Actually, that was not an OPTION. Bridgeport found out that the linear scale on the Z (quill) could mis-read under heavy milling. This would cause the Z axis to try and correct its position. Not good.
Bridgeport issued a recall/upgrade in which the Z motor was replaced with one that included a rotary encoder at the end of the motor. Of course this involved a lot of work to rewire the machine, etc. The dealers were reimbursed for a bout an hours work and of course this took the better part of a day including driving. Therefore I do not know how diligent the dealers were about doing this.
The question is simple, do you have 2 or 3 cables coming off your Z motor?
Given the correct configuration of the machine, a matching schematic can be found.
My office had a habit of "selling ice to Eskimos". They would sell a three axis conversion for a SX machine. This involved the mounting of an additional cabinet for the 3rd axis drive and the hard drive. This bit them in the rear later when the upgrade kit came out and the original BMDC did not support an additional axis encoder input.
George
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(Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)
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