This is my home-built equatorial platform on which I mount my 222mm and 444mm Dobsonians to allow me to carry out digital video imaging of planets. The platform was built prior to the opposition of Mars in 2007 to allow me to use my undriven 222mm Dobsonian scope to image Mars that opposition. The platform which allows uninterrupted tracking for up to 80 mins, has been in regular use ever since then.
Here you see the main mechanics and motor of the equatorial platform. In the picture you also see a large compass board on the right-hand-side which is used to set up the platform and align it correctly in azimuth. The compass board uses an oil-filled ship’s compass I bought at a bargain price in a car-boot sale on the Isle of Wight.
At the far end of the platform’s base board are the two rollers that support the two sectors at the North end of the top board. One roller freely rotates whilst the other one (far left) is driven from a synchronous motor via a worm and wheel gearbox (seen centre left in the picture). In the first incarnation of the platform I used a pair of stepper motors driving directly onto the shaft of this roller. In 2009, however, I removed these and replaced them with the current synchronous motor and gearbox. This has massively reduced vibration, as well as backlash and slippage issues.
The black box you see in the photo of the baseboard is the drive unit for the synchronous motor (connected to end-position microswitches). The angled plate on the right holds the freely rotating rollers that bear on the similarly angled south sector of the top board.
From early 2014 have also successfully used my 18″ Dobsonian, Fossil Light, on the platform for many imaging sessions. The platform was actually designed to take the much greater weight of this scope but I never had the courage to try it out until early in 2013 when I used it for a Jupiter imaging session. The exercise of using this bigger scope on the platform has been a great success as I hope you will agree when you look at some of my Jupiter and Mars images from this period.
You can see some pictures of the set up with Fossil Light mounted on the equatorial platform below. It takes about 15mins from decision point to having the fully assembled scope on the mount – not as quick as the set up for Mr.Orb Inspector but quite doable once you get used to the much increased weight of some of the separate components!