The back view shows the X-axis linear optical scale.
The unit had a very heavy cast-iron base and was quite stable. It moved smoothly and was quite repeatable.
Many times the hole locations I was measuring turned out to be an even fractional dimension, I learned to expect this in a motorcycle engine designed in 1957. I was sad to sell the unit, especially at a loss. The landlord had learned I was living in the shop and did a "soft eviction" by not renewing my lease.
I had built and entire second floor inside the shop, doubling the square footage to 2000 Sq feet. Those 2x4 studs behind the machine are supporting the mezzanine floor.Its a shady legal area. The landlord has to tear out all the "improvements, but they can't really sue me since they have no proof I built it. I got the last laugh. I designed and built the mezzanine really solidly. It was glued and screwed and survived the big 1989 earthquake. When the landlord hired a crew to tear out the second floor, they did not realize how well it was attached to the wall and they collapsed the back wall. The machine shop that was on the other side of the wall got quite a surprise that day.