Grinder failures

[pedrobedro]

Commutator failed on my Metabo a few years ago during the lockdown and The place I bought it from was shut so I bought a small Makita to fill the gap and it has been brilliant. I got the Metabo repaired under warranty and it lasted about 3 months then went again same fault. It was repaired again and has been alright since. My previous Metabo lasted 11 years and I bought a new armature and repaired that as well.

 

[Memmeddu]

That's just not true, hence them selling brushes.

Our Metabo had its brushes changed, then died a couple of years later.

Be interested to know how to do a post mortem on them.

Still can't bring myself to bin the dead one, hope to resurrect it one day.

Post mortem is the bin.
Diagnosis and repair is what you have to aim to.
Few tips , easy stuff .
Power cord
Plug
Switch
Brushes
Brush holder

Power cord is easy you don't even need a tester .
Take a bulb connect to the cord it will light on the cord is going
Light on slowly or not full bring if the cord has continuity but it's burnt
Led light bulbs will strobe if it's only one wire

Plug if the cord it's good ,by moving it nearby the plug

Switch , bypass it and give power ,motor will start to spin .

Brushes visually they have not to be burnt ,copper strands will look up burnt ,as well as the graphite,both can be damaged or worn down.

Brush holders can be deformed by the heat or corrosion, brushes might transfer material to them ,or because of slack can electrocorrode it causing the brushes getting blocked on them , that's can be caused by dust too .

Those are easy , armature and stator are more complex to be checked and they require a proper multimeter to be examined .
They can be both visually checked that's the first control to do.
Looking for burns in the commutator and or on the windings, broken wire etc .
Then continuity ,if it's open circuit there's a damage
Resistance it has to be even on the two halves of the stator.
On the rotor it has to be checked both between the commutator things sequentially one after other and between the opposite 180° apart.
And the resistance has to be always the same .
Rotor bearings failure can give you similar symptoms than a burnt rotor.

Hope to have been exhaustive explaining how to check your grinder.

 

[Windy Miller]

My cheapie from Vevor lasted no time at all trying to grind out the chassis on my van - but my Makita worked its guts out and kept on truckin'.
It might be a bad move, but I have ordered a Ferrex 1200w variable speed 125mm corded from Aldi online.
At £25 with a meaty motor & a 3yr Warranty, I figured it was worth a punt.

I have one of those Ferrex ones - really handy to have the variable speed with a wire brush wheel on it. Can’t comment on its grinding ability as it only ever has the brush fitted.

 

[Migmac]

Is there something in the water??

So far this year (it’s only march) I have killed

1x Dewalt - about 15 years old but used a few hours a week for a fibre pad

1x Bosch. I bought it when I was 13. Came in a metal box

2x makita both bought since Rona started. One gave a really good light show out the grille then let out the magic smoke. The other skipped the light show and went straight to smoke.

I tend to get a couple of years out of a grinder but this lot all died since Christmas.

Jeez your rough on the stuff

 

[hotponyshoes]

With the older ones it's at least worth stripping them down to see what's wrong and pricing up the parts for repair.

Maybe not for the brushless ones, they really only have 2 replaceable parts, the motor and the ecu (at my level of diy anyway) and neither of those are economic to replace.

 

[Turbo]

Is there something in the water??

So far this year (it’s only march) I have killed

1x Dewalt - about 15 years old but used a few hours a week for a fibre pad

1x Bosch. I bought it when I was 13. Came in a metal box

2x makita both bought since Rona started. One gave a really good light show out the grille then let out the magic smoke. The other skipped the light show and went straight to smoke.

I tend to get a couple of years out of a grinder but this lot all died since Christmas.

Time to try out a Metabo?

 

[Smouser]

I have two Lidl Parkside variable speed grinders which failed in no time at all.

The second one was a replacement for the first (they told me to keep the first one and they sent a replacement).

I suspect it is the variable speed units that fails (because that is where the smoke came from).

They are still lying on the shelf and I will probably bypass the variable speed bit or see if I can get cheap spares for it somewhere one day.

 

[GRW]

I have two Lidl Parkside variable speed grinders which failed in no time at all.

The second one was a replacement for the first (they told me to keep the first one and they sent a replacement).

I suspect it is the variable speed units that fails (because that is where the smoke came from).

They are still lying on the shelf and I will probably bypass the variable speed bit or see if I can get cheap spares for it somewhere one day.

I'm waiting delivery on an Aldi/Ferrex 1200w variable speed 125mm grinder.
I hope I don't have the same luck!

 

[Memmeddu]

Time to try out a Metabo?

Definitely a good choice but it has to be the ones with some power I don't trust their low cost ones

 

[JOEPRO]

I've burned through some Bosch Grinders before. Usually one a year or so.

Then I bought a Milwaukee Fuel m18 grinder. Battery powered and the same power as mains grinder really good. In fact one of my best tool purchases.

It did have one issue- the motor bearings went in it. But spares are readily available online and I replaced both bearings myself and its been running as new again the last 6 months. Had it about 3 or 4 years now and it gets hard use on my cars with hours on end of grinding and wire brushing.

 

[tom 748]

will stick with makita,easy to repair

 

[Morrisman]

Two of mine died in one week, one terminal, one is 'nearly' fixed by a good clean, but it still makes a wierd noise when first started.

Whatever happened to the days of the £8 Screwfix grinders, that came with a 3 year warranty? They rarely lasted 3 years, but for that price I just binned them and go buy another. Now you can't get a junk make for less than about £35

 

[pedrobedro]

Time to try out a Metabo?

I was all Metabo for grinders but as I mentioned earlier my last one (WE14, not cheap) only managed months before it packed up, never had any hard use. It was repaired under warranty and lasted 3 months before same again and was repaired under warranty again, new armature both times. I bought a lighter smaller Makita which is a nice grinder but I also repaired my old variable speed Metabo which was 12 yo when it failed, new armature and brushes and it's back up to speed. I still like the Metabo and think it must have been a bad batch of windings that caused the problems.

 

[Memmeddu]

I was all Metabo for grinders but as I mentioned earlier my last one (WE14, not cheap) only managed months before it packed up, never had any hard use. It was repaired under warranty and lasted 3 months before same again and was repaired under warranty again, new armature both times. I bought a lighter smaller Makita which is a nice grinder but I also repaired my old variable speed Metabo which was 12 yo when it failed, new armature and brushes and it's back up to speed. I still like the Metabo and think it must have been a bad batch of windings that caused the problems.

I've had issues with mine in less than a week it had loose all the grease from the gearbox.
Sent to Metabo , same issue.
Never came back to them
Opened added an o-ring
Still leaks I'm just living with it.
Bought in 2017 still going strong.

 

[Migmac]

Well I thought I’d done my cheap n nasty ferrex grinder in today. Dropped it from 10 or 12 feet onto concrete. Everything is fine, no cracks in any of the plastic, it fired up straight away. Changing the disc just as a precaution, I guess it took the hit