Jump to content
  • Join the online East Midlands astronomy club today!

    With active forums, two dark sites and a knowledgeable membership, East Midlands Stargazers has something for everyone.

Motorising the dome.


Graham

Recommended Posts

I have finally got round to motorising my dome.

Took me while to work out the best way of doing it but i got there in the end.

A simple drive wheel that runs on the top of the internal lip of the base of the dome.

 

DSC_0024.JPG?raw=1

 

Drive is a 12 volt reduction geared motor.

It should have been a 5 RPM motor but I have been sent a 30 RPM motor by mistake, this will get changed over.

A set of Aluminium belt driven gears reduces it down further.

 

The power is first taken through a PWM unit to give me full control over the Motors speed and direction.

It then passes through a digital timer so I can switch the drive on and off as a set sequence giving me infinite control .

 

With the current motor the sequence is drive for one second then a delay for ten minuets then drive for 1 second and so on.

 

The power is taken from the hub I made for the mount so as the dome rotates it is always in the same position ref the mount and is always directly behind the scope.

 

All I need now is a clear sky to test it 

  • Like 2
Link to comment
Share on other sites

That's impressive Graham, can you explain the maths involved.

 

I worked it out that in a 24 hour period there is 86400 seconds, your dome moves 144 seconds in that time. So say you have a 8 hour session your dome will cover just 48 seconds of sky. Is that enough dome movement, I think I'm confusing myself.

 

 

 

Edited by Doc
Link to comment
Share on other sites

11 minutes ago, Doc said:

That's impressive Graham, can you explain the maths involved.

 

I worked it out that in a 24 hour period there is 86400 seconds, your dome moves 144 seconds in that time. So say you have a 8 hour session your dome will cover just 48 seconds of sky. Is that enough dome movement, I think I'm confusing myself.

 

 

 

 

In the one second of power 'on' the wheel which is 120mm in dia rotates just under half a turn thus travelling approximately 180mm around the edge.

The obs opening is about 500mm wide.

The idea is to move the dome as the edge of the opening approaches the fov of the scope moving the opening to the opposite side of the fov.

Under normal 'manual' moving I have to rotate the dome every half an hour or so.

This is just a starting point I will have to fettle it as it runs.

Once the 5 RPM motor arrives the 'on' time will be longer or the delay time will be shorter.

Link to comment
Share on other sites

Mick that is for a future project currently under design when I will change it to a stepper motor driven set up.

It will then run at sidereal rate or Luna / Solar depending on what I am doing.

I will also get it to be controlled by Maxim so it goes to the scopes position automatically.

Link to comment
Share on other sites

Been running a full blown test on the drive this morning.

All in all I am very pleased with how things have gone.

Scope stayed well within the opening of the dome.

One mod I will be doing is to add a roller to the inside of the dome to stop it moving out when rotating.

 

Quick video of it in action.

 

 

 

Link to comment
Share on other sites

First light for the drive. 

Went extremely well. 

I even managed to get some sleep whilst it was all running. 

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.