Azimuth drive for Dobsonian mount

[mikey152]

I would like to build a simple azimuth drive for my home made Dobsonian mount. Can anyone suggest parts I need and where I can purchase them from?

[bomberbaz]

4 hours ago, mikey152 said:

I would like to build a simple azimuth drive for my home made Dobsonian mount. Can anyone suggest parts I need and where I can purchase them from?

problem you are going to have with a simple azimuth drive, which I have no doubt is buildable is that your object in view will still drift up or down in the field of view.

You would be better building an equatorial platform which is designed to keep the object in view by following the equatorial plain.

There is loads of info on the net, just google it, the one below is a guide from sky at night.

Build a Dobsonian equatorial platform - BBC Sky at Night Magazine

[mikey152]

I definitely don't want an equatorial mount  I have built one and do not like them at all due to the awkward angle the eyepiece often  ends up in. Also they need to be accurately aligned to the pole star each time it is used. I know an object will drift out of the field of view, but I am only interested in viewing an object for a few minutes without it moving out of the field of view. 

[Mandy D]

21 minutes ago, mikey152 said:

I definitely don't want an equatorial mount  I have built one and do not like them at all due to the awkward angle the eyepiece often  ends up in. Also they need to be accurately aligned to the pole star each time it is used. I know an object will drift out of the field of view, but I am only interested in viewing an object for a few minutes without it moving out of the field of view. 

I know this will probably not change your mind about the EQ platform, but it is not quite like a regular EQ mount in that it is incapable of tracking for the long periods that a mount is, thus your eyepiece is not going to move very much. Regarding accurate polar alignment, that is only required for long exposure photography. You have already stated that you are happy for the object to drift across your field of view, so a very rough alignment will work.

[Stu]

28 minutes ago, Mandy D said:

I know this will probably not change your mind about the EQ platform, but it is not quite like a regular EQ mount in that it is incapable of tracking for the long periods that a mount is, thus your eyepiece is not going to move very much. Regarding accurate polar alignment, that is only required for long exposure photography. You have already stated that you are happy for the object to drift across your field of view, so a very rough alignment will work.

I agree with that, I only ever plonked mine down North and level and it did a very good job. Never found the eyepiece in too tricky a position, so I’m a bit confused by that. Just az drive seems like quite a lot of effort for not that much gain. However, the OP has made an EQ platform so know what they do and they are not for him.

@mikey152 can you post some images so people can see the design of your dob as that may determine what would work best.

[Mandy D]

7 minutes ago, Stu said:

 However, the OP has made an EQ platform so know what they do and they are not for him.

I'm not sure he has, because he specifically states "mount" not platform.

[Stu]

16 minutes ago, Mandy D said:

I'm not sure he has, because he specifically states "mount" not platform.

Hmm, well spotted 🕵️‍♀️

@mikey152 do you mean EQ mount or EQ platform? Platforms are great to give dobs around 45mins tracking with very simple setup. They also keep the eyepiece in a very useable position.

[Mr Spock]

Ditto on the EQ platform. I just plonk mine down and off we go 

[mikey152]

I haven't made a platform . I have made an equatorial mount  which I don't like particularly at the angle that an EQ mount has to be here in tbe UK. My mount is the Stellafane type so I can rotate the tube to put the eyepiece in a convenient position.  Would the telescope not be at an awkward angle as the platform would need to be at 53.5 deg here in UK?

[Mr Spock]

2 minutes ago, mikey152 said:

Would the telescope not be at an awkward angle as the platform would need to be at 53.5 deg here in UK?

That's not how EQ platforms work - see my image above, it is flat  I'm at +53.39°

[bosun21]

No the platform is actually not set at 53 degrees, it's the wedges inside them that are cut to match your general location.

[mikey152]

I don't quite understand how the platform can be flat. I have looked at them and the platform is at an angle which surely must be at the latitude you are at. I know the platform is flat and you just plonk your dob on it but it must be at an awkward angle otherwise how would it track a star?

[mikey152]

I am reading up on how to make a platform so I can fully understand how they operate. Ideally I would like to be able to transport it as there is far too much light where I live so would want to go up onto the moors which aren't too far from me. Would the platform have to be transported in 1 piece or could it be split to reduce the weight and still be able to be put into use in a short time ?  I can split my DOB mount into smaller parts and put it together in a matter of a minute or so

[bosun21]

EQ platforms generally come in two pieces. A top and section and a bottom section where the workings are located. They can be separated easily for transport. The wedges are tapered to your location and will give you roughly 45 - 60 minutes of tracking before needing to be reset. The angle of the scope does slightly change as the platform traverses but only slightly and not enough to alter the eyepiece position by any margin. Think about how much a star will move in latitude in 45 - 60 minutes. That's how much your scope will tilt on the platform.

Edited November 14, 2023 by bosun21

[mikey152]

Thanks for that. I do get it now. As the scope is only moving for about an hour, it will never get at an awkward angle and be fairly level most of time.

[PeterStudz]

I built an EQ platform for my 200p Dob which has a homemade base. The thing has been a revelation and greatly improved my observations. 

The one I made was from an excellent thread on here (see below). It’s simple, can be constructed with basic tool - eg electric drill, hacksaw, panel saw, screwdriver and materials easily available from eBay plus some plywood from just about any hardware store like Wicks. If you look through the thread there are complete instructions, even links on where to by your bits and bobs. 
 

 

[mikey152]

Cheers for that. Am seriously looking into building one.

[mikey152]

Another question . Would a Nema17 stepper motor be powerful enough to move a EQ platform smoothly. I can imagine a lot more torque would be required to drive a platform rather than  a conventional DOB mount ,particularly mine as both my azimuth and altitude bearings are lazy susan and if anything run too freely. Another advantage I could see in a platform would be the possibility of being able to plonk both my telescopes on the same platform and as I am hoping to make a 12 inch mirror next year ,the possibility could arise of being able to use the same platform for all 3? What are peoples thoughts on this?

[Mr Spock]

My EQ platform uses a Celestron motor https://www.amazon.co.uk/Celestron-93514-AstroMaster-PowerSeeker-Motor/dp/B00039R23G?th=1

[PeterStudz]

Those little EQ1 motors mentioned above are all virtually identical (whether they are branded Celestron, Meade or whatever) and probably all come from the same factory in China.

I got mine from here…

https://www.firstlightoptics.com/sky-watcher-mount-accessories/ra-economy-motor-drive-for-eq1.html
 

Initially to power an EQ1 mount which it’s designed to do. Then used to drive my DIY EQ1 platform. One of the best and cheapest  astronomy purchases I’ve made. 
 

It drives my 8” Dob with ease and my homemade base is relatively heavy and solid. I believe that @Mr Spock uses his platform with a similar/same motor drive for his 12” Dob. A 12” Dob is PROBABLY the safe limit, but as long as everything is well balanced you actually don’t need a powerful motor. 

Edited November 15, 2023 by PeterStudz

[mikey152]

A Nema 17 motor is much cheaper and with  an arduino UNO  driver is seems  it might be a better option. Thanks for the input everyone. Much appreciated