Fadal Spindle motor, replace or repair?

Got a 1999 fadal, and the spindle starts to surge up and down up and down, when going to the high rpms, like 6500 or above. 7500 is max for this.
It's advertised as a 15 horse machine, but I think it's really only 10?

Anyway, repair guy says it's because of coolant, chips, and just plain dirt that has accumulated through the years causing this. It either needs to be cleaned with a baking process, windings re-coated, and replace the bearings, or just buy a new one.

I don't know which way to go, I just found out about it today, so I haven't shopped any pricing yet on rebuilds. Also, don't even know where to look for that.
I believe a replacement will be around $1500 ish? Saw that on one site, but haven't searched much beyond that.
What do you think, are they worth rebuilding, or do I just get a new one? Or a refurbished one?

Check the windings with a megger. That will tell you if the coils are good. That should be a sealed Baldor motor. It's funny, I was working on one about that vintage just today. Has bad bearings, Will be back next week to pull the motor and open it up. It's just a standard 3 phase C face Baldor VFD rated motor.
Surging sounds like it could be a problem with the drive. Does your motor have an encoder on the end? The one I was working on has an electric fan on top of the motor. I pulled the fan assembly off and there is a small stub shaft for an encoder. Since it doesn't have rigid tapping there wasn't an encoder mounted. This machine has the 2 speed head selected with pulleys and belt tensioners.
Most VFD drives are smart enough to shut down if they sense leakage to ground through the coils and throw an alarm message. I'm no expert on Fadals but I would be looking at something else. There was a sensor on the front top pulley, possibly to read spindle rpm? If that's what it's for and it's getting flakey, that could be your problem.

As a side note I have been using FadalCNC.com for parts and tech support for a few years now. My deal is if you support me with tech support I'll buy my parts from you. Well since Chris retired, I can never get anybody and nobody get's back to me.
Yesterday I found a new company called Compumachine.com up in MA that was very helpful. Tech support by a fellow named Bob, seems to really know his stuff. Guess where I ordered parts from?
I'm an independent service tech working on a wide range of machines. I need to partner with company's like this to serve my customers as best as I can.

Bill

Thanks bill. I don't know how to check any of this. I had a service tech come out and diagnose the problem. They said there was some leakage, due to the coolant that occasionally splashed up there and got inside over the years. It's not a sealed motor, and I do have rigid tapping, so yes, there's an encoder on it.
He seems to feel it's best to clean up and rebuild that motor, or replace it, before it takes out the drive as well. I dunno what to believe, just don't want to blow out something else just because I was reluctant to fix it.

It doesn't sound totally right to me also. I'm a bit concered there was some "leakage" A dirty motor is easy to check with a megohmmeter. Despite the big name, it just injects 500, 750 or 1000 volts into the windings and measurures how much of that gets lost to ground, or the motor case, because the insulation of the windings if down.

I cant see how a motor ramp's up and down. The motor is running, at any speed, that would kind of discount a wet motor.

I'm thinking dodgy encoder or drive. I cant see a motor whizzing and farting, just because it has dirty coils. That will fault all the time, not just when its at the top end.

I'm with Phil (Machtool) on this. Call Bob at Compumachine on Tuesday. Have model and SN handy. Your description of how it's running points to something else.
A megger should be part of any service tech's kit.

Bill

machtool said:

It doesn't sound totally right to me also. I'm a bit concered there was some "leakage" A dirty motor is easy to check with a megohmmeter. Despite the big name, it just injects 500, 750 or 1000 volts into the windings and measurures how much of that gets lost to ground, or the motor case, because the insulation of the windings if down.

I cant see how a motor ramp's up and down. The motor is running, at any speed, that would kind of discount a wet motor.

I'm thinking dodgy encoder or drive. I cant see a motor whizzing and farting, just because it has dirty coils. That will fault all the time, not just when its at the top end.

Click to expand...

I'm a bit skeptical too about his diagnosis too.

A dirty motor is easy to check with a megohmmeter. Despite the big name, it just injects 500, 750 or 1000 volts into the windings and measurures how much of that gets lost to ground, or the motor case, because the insulation of the windings if down.

Click to expand...

That might very well be just how he checked it, I don't know. I know I am VERY much questioning the quality of the encoder for the spindle.

Came here searching for answers myself to revive an old post our 4020 recently purchased is full of old swarf inside of it and it’s thick and sticky. Right now everything still works fine so I’m looking for an alternative to your options. I’d like to just take it apart and spray it down with hot water as clean as I can get it and call it a day. Been awhile since I’ve pulled an ac motor down and this is definitely larger than anything before but it seems to me if I can at least get the metal chips out before any damage occurs and toss a new fan and filter top on it I can buy some more time before it needs replacement. Anyone here ever attempted cleaning their own spindle motor? Granted it’s not a bake and rewind but it seems it would do justice before symptoms start to occur versus leaving it and hoping for the best.

In my day I have seen a lot of motors get damaged by water. That old dry insulation will wick the water up and short out a coil. I once spent 4 days blowing hot air through an irrigation motor that got soaked from a broken pipe. The megger showed about 50K ohms and it would have blown on startup. After a day of heating it went down further, as the moisture was driven through the insulation. The owner of the golf course was desperate as we were in the middle of a heat wave. On the fourth day it hit 1 megohm and it ran just fine. A week later about 100 Megohms as the heat of running a dry air finished the job. Did a similar job on a 1000KW generator in a flooded pit.

My advice is pull the motor and have it cleaned dipped and baked and new bearing put in. Go for another 20,000 hrs and do it again. Do not wait for a failure and a rewind as at that point a new motor is cheaper and you have to contend whether the motor shop did a good job, or overheated the laminations and ruined the magnetic permeabilty losing a big chunk of efficiency and power. 3 Phase motors run or they don't and taken care should easily do 100..YEARS!

Carefully check your spindle encoder. The wiring connector on mine came loose and exhibited similar symptoms.