DIYbanter - View Single Post

Ecnerwal[_3_]

In article ,
wrote:

On Thu, 01 Dec 2011 17:11:55 -0800, wrote:

I am forever looking for a better way to finish small parts. I have
been looking at buffing machines and the first thing that struck me
was the price discrepancy between them and comparable size bench
grinders.

Whereas I can get a 1/3HP bench grinder for $40, a no-name buffing
machine of the same power is $105. If one goes up to, say, Baldor, one
is lucky to see any change from $300.

Why is that? Is it a bearing issue? Why would a $40 bench grinder not
be able to do the same job as a more expensive buffer?

Michael Koblic,
Campbell River, BC
Greetings Michael,
I have converted several grinder motors to buffers. This usually
just involves removing the grinding wheel and slipping a buffing wheel
arbor over the motor shaft. However, some of the adapters run out a
lot and so need to be bored and sleeved. Also, sometimes the part you
will be buffing will bang into the grinder motor so the buffing motors
have longer shafts and often the shafts are a larger diameter. I
haven't let this deter me though. I have converted a few 1/2 hp
grinder motors to buffer motors by removing the rotor from the motor
and lengthening the motor shafts. The shafts were lenghtened by
cutting smaller O.D. threads on the motor shafts than what were there
originally. So for a 1/2 dia shaft the thread would be 3/8. I then
turned the motor shaft smaller by about .06 for about .500 past where
the thread ends. Then a shaft extension with a 3/8 thread and a
counterbore is threaded onto the motor shaft and secured with Loctite.
Finally the extension is turned so that it runs true and the motor is
re-assembeled. I support the motor shaft in a steady rest in order to
centerdrill the extension and then use a live center to support the
shaft for final turning. This method has worked very well for me. I
only add about 2 inches to the original length though. With the
tapered buffing wheel adapter in place the overall extra length is
about 3 inches. It's really not that time consuming to do the motor
work and if you have the time and not the money it pays. It's also
good practice on the lathe.
Eric

Once upon a few decades ago I turned a shaft for a buffer for an
armor-making friend (he eventually got serious abut his armor, and then
I gather he got elbow damage, which I think may have taken him out of
the game.) He had some special requirements as far as reach, etc
(buffing breastplates and helms), and probably spent more than $40 on
the thing (the plywood alone would likely add up to that today) but the
fundamentals were not expensive - belt driven arbor (might have been
simply two pillow blocks and a pulley, really), a long shaft, reverse
threaded on one end (my first left-hand thread job, worked fine) and a
support structure (a nicely made angled plywood box, which required
thought to make, and provided him with a wide stable floor-standing base
and a narrow out of the way arbor support and belt guard.) The actual
motor would be any old motor you'd care to throw on the belt, cheap or
free to a good scrounger.

Half the price of any Baldor is the name, the next 25% is hopefully
still good bearings. A buffer does put more force on the bearings, in
the sense that a long shaft having work pressed into it has more
leverage at the bearing - and a $40 grinder probably has crap bearings,
whether they be sleeve or terrible ball. Now, if you are not talking
about extending the shaft, because the parts you are working with are
small enough to be buffed with the wheels in the same position they are
on the grinder, I suspect you would be fine with the $40 grinder, until
it craps out, which might well be a while, but won't be as long as
something with decent bearings.

Depending on your buffing jobs, you might also look for super-cheap
(used will generally get you more for the money) wood lathes, which can
be set up with a long arbor between centers and multiple buffs. Rather
than multiple buffing machines or changing wheels, IF the parts can be
worked without needing a free face to the wheel, you can load up 3-5
buffing wheels and move from one to the next with no time for setup,
other than cleaning the part.

--
Cats, coffee, chocolate...vices to live by
Please don't feed the trolls. Killfile and ignore them so they will go away.