METABO Angle Grinders Part Function - Advice Required?

RunAgroundHard

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Not boat but very much practical that maybe can help me repair a tool.

I am fixing this grinder. It starts at full chat then quickly reduces speed and has no torque. The grinder is used in stone carving and was severely contaminated with marble / chalk stone dust inside. One of the carbon brushes was sticking and therefore not making sufficient contact to work at high speed, I think. All the dust is cleaned up and the brushes move freely.

However, there is a small magnetic plane bush at the end of the rotor, part number 70 "Metabo Taco Disc". The image in the description shows a brush, which is the wrong image as the brushes are item 58.

Metabo 00492000 Wea 15-125 Quick Eu 1500w 125mm Angle Grinders 230v Spare Parts SPARE_00492000_EU_230V from Spare Parts World

My question. This small disc about 20mmm OD, 10mm ID, 4mm thick sits right on the end of the shaft. It has split and separated into two halves. In front of it is dust cover, then the shaft bearing proper. The disc is made from magnet material and it is magnetic. Would that disc have a function that the magnetic feature would contribute to, such as controlling speed or limiting speed? It does not clamp on but sits inside the plastic housing behind the bearing dust cover. Above the disc on the other side of the plastic housing is item 10, an electronic control unit. The shaft appears to be a yellow metal of some sort, it is not magnetic. I have ordered a spare part but curious what it does.

Any ideas?
 

rogerthebodger

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There is a washer item 15
Metabo Washer,7,05X19,5X0,2
Product Reference: 339006390

Is this the one you are looking at

Item 10 looks like an electronic control unit,

On my angle grinders the speed control is simply adjustable speed control that effectively adjusts the voltage using a thyristor to control the voltage.

I cannot see any feedback control to adjust the speed on any of my grinders.

If the washer was some form of speed sensor it would have something creating pulses to measure the speed of rotation to feedback to the controlling electronics.

If it is item 15 and magnetic it could just a shield to help prevent grinding dust from the bearings
 

RunAgroundHard

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Thanks for the comments.

I cleaned up and reassembled the grinder after supergluing the two halves of the magnetic ring together. The problem persists. Ordered new parts, including a new magnetic ring, so we shall when that is fitted.
 

ean_p

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Are you talking about item 70, the tacho disk....as this may if it revolves with the shaft induce a pulse in a component on...! It does sound all a bit advanced for an angle grinder though!...I'd be looking more at the quality of the condition of the comm and the assurance of the pressure of the brushes on said comm......but who knows!
 

penberth3

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Thanks for the comments.

I cleaned up and reassembled the grinder after supergluing the two halves of the magnetic ring together. The problem persists. Ordered new parts, including a new magnetic ring, so we shall when that is fitted.

A new grinder is about £50, why are you messing about?
 

Alex_Blackwood

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Not boat but very much practical that maybe can help me repair a tool.

I am fixing this grinder. It starts at full chat then quickly reduces speed and has no torque. The grinder is used in stone carving and was severely contaminated with marble / chalk stone dust inside. One of the carbon brushes was sticking and therefore not making sufficient contact to work at high speed, I think. All the dust is cleaned up and the brushes move freely.

However, there is a small magnetic plane bush at the end of the rotor, part number 70 "Metabo Taco Disc". The image in the description shows a brush, which is the wrong image as the brushes are item 58.

Metabo 00492000 Wea 15-125 Quick Eu 1500w 125mm Angle Grinders 230v Spare Parts SPARE_00492000_EU_230V from Spare Parts World

My question. This small disc about 20mmm OD, 10mm ID, 4mm thick sits right on the end of the shaft. It has split and separated into two halves. In front of it is dust cover, then the shaft bearing proper. The disc is made from magnet material and it is magnetic. Would that disc have a function that the magnetic feature would contribute to, such as controlling speed or limiting speed? It does not clamp on but sits inside the plastic housing behind the bearing dust cover. Above the disc on the other side of the plastic housing is item 10, an electronic control unit. The shaft appears to be a yellow metal of some sort, it is not magnetic. I have ordered a spare part but curious what it does.

Any ideas?
Is this the part? looks like it should be attached to the brass/bronze part. What you describe as the shaft? It may be something to do with speed control as the word "Tacho" may suggest. It may also have something to do with the Metabo braking system??? Me thinks wait for the new one and see what transpires.
Metabo Tacho Disc #MTB-343433060 - Tool Parts and Accessories - PartsWarehouse
 

RunAgroundHard

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Is this the part? looks like it should be attached to the brass/bronze part. What you describe as the shaft? It may be something to do with speed control as the word "Tacho" may suggest. It may also have something to do with the Metabo braking system??? Me thinks wait for the new one and see what transpires.
Metabo Tacho Disc #MTB-343433060 - Tool Parts and Accessories - PartsWarehouse

That's the part! The magnetic ring has separated from the brass bit. Indeed it does look as if it should be one assembly. Thanks for the effort that you put into finding that image.
 

RunAgroundHard

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Just to close the thread.

I changed out the Metabo Tacho Disc #MTB-343433060 as noted in post number 9. It is pressed onto the rotor shaft so it needed a bit of careful manipulation with pliers to pull off. I used my drill press to push the new one on. No doubt and electric repairer would have the small pullers, pushers to remove this. The grinder now runs up to speed and stays at a constant rpm as it should.

Thanks everyone for your contributions.
 

Alex_Blackwood

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Just to close the thread.

I changed out the Metabo Tacho Disc #MTB-343433060 as noted in post number 9. It is pressed onto the rotor shaft so it needed a bit of careful manipulation with pliers to pull off. I used my drill press to push the new one on. No doubt and electric repairer would have the small pullers, pushers to remove this. The grinder now runs up to speed and stays at a constant rpm as it should.

Thanks everyone for your contributions.
That's great thanks for feed back. Tried to do a "Like " but that option seems to have been removed, at least from my log on 🥴
 
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