Alignment tool for SME V + Shelter

Nandric, in all alignment procedures (except the SME) it's mandatory that a prescribed stylus-to-pivot distance (sometimes called 'Effective Arm Length') be maintained (thus necessitating slotted headshells ;-)

Further, a fixed arm length requires a specific (for that tonearm) spindle to pivot distance, and most tonearms come with an appropriate (though not always well crafted) template. If the one you got is sloppy, or non-existant, it's best to make your own out of a piece of acrylic. Slip one end over the spindle (with the platter removed) and, through a tiny hole in the template drilled the correct distance from the center of the spindle, scribe or draw an arc on the arm board. You can drill the arm mounting hole(s) anywhere along that arc.

Dan asserts that "With an arc-style protractor made for the table/arm combo, there is no need to measure P2S" (I think he meant cartridge/arm combo,) but unfortunately, this is true only if the arm mounting holes have been drilled, and the arm mounted with utmost accuracy, the correct distance from the spindle, per the tonearm manufacturer's specs. In reality, that is REALLY HARD TO DO without proper shop tools, drill press, etc.) If there's any doubt (and even if your TT came with the TA mounted) it's best to field-measure your particular equipment setup and provide the actual P2S dimension to the toolmaker prior to fabrication ;-)
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Table/arm. P2s and effective length are not dependent on the cartridge used.

Setting P2S is the responsibility of whoever mounted your arm, quite possibly the 'table manufacturer. So, yes, I can see the need to measure this ONCE when having a protractor made up because you can't really trust that the arm is mounted exactly right.

But then again, this is the beauty of articulating arm boards. You don't have one on your table? Sorry. ;-)

We've, well those who have been paying attention, covered all of this several times before. A search here will turn up past discussions on this. Bye.

Dear Dan, If this is the answer to my question then we have
the problem that one can move the arm in relation to the spindle-pivot distance as well as move the cart in relation to the 'slots' on the heashell. With 2 moving dimensiona I am not sure about the result.BTW the slots are
to provide for the distance between the stylus-tip and the fastening bolts because this distance differ by carts.Or so
I thought. I am not a technical guy but I know that the spindle-pivot distance is fundamental.
Regards,

"P2s and effective length are not dependent on the cartridge used." True. They are instead dependent on the tonearm design and must not be changed. Providing slotted headshell mounting holes therefore allows mounting the cartridge so the exact stylus-to-pivot distance required by the manufacturer can be set, regardless of the cartridge's stylus-to-mounting hole dimension. So with (most) arms you need to be able to adjust the fore/aft position of the cartridge in the headshell. The spindle-to-pivot distance is also specified by the tonearm manufacturer/designer and combined with the specified EAL (effective arm length) provides the correct arm geometry.

Nandric: "BTW the slots are to provide for the distance between the stylus-tip and the fastening bolts because this distance differ by carts. Or so I thought." That is not correct. The slots are to allow one to shift the cartridge fore or aft until the stylus tip is the PROPER DISTANCE FROM THE ARM PIVOT ;-) That distance is called the 'effective arm length', and is pre-determined by the tonearm designer.

Hello again. I realized that with the SME slide mount you can set effective length easily. I suggest people draw themselves a picture so that the relationships between these distances become clear.

Also, I suggest researching arc-style protractors. It is not necessary to check p2s every time you check cartridge alignment because the arc is drawn at the correct effective length and the arc is registered properly by the spindle hole.

Another advantage is that with this type of protractor everything is fixed in place, platter, protractor, etc., so there is no moving of the protractor (ala DB) while you are trying to hit a gnat's ass with the stylus.