"Ted Frater" wrote in message
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Tom Gardner wrote:
"Ted Frater" wrote in message
...
snip

Dont cange rotation? Id be grateful for aproper technical explanation for
this.

I do that regularly and it doesnt effect the life ofc the brush, in fact
it extends the life. you get more work done this way.
Read my last post on brush usage.
Could it be that as you sell these youve a vested interest in seeing the
brushes last as little as possible?
Its not meant as a chriticism just an normal engineering question.


I've found the best way to sell more brushes is to just keep my mouth
shut!

If you're reversing a brush, it is not the right brush, speed, alloy, HP
or trim...take you pick of one or more. If the wire is laying over by
more than a couple of degrees, something is wrong. Engineers sometimes
spend weeks with clients analyzing an industrial application to match all
the variables. On the other hand, for general shop use the cost is no
real concern and no brush manufacturer makes any money on that family of
products.

Ok you sell wire brushes,
however I am sorry but I have to disagree with you on theis question of
reversing rotation .
you can all try this simple test at home.
take you 2 to 6 month old tooth brush,
take a pair of sharp kitchen cissors,
trim 1/8in off the bristles wether there real or nylon.
then use it.
youll know the difference right away.
Why?
because you have restored the end of ythe bristle to its original sharp
square end.
its that sharp ness that does the work wether its a tooth brush or your
rotary wire brush.
Restore that sharp edge and you restoreits cutting ability.
its like sharpening any cutting tool wether its a drill,lane iron ,
chisel orlathe tool.
Come on!! you all know a blunt tool cuts less than a sharp one.
By reversing you then use the other side of the wire thats not been
blunted.
All cutting tools get blunt with use ,so does a wire brush.
And yes, its a good enough resason to buy a new one, if you dont know how
to sharpen it.


I don't have much access to markets that service end users so I don't have a
vested interest in "selling brushes". I don't sell retail, my biggest
markets are food service and industrial.

If you reverse the rotation before the wire starts to lay, that's OK. What
usually happens is the operator starts pushing the work harder into the
brush and starts a cascade failure. It's an unconscious act. Most people
under-power, under-rev and push to hard, then reverse the brush. You're
bang-on with the shape of the ends of the wires, it's the edges that do the
work. A good oil tempered wire brush is self-sharpening to a good degree
and the wire will microfracture exposing a fresh cutting edge do to highly
localized heat cycles on a molecular level in the very tips of what is
basically tool steel wire. If you reverse the rotation on an oil-tempered
wire brush after it has started to lay, the wire will start to break at the
hub due to hysteresis. An inexpensive hard-drawn wire brush will wear
smooth ends on one side of the wire instead and is not as susceptible to the
hysteresis that prematurely fractures the wire that is more the equivalent
of hot-rolled steel, so reversing it won't do as much damage to the
molecular structure of the wire. A brush can be sharpened using a stone.

You're toothbrush analogy is off base because as you shorten the trim of any
brush, you change the stiffness in addition to squaring-up the ends. But, in
a way you are right by reversing rotation if you only use hard-drawn wire.
All imports are of this variety and they have good value for occasional or
home-shop type use. If you have an oil-tempered domestic industrial type
brush and the hp and speed, don't reverse it, you won't ever need to or want
to. Any time you see a wire wheel that the wire is brass plated, it is made
from rejected tire-cord wire. It's hard-drawn and not really brush quality,
it's really, really cheap at 19 cents a pound. Good hard-drawn wire costs
$1.75 a pound and good oil-tempered wire costs $3.50 a pound. Typically, a
hard drawn 6" wheel sells for about $4.00 in a blister pack. An
oil-tempered 6" sells for about $13.00 and a 6" knot-type for about $20.
Finer wire costs more. Stainless, about double. I'd venture to guess that
you use import hard-drawn wire wheels?

All this applies to crimped wire wheels, knot-type wheels are a different
ball game. You'd better have the hp and speed or they won't work well at
all. Too much speed and they don't work right, they burnish rather than
cut. Imports are all hard-drawn wire and don't work well or last long.
There's a plethora of knot-type cup brushes that are imports that are just
dreadfully inadequate, but they sell like hot cakes!