Back to Ganoksin | FAQ | Contact

Polishing motor


#1

Oops! In my last post about this I said you could vary your rpm via
choice of wheels. What I meant was you could vary your sfpm as
needed. The 8" Harbor Freight grinder I referred to has a 3/4 HP
motor. Some of the flea market motors are 1/2 HP or less.

Judy referred to buying a purpose built setup for $200. I checked
and the decent, fairly heavy duty units are about $700 to $1000 now.
For a DIY budget, $100 for the motor and spindles, $75 for materials
(wood and PVC) to build a hood or two small ones (one for each side)
and $50 for a shop vac or shop vac motor and filter. About a day to
put it all together (eight to ten hours). The difference in price is
$700-$225=$475, so your time goes at $47.50 to $60/hr. I guess some
of you are making more than that and should go on and buy a unit. I
don’t make that much and think I could actually do it in less time
once I spent some of my TV time noodling out a plan. Oh, and I forgot
the shipping and taxes, so maybe you’d better be making more than
$60/hr to justify the purchase. But diff’rnt strokes, eh?

Don, I hope you’ll post on what you decide to do. You Meixner boys
are always interesting.


#2

I purchased the HF Motor. Cut off the Threads. (Spin up the motor and
use a hacksaw acts as it’s own lather) Purchased some Tapered
Spindles, used a Lathe to bore out the holes to fit the motor
Spindle.

No hood or vacuum yet.

You can get the smaller tapered spindles from Foredom. Ss noted
above, their bores are of a different size than the motor spindle of
the HF motor.

Good News. Cheap Bad news HF motor has no power and bogs down too
easily.

Bristle disks might be fine for it, as I was trying to use it with
consolidated wheels.

Best way to go, get a grinder motor and do this with. It will give
you far more options. Unless you are a HIGH production Jeweler and
need every step ready to go.

Again, Bristle disks would probably work very well this way.

Cheers!


#3

Hi Gang,

Just a quick note about frankenforming an el-cheapo bench grinder
into a buffer. Fine old tradition. I think it was one of the first
tools I ever modified, and that first one lasted at least 10 years of
heavy use.

But in regards to the advice to chop the spindles short, and bore out
the sockets of the buffing spindles. (the tapered threaded bits) You
don’t need to. In fact, it’s not a good idea: you want as much shaft
to grab onto, with as much material in the socket as you can get. You
can get the threaded spikes with several different bore diameters to
fit whatever spindle diameter you end up with.

The old HF grinders had 1/2" spindles, to fit 1/2" hole grinder
wheels. I don’t know what the current ones have, possibly 13mm, or
possibly still 1/2". But 1/2" bore is a pretty standard size for
buffing spindles. The only weird ones are the tapered ones for the
"real" Baldor buffers. Don’t get those. You’re looking for the ones
with the set screws. I’ve seen them as 5/8" and even 3/4, and 3/4=9D
threaded as well. Just be aware that they come in right and left
handed versions, for the different sides of the buffer. You need
both. (Assuming you have spindle coming out of both sides of the
motor.)

To mount them, just unscrew the grinding wheels, remove the guards,
throw all that crap away, and then measure the diameter of the
spindle. Buy a set of buffing spikes to match, then slide them on
over the threads on the spindle. If you like, you can file a flat
across the threads on one side of each spindle, to give the set
screws on the spikes something to grab onto. Not entirely required,
but probably a good idea. (The set screws will grab onto the threaded
spindle, but may end up pushing the spike cockeyed. A few seconds
with a file to give a flat spot is time well spent.)

Regards,
Brian


#4

If you have a place to do it to you can vent right outside also.
Dust and fumes are hard to filter well. Filter it to catch the big
stuff and let the rest go out the window or wall. Got a 2 sided
squirrel cage blower pretty reasonably that draws pretty well.


#5

Hi Monica,

Yes, it could be as simple as buying the motor, taking off the
grinding wheels and shrouds and attaching spindles. I didn’t look
very hard, but I found spindles for $8 to $12 each depending on your
shaft diameter (1/2" vs 3/4"). Then you need a couple of 6 to 8 inch
wheels (depending on what your motor height will accommodate and
what you feel you need—I get by with 6 inch wheels for average
jewelry pieces). This is enough for you if you will work outside or
in the garage with the door open. About $25 to $50 for the motor,
$20 for the spindles and $15 for two six inch wheels. About $60 to
$85. Of course, if you work inside, you will want a dust collector.
This could be as simple as a sturdy cardboard box with the top and
one side removed, with the open side sitting on the table or plywood
base on which your motor sits. Just rig a place for a hose to enter
with some duct tape and find an old vacuum or shop vac. My local
Craigslist shows at least two shop vacs for $30 or less. So you’d
have a total of $90 to $115 spent.

It would be better to spend some time or money and either build some
hoods out of 1/4 inch plywood or buy two of the small hoods that fit
on one wheeleach ($40 eache). You can even put a hose at each wheel
and a blast gate so that only one wheel draws air at once. I suppose
you’d end up spending about $30 more on plywood and glue, filter,
hoses, etc. but you’d have a nice permanent setup for about $120 to
$150.

You should check ebay, because there are some small units with a
hood and filter for about $330. Whether chasing around for parts and
building hoods is worth the $180 to $210 you’d save is an individual
decision. What you could build would probably be a bit better than
the small ebay units, though. All of what’s necessary is pretty easy
to fabricate out of plywood or various foamcore boards or whatever
you have and can work.


#6

Hello again Orchidland and Monica,

I posted previously about my decision to purchase a polishing
cabinet withBaldor motor, lights, and powered exhaust through a
filter. This is a follow-up.

Some have posted about the importance of having a dust collector.
Very important. Early in my creation of a workshop, I also converted
a bench grinder motor with spindles to accept polishing wheels. I
did not create a dustcollector. The result was dust all over my
workshop!! I mean ALL over, inside surfaces, on the ceiling and
walls, etc. When I began to cough up black phlegm I realized that
this was dangerous. In addition, the grinder motor"lugged" down and
would not maintain speed. That meant it took longer to polish
anything - throwing more dust all the time.

So I watched for a discount on polishing units and brought one. It
was the difference between night and day - motor maintained speed,
good light overeach polishing wheel, excellent exhaust though the
filter. Money well spent. Here we are 20 years later and the unit
still performs perfectly. I’d buy it again in a heartbeat.

DO have a dust collector with powered intake to pull the dust out of
the air, and trap it.

Judy in Kansas, where summer is really here. - temps in the 90s and
humidityrising.


#7
DO have a dust collector with powered intake to pull the dust out
of the air, and trap it. 

Yes, Judy, you are right. About 15-20 years ago I had a small unit
which pulled air into a small filter, but it was not strong enough.
I got an odd cough, and went for a chest X-ray which showed some
debris inside the top part of my right lung. I asked for credit for
three summer months from my metal dealer who also, at that time,
dealt in tools. They are a refinery in St. Paul, MN, called Stebgo,
and I am still quite loyal to them. I got a big cabinetunit with two
right hand spindle motors on it, and the large bags collection
system inside the cabinet. It does a good job, and makes me some
money occasionally when I send in the captured dust for refining. It
is loud, and I have to turn on its lights, motors, and fan in not
too rapid a sequence to avoid flipping a breaker in the electrical
box. This is an indication, I think, that the fan is very powerful.
I am so glad that I have it! M’lou Brubaker, Goodland, MN


#8

My original polishing motor was originally a bench grinder. I
removed the grinding wheels and guards etc and attached two threaded
tapered spindles to the motor shaft. It worked just fine but threw
crud everywhere in the outside shed where it was located. Later I
wanted to move it into my clean inside studio so I built a cabinet
for it out of plywood compete with a couple of guards around the
buffing wheels. I connected these to a vacuum cleaner with some PVC
pipe through holes near the back of the guard. I then wired both the
vacuum cleaner and the motor through a relay switch with a large red
stop button. Everything works fine and there is very little crud in
guards and none beyond.

Cheers
Jen