Should the OEM tech have megged the motor.

cmccull166 · Nov 21, 2019

Question
My local repair didnt have a scope to check the signal from the spindle encoder to the board .

He called the OEM all he wanted was the encoder checked once he knew it was or wasnt getting a signal he could fix the problem.

The OEM tech came the first trip to scope the spindle encoder when he didnt find an issue reassembled encoder and left.
I ran it for about 8 hours ..Same alarm...Back to square one.

The OEM came a second time ,this time I knew about megging the motor which he did ...The motor is shorting so now I know it needs rewound.

Shouldnt he have megged the motor the first trip when he found nothing wrong with the encoder?

crossthread · Nov 21, 2019

In my opinion...no. Unless that spindle motor is prone to shorting a winding to ground, megging the motor would be pretty far down on my list of things to check.

Garwood · Nov 21, 2019

Spindle drive alarm should give at least a hint that the problem is related to the motor shorting out instead of the encoder no?

If this is a VMC megger the wires to the spindle motor too. Those wires move a lot and can wear through.

I wish there were more "My CNC tech is just amazing and never leaves me wondering why he isn't flipping burgers somewhere!" type threads.

Vancbiker · Nov 21, 2019

cmccull166 said:
Question
My local repair didnt have a scope to check the signal from the spindle encoder to the board .....

My question is, how does one actually expect to be a capable CNC tech and NOT have, or have use of, an o'scope?????

Without a scope many repairs just become an exercise in being a parts changer at big expense to the customer.

Alloy Mcgraw · Nov 21, 2019

Garwood said:
I wish there were more "My CNC tech is just amazing and never leaves me wondering why he isn't flipping burgers somewhere!" type threads.

Humans tend to dwell more on the negative, then the positive.

I feel bad for my buddy who owns a storefront business.

He may go the entire year with only a handful of customers that are unhappy. But when looking at online reviews, it's 10 to 1 negative reviews.

When someone has a negative experience, they never shut up about it. Quite the opposite with positive experiences.

If it makes you feel any better, we use an independent tech that is good at what he does, quick, fair, and shows up when he's says he will.

jim rozen · Nov 22, 2019

cmccull166 said:
Q...The motor is shorting so now I know it needs rewound.

How bad was the short? If it was 100 megohm to ground, he might be excused. If it was
100 ohms to ground, no excuse.

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