Angle grinder - brush is sparking badly
AL_n
minutes, one of the brushes started sparking badly. I could hear the arcimh
amd and see the flashes right through the yellow casing! I removed the
inspection cover and ran the grinder, I could see bright blue sparking
travelling right around the commutator ()if that's the segmented copper
drum that the brushes rub against) and flying out from where the nearest
brush contacts the commutator. Is this something I should worry about, or
is it normal? Is there any maintenance operation I can do to cure it?
Thank you.
Al
AL_n
news:Xns9F239E4A...@130.133.4.11:
> I purchased a 9" angle grinder (Wolf) on eBay
PS.. I should have mentioned that the grinder is brand new - never used
prior to purchase.
harry
if it's new, don't touch, send right back. Should be under guarantee.
The Natural Philosopher
let brushes bed in, if it persists, take it back. Could be shorted turn.
AL_n
news:fef169f8-e275-409a...@n28g2000vbs.googlegroups.com:
Yes, I could send it back, but I was hoping I wouldnlt have to. But I guess
I'll have to. It arcs really violently when actually cutting, i.e., when
the motor is under load.
Thanks also to N.P.
Al
The Natural Philosopher
That is pretty consistent with a brush not being bedded in.
with electric RC/aircraft and brushed motors, its enough to make em
unflyable - or was till the advent of 2.4Ghz sets.
The technique is generally to run for 10 minutes or more on no load. For
the greatest mechanical wear and least arcing.
Once the brushes 'fit' the commutator it should stop. Apart from a sort
of twinkling in the gap.
>
> Al
AL_n
@news.albasani.net:
> That is pretty consistent with a brush not being bedded in.
>
> with electric RC/aircraft and brushed motors, its enough to make em
> unflyable - or was till the advent of 2.4Ghz sets.
>
> The technique is generally to run for 10 minutes or more on no load. For
> the greatest mechanical wear and least arcing.
>
> Once the brushes 'fit' the commutator it should stop. Apart from a sort
> of twinkling in the gap.
Thanks. I tried that, but it was arcing as violently as it did under load,
now. It sounds almost as bad a s Frankinstein's lab! I took the brush out
to have a look, and it had worn down about 4mm-5mm! And there were bits
chipped off from one edge. Is it worth trying to clean up the brass
commutator a bit with a toothbrush or something? I guess it is abrading the
brush for some reason. Perhaps some stone chippings got in there or
something.. I was cutting concrete.
One thing surprised me: the wire that goes to the graphite brush is not
fixed in! It goes into a hole in the graphite but there is nothing holding
it in place other than good luck! Is that normal?
Al
John Williamson
refund.
--
Tciao for Now!
John.
The Natural Philosopher
AL_n
>> No. It's a defective unit, take it back, and insist on a replacement
>> or refund.
>>
>>
> I am coming to the same conclusion.
I have got the seller to agree to a large discount if I keep it, so I'd
like to at least have a crack at repairing it.
I can see now that one of the copper contact bars on the commutator is
standing slightly proud of the rest. I could have a go at flettening it
down with some 1000 grade wet&dry.
I'm not sure why it would have become proud of the rest. Anyone seen that
before?
Al
Andy Dingley
> I can see now that one of the copper contact bars on the commutator is
> standing slightly proud of the rest. I could have a go at flettening it
> down with some 1000 grade wet&dry.
Usual practice is to turn them in a lathe. You'll want more than 1000
grit if you try and sand it, and sanding is also bad as there's a risk
of grit embedding in the copper, then turning into a brush-chewing
device in the future. Mind you, modern brushes are a bit tougher than
old.
I'd set up some sort of lathe centres to support the ends of the
armature, then file it rather than sanding. An accurately circular
commutator is important, else you get sparking across the dips.
> I'm not sure why it would have become proud of the rest. Anyone seen that
> before?
Usually by a commutator segment becoming loose, which is a bitch of a
problem to fix. Epoxy might do it, but it helps if you can get the
segment out first - or else clean it and trust to thin cyano. On big
commutators, they're sometimes drilled and screwed through the face
(with a well-countersunk screw).
Andy Dingley
wrote:
> let brushes bed in, if it persists, take it back. Could be shorted turn.
An open coil is more likely than a shorted one. On an armature this
small, single coils don't short, they go several at a time and so the
fault for a short would be much more obvious than merely increased
sparking.
Dave Plowman (News)
AL_n <fgdf...@fghfghfg.com> wrote:
> I have got the seller to agree to a large discount if I keep it, so I'd
> like to at least have a crack at repairing it.
> I can see now that one of the copper contact bars on the commutator is
> standing slightly proud of the rest. I could have a go at flettening it
> down with some 1000 grade wet&dry.
Hope the discount is large enough to cover the cost of a new armature etc
- and that's assuming one is available as a spare. Isn't Wolf one of those
once pround names now just made in China etc like everything else?
--
*Save a tree, eat a beaver*
Dave Plowman da...@davenoise.co.uk London SW
To e-mail, change noise into sound.
AL_n
news:f87c1c04-0cc1-48e8...@v7g2000vbk.googlegroups.com:
Thanks for the info.
I bought this Wolf gringer to replace my old CE one whose switch stopped
working. The armature and brushes look almost identical, as if they may
have been made by the same company. The new one is Wolf and the old one os
CE. I'm just wondering if I can take the armature out of the old grinder
and put it in the new one. Probably too much to hope for!
If I keep this faulty Wolf one, I get it for almost nothing. So I'd rather
buy a new armature for it (or even get the old commutator professionally
repaired, rather than pay out for a whole new grinder. I read somewhere
that Wolf tools recently went bust so I don't know how feasable it is to
buy components for them.
Al
manzoo...@gmail.com
Bob Minchin
the holder, worn too short or the spring is weak usually due to over
heating.
If they are both sparking then all probability is that the armature is
knackered and usually new ones are more than the tool is worth.
At one time Wolf was a very good brand (1950s and 60s) but the name has
been sold and appears on all sorts of Chinese low quality tools these days.
newshound
However *my* experience with various drills, vacuum cleaners, angle
grinders, etc is that it is very often worth replacing worn out brushes.
First symptom is sometimes device stopping without much preliminary
sparking.
I agree that armature failure gives dramatic sparks.
If the manufacturer's brush prices are too silly, I've not had problems
with eBay clones. Also, I've cut down or abraded larger brushes to fit
motors on a number of occasions.
Weatherlawyer
Brian Gaff
Ithought this shower had almost caught up too
Brian
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<manzoo...@gmail.com> wrote in message
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Brian Gaff
grinder museum yet?
The number of queries, old and new we seem to see on this list does make
one wonder if, in the future archaeologists will find these devices and
wonder what early humans did with them, they will probably assume they were
used in some ritualistic worship tradition or something.
Brian
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Rod Speed
"Brian Gaff" <bri...@blueyonder.co.uk> wrote in message
news:nu1qm5$mh1$1...@dont-email.me...
> grinder museum yet?
> The number of queries, old and new we seem to see on this list does make
> one wonder if, in the future archaeologists will find these devices and
> wonder what early humans did with them, they will probably assume they
> were used in some ritualistic worship tradition or something.
We have an excellent idea of what the Greeks and the Romans got up to now.
rick
> been sold and appears on all sorts of Chinese low quality tools these days.
circular saw, jigsaw ... all powered by wolf 2/8" single speed hand drill.
All in cast aluminium not a piece of plastic in sight.
The set is now more than 60 years old.
newshound
newshound
Dave Plowman (News)
hand. And, of course, the speeds were all wrong.
--
*Friends help you move. Real friends help you move bodies.
tabb...@gmail.com
> In article <nual01$k85$2...@gioia.aioe.org>,
> rick <rick_hughes@_remove_btconnect.com> wrote:
> > On 16/10/2016 15:24, Bob Minchin wrote:
> > > manzoo...@gmail.com wrote:
>
> > >
> > > At one time Wolf was a very good brand (1950s and 60s) but the name
> > > has been sold and appears on all sorts of Chinese low quality tools
> > > these days.
>
>
> > My Father has a Wolf muti set up ... Drill stand,wood working lathe,
> > circular saw, jigsaw ... all powered by wolf 2/8" single speed hand
> > drill. All in cast aluminium not a piece of plastic in sight. The set is
> > now more than 60 years old.
>
> And the time taken to fit an accessory meant it was quicker to do it by
> hand. And, of course, the speeds were all wrong.
It's also a question of what folk could afford. I remember balking at a hammer drill at £80 in the 1980s.
NT
Rod Speed
<tabb...@gmail.com> wrote in message
news:56277ced-9eca-4151...@googlegroups.com...
the whole house from scratch on a bare block of land and
was spending vastly more than that on the materials.
Bought a big circular saw too.