proper use of arc protractor ?

Yip's Instructions that accompany the Tractor were IMO well written, and easily-clearly understood.

As was mentioned in your other thread, the goal of correct overhang is to get the stylus to precisely trace the Arc from start to finish of Arc.

It is permissible to rotate the Tractor to accomplish such, as this is not a Sight Line Tractor, like a Geodisc, or the Turntable Basics Mirror Tractor (as two examples).

It is a lot of fidgeting, no doubt about it, and I almost took two hours to use my Mint Tractor to properly set up my Cartridge.

You must achieve proper overhang first. Then you lastly move on to achieving correct Zenith Angle.

This is the adjustment, of insuring the cantilever tube of the Cartridge is in alignment with the two null grids on the Tractor. These are actually microscopic, and almost an impossibility to do by naked eye. A magnifying galls, and a Loupe (Yip calls it a Lupe) will surely ease the process of this alignment.

But as you slightly nudge the cartridge within the headshell to adjust Zenith Angle, you most likely will also nudge the overhang, and it will again be slightly off.

This is what causes the Mint Tractor to be a lengthy process, going back, and forth, double, triple, quadruple, etc etc checking, to insure both adjustments are dead on.

Then one must finally snug the headshells screws reaonably snug, then check again. Then the final finishing tightening of the Cartridge to headshell, and again, another check must be done again.

One you see that the Stylus will perfectly trace the Arc with headhsell screws finally tightened, and that Cantilever alignment is nuts on to the null grids, you are then finally done! Whew!

The Mirror itself can also be used as a decent check of azimuth angle of the Stylus itself, by viewing from the exact front of the cartridge as the Stylus carefully rests on the mirror, that you want to see the Stylus, and a reflection of the Stylus, that both images look perfectly symmetrical, like an hourglass shape. Again, use a magnifier, or loupe to aid you.

Since the Mint Tractor is an overlay onto a sheet of (real) glass, you might note some scratching of the surface, caused by the Stylus. This can be lessened be wiping the surface of the Tractor with a little alcohol on a clean piece of Kleenex. Mark

I would just add a couple suggestions to Mark's very good post above. I presume your Mint is designed for your specific arm (and cartridge, if the headshell has holes but not slots like SME arms).

First, you must make sure that the turntable platter does not rotate (or move at all) while using the Mint. I wedge a pencil eraser in between my platter and subplatter to prevent this movement. Don't forget to remove the "brake" before you try to spin LPs again.

Second, make sure you have a very good light while working. This can help you see and prevent eye-strain.

Make sure the anti-skate is set to zero. Also, the VTA will change overhang slightly, so make sure your VTA is very close to where it will end up if you frequently adjust this for different LPs.

Relax and be patient. It takes time but the results are well worth it.

I noticed that the mintlp has a thickness of abt 3 mm which is thicker than most LP. If changing VTA changed overhang wouldn't playing with a thinner LP means that over hang will change . As such VTA need to be lower according to difference in thickness between mintlp and LP ? Is my observation correct ?

Yes, Audioblazer. I think you observation is correct and I don't know how to get around this. My point was just that the VTA does change the overhang, so I set VTA roughly where it will end up (because I don't change VTA for each LP with my SME V arm) before I try to align the cartridge with the Mint.

I would think that Kip took this into account when he designed his glass protractor. I think it is close to the thickness of a 180g LP, but I haven't actually compared the protractor to various LP thicknesses.

"It is permissible to rotate the Tractor to accomplish such"
Not sure I understand this statement.
Once tip is on arc line of outer point, is it permissible to rotate the protractor (not the platter- if not why not?) and place tip on inner point?
Is this correct?
Thanks.

No, one should not then rotate-move the tractor when going in between inner, and outer points of the arc of protractor.

Only initially, if the protractor itself is grossly off the mark. If one cannot trace the Arc perfectly, one could possibly have the Protractor positioned slightly incorrectly.

One can then move the protractor, but then must start all over again with the overhang adjustment.

I think I have this right. Mark

If you could let us know where you live, perhaps a fellow Audiogoner would be willing to come over and help. Using the MintLP or any other arc protractor is not difficult, just time consuming. I have greatly benefitted from watching a couple experienced audiophiles walk me through the procedure. Getting 98% of the way there makes a big difference. The magic really happens in the last 2%

It appears that you are beyond the standard degree of frustration that can come with trying to nail cartridge alignment. This exponentially increases the risk of destroying a cartridge or damaging a tonearm. Relax and take a break for a day or two before approaching it again.

Thanks for clarification.

No doubt, it is much easier to show someone how to use an arc protractor than explain it in a forum.

There is an infinite number of arcs on the platter that match the arc of the protractor. However, there is one and only one arc that will also match the radius of the effective length of the tonearm from the mount position. (Actually, there are two arcs that match this but we don't care about the one on the right side of the spindle, unless we want to play backward.)

This is why the arc needs to be moved in the beginning of the process. The idea is to have the stylus land on one side of the arc at one extreme end of the arc, and land on the opposite side of the arc at the other extreme end. So, you can move the arc, and/or the cart until you find a position where the stylus is hitting just a little off the line at either extreme. That should leave the last adjustments needed only in the slots, and that is where the platter and protractor can be locked in position.

LIke I said, it is much easier to show someone than explain it. But once you figure it out, or see it, the first time it becomes very second nature.