High usage of motor brushes Aldi Grinder

Secret_Sipper · 20 May 2017

I have a 10 year old Aldi powercraft 4 inch grinder which I had used to grind lips off brake discs, cut the odd brick in half and such on.
About 12months ago it started with the intermittent stop/starting which turned out to be brushed. Luckily they supplied some spares which I changed.
Over the last few weeks they have gone again and I've bought some cheap ones in eBay to get me going. After fitting these Thursday all was back up and running. Late Friday afternoon, it started with the intermittent stop/starting again so I'm assuming (without properly checking( it's ate them set of brushes. It did do quite alot of hard graft Thursday with cutting base panels on fencing and grinding the inside of a gnarly concrete fence post.

Any tips or help as to what could be causing the excessive usage? If it's terminal, I'll look at replacing it with a Makita but if it can be saved with minimal fuss.. it's worth a few hrs of my time to fix

Cheers

Doggit · 20 May 2017

It'll be the rotor spindle that's worn/brocken, and that's why it's churning up the new brushes. Cheaper to replace it nowadays.

chappers · 21 May 2017

Doggit said:
It'll be the rotor spindle that's worn/brocken, and that's why it's churning up the new brushes. Cheaper to replace it nowadays.

Yep probably caused by running the bushes down to the metal, might be worth a quick look inside to see if there is any obvious damage to the rotor which could be fixed, but to be honest with it being 10 years old I think it has probably already earned it's money and whilst I admire you're make do and mend approach, it's probably time to send this one to the big grinder home in the sky.

Secret_Sipper · 22 May 2017

Thanks for your replies. I was more interested than anything. I did take another look inside and replaced the brushes with a second pair I bought. Cleaned in the insides down best I could and reassembled.
It did work for a short time, just enough to cut me a square guideline in concrete where Im going to be putting in a gate post and then bite the dust.
For seeing it's timely end I ordered a Makita GA4530 which is on its way.

Rest in peace my friend

chappers · 23 May 2017

sounds like it's more than earned it's money, in future the usual signs than brushes are on their way is that the motor will start to sound a bit sparky if that makes sense

mattylad · 24 May 2017

Aldi currently have these in stock again.

foxhole · 28 May 2017

Have same problem with hitachi grinder, though it's only 2 years old.

bernardgreen · 29 May 2017

markyb555 said:
Any tips or help as to what could be causing the excessive usage?

Excessive brush wear on new brushes is invariably due to the commutator being damaged by arcing from the previous set of brushes.

When changing brushes the commutator should be inspected and checked that the segments are smooth and level and the insulationg material between them is clean and free of metal contamination. If possible the commutator surface should be polished by spinning the motor shaft ( using an electic drill or similar ) and using fine grit sand paper to smooth and polish the segments.

This one was recovered enough to give another year of life.

Rapid wearing of new brushes may also be due to shorted segments or defective windings on the armature causing arcing when running normally.

Secret_Sipper · 29 May 2017

I watched a video on YouTube about cleaning it up with fine grit but it was fairly full of contamination. It ran for a few minutes after reassembly, then blew the fuse on the extension lead. Feels rough to turn so I bought another. If I had more time to play with it I'd have tried further, but I needed it pretty sharpish hence the Makita purchase.
Thanks for your explanation

noseall · 30 May 2017

Throw them all in the bin and buy a Bosch blue.

Aldi FFS.

chappers · 31 May 2017

foxhole said:
Have same problem with hitachi grinder, though it's only 2 years old.

yep bought a 4" because it was cheap to get me out of a hole, binned it after about the same time, their tools are total garbage last tool I bought of theirs was a cordless drill, which had switch problems within the warranty period, it went back time and time again ( I reckon 6 times in 4 years)never quite making it to the two year mark, to be fair their customer service was excellent and they replaced it each time no question, but in the end I gave it away to a mate for DIY stuff, couldn't be doing with not having it all the time. Not sure when their stuff went down hill, my first cordless was a hitachi that I bought second hand off a chippy who was packing it in, he had used it for 2 years and I got another 4 years out of it before the batteries went

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High usage of motor brushes Aldi Grinder

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