#equatorial mount

[skate-tautoloandsym]

Monture équatoriale pour mieux pouvoir suivre les astres. Assez lourd. 赤道儀式架台。重い。

[astrodiy]

Here some news about the DIY.

You can see the mount without the "Main Axis" but with the big bearing that will carry it.

Then you have the gear box with pulleys, bearings and the stepper motor.

If you watch carefully, you'll be able to see the microstep driver in the background.

[astrodiy]

The concept

Hey Hi ! 

Let's talk about the general concept that I designed.

The idea is to have a first board capable of being stable on any field. To do this i'll use 4 adjustable furniture pods. It allows me to put the mount anywhere without caring about where is the north.

On top of this first board, let's have fun and put a slewing bearing. This big piece of 8kg and 30 cm external diameter, will have two functions: The first is to allow the on top overall rotation and the second is to stabilize the mount.

Then another board comes on top of the slewing bearing. It will support the overall on top weight and will carry the car lift.

The car lift will permit a precise and large range of observation sites.

Finally we will have the last board which will carry the rest:

An attachment for a small laptop

A scooter 12V battery (cheap, quite lightweight and enough power for all the night) 

The gear box

The main axis

Now that the design is decided, let's make some more precise plans ...

[astrodiy]

Step One: Preliminary Study

The first question was: Equatorial or Azimutal ? The answer is easy. Azimutal needs 2 motorized axes so make things harder to build. Then that kind of mount is not suitable to astrophotography because of the blur caused by field rotation of the optics.

The second question was: An equatorial mount ok but ... What for ?

I'm fond of deep sky astrophotography, so I want a device which is able to follow the deep sky objects (not especially planets nor comets). The thing is that I want something able to follow objects for a long period without touching anything.

So I need :

Stability

Accurate tracking

Long time traveling

Heavy weight carrying capability

I've seen lots of home made equatorial mount but none of them where really fitting my needs :

Some of them are nice and accurate like the Serge Bertorello one :

1. The Smooth Area mount 

The problem with that kind of mount are :

It's HUGE

The smooth area (in green) allow few hours of tracking

It uses a threaded rod which wear out quickly and transmit vibrations.

I've a small car, I'm lazy (not want to repair it every month), so I've decided it wasn't for me.

2. The Equatorial Table (ot platform)

Lighter than the smooth area mount, the Equatorial table seduced me for a while. But then problems came.

It's nice when you have a dobson but I don't. You have to place on top another pointing system which add more stuff to do. And finally, you have a limitation of the angle of polar axis regarding the spot you observe. 

You can find here some web sites if that system interests you :

Nice one - in french but with nice illustrations -

Another nice one - with plans an in english -

3. The Cam Board

Lighter and lighter, the cam board is a famous and easy system for astrophotography.

Ok it seems pretty cheap and to be frank ... it is.

The carrying capability is weak, it's still using a threaded rod and to finish with this system, it's hard to make it accurate.

Conclusion : Let design a brand new one with the combination of all pros and trying avoiding cons.