Tonearm Alignment Dimension Calculator
Below is a calculator you can use to determine what your Pivot to Spindle distance should be based upon your tonearm manufacturer's specified Effective Length.
While we always aim for total accuracy in the pursuit of vinyl playback, if there is some variation between the actual pivot to spindle distance and the calculation it may not be cause for alarm.
As long as you have enough play in your headshell slots (or have an adjustable SME-style mount at the tonearm pivot) to move the stylus into the selected effective length groove (Baerwald or Loefgren) you can know you have achieved an accurate result. If you cannot slide the cartridge forward or backward enough to have the stylus fall into the selected arc then there are two likely reasons:
Your tonearm was not mounted to the armboard using the proper spindle to pivot distance. Fix this by loosening the arm base and readjusting the tonearm.
Your tonearm manufacturer used non-standard assumptions for the innermost groove radius assumption.
Still can't get it to work? Follow the 4-step directions in the WallyTractor's supplementary section on "Measuring Spindle to Pivot Dimension". We can help you get to the bottom of it!