Do you routinely change your motor brushes?

[ericdockum]

Newbie buying a lathe, not so much sliding down a slippery slope as taking a running jump!

I was just reading the manual for a AH-1218vs lathe, when I noticed that, in big letters at the end, it says you should change the motor brushes every 60 hours running time. Doesn't seem long, but for a hobby rated machine with occasional use I guess this will be a while. Even so perhaps I should order up some as spares in case they become difficult to find...

But does anyone actually change motor brushes out as a preventative maintenance item following the manufacturers recommendation?

I guess if you don't then you run increasing risk of damaging the motor. However changing out brushes that are nicely bedded in for new ones may generate wear, and eventually the brush holder may get damaged, as although the holders are designed to allow easy brush change, they may not last for ever themselves.

I suspect how gently/often you start up will also have an effect, also how clean the cooling air is etc. etc.

But does anyone actually "fix them before they are broke". And is it an issue buying secondhand?


thanks,

eric.

 

[Chrispy]

I would look for a lathe with an induction motor, much quieter and no brushes to wear out!

 

[Graham Orm]

I've noticed recently that power tools often come with spare brushes. Never used them.....yet

 

[CHJ]

I would look for a lathe with an induction motor, much quieter and no brushes to wear out!

+1 for that comment, a motor designed to possibly wear out its brushes after 60 hours of use has not been designed with a lot of 'spare' in its specifications.

5 hrs a month average? somewhat less than one would expect even for a machine in a hobby environment.

I would consider asking Axminster if they are serious about this life expectancy, either the commutator specs are not good or the brush current loading is high even a humble old school sewing machine motor has life in the high hundreds.

Edit: rather cynical thought but maybe it's to all to do with avoiding unhealthy motor operation and meeting the 3yr guarantee.

 

[CHJ]

Slightly off topic but I notice Aximinster advocate the use of Dry lubricant spray around the machine. Just make sure it's of the PTFE or similar type.

Never be tempted to use a silicone based spray, or sealant for that matter, anywhere near a brush motor, even a small contamination on the com. or brushes can cause poor performance.

 

[jpt]

Never needed to change them in any tool yet.

I would recommend joining a club as you will find them very helpful.

As you live in Thrapston I would recommend the Peterborough club link below.

john

 

[ericdockum]

Have had a mail from axminster saying they have brushes in stock for less than 2 quid a pair, but they are not listed on the web, you have to phone for them. They also suggest I call their specialist advisor to discuss the comment in the manual.

I agree that 60 hours is arguably not fit for purpose. Also I have never had to change brushes on anything else in the last 30 years, so it does seem a bit strange.

Thanks for the other comments gents, . Indeed if there is a guarantee, and you have failed to change the brushes, what then?

However there are a lot of similar machines out there but I can't find a lot of screaming that the brushes were all failing. The comment itself is on a high level wiring diagram that is not in the manuals for the other Axminster lathes, so perhaps it has slipped through the editing because it was not text....

I'll give Axminster experts a call on Monday.

 

[Dalboy]

Having been a Plant mechanic for 25 years I spent many hours repairing small electrical plant ie: drills routers sanders planers as well as larger pieces and have never heard of changing or even changed brushes in such a short period of time. And that includes the customer repairs of DIY tools.

 

[Inspector]

I have a 12 x 20 midi lathe that has made in excess of 500 pens and have yet to look at the brushes. I just looked at Grizzly's online manual and it says to check the long life brushes every 10 to 15 hours and replace them when they are worn down to 1/4". I suppose I should look at them soon. :roll:

The brushes on starters and generators on aircraft I remember had a groove running down the narrow side as a wear indicator. When the groove was almost gone it was time to replace or overhaul. A nice system that would be useful on brushed motors but adds to the cost of them so is likely why it isn't standard.

Pete

 

[CHJ]

A couple or maybe three things that influence brush length.

1. First and foremost on the majority of motors is the brush spring length/reach, need to replace the brushes before reaching its limit to maintain adequate commutator contact.
2. If brush holder inner face is not close to commutator, before brushes are short enough to tip sideways out of the end.
3. Before the brush copper tail (if fitted) that's embedded in the brush body is exposed and comes in contact with the commutator.

Of course 2 & 3 should be taken care of in design and controlled by 1. in the first place.

 

[ericdockum]

just to close out the story

Talked to Axminster, they suggested that people don't change them until they have some sign of failure. So why it is in the manual The code for the brushes is BURT003633 , this is not a catalogue or website listed item but can be ordered by telephone. The price is £1.84 for a pair so if you need them it might be best to add this to another order to avoid paying £4.95 P & P on top !

The non variable speed version of their 1218 lathe is an induction motor apparently, so then the choice is moved to motor type v twist the knob speed change....

thanks to all for the comments.

 

[stevenw1963]

. The price is £1.84 for a pair so if you need them it might be best to add this to another order to avoid paying £4.95 P & P on top !.

The reason for the extortionate P&P charges are simple, they stick it in a big envelope with one of their very large, very heavy catalogues, whether you want one or not.