Anybody out there know of a good way to reliably determine a frame BC? We try to match lens BC's to frame BC's (when necessary) with our surfaced lenses so they fit and look better.
I've tried to use a lens clock to line the three pins up on the frame front or back, but it's hard to keep the pins from sliding and measuring the wrong curve.
I've tried to measure demo lenses and they don't always fit right and sometimes are too flat or curved anyway. Sometimes I'll measure up to 2.00 D difference in curve between OD and OS demos simply because they fit better in one side than the other.
Our frame tracer on our Santinelli edger also has a habit of reading way too steep or too flat (verified by lens clock on the actual frame) so this isn't a great way either.
Any thoughts? Do they make a frame basecurveometer? I might be getting a 4T tracer, do they read frame curves pretty accurately?