Hurco KMB-IS CNC update

Leith,

Ok the brush end looks odd to me. There shouldn't be copper lines on there like that unless its a copper stranded brush, and even so it still looks odd or marred. I don't think they had them in these and only a carbon type like you would see in any DC motor. I may go pull one out of my motor to see what it looks like. If its regular carbon brush, I would clean the end off and see if it makes a difference. I will be heading to the shop soon and I will take a look to check what is in mine, but I think they are just the standard old type brush.... will find out soon.

Your making great progress now, going to need to oil your ways for movement soon. Does the E-stop work to shunt the amps, or did you bypass everything and fire the amps directly off the Variac? I always wanted one of those old time Variacs, thought they were cool... just crank up the voltage to whatever you want.


Robert

I agree with Robert, those brushes do look strange, so that warrants opening the motor and doing a thorough clean-up and check of the rotor and commutation, stator and especially the tacho generator and it's brushes.
Use very fine grit sand paper to clean the commutation on the rotor and tacho, take your time doing it as any rush will cause a lot of damage to them. Also check for discolouring on the rotor windings.

Leith,

Ok yes the brushes are just plain old carbon type. I have a picture attached from one of the motors from the 2nd machine, but same identical silver frame Electro-craft motor. I would clean them all up, as you can see in the pic it should be black. I would find a pencil or something with about the same arc and then wrap the sandpaper around it to do the cleaning. Just like Tom stated, use some fine grain sandpaper to do it with. It would be nice if this is the only issue, but I have a feeling the armature is in not so good shape with all of that copper build up.

There is another possible reason, but I don't believe this... and that is it sat for so long that it did similar to a di-electric connection and corroded some of the copper onto the brush. I doubt this is what happened, and there is probably more going on down in there. But you can at least clean everything up and see what happens. May get lucky with a lot of elbow grease.

Will post some other things in a bit.

Robert

One other thing that I didn't ask was how many hours are showing on the meter at the rear of the machine. That can somewhat tell what the usage was. If I remember correctly, the hour meter only energizes when the servo's are energized, so it would be a fairly accurate measure. This would give a idea of how wore the motors are.


Robert

_big_ wrote:
It connects in to the TB on the bottom of the relay module. I had sort of assumed its some sort of machine status indicator.

I probably need to figure out what the terminals it connects to are for.

Ok yes this makes more sense now, especially if wired into the TB3... this is most likely a output connection for a indexer. Not to make it full 4th axis CNC, but to have a "automatic" indexer mounted on the table and the output from the TB connector through the black box fired the trigger for the indexer to spin to the next "spot". This is useful in making spline shafts and spur gears, as you would make a cut, index, make cut, index, make cut, index repeated.... makes machining spurs and splines automatic instead of someone standing there having to "index" for the next cut and restarting the program over and over.... plus since it is a Opto22 board, it would be isolated and would make sense that it is a output trigger and not a "input" to the MPU board. Got to be what they were doing... get me the TB3 connector numbers and I will try to trace it for you. Plus, I will try to look through my paperwork to see what Hurco had for a "indexer" option.

Also, yes you could be correct and it could be a status output for say external coolant, but I believe it will be for a indexer as that would be something they would wire into the Amphenol connector.


Robert

Leith,

Ok here is the indexer schematic. I am sure that is what the black box is for. If you look at the upper left corner of the plan, it shows the TB3 connections. TB3-1 is the +24 to the indexer and TB3-22 is the index trigger.

Check the TB3 numbers and maybe this will figure it out.


Robert

Unfortunately, the hour meter is sorta there but all broken up and unreadable.

I've considered opening up the motor to look at the armature. But... based on Youtube videos, they say opening the motor is tricky business and you'll probably end up destroy the motor without the benefit of special tools and knowledge.

At this point the motor is useless so opening it up is an option. Can you offer any advice before I try this?

Good feedback on the brush condition. I really don't know what they are supposed to look like. Apparently the copper streaking is not a good sign. Perhaps those copper streaks are shorting armature segments together and causing the overcurrent.

I think the next step is to carefully take fine sandpaper to the brushes and get the copper off. Pretty low risk.

If that doesn't work (and maybe even if it does) take the motor apart and look at/clean up the armature.

I have come into possession of some scrap electro craft motors. They are generally smaller than the ones in the Hurco. I'm thinking about practicing disassembly procedures on them. I can find out what I'm up against.

The E-Stop doesn't work yet.

However, power to the machine is coming from a plug strip. This plug strip has a switch. This switch is serving as the E-Stop.

The quill looks to be reasonably lubricated. I've cleaned up the Y axis and its not dry. I'll put a little oil on it.

The X axis is completely covered by the table. The ways are not obviously visible. I'll try to see if I can look up inside and get some oil on the ways.

We've ordered some parts for the oiler, but they are not here yet.

_big_ wrote: Unfortunately, the hour meter is sorta there but all broken up and unreadable.

That is a downer as you could get a idea of how wore out it is...

_big_ wrote: At this point the motor is useless so opening it up is an option. Can you offer any advice before I try this?

Good feedback on the brush condition. I really don't know what they are supposed to look like. Apparently the copper streaking is not a good sign. Perhaps those copper streaks are shorting armature segments together and causing the overcurrent.

I think the next step is to carefully take fine sandpaper to the brushes and get the copper off. Pretty low risk.

I haven't taken one apart, so I can't say how it will be. I would definitely try cleaning the brushes gently, blow out the holes and then re-try the motor. But yes the smaller motors are what I would experiment with on taking apart.

Yes, like you are saying I also believe the copper on the brush is shorting between the copper lines. Just odd that the brush looks the way it does as I have never seen one have such defined lines on the brush like that. Usually just has some of the copper marred into the brush, but that one looks almost like it fused the copper on in perfect lines... just strange how it looks.

But yes, I would clean with sandpaper and blow everything out and try it before taking apart. With the thought that you may not get it back together without some type of special tool would push me down the path of trying all that I could before disassembly.


Sorry, wish I knew what you were up against on taking apart

Robert