Sine bar errors

[PJs]

Thanks Paul. I have considered lapping them by holding the long side (hypotenuse) as a reference and work on the 90, but feels difficult to adjust the obliqueness with any thing I have to accurately hold the correct angle and allow the slow whittling away till I get there. The other thing is my height gauge only measures to 3 places plus a floater half, and the long side of 30-60-90 is just slightly bigger than my 3" 10'th mic, which is my largest. It would be difficult to check to any accuracy as I go along and wouldn't want to bug my son. Need to crunch some numbers to see what I "could" hit with 3 decimals and how I might hold it to get there. I'd love to salvage them as the 30-60-90 is the one I really wanted but just couldn't justify sending them out or much more time on them.

Interestingly, both sets of these have one side that is ground perpendicular to the plane and the other two are ground in the run. Definitely Friday units while the QA people were out to lunch.

I only have one set of 123 blocks and believe it or not they are from the same people. When I got them I measured and swept them every way I could thing of and they are withing 2 tenths in all directions and parallel. They are oversize by 2 tenths but are definitely matched, but like you say it's not a priority...Straight/square/parallel is workable for my meager needs. I use them more on the granite than for setup but do use them occasionally for a set up for lapping perpendicular to a small granite I have. I do like your idea of a solid block though, as the threaded holes on these are worthless and cobby but for $20 I can live with that. I'll keep an eye out for them.

Me too on the learning and fun! ~PJ