Brief drive review for EQ mount

[asimov]

Hi.

Just a quick post to show you the tracking setup I came up with to drive the 12.5" newt.

The radial arm is constructed out of galvanised sheet metal & tack welded together. It is 209mm long & attaches to the RA axis. There are 2 lengths of 1/4" X 20 TPI all-thread, curved to the radius of the arm & tacked in position. Attached to the 1.8 step motor shaft is a piece of the same all-thread. With this reduction, it is necessary to have the motor rotating exactly 1 RPM to track at the correct rate. The close up of arm & stepper is just a representation of the setup used..(a previous prototype that failed)

She's a rough set-up as you can see, but it works, & works good. Total cost was about 10 bucks for the all-thread. & my labour if you want to include that. The stepper & controller were free. Same for the battery, which was a 12V car battery from the local dump cut in half to make it 6V.

Still some fine tuning to be done at my leisure.

[davidpretorius]

nicely done mate!

[netwolf]

Asimov, I know you have been trhough a few iterations before geting it right. Given your intrest in Equatorial Mounts. Here is a link i came accross that may intrest you and the others. I have collected quiet a few designs in my umm research.

$75 US cost for materials. Plans available by email. It looks pretty easy for a tinkerer like you tot put together.
http://www.charm.net/~jriley/sky/mount1.html

And the Eye of the Newt...
http://www.cloudynights.com/item.php?item_id=1072

Some ideas for you all to toss over.

[asimov]

Hi wolfie, thanks for the links. I've seen them before. Just to give you an idea on how long I've been researching EQ mounts. Heres a pic of my 1st EQ made back in 1978. :D

[netwolf]

Jee Asimov... I was just 2 years old then..

[asimov]

I was 15 at the time.:) There was no such thing as a dob back then of course.
I'm quite happy with my mount though. Works fine. It was just my pig-headed notion of driving a big EQ mount for under a hundred bucks that I had 'trouble' with lol. Seeing I did it for less than 50, I'm stoked. :thumbsup:

[elusiver]

1978?? i wasn't even BORN!!! top work asi.. i'm sure u've posted before that u've been working on this project for a while.. so u must be happy? has she had first light yet? how long does it track for?

el :)

[asimov]

:confuse3: I can see myself building a dob soon, just to see what all the fuss is about! I ain't a 'rule follower' though....I'll come up with my own design ;)
For under a hundred bucks driven? :evil:

[asimov]

G'day YOUNG FELLA! (EL):P First light sunday night just gone. Tracks really well. Should be able to track for 5 hrs before re-setting. Yep! I'm definately happy.:) Been working on it for near on 2 yrs.:thumbsup:

[elusiver]

5 HRS!!!!! AWESOME!!!!!

so i take u'll be gettin into astro photography now??? :P


el :)

[asimov]

Well, I don't reckon it'll be much chop for long exposure stuff...all-thread straight off the shelf is not high precision stuff. = big periodical error. This stepper takes pretty coarse steps so even though I can't see the steps by eye even as high as 212X mag...I reckon it'll be seen in the camera. Need to make some all-thread in the lathe & micro-step the motor for that. Short time exposures should be ok though. Just have to test it better to see what it's capabilities are I guess..

[asimov]

After saying all THAT...I also thought that this drive setup had buckleys of driving it & not seeing the steps taken by the motor in the EP.....go fiqure.