COG lies between the mounting holes/screws at the microscope's base. originally i want the pivot connection to the tv arm lies below COG to reduce if not eliminate entirely torsional force on the pivot. but that setup will probably disturb area near lens tip where i will mount led lighting there, so i moved the pivot connection to the back of the base, this way i have more room around lens tip and also more bench space behind the scope in case i want to put something or if have bigger pcb that needs bigger depth. in case the arm unable to hold the torsional force, i was thinking to put shims or spacers between the base's bracket and the arm connection to hold/lock the position of vertical angle (YZ plane) but luckily it turned out the pivot is able to hold the torsional force due to the COG/microscope's weight without the need for the shims, thumbs up to this china designed arm. so the vertical angle also nicely and freely changeable.
i can either use a table on the arm's base if i need extra height or big flat surface, but i can also use without it, just work on the bench where the microscope will stand on. stability? this is very stable as a car, i believe no small kid let alone a cat can tip it over due to the weight and stand's base dimension on both X and Y axis. we need very steep angle to make it tumble. even hard for me to turn and lift, this thing maybe near 10kg already, the boat anchor type of microscope that requires 2 arms to hold. originally the main requirement is only adjustability on Z axis height to obtain focus to object, diying that will be quite hard for me as machineries required i dont have. so i picked the off the shelf tv arm in place, saved me alot of trouble. this articulated arm can also move a little bit to sideways and vertical angle adjustability, so more degree of freedom and a bonus to me.