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How to use Feickert Protractor on SME V Tonearm

I just bought a Feickert Next Gen Protractor. So far I just measured the spindle to pivot distance, it was set to 212mm. This is using a Denon DL160 cartridge setup using a paper protractor from the web. The spec for the spindle to pivot distance is given as 215.35mm. My turntable is a Gyrodec with mounted SME V tonearm. So I started thinking about how this would work using the Feickert protractor, each time I move the sliding mount of the SME V, I would then need to adjust the position of the sliding spindle to pivot distance of the Feickert protractor and thereby moving the alignment point. This seems like a never ending loop of adjust SME V slide adjustment, then re-adjust the spindle to pivot distance on the Feickert to get the correct alignment. Am I missing something, it seems like a very interative process to use the Feickert Protractor with a SME V tonearm. I bought the Feickert to make alignment simpler and more accurate. How do others use the Feickert Protractor to align the SME V tonearm cartridge?
hartonr
hartonr OP
4 posts
 
OK, I understand the use of the Mint protractor. The reason I went with the Feickert is so I can align my SME V with different cartridges. I did not want to measure each new cartridge and then get a new Mint protractor each time. So, please only give advice on how to align the SME V arm using the Fieckert protractor.

Thanks
peterayer
1,382 posts
 
As far as I know, SME did not assume anything about the cantilever length.
They assumed there would be an industry standard horizontal dimension
specification of 9.5 mm from the center of the cartridge mounting holes to
the stylus tip, regardless of the length of the cantilever. This is the
measurement that YIP at MINT needs to provide an accurate protractor to
customers who own SME tonearms.

I have precisely measured this distance on two of my cartridges. Fortunately,
they have the same mounting hole to stylus tip distance of 9.27mm so I can
use the same MINT protractor for both cartridges.

Yip needs this measurement so that he can calculate the pivot point to stylus
tip distance to accurately draw the currect radius for his arc protractor. The
offset angle of the headshell comes into this calculation as the radius is the
hypotenuse of a triangle formed by three lines: the pivot to stylus tip
(hypotenuse), the pivot to a point centered between the cartridge mounting
holes and the center point between the mounting holes to the stylus tip.

Once calculated accurately, the MINT protractor is an extremely good
alignment device.
john_gordon
116 posts
 
As has been mentioned, any two point protractor can be used to set up an SME, or any other arm for that matter, irrespective of whether the arm base slides, the mounting board pivots, or there are slots in the headshell.

The SME approach which is based on a nominal effective length design predates all current production arms and has many advantages, and is neither naive nor ill considered. As has been mentioned not all cartridges are the same, and the SME design principle was based on that fact.

Arc protractors are a relatively recent innovation, and are dependent on accurate effective length measurement, so as as to enable the correct arc to be created, otherwise the are inaccurate. They also require accurate mounting of the arm to suit the effective length. The SME approach does not require the pivot to spindle distance to be fixed, therefore the arm mounting is not critical. it is adjusted to suit the cartridge. Understanding this is important and there is much misinformation about SME arms because of a misunderstanding of the basis of tonearm design, often on the part of those who should know better.

There is a description of SME geometry here
as well as other aspects of design such as the importance of spindle sizes, and protractors such as the SME and the Dennesen Sountractor.

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