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Cheap power tools #142932 04/04/05 06:59 AM
Joined: Aug 2001
Posts: 7,520
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pauluk Offline OP
Member
A neighbor asked me to have a look at this polisher. It was pretty clear that the switch had disintegrated and needed replacing, but just look at the construction and fixing arrangements for the motor:

[Linked Image]

The bearings sit in plastic moldings in the two halves of the casing. The shell of the field stator assembly relies similarly on two little plastic lugs on the case moldings to keep it from rotating, as you can see from the little notch on the end.

The brush and rectifier assembly is on a plastic carrier which just drops on to two more moldings on the bottom half of the case and relies on a couple more projections on the top half to keep it in place:

[Linked Image]

Now is it just me being picky, or does this seem like a really cheap and nasty way of constructing a motor for a power tool? The whole thing seems to rely entirely on the two halves of the case being perfectly aligned just to keep the armature correctly centered within the field.

Oh, and when I pulled the armature out of the stator in order to get everything lined up and re-assembled, look what happened. One of the field magnets just came straight out with it! I guess they skimped on the glue. [Linked Image]

[Linked Image]


[This message has been edited by pauluk (edited 04-04-2005).]

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Re: Cheap power tools #142933 04/04/05 08:44 AM
Joined: Jul 2002
Posts: 8,359
Trumpy Offline
Member
Hi Paul,
Yes these tools definitely aren't made with any sort of longevity figured into the design or manufacturing processes.
How much would a tool like this cost to purchase?.
I'm guessing that it's one of the very cheap brands, like the one's here that have popped up at our supermarkets.
I've never thought of buying an Electric Drill with my groceries.
But generally they are priced under NZ$20 and as the old saying goes "You gets whats you pays for".
Paul I take it this is a Double-Insulated Appliance, but in the bottom pic there is a screw holding a wire and terminal to the outer part of the motor "body".
This obviously isn't for any kind of earthing is it?.
Going by the brushes and the commutator, the brushes aren't applying equal and even pressure on the commutator either.
I wouldn't personally use a tool of this particular quality for very long in one spell, it may melt in your hands, given the large amount of plastic in it's construction.

Re: Cheap power tools #142934 04/04/05 05:56 PM
Joined: Jul 2004
Posts: 145
C
chipmunk Offline
Member
These days, I'm afraid it comes down to one of 2 things
<OL TYPE=1>

[*]Is it going to last 12 months?

[*]If no to first question, is the number of returns and replacements multiplied by the cost going to be smaller than the profit margin?
</OL>
If either of these is yes... YAY, sell garbage, rake in the money.
The PC industry does the same, everything's about price, whereas years ago people would think "if I buy this which is 3x as expensive, it will be better" and they'd be right. Now it's "3x the price? RIP OFF" and they walk away and buy the cheap stuff [Linked Image]

Re: Cheap power tools #142935 04/05/05 05:57 AM
Joined: Aug 2001
Posts: 7,520
P
pauluk Offline OP
Member
I've moved this over to the Photos Area for a wider audience, as this is something which is a universal issue these days:
https://www.electrical-contractor.net/ubb/Forum5/HTML/000901.html


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