Improved design mill spindle dial indicator holder introduction.
(I forgot to explain how to construct the preset friction joints. If you are interested, have a look at 8 min in. I use spring washers to give the tension, but I bend the spring washer edge that would cut into the surface away a little, to give a smooth contact that does not dig in. You can see the grub screws that pinch on to the thread to lock the friction setting, use soft e.g. nylon or copper inserts in front of these grub or set screws to avoid damaging the threads. This works so well the knurled adjustment screws could be replaced with plain cap screws as adjustment is seldom required).