These concealed furniture castors from Bunnings are excellent for the rotating base of a home made dobsonian. still use thelaminate as the rollers will roll quite effectively and if the mount is too free then it is a simple matter to make a spring loaded friction pad to give a bit of "Grab", all you need is a compression spring and two 3/8 inch washers, a 3/8 inch bolt with two nuts, a bit of white cutting board n glue.
I have put them on the 8 inch f6 dobsonian and it is silk smooth.
next is the home built 10 inch newtonian/dobson.
