My first machine was a Brown and Sharpe VC1000 with the Bendix A5M control. About 16,000 lbs smooth as silk.
Retrofit? that was/is a great operator friendly control! It had resolver feedback to the control, and tach feedback to the servo drives. The servo drives were GE HiAk drives. They take +- 10 volt signals. As does the spindle drive, GE Valutrol. All very friendly for newer controls. The motors were 2hsp GE DC motors, 90 volts servo power supply. Encoders could be fitted instead of the resolvers, not a problem. The resolver circuit in the Bendix control is awesome how it worked, it could also detect a bad or intermittent signal from the resolver. Try THAT with an encoder circuit!
The Bendix control, like the Bostomatic was based on a Data General computer. Having worked on Data Generals for years, it was like an old friend electrically. Easy to troubleshoot to the chip level.
The fourth axis used inductosyn scales fro feedback, and positioned to 360,000 parts of a circle. The inductosyn uses printed circuit "antenas" (?) and is very simular to the resolver in operation, in fact it used the resolver circuitry with an extra op-amp for feedback.
IF you have the room, that old iron can be had for less than scrap value, and is much more massive, stiffer and slower than modern VMC's. The key is really the room it takes up, and the floor thickness to support it. Moving it was not too hard to do. That was my first big machine, and was easy with a couple bottle jacks and a borrowed pair of skates from a local shop. A local cement (cistern) factory supplied a boom crane for about $120 to lift it and move it... Get creative, if you have the room.
Pete  |