3. Astronomy - mounts ( The Wheel)


Building this mount was great fun. A bike wheel fastened to a sheet of plywood and braced on a couple of trestles so that the wheel spindle (The RA Axis) points at the pole. I used the equatorial wedge from my first project to achieve the correct angle.

The wheel only rotates a few degrees which is equivalent to 15 mins of viewing time. Rotation is achieved by winding a 2mm pitch threaded rod at 1 RPM. The purple wheel is turned by hand to match the motion of the second hand of a watch.

I had some good results from this contraption in the 2 weeks my wife would let me have it in the garden. Eventually though the grass started grow and it had to go.

Still, at a cost of £2.00 for the wheel (everything else was in my scrap box) it is yet another low cost approach.

If I was to do it again, I'd use a 0.5mm thread pitch rod and a much smaller wheel.

Some of the results from the tracker


The wheel actually worked well. The problems with these images are:

1. Too much light pollution;

2. A badly focused lens on the camera - most visible in top image. The lens won't focus at infinity;

3. The mounting is unwieldy. But if you live in a rural area with some unused space in the garden then you could do much worse than a nice alloy bike wheel set up as a permanent mounting for your astro camera.