-2021, 01:49 PM
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Ageing badly.
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Join Date: May 2008
Location: Cloudy, light-polluted Bribie Is.
Posts: 3,681
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I used a 4WD recovery winch with some 3mm SS cable and pulleys. Steel-framed 5m x 5m roof. Ran on V-pulleys along some raised bar. Plenty of grease and worked a treat.
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