Making an equatorial platform
Posted 26 July 2005 - 09:34 PM
Posted 26 July 2005 - 10:02 PM
I have been trying to get my arms around some of the different approaches, looking for the easiest build.
By all means, Please post your project!!
Posted 26 July 2005 - 11:17 PM
I have been collecting notes for a while, and with your permission I'll chime in with what I have found out here and there, but I'm interested in your timing motor approach!
Posted 27 July 2005 - 05:03 AM
I made my first eq. platform in 1983(wrote an artikel about it in S&T). But after a while I made me a lower one because my first experiment was much to high(also changed the tracking system). The platform I'm using now is about 6" high and support a 90 lbs Newt. Using just 1 AA battery my platform/DC motor tracks stars for about 6 hours. I have to rewind the system every 2.5 hours. Almost no force is needed because the complete system is perfectly in balance due to the airpumps pushing force in the base of it.
Yes indeed Ed, to few ATM's use these systems.
Posted 27 July 2005 - 07:49 AM
So my first step was determining the center of gravity of the whole telescope and platform. My OTA weighs 41 lbs, rocker box 21 lbs and I estimated the platform will weigh 7 lbs. Each of these components have their own center of gravity and distance apart so the calculation is done exactly the same as balancing a Newtonian and using an Excel spread sheet I computed the center of gravity to be 13.5 inches above the bottom of the platform. Do I need to elaborate on this, it's pretty straightforward?
Posted 27 July 2005 - 08:22 AM
Posted 27 July 2005 - 08:31 AM
Posted 27 July 2005 - 08:51 AM
Please post! I wish to build one, too!
You can come and have a look at mine (not self-built, one of Brian Reed's platforms).
You can even try it out on one of your scope next time we observe together - at least until I make it the ground board of my scope .
Posted 27 July 2005 - 09:14 AM
Posted 27 July 2005 - 09:27 AM
Posted 27 July 2005 - 04:06 PM
Posted 27 July 2005 - 06:01 PM
I was wrong, my OTA weighs 48 lbs and is 20 inches above the ground board or platfrom. Also the rocker box center of gravity is 3 inches above the platform but combined with the weight of the platform should be 2 inches above the platform. This gives 18 inches between the OTA and rocker box/platform combo. This gives the equation:
48*X = 28*(18-X) Solving it X = 6.6 inches. (18 - X) + 2 inches = 13.4 inches is the height of the whole center of gravity above the platform. In any case it doen't need to be very exact at all and it will likely work for different scopes. Just be careful though, if you put a scope on it with too high a center of gravity from this it could tip over!
Posted 28 July 2005 - 07:12 AM
Posted 28 July 2005 - 07:26 AM
Posted 28 July 2005 - 07:47 AM
Posted 28 July 2005 - 05:18 PM
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Posted 30 July 2005 - 08:13 AM
Next I glued two triangles shown here which form a channel for a wedge to slide in. This will be a slow motion adjustment driven by an AC reversible motor driving a 1/4-20 brass rod. This channel is lined with ebony star bottom and sides and the wedge made from maple plywood will have Teflon on both the bottom and top with Teflon tape on the sides.
Posted 30 July 2005 - 08:20 AM
Posted 30 July 2005 - 08:38 AM
Posted 30 July 2005 - 09:10 AM