The original builder of the mount for my 10" Dob used a strip of aluminium screwed to the top of the tube box and hooked into the mirror end of the tube. If I added a heavy 2" barlow and eyepiece it upset the balance. Here's my mod to make adjustment quick and easy.
The clamps are from the tops of 20l chemical drums. They were about 1mm smaller in inside diameter (289mm against 290 for the tube OD) than the tube but by drilling out the spot welds and pop riveting in a 12mm extension they clamp up nice and firmly when lined with some left over sticky back felt. Probably been done before, but thought I would share anyway.
Found they slipped after "bedding in" a bit Stephen, The tube is 1.5mm Steel and the mirror is pretty heavy too. The MkII version has 10mm round section rubber glued inside (Clark Rubber), solid as a rock.
$14 for 2 metres. which makes it a total $16 the pair.
