Skateboard Wheel Dob Mount
Submitted: Tuesday, 4th July 2006 by Geoff Liddicoat
Here are a few details of the DOB mount I made out of light gauge steel tube, and some round.
The materials cost me a total of about $30 unpainted.
You need to be handy with steel fabricating and have either a MIG welder or an oxy set. I made the frame along the same dimensions as a 10 inch dob timber mount.
The lower frame for the adjustable feet and center swivel is made of 20mm X 50 mm X 1mm thick tube welded to a center piece of 40 mm pipe 50 mm long. The center swivel is 18 mm rod 120 mm long with a hole in the end to take a large split pin. I used skateboard wheels for the feet.
The upper removable scope holder frame is of 15 mm square, 1 mm thick. I made the half round bearing suface for the Alt scope movement of 15mm X 3mm Flat steel and stuck on Teflon, so this part is no different from a normal DOB mount. The bottom of this frame has a piece of 40 mm round 3mm thick, 100 mm long with two old bearings fixed one each end. This allows the top section to be dropped onto the 18 mm rod, and held with a large split pin, made to remove easily. Any reasonable old bearings can be used and a piece of rod to suite, as long as it is thick enough.
I mounted skateboard wheels onto 25 X 5 mm flat steel bent to suit the circumference of the wheel track, and this is screwed onto the frame with 6mm screws and nuts. I slotted the holes to enable fine adjustment of the wheels for running on the circular 19mm MDF board which has a laminex finish. The MDF board is screwed to the bottom 3 legs with packers for adjustment. I marked 0 to 360 degrees on the board with a pointer, mostly for show.
I made a simple brake on the bottom of the 40 mm tube to prevent the scope from slewing on uneven ground. Only slight pressure is needed for this.
On the sides of the frame are the 12 volt battery cradle and the heated box for the eyepieces.
The mount works well and is about three quarters of the weight of a timber mount. It comes apart easily for fitting into the boot of the car.
It is a lot of work for these advantages, but I like to experiment!