Want to Buy a Kit?

Parts and kits now available for sale:

Kits from 30GBP up to 130GBP.

You can just purchase the curved rod and source all the other parts yourself if you wish.


My Kits do not usually include a finderscope and you will need your own 12v supply. You can add or take away any of the parts listed below.

Construction time can be as little as 5 hours - well I have made a few by now! Plus a couple of hours to calibrate and align the tracker.

 

Construction details here

Parts list with prices

3. Astronomy - mounts ( Barn Doors)

The design for this barn door tracker is taken from an excellent article by GARY SERONIK. See his article here. Note that dimensions differ between Gary's model and mine, as the pitch of the rod influences the overall size of the barn door.

A recent (2015) version of the mount. The wooden wedge means that the camera is level above the mount when the mount is polar aligned.

The long CCTV type ball head is made up of sections and can be extended or reduced in length.

 

 

This shot of Altair is 60 secs exposure with a 150mm lens at F5.6 - it shows excellent tracking capability of the barn door.

the main drive wheel turns an embedded nut to drive the 4mm curved brass rod upwards at precisely the amount needed to track stars as the appear to move in the sky. The main drive wheel is driven by a smaller cog fixed to the output shaft of the low RPM motor. Drive ratio is about 3:1

A spring holds the motor cog in place and elastic bands can be added to provide tension to keep the doors closed

.

This image is 4 stacked shots - 60 secs, 150mm lens at F5.6 - centred near 17:45 hrs, 55 deg N

The motor is controlled by a voltage regulator outputting at around 6volts. Voltage regulation down to 1/10th of a volt is possible with this circuit. I've recently added a diode to protect th circuit from a reversal of polarity.

Andromeda, 100mm lens, 60 sec exposure.

    Viewed from below, the improved motor on the production model can be clearly seen. A wood screw firmly fixes the motor in place while a small spring allows the motor to articulate and engage the driven cog. This allows the doors to be opened up, the drive wheel to be spun back into the start position and the drive train re-engaged for another 2 hrs of tracking.

Of course this moves the alignment and the camera will have to be realigned.

 

Vega in Lyra, taken 26th Oct 2013. 60 x 4 sec exp.
 

The tracker worked well, keeping good time. The photos aren't all that good as there's lots of light pollution and even a 2 min exposure at F11 shows too much noise.

 

Cygnus 60 sec exposure with 100mm lens. Some lens effects near edge, but centre field is all round stars - just need abetter camera.
.      

- see initial photos here

Now available - Kits, Parts and Instructions - click here

Making the curved brass rod is the trickiest part of the process, and the most critical. Rather than bend the 500mm length of rod by hand or around a formed shape, I decided to invest time and effort in producing a bending rig to give me more control over the process.

The rig allows me to produce a curve which is ever so slightly oversized. I then use wire and string it like a bow, tightening the wire until the curve is the correct diameter. The "bow" is then heat treated to remove stresses in the metal that may cause cracking later on and to allow it to set into it's new shape.

As the 4mm rod has a pitch of 0.7mm the radius of the curve has to be 160mm. The rod is cut up into (approx) 160mm lengths after bending. This should allow over 2 hrs of operation from almost fully closed to almost fully open. 160mm is also the distance from the pivot point of the hinge, to the centre of the hole the rod threads through.

Top