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That is certainly a much better way than trying to rely by eye, in which nobody would be able to fully zero platter runout.
Lining up dots doesn't of course insure one has the Platter optimised, and it all depends on just how well the Platter was adjusted from the factory, and whether that Platter has maintained its precision over the years.
As an example, I bought my HW-19 Platter used, here, from another Audiogon Member. What I found, was all 3 Screw Pins were fully retracted into the Platter, and thus there was absolutely no 3-Point Suspension in use.
It was sort of common, that an end user would believe he/she could tweak the Platter for even better zero, and actually caused more runout due to amateurish attempts.
I went with a inexpensive Dial Indicator, and Dial Indicator Vacuum Base, which could be set up alongside the Table. I simply made a Platter Mat from thin paper to prevent the Dial Indicator Tip from scracthing the Platter.
Even still, it was a lengthy process of experimention, and tweacking screws at about a literal 30th of a turn, to get correct final results. And those final results were initially about .006" +-.
But, later, when doing a lubrication maintainence, I thought I would be safe by simply aligning back the Dots, and all would be exactly the same. it wasn't, I had found the Platter deviated from my earlier hard work.
So, again, ut comes Dial Indicator and Base, and then got the Platter to an even better .003" +- runout.
One good tip, so you don't lose your hard earned adjustments when doing any Bearing removal for Lubing, etc.
Clamp the Platter with Platter Clamp, and remove the entire Platter, and Platter Bearing in one entire assembly, and keep them together. Then simply do your Bearing Well-Bearing Cleanm and re-lube, then re-install.
This ensures nothing then moves from the underside of platter, to the Face of Flange of the Bearing itself. Mark
Bpoletti: You are of coarse assumming that you can blindly place the platter at the same exact spot each time. That is impossible. Also, your way implies that the manufacturing process of each individual piece IE: platter/ plinth / bearing surface, etc... is "true". "True" rarely happens, especially in the price range of components we are talking about. Since posting this, I aquired a dial indicator. Needless to say, my business card way of doing it is extremely accurate!
@Slaw Balance is both the vertical and horizontal movement of the platter.
When a car tire is balanced the mechanic does not use runout.
Setting the platter by matching the dots works great, IMO, on my TNT Mk III.
I agree with Bpoletti, you are splitting hairs, no platter is perfect, horizontally or vertically.
The only platter runout problems I've ever had were associated with previous users that changed the leveling screws in the first place. (I've bought several used including my current original Aries.)
It doesn't take much to place the platter at the recommended position. That seems to result in a good runout.