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Bench grinder question


#1

This brings up a question that’s been on my mind lately. I’m due
to be buying a new bench polisher soon, and I’ve been pricing
them in lapidary catalogs (shaking her head with sticker shock).
I’ve also been perusing the Harbor Freight Tool catalog, and I
noticed several bench grinders with what seemed to be the same
kind of motors, for far less. Question: are they indeed the same
motors, and can they be adapted with cone type arbors to use
buffing wheels?

Janet Kofoed


#2

Please contact the author off list!

Could you post the Harbor Freight Tool phone #. I lost mine.

Thanks
Deb


#3

Hello Janet, As long as the motor is powerful enough and of a
continuous duty type it will work fine. Most polishers require at
least a quarter horse -power motor. I think allmost all grinders
are of the continuous duty type. When you get the new motor,
measure the shaft and order a tapered spindle for it from a tool
supply house. Have fun. Tom Arnold


#4

Hello Janet, As long as the motor is powerful enough and of a
continuous duty type it will work fine. Most polishers require at
least a quarter horse -power motor. I think allmost all grinders
are of the continuous duty type. When you get the new motor,
measure the shaft and order a tapered spindle for it from a tool supply house.
Have fun. Tom Arnold


#5

Hi Janet,

You get what you pay for. The low priced stuff from Harbor
Freight & other importers is not the quality that you get from
Diamond Pacific & most other US manufacturers. Many of the import
motors use sleeve or plastic bearings & light weight motor
windings. The armatures generally aren’t well balanced. Aside
from being under powered, the poor balance will causes any wheels
or other tools mounted on the shaft to have a certain amount of
runout. This runout can cause problems if your grinding some
materials on a hard wheel.

Dave


#6

Janet, I’m sure the quality is not the same, but the prices are
so low I view the motors as disposable. I recently bought a 6"
grinder with a 1/2 horse power motor from Home Depot for $35.00.
I took the grinders and shields off and replaced them with
mandrels from Rio. The motor is “Ohio Forge” or some such name.
Made in China. However, it is a sealed ball bearing unit and
runs well. Even has lights over the wheels. Now I’m building a
dust containment box (sized to use the same filter as my home air
conditioner). The hard part will be training the hamster to run
the fan.

John McLaughlin
jmclaughlin@supreme.sp.state.az.us


#7

Janet:

Pay close attention to RPM and the nasty problem of dust. Take
it from someone who started with a second-hand bench polisher,
you really owe it to yourself and your family to invest in a good
dust collector. I’m assuming you would use this every day. If
the motor is the proper RPM, you can mount it on a countertop
next to a “fishmouth” enclosure and put the dust collector on the
floor beneath it. Handler has been making a good unit since God
was in diapers that will serve you well, guard your health-both
resporation and hearing (I used a big shop vacum for years
because I thought it was cheap!)and collect your precious metal
dust for refining as well. The shaft should accomodate a tapered
spindle available thru any tool supplier. You’ll be using this
thing for many years and it all might cost you $6-700. I have
come to learn that the cheapest thing can be very expensive. Let
me know off list if I can be of any help.

Best of luck;

Steve


#8

I have bought the little 6" Delta grinder from Home Depot ,
taken off the Grinding wheels and weel guards, added the tapered
adapters on each end right over the threads. You need bouth a
right hand and left hand taper adapter. Home Depot has been
selling these grinders for $39.95- They list for about $80. You
get a polisher with reasonanly long shaft extensions and they
work great. The asmaller diameter motor than the other cheap
grinders is a plus, giving more working room. You also get the
delta name which may indicate better specs and quality control
than the other Asian versions.?? Jesse


#9

Do you need only a polishing lathe? How about the dust
collector? In the long run, I think you’d be better off
purchasing a unit specifically designed to suit you needs.
Definitely avoid the low end discount equipment.

Costs more in the long run department
Wayne Lenkeit


#10

dear Janet about the grinder polishers …the ones that are so
much more money are so because they are completely inclosed not
needing any servicing ever …where as the others are open and
exposed to the elements …dust…metal…compound…which work there
way into the motors heart and pretty much kill it …over time
…depending on the amount of grinding you do… H


#11

Janet, I have built polishers , using the inexpensive bench
grinders. Yes, they will work. You can use the spindles from
jewelry tool suppliers. To be useful for a good amount of
polishing, you should set up some sort of dust collection, which
can be relatively simple to very complex. You would only have to
do the math, to determine it’s economic feasability. I still use
the small polishing unit that is sold for about $300. I can’t
remember having had to do any repair on it, since purchasing it
in the mid 60’s. Curtis


#12

Hi

A quick warning abot using bench a grinder without an effective
enclosure. As I don’t do a lot of grinding, I took an old
grinder apart, put the spindles on and semi enclosed it in a card
board “cage”. I used no vacuum. I used the grinder for silver
polihing with rouge. My set up was in the garage.

One day my wife asked “What are these red smudges on the
carpet?” . I knew right away the source! The rouge powder was
so fine that I coudn’t see it on the garage floor but as I stood
in it, it collected on my shoes and I tracked it into the house!
It is tough, if not impossible to remove from carpet. (It took
awhile but I was forgiven)

I would say a polisher should be of variable speeds to be
effectice. Either a switch or floor pedal is nice.

Bob B


#13

Regarding the bench grinder question . . . Tom is absolutely on
the mark about needing to order tapered spindles (make sure, if
you have shafts on both sides of the motor, that you remember to
order a LEFT tapered spindle, AND a RIGHT tapered spindle.) One
other thing that may have to be done to the motor shaft(s), they
may have to be shortened so that when the tapered spindles are
applied, they fit into the dust collector. I had to cut off all
the thread (which was on the shafts, on the motor which I
purchased from Sears.) The threaded part of the shaft was the
very end of the shaft, AWAY FROM where the shaft fits into the
motor. DO NOT CUT the shaft at the very edge of the motor, you
won’t be able to fit the tapered spindles on if you do!.

Cutting the shaft was not difficult, I did it with a hack saw
(metal cutting blade) in only a few minutes (thought it would
take forever, but was pleasantly surprised.)

Good luck!


#14

Yes these motors can be setup to handle cone arbors. If the HP,
RPM, bearing type, ampere rating, and seals are the same, then
yes, they are technically the same. Look for sealed ball bearings
for the best lifecycle. Sleeve bearings are as they sound, a
simple brass sleeve open to all the dust you can throw at it.
Motors are also rated as to their ability to withstand hard use,
called a service factor. Look for at least a 1 service factor.
The higher the better but for most general applications a one
will be sufficient.

All motors(with like specs and factors) are not created equal.
But I have seen some brands of good old ( usually newer)
American motors fail as quick as a cheap import. I can’t go
into all the detail here. But I think since the load on a motor
for buffing and polishing is relatively low, you will be OK with
a lesser brand name for general shop use. Of course if you will
tax the motor hard day in and day out, then it would probably be
worth the investment in a heavy duty motor with a high service
factor.

Most grinder/buffer motors are about 3600rpm, capacitor start,
HP from 1/4 to 1., with sealed bearings. Dust collection is a
big plus. Shields are necessary for safety. The type of base
is a major consideration as this dictates the installed height
as well as other mounting factors. A 1/4 hp motor is not well
suited for heavy shop use. 3/4 hp has fit all my needs over the
years. Hope this helps some.

John g


#15

Dear Janet, The motors used on such bench grinders (as You
described) are not of the same quality as those found on larger
dust collection benches, such as those made by Handler or Baldor.
These types of motors have sealed bearings and usually come
equipped with tapered shafts that use a special, high quality
tapered spindle (threaded). These type of shafts allow one to
change to different fittings very quickly (as least as compared
with the “set-screw” type that you are probably more familiar
with). These units are also available with two speed versions
(for that occasional time when a slower speed is needed- when
exactly that is I haven’t had a need for yet). But their $200 +
cost is pretty daunting.

If you are considering the smaller bench-top type of dust
collection unit, the motors generally packaged with these units
are inferior to the type used in the lower-priced bench
grinders; they have un-sealed sleeve bearings that are often
exposed to all the polishing dust (obviously not a durable
design). The mechanical switches on these units also leave
something to be desired as well. The motors found on the bench
grinders offer more protection for their bearings and generally
have slightly better switches too. In fact, this is the very
type of motor that I have been using for the last ten years with
more than adequate results. Since these bench-grinders often
sell for less than $70, I figured that this would at least,get
my foot in the door for my polishing needs. I decided that when
this cheap unit conked out, I’d probably be able to afford a
"real" Baldor or Handler motor at that time. After ten years,
I’m still waiting for it to die! As for the dust collection units
themselves, well, the bench top units are pretty feeble. I
suspect that a good shop vac (properly sound-dampened) has
better suction than these units. But I am still using one of
these units any way, saving my money for one of the better dust
collection units someday.

         Hoping this helps,  Eben

#16

Hi John: As an ex-FedBuKrat, couldn’t help but notice your
post. You are aware, I’m sure, of the laws governing employment
of minors? Are the hamsters teenagers? Do you require more than
an 8-hour day? Do you give them appropriate break and lunch
times? Do you pay them overtime? Be very careful in this area:
you could well run into all kinds of problems with state/Fed
agencies over labor law violations! Animals are people too!
(Just pulling your leg; couldn’t resist a little spring-time
sillyness!) Sharon Holt


#17

Dear Jessie,I urge you to not use these grinders for
polishing.Polishing throws very fine particles of abrasives into
the air…deadly on your lungs and not bio-degradable.Invest in a
double shaft commercial polishing lathe,2 speed,with a powerful
FILTERED exhaust system.Your results will be better and you will
extend your life span.Use your present purchase for grinding
,etc A lot of these lathes can be purchase used at auctions or
from scond hand machine dealers specializing in Jewelry
equipment.

Good health,

Stanley R.Rosenberg


#18

Pardon my candor but I haven’t heard so much baloney in a long
timeThe reason the Jewelry supply grinder is
$300–$400–and more is because Our pals in the Jewelry Industry
take an American made overpiced grinder/polisher Mark it up with
profits that would make Jimmy Hoffa rise from the dead and sell
it to Jewelers that truly believe if it’s so expensive it must be
good. AND there not that expensive because their motors are
sealed!! lots of motors are sealed including the one produced by
Delta, one of the few American companies that don’t charge
unreasonable profits. Take a Delta buffer build a small dust
shield and when and if the motor goes out throw it away and get
another one!Ever notice how hardware tool
prices stay the same year after year and jewelers tools go up
every new catalog printing!!!I gues it’s because their
sealed in all that great plastic!!!

Preston J. Reuther

Preston J. Reuther Master Wire Sculptor
http://www.wire-sculpture.com
preston@wire-sculptue.com
Get THE WIREWORKER a FREE newletter on
making hand crafted wire jewelry


#19

Thanks to all of you who have responded to my bench grinder
question. Your input has been invaluable. I’ve been using a
cheapo open-bearing motor unit that I bought twenty years ago. I
had the motor replaced about ten years ago, but the replacement
was identical to the original motor. I think that with
relatively little money and some time, (I always seem to have
more time than money), I can come up with a unit that will be a
substantial improvement over what I have.

Janet Kofoed
fine handcrafted jewelry
http://www.voicenet.com/~kkofoed/jewelry.html


#20

Janet:

I used an inexpensive polishing unit for years. I used to do
alot of buffing and considering the strain and fatigue that is
caused by production buffing I invested in a better sealed unit
described as a lathe motor. The inexpensive unit had alot of
runout and vibration that caused unnecessary fatigue. The lathe
units run true with no runout. If your buffing needs are minimum
then an inexpensive polishing motor will do. If your buffing
needs are constant then a better motor will pay for itself in
time. Sometimes things are just a matter of economics and then we
make do.

Kenneth Gastineau