I always check azimuth in the middle of a thrift store record. And several 1/1000ths of an inch matters not! Not in the real world!!
LP Thickness/Taper
If anyone has ever wondered how LP thickness varies from lead in to runout, I just measured it. It's well known that there's a taper to LPs, but I have never seen any actual data.
This is a 120 gram record. The thinnest part near the beginning of the first track is 0.0415", and the thickest part at the very end of the last track is 0.0470" (+/-0.0005").
I know there are many ways to set azimuth, but most most people tend to do it optically with a mirror on the platter. So, if you set your azimuth like this and are confident that you have it perfect, it will automatically be 0.12 degrees off due to the taper of the record. I'm sure all records will have a slightly different taper, but I can't see it varying too much.
