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imhotep
Pooh-Bah
Reged: 02/14/07
Posts: 1429
Loc: Tampa, FL
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I'm reposting this one here after a complete flop in the Reflector forum. Here's a question for any EzCBP owners.
I just took delivery of my EzCBP kit. It will support a 12.5" f/6 truss-dob that weighs about 70lbs. I've decided to go with a generic upper board so I can use this platform easily with any dobsonian that is within the size and weight limits of the kit.
My question concerns resetting the platform each hour. I've looked at all the sample photos on Ted's website, and I see a couple of innovations that assist the reset process. My favorite is probably Tahir Saban's which is pictured near the center of the webpage's height. The handle looks like a good solution, but I'm still skeptical of lifting my 70-lb telescope via a handle like that. Plus, the lifting has to be done with care and then set down gently.
Do you have to liberate the motor of all friction and weight before resetting, or is it okay to just turn off the power and then slowly push the upper board back to starting position with the motor turning backwards the whole time?
Thanks for your help.
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Curt
8" F5 Newtonian Astrograph
Orion 80ED CUSTOM
Edmund Optics 4.25" 'Palomar' Newtonian, 1968 vintage
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Moki
super member
Reged: 11/06/05
Posts: 429
Loc: Under the Clouds
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Here's how I did it with mine (supporting a 12.5" at ~ 100lbs):
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"In questions of science, the authority of a thousand is not worth the humble reasoning of a single individual." Galileo
12.5" F5.3 Dob on EQ platform
8" F7 planetary Dob / EQ Platform
Current ATM projects:
Xtal-Controlled EQ platform motor drive - finished... It works!
Motorized focus for planetary (moved to the bottom of the list for now)
10" F5.5 Verylight PushTo
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Moki
super member
Reged: 11/06/05
Posts: 429
Loc: Under the Clouds
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A wider view of the ground board. I've sinced replaced the EzCPB platform with a VNS type for better stability.
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"In questions of science, the authority of a thousand is not worth the humble reasoning of a single individual." Galileo
12.5" F5.3 Dob on EQ platform
8" F7 planetary Dob / EQ Platform
Current ATM projects:
Xtal-Controlled EQ platform motor drive - finished... It works!
Motorized focus for planetary (moved to the bottom of the list for now)
10" F5.5 Verylight PushTo
Edited by Moki (10/07/09 10:06 AM)
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mark Jimenez
sage
Reged: 01/08/07
Posts: 339
Loc: Atlanta GA.
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Very nice job Moki. Kurt, I built one of these a few years ago for a 16" scope. By the time I got the platform working smooth and stable, there was pretty much nothing left of the original kit exept the motor. I had no problem just lifting the edge of the platform (really just enough to take the load off the friction wheel) to reset the platform. I should think mokis solution would be more that adequate.
FWIW, I found that ball bearings from in-line skates are a good cheap replacement for the plastic shower door rollers in the kit.
-Mark
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Celestron ASGT
Astro Tech 8" f4 Newt
QHY8
Meade DSI pro
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imhotep
Pooh-Bah
Reged: 02/14/07
Posts: 1429
Loc: Tampa, FL
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Thanks for the feedback.
Moki, let me make sure I understand. So you push down on that metal bar and it lifts the sector off the motor roller? It seems like such a small level arm for lifting that much weight. I like the idea, just trying to understand how it works exactly.
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Curt
8" F5 Newtonian Astrograph
Orion 80ED CUSTOM
Edmund Optics 4.25" 'Palomar' Newtonian, 1968 vintage
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Moki
super member
Reged: 11/06/05
Posts: 429
Loc: Under the Clouds
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Quote:
Moki, let me make sure I understand. So you push down on that metal bar and it lifts the sector off the motor roller? It seems like such a small level arm for lifting that much weight. I like the idea, just trying to understand how it works exactly.
That's correct. It works on the lever principle. The side of the bar you push down on is about eight times longer than the side that does the lifting, giving an ~8:1 advantage. If there is 35 lbs of weight on the roller (with my 12.5" at 100+ lbs) then I only have to push down with a little over 4 lbs of force to lift the platform just enough to easily roll it back to the home position.
All of the materials (except the socket head screw - it was in the junk box) came from Lowes. The bar is a piece of 1" x 1/4" thick aluminum.
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"In questions of science, the authority of a thousand is not worth the humble reasoning of a single individual." Galileo
12.5" F5.3 Dob on EQ platform
8" F7 planetary Dob / EQ Platform
Current ATM projects:
Xtal-Controlled EQ platform motor drive - finished... It works!
Motorized focus for planetary (moved to the bottom of the list for now)
10" F5.5 Verylight PushTo
Edited by Moki (10/08/09 02:54 PM)
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Moki
super member
Reged: 11/06/05
Posts: 429
Loc: Under the Clouds
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If you would like to PM me I can give you some other pointers on the EzBCP platform that I learned building and using it.
There's one thing in particular that you need to watch out for as it's a safety issue with the platform. This isn't restricted to just the EzBCP platform but applies to all platforms of this type, especially at lower latitudes. I learned the hard way to put a "rim" on the back side of the north sector to prevent the rocker plate from being pushed off the supporting rollers by accident. I accidently pulled when I should have pushed one night and suddenly had the entire 100lbs of scope coming down on top of me. No damage done but I learned a lesson. Every platform I've built since has some type of "safety" feature that prevents this sort of accident.
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"In questions of science, the authority of a thousand is not worth the humble reasoning of a single individual." Galileo
12.5" F5.3 Dob on EQ platform
8" F7 planetary Dob / EQ Platform
Current ATM projects:
Xtal-Controlled EQ platform motor drive - finished... It works!
Motorized focus for planetary (moved to the bottom of the list for now)
10" F5.5 Verylight PushTo
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imhotep
Pooh-Bah
Reged: 02/14/07
Posts: 1429
Loc: Tampa, FL
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Moki, thanks for your help and elaboration. PMing you now with some more specific questions.
--------------------
Curt
8" F5 Newtonian Astrograph
Orion 80ED CUSTOM
Edmund Optics 4.25" 'Palomar' Newtonian, 1968 vintage
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imhotep
Pooh-Bah
Reged: 02/14/07
Posts: 1429
Loc: Tampa, FL
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After joining the eqplatforms yahoo group I found a powerpoint in the files section that has shed tons of light on my questions. I'm now crystal clear on how to calculate all dimesions for a platform with a full south sector to compliment the north sector. That's my plan instead of the single roller in the EzCBP kit.
I'm also going to replace the plastic rollers with metal bearings. Any specific kind I should look for, or are basic rollerblade bearings good enough?
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Curt
8" F5 Newtonian Astrograph
Orion 80ED CUSTOM
Edmund Optics 4.25" 'Palomar' Newtonian, 1968 vintage
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