It is currently Sun Sep 23, 2018 6:15 pm

All times are UTC




Post new topic Reply to topic  [ 5 posts ] 
Author Message
 Post subject: Motor info please.
PostPosted: Sun Nov 25, 2012 7:18 pm 
Does anyone know the RPM speed of the RA motor for an EQ1 mount?
Searched online but no luck.
Peter.


Top
  
 
 Post subject: Re: Motor info please.
PostPosted: Sun Nov 25, 2012 8:17 pm 
Offline
Member
User avatar

Joined: Mon Oct 12, 2009 6:47 pm
Posts: 1256
Location: Bolton
According to this thread:
http://www.cloudynights.com/ubbthreads/showflat.php/Cat/0/Number/5099493/Main/5071162
the EQ1's crown-wheel has either 96 or 100 teeth, so you'd need the motor to drive the worm-gear at around 0.068 rpm.

I used to have an EQ1 with a variable-speed motor, a bit like this one:
http://www.ebay.co.uk/itm/Single-Axis-D-C-Motor-Drive-EQ1-Equatorial-Mount-/160535296358


Top
 Profile  
 
 Post subject: Re: Motor info please.
PostPosted: Mon Nov 26, 2012 12:16 pm 
Thanks for that Ross
Hmmm... less than 1rpm? I have a stepper motor + gearbox which might do the trick,
I have had the EQ1 for some time and was going to throw it out until my astro interest was re awakened after joining BAS!
I am in the process of stripping down the head and getting rid of the sticky goo which seems to be everywhere including the gears, and replacing it with Lithium based lube.
I hope to use the finished head for imaging with DSLR / webcam, rather than observation.
Regards
Peter

PS if I used extra gears and increased the motor speed, would this increase accuracy even on such a low end head or is it a waste of time?

Forgot to add, I have counted the teeth on the main gear and I made it 100 so that seems to fit.


Top
  
 
 Post subject: Re: Motor info please.
PostPosted: Mon Nov 26, 2012 4:29 pm 
Offline
Member
User avatar

Joined: Mon Oct 12, 2009 6:47 pm
Posts: 1256
Location: Bolton
Yes Peter, a stepper-motor is ideal for this application.

If you remember that your mount needs to turn at the same speed as the Earth - once every 23 hours 56 mins (= 1436 mins) and your crown-wheel has 100 teeth, then the worm-gear needs to rotate 100 times per day, i.e. evey 14.36 mins - hence 0.0696 RPM.
If there are any other gears in the drive-train then their ratio needs to be included in the same way, but I'd have thought the fewer gears the better - they are only going to add more back-lash.

I'm not sure that it's worth spending a lot of effort on system based on a cheap 100-tooth gear, but if you only want to do wide-angle images with a DSLR and lens then it may be good enough. For better results you'd need bigger precision gears (a crown-wheel with 300 - 400 teeth works well).
And the other thing you're lacking is a quick method of polar alignment: there's no provision for a polar-scope on the EQ1.

But why not arrange to borrow the BAS Astro-Mount:
http://www.boltonastro.co.uk/forums/viewtopic.php?f=17&t=156
and see how you get on with that first?


Top
 Profile  
 
 Post subject: Re: Motor info please.
PostPosted: Mon Nov 26, 2012 10:42 pm 
Thats a very good idea Ross, I'll see how things work out when I put my EQ1 back together.
Thanks for the help and advice!
Peter


Top
  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 5 posts ] 

All times are UTC


Who is online

Users browsing this forum: No registered users and 2 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
Powered by phpBB © 2000, 2002, 2005, 2007 phpBB Group