Replacement carbon brushes ?

[paulm]

Think the carbon brushes on my Record Power DX1500 dust extractor are just about worn out as it is sometimes not starting last couple of days. I've had it since 2001 and used it heavily though so not too bad I guess :lol:

Having just called Record to check prices they are £30 for a pair :shock:

Not sure of the chances of getting straight replacements elsewhere or where to try for them, anybody else done similar in the past or have some ideas please ?

Cheers, Paul

 

[wizard]

check that is the problem first

 

[paulm]

Good idea given they are not the fiver or so I expected! I'll take a proper look tomorrow. Have made an enquiry with somewhere else also that I found on Google so see what they say also.....

Cheers, Paul

 

[wizard]

First check the brushes if they look ok check there is power before the switch then after the switch

 

[CHJ]

Paul, if the brushes are worn short resulting in intermittent contact with the commutator then try and locate a local motor repair centre and go along with a sample brush.
They may not have the exact item but may well have something you can file down to fit the brush carriers.

Got any old car Dynamos lying around?

 

[wizard]

lots here
http://www.ebay.co.uk/sch/i.html?_t...bon+br&_nkw=carbon+brushes&_sacat=0&_from=R40

 

[paulm]

First check the brushes if they look ok check there is power before the switch then after the switch

The switch is illuminated and still lights up, but the motor doesn't start every time, although it has started after a few attempts.

I think that means the switch is probably okay ? Or maybe it means power to the switch but not necessarily after it ?

The casing does seem to get hotter than I recall, so thought it might be a thermal cut out which is why it will start again after a while, in which case I'm not sure why the motor would be running hot.

Guess I need to take a proper look in the morning and narrow down the possibilities as best I can with my limited knowledge of motors and some guidance from here !

Bit annoying really, as I was just getting up a head of steam in rationalising some of my wood stocks and this extractor is the main one for the bandsaw which has been working overtime last few days !

Cheers, Paul

 

[paulm]

Paul, if the brushes are worn short resulting in intermittent contact with the commutator then try and locate a local motor repair centre and go along with a sample brush.
They may not have the exact item but may well have something you can file down to fit the brush carriers.

Got any old car Dynamos lying around?

No spare car bits unfortunately Chas, lots of other junk though :lol:

I guess there aren't different ratings or capacities of brushes then, as long as I can get or adjust a pair to the right size (and can make a clip or solder connection ) then it should work okay, so just need to go on the dimensions and file down if I can't get the same size ?

Cheers, Paul

 

[wizard]

I sand them down on wet and dry paper

 

[CHJ]

Paul, there are different specs for brushes in the commercial world, high starting current, wear rate, special self lubricating, those designed to work at 30,000 ft. etc. but I think any you can get to fit will do you ok.

Had a look in my spares draw but the only ones I have are for a small angle grinder and some that came from large aircraft generators/convertors (replaced on servicing) that I cut up when needing some graphite contacts.

If the brushes are worn you may need to clean up the commutator with some fine glass paper. (don't use emery).

As you say it appears to have been getting hotter, check when you fit replacements that you are not getting excessive sparking on the commutator which may indicate an armature short. Look for two or three segments with extra edge burning.

You should find some near enough in that bay link though.

 

[paulm]

Great, thanks guy's, will be back in the morning with an update or more dumb questions !

Cheers, Paul

 

[paulm]

All sorted

When I opened up the motor casing there was piles of fine dust inside ! Explains why on start up yesterday it had started blowing some fine dust out which I had thought was just dust that had settled on the rim and been blown off.

Vacuumed it all out and blew off all parts of the motor with the air line, checked the brushes which were 6mm x 8mm and 25mm long, seemed to be plenty of life left in them as I had to compress the springs a fair bit when refitting them. No signs of wear or burning on the bit where they contact (armature or commutator ? Can you tell I'm not technical :lol: ).

I had checked the paper bag pre-filter when I took it off and it seemed intact, and the main cartridge filter seemed pretty clean inside it but I blew it off with the airline anyway before refitting with a new paper bag filter just to be sure.

Reassembled and all worked fine, running much cooler now too and the suctions better.

I think the main cartridge filter must have had a knock when I was brushing excess dust off of the paper bag filter which I do occasionally, and affected the seating and sealing of the base of the cartridge where it meets the motor casing, allowing some dust up into the casing and affecting the motor operation ? It wasn't obviously not properly seated when I took it off, but I guess it wouldn't take much to cause a problem, so made sure to reseat it firmly when reassembling.

Been using it on and off for a couple of hours this morning and seems to be fine now thankfully

Thanks for all the help and suggestions guys, appreciated.

Cheers, Paul

 

[CHJ]

There you go, worrying about the wrong thing again. :lol: but at least you have a new experience to add to the collection and a good link source to bits if needed.

Glad it's sorted, funnily enough got diverted from planned projects this morning * and am currently in the middle of trying to squeeze another quart into the pint pot of a garage workshop with a little less wasted space.
Shown up an awful lot of crud settled in unwanted places, fortunately vacuum innards is not one of them as motor has dedicated cooling circuit.

* your fault I skinned my shin trying to get at the box where I thought I had some brushes yesterday.

 

[Random Orbital Bob]

That seems fair

On the DX issue Paul. My RP ones are temperamental from time to time and dust getting in the workings is one thing I've had before. More common however is the brushes slipping far enough away from the round thingy in the middle (stop me if I'm getting too technical) to get a decent contact. The springs were fine but with mine I notice two screws which hold the assembly down seem to rattle loose every now and then causing the brushes to move backwards. Give them a tighten and its good again for about a year.

 

[scrimper]

Vacuumed it all out and blew off all parts of the motor with the air line, checked the brushes which were 6mm x 8mm and 25mm long, seemed to be plenty of life left in them as I had to compress the springs a fair bit when refitting them. No signs of wear or burning on the bit where they contact (armature or commutator ? Can you tell I'm not technical :lol: ).

From what you have written I would suggest that your problem was caused by a sticking carbon brush, that is one of the carbons sticking in it's holder, generally carbon brushes on Vac type motors will outlast the machine, they wear down very slowly, if a brush is a little tight or stuck in it's holder as it wears away over time it will loose contact eventually and the motor will cease to run, your action in removing and replacing the brushes probably cleared the fault, if it happens again just take the brushes out and sand a little bit of the sides and so that the brushes run freely.

The trailing edge of a carbon brush will exhibit a little burn mark; that is normal but if the edge is well rounded that would indicate a faulty armature (bit that goes around) causing excessive sparking burning the brushes away.

(I spent 35 years running a electrical repair business so have quite a bit of experience with motors)

 

[paulm]

Some more good advice, thank you Scrimper, hopefully sorted for now but will keep that in mind in case of any further issues with this or indeed other motors.

Cheers, Paul