[jbeech]

2 CNC 372 . . . is stamped into the base of my Bridgeport Series II CNC mill.

I'm trying to determine year of manufacture, but it's out of the range of serial numbers I've found listed online.

Moreover, a page in the manual shows a photo, which based on appearance leads me to believe this machine is post serial #7126.

Frankly, I am baffled and any help would be appreciated.

[machintek]

Boss 6 with stepping motor control

George

[jbeech]

Thanks for your response George. Any idea of the vintage?

[machintek]

I would say early 80s. The Series 2 was only available in the BOSS 6 flavor on. I started with Bridgeport in 1982 and was installing these. Within 2 years the stepper controls were replaced with servo motors resulting in the BOSS 8 and then 9.

George

[jbeech]

Thanks George, it's kind of you to take time to share your thoughts. I appreciate it.

[josemx]

Hello George.

I have a Bridgeport BOSS 6, he is practically equal to which has jbeech. Everything worked well but a good day I stop working z-axis. It looks for the cause of the problem and found a transistor of commutation in short circuit. It changes it and I work just a short time before it returned to fail. It reviews all the associate circuit and it changes to the bridge of diodes and a transformer, I placed the transistor new and the same, work just a short time and returned to fail. According to your experience, what is what can be causing that two of the four transistors of commutation of z-axis fail?

[machintek]

Very common problem. Either DC current too high and/or voltage from transformer T2 too high (limit is 63 VAC). Make sure fuse holders have no corrosion too.

George

[jbeech]

George,

It never occured to me to eyeball the numbers on the dataplate on the cabinet door, but that's where there are two numbers, which lead me to believe the serial number of my machine is #7260. While these numbes are for the control enclosure, I'd bet Bridgeport would use that number for the mill as well (or vice versa, actually). Especially as this jives with my manual's photo indicating my machine is post #7126.

While it's a meaningless piece of trivia at this point . . . "happiness is" aptly describes me at this moment. Meanwhile, Lynn tolerantly says, "Boys with their toys."

[josemx]

Hello George thanks to respond.

It was being able the transistor to make the measurements that you indicated to me and the results are:

The voltage when coming out of T2 this within the rank that indicates the handbook: 57-63 VAC.

The static current according to the handbook must be between 8,1 and 8.3A. After putting the transistor that did not serve and measuring I obtained 8.03A.

The current with the step motor in movement must be between 4,6 and 6A, according to the hanbook.

When I give advances in Z of the 1” current is 5.0A, it is within the rank.

When I give advances in Z of the 0.1” current is of 7.38A, this by above of the rank.

When I give advances in Z of 0.01” and Z the 0.001” current is of 7.99A, this very by above of the rank.

It interchanges cards of SMD X to Z and the measurements were the same.

What I must fit so that the current this within rank of the 4,6 and 6A when the motor this in movement?

Greetings

[machintek]

Current is OK. As the motor spins up to rapid the voltage will go up and the current will go down. I have seen current at rapid down as low as 2 amps. This means a motor with strong magnets. As stepping motors age, the magnets get weaker and the current will go up.

George