[TheForge] Re: Cutting steel

[Mike Spencer]

Bruce> You can pick up an angle grinder + attachments (not,
Bruce> unfortunately, including a cut-off wheel) for $15 at flea
Bruce> markets (new).  The grinder is crap and the bearings will blow
Bruce> on you,

Here's a grinder bearing factoid I picked up recently:

My circa 1978 4.5" B&D grinder recently developed shudder and I
determined that the bearing on the output shaft was worn out.  The
Halifax B&D place listed the part but no longer supplied it [1].  The
big bearing and power-train place in Halifax would supply it but
pointed me to a local guy I didn't know existed because shipping the
small sale was more liability than profit for them, else a 3-hour
round trip drive for me.

The local guy went to great pains to enlighten me: the bearing he
stocked would fit perfectly and would work but was too "tight" for
high speed use, had a high(er) likelihood of wearing out and/or
seizing up under heavy use.  His bearing was something like $7, the
one with the correct tolerance (or pre-load, I guess it is) would have
to be ordered and would cost more.

(I bought the cheap and available bearing.  We'll see how it holds up
under light to medium usage after I put it back together.)

While I'm at it...

I picked up an old skill saw along the roadside on junk day.  From the
sound, one or more bearings were worn out.  Took it apart and learned
that the makers had found a cheap alternative to getting precise fits of
bearings into the case: 

   + Cast the bearing bores as a loose fit and 

   + Skip machining them to tolerance.

   + Cast little pits around the bearing bores and

   + Put little stiff rubber blits in the pits.

   + When the split case is assembled, the blits center and support
     the bearings.

The rubber blits were deformed, after much usage, so that the bearings
were loose in the case.  When I turned all of the rubber blits over
and re-assembled, the saw worked fine.  I assume that new blits, either
as proper replacement parts or made from suitable stuff found in the
scrap bin, would be nearly as good as new.

[To refer back to the Subject: line, this saw now has a thin cutoff
wheel in it for places where the saw configuration is better/easier
than the angle grinder one.]

- Mike

[1] The parts guy remarked that this was a "really ollld tool".  Hah.
    I have two B&D tools that are closer to 80 years old that work
    great.

-- 
Michael Spencer                  Nova Scotia, Canada       .~. 
                                                           /V\ 
mspencer at tallships.ca                                     /( )\
http://home.tallships.ca/mspencer/                        ^^-^^

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