Pickup SRA - starting from a 500x microscope

Thanks for this Phil. Can you calculate angles with Pixelstix as well or do you just import your image into Pixelstix, correct the image to 180 degrees and then move it to ImageJ to calculate the angles? I will download ImageJ.

Indeed, for me getting a perfect 180 degree image to start with is very difficult.

Thanks for the link too.
Sly

One problem I can think of with using the trusted ear method of determining the proper angle, any of the angles involved, is that you never know when you have achieved a local minimum, in terms of distortion. That is why a technical method should yield better results. Analogous to trying to determine the ideal best sounding speaker locations by ear. Technical solutions should yield better results than ye olde move a little, listen a little method.

SMoffat - You can use Pixelstix for both horizontal and angle calculation. Sorry I should have mentioned this sooner is another good 'horizontal' calculation program is Go Horizontal. Its costs less than $5 too and is even more simple to use.

I would go with Go Horizontal for the 180, and then ImageJ for the angle calculation. Pixelstix combines both but is more complicated to use.

Something to keep in mind is that all LPs are different- so the 92 degree SRA should be considered an approximation.

The simple fact of the matter is that the cutting stylus only lasts about 10 hours before replacement is required to continue doing low noise cuts on the lacquer. To replace the stylus, the cutting engineer has to remove the cutterhead from the lathe to do the job. Once done, it is then a matter of re-installing the cutterhead and getting it to work right again. That involves a number of test cuts until a number of the variables are worked out. These include stylus temperature, cutting angle, cutting depth and pressure (similar to tracking pressure, but cutting instead and somewhere between 60 and 70 grams is typical on our cutterhead).

The simple fact is that while you have to have a certain rake angle, in practice it might be 92 degrees and it might not. What it is will be whatever was required to get the cutterhead to cut a groove properly. As a result, all LPs are slightly different; 92 degrees is a good average.

Interesting that the OP is trying to figure out a method for setting the correct 92deg SRA on an Atlas yet the venerable Mr Carr at Lyra ( for whom I have the highest respect and admiration) is not a great fan of SRA.
A bemused Atlas owner !