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Anybody ever fixed a GRS powerhone?


#1

Greetings all:

Just a quick question: I have a GRS system, and a whole slew of
various sharpening and grinding machines of multiple types for
everything except gravers. It seems a little silly to me to pay north
of $800 for GRS’s custom rig, especially when the power unit looks
like a motor in a box. (There are some parts of it I will buy, but
the motor in the box? not if I can avoid it.)

Anybody ever worked on one? Their blurb mentions isolated bearings.
The things I need to know:

(A) how fast does the disk spin? (roughly)

(B) the newer ones reverse. Does this really matter?

© did they really isolate the disk spindle on its own bearings, or
is it mounted directly on the motor?

Before you get too tweaked at me, I’m already looking at a minimum
of $400 for the parts I’d rather not make myself. Another $400 for a
motor in a box seems like more than I really want to spend if I can
avoid it. (Especially as I have a crate of spare motors stashed next
to the lathe…)

This is how you survive as an artist: you learn to scrounge and
improvise. (“Adapt, improvise and overcome”)

Regards,
Brian.


#2

I’m in UK so I’m using 220v at 50Hz. I haven’t looked inside so I
don’t know about the bearings, but my one revolves at 164 RPM. Its
single speed and direction only and I’ve never found a need to change
the direction.

Regards, Gary Wooding


#3
Before you get too tweaked at me, I'm already looking at a minimum
of $400 for the parts I'd rather not make myself. Another $400 for
a motor in a box seems like more than I really want to spend if I
can avoid it. (Especially as I have a crate of spare motors stashed
next to the lathe...) 

I would highly recomend taking a look at the power hone by TW
Designs

http://users.commspeed.net/ttwhite/hone.htm
http://www.handgravers.com/sharpening.htm

A number of people on the Lindsay forum have them and I hear nothing
bad about the unit. The advantage this has over the GRS unit is
simply the speed at which it can spin the disk. The GRS unit is
really slow (200 rpm iirc), and the Powerhone can get up past 2500,
which makes a big difference if your using any sort of carbide
material for your gravers. At $300ish, its a great by for such a
robust machine.

There are also a couple of threads with individuals that have built
their own sharpening rigs, including myself.

http://www.engravingforum.com/showthread.php?t=1637
http://www.engravingforum.com/showthread.php?t=474

P@
www.patpruitt.com


#4

Hi Brian,

I’ve torn down a powerhone a couple of times. The bearings are
isolated. The drive is a belt setup. Nothing much to a powerhone, the
motor, the driving and driven pulleys, shaft, platen and bearings,
the belt and a switch. The disc spins about 100 rpm (I’m guessing),
fast enough to cut, slow enough to not build up heat.

I wouldn’t need the reverse switch, but my guess is that it’s
function would be to allow you to polish both of the cutting edges on
a square graver parallel to the face, so you don’t get those tiny
grooves that show up as lines in a bright cut. I use a ruby stone to
finish and polish parallel to the face by hand so it wouldn’t be
something I would shell out good money for.

If you are only needing to sharpen gravers, a good alternative to a
powerhone for a bit less $$$ is the new sharpening system from
Lindsay. It consists of a few jigs (two for each different graver
angle, from about 92 to about 110, and two for flats), an adapter to
affix the graver to the jig and four diamond sharpening stones from
260 grit to 2000 grit. It works very similar to the old-school
home-made sharpening jigs made from wood, but is setup to grind
Lindsay’s graver geometry (which works really well, imho). The major
advantage is that graver angles are absolutely perfectly repeatable,
and resharpening takes only a few minutes. I sharpen three or four
gravers at a time before I start on a job, and if one breaks or
dulls, I just chuck up a new one and drive on. No need to make a few
test cuts to find the sweet spot in the new graver. It is exactly the
same as the previous one. The major downside, is that it is set up
for 3/32 square gravers only, which works fine for me as that is
virtually all I use these days anyway. I still use my powerhone for
rough grinding, sharpening rounds and onglettes, etc, but it’s not
worth what a powerhone costs to be able to do it with power. To this
cheapskate anyway. Worth a look at airgraver.com.

Standard disclaimer.

Dave


#5

Hi Pat: (and everybody else)

Yeah, that’s pretty much what I had in mind. Seems silly to pay big
bucks when I have the tools to make the tool I need pretty easily.

I’m definitely getting GRS’s QC sharpening fixture, as I use QC
shanks. I like theirs because of the wide range of available angles.
As my friends can attest, I never do anything the ‘normal’ way, so I
have a bunch of really weird tool geometries to deal with. The GRS
fixture lets me get most of the angles I need. (not all of them are
for engraving, some are for damascene, or overlay work.)

Thanks for all the help.

Regards,
Brian.


#6

Funny you should ask, Brian.

I think GRS tools are the greatest thing since sliced bread. Greater
in fact, since I’d rather slice my own bread than shove a dull
graver, by hand force alone, through X-1 White Gold.

So I own a gravermach, gravermax, system 3 (no one uses much), a
powerhone sharpener, three GRS engraver’s balls, benchmates and all
kinds of accessories.

But I cheaped out on my second sharpening system. I used a lapidary
unit I wasn’t using so much, a horizontal disk unit that uses the
same size disks as GRS. I enclosed it in a leftover metal box from a
small cadet forced air wall heater, with a wood base I made for
height. Then I bought a ceramic hone, and a adjustable graver
fixture from GRS and viola! Works pretty good. But now I need a third
sharpener, oh well.

Michael Babinski


#7

Hello Brian,

Another $400 for a motor in a box seems like more than I really
want to spend if I can avoid it. (Especially as I have a crate of
spare motors stashed next to the lathe...) 

I have one of the older models of the power hone. It’s a relatively
simple machine, and I have only replaced the switch once, and if I
remember correctly, there may have been a belt or some other smaller
type of issue that needed to be replaced in over 25 years. I do
believe that you should be able to make something similar without
too much trouble.

The main thing you want to create is an evenly level spinning
surface. I don’t know what the rpm’s are, but it’s not excessively
fast. The disc spindle is really the heart of what keeps the discs
true, so I would consider paying for those parts. I have a little
quick-change hub on the main plate so I can change the wheels on the
fly. This was not an original feature on mine, but it may be
standard now. Another feature of the newer ones is the stand for the
holding chuck for the gravers is now stationary. My stand is
completely separate, which is nice because I can accommodate just
about any length of tool at any angle. The drawback is that my
machine top has a very slight dome to the cover (corrected on newer
models), and if you aren’t careful, it’s possible to have the stand
base slide off to the side while you use it, resulting in slightly
different angles across the sharpened face. I never had reverse on my
unit, so I have never missed it. I’m not really sure what particular
advantage it would offer.

If it’s in your budget after you’ve built the sharpening hone, I
would really recommend the GRS dual angle sharpening fixture. It’s
much nicer, and easier to use than all of their other fixtures. I
ordered one immediately as soon as I had used it, even though I had
purchased the quick change unit shortly before. (I’d be willing to
part with that, barely used!) You move the head of the fixture so
that all of your angles are maintained relative to each other, and
not trying to reset the graver and the angle each time. The ceramic
wheel for use with diamond spray will give you the brightest polish,
and absolutely crisp edges, so I recommend that as well.

Good luck with your endeavor!
Melissa Veres, engraver


#8

Hi Brian,

I have an old “original” GRS Accu-Finish, having picked it up at a
used tool auction several years ago. It like the other GRS products
I have is heavy duty, well made, built to last. It is, indeed, a
motor in a box. The lap shaft is belt driven, vertically positioned
in the box and appears to have substantial thrust and radial
bearings. I just timed it (by seat of the pants method) and would say
it is very close to 200 rpm. On this old one the lap diameter is 5
inches.

It also is counter-clockwise rotation only, and depending on what
you’re doing with it reversing might be really nice. I used to use
it for re-sharpening some of my steel scalpel blades-a situation
where reversing would be wonderful. For graver sharpening/polishing I
suspect reversing is unnecessary.

On the other hand just today I was “junking” and bought a Quisinart
food processor in excellent condition at a thrift store for $3.99!
It’s a heavy duty, japanese made machine, with direct motor shaft
drive and excellent bearings. The motor is rated at 560 Watts (120 V
@ 4.66 A) and whips right along. It can be slowed down with a simple
light dimmer switch but, perhaps, not enough for laping purposes. A
more sophisticated motor control might do it. I’ve seen other brands
of food processors that DO NOT have substantial bearings and may be
best left in the junk box.

All in all the GRS Accu-Finish, in my opinion, is an excellent
product- but a pricy one. There are lots of alternatives, re-cycling
a Quisinart being high on the list.

SCROUNGERS ARISE!!

Dr. Mac


#9

You might want to consider the GRS Dual Angle Sharpening Fixture. You
can use it for tools with or without handles as well as those in QC
holders.

KPK


#10
I never had reverse on my unit, so I have never missed it. I'm not
really sure what particular advantage it would offer. 

Somebody already posted what I know on this topic - links to others
who have done this and stuff. I suspect that the real reason for
reverse is to use the abrasive efficiently, especially with diamond.
You’ll tend to wear down the left side of the crystals, and if you
reverse you’ll catch the right side. It’s obvious that it makes no
difference to the tool whetherit’s CW or CCW, so I would think
that’s the reason for it.


#11

We have a newer grs powerhone and an older one at work. I much
prefer the newer reversing one because if you want to polish both
heels of the 90 degree v and other v gravers correctly you will not
be pushing the business end of the graver into the direction of
rotation when doing one of the heels. Which is not a good thing to
do, maybe even a little dangerous. I got used to using the reversing
one but now its at the other end of the shop and I hate the old one.
Both have had plenty of use and have stood up well.

At home I have some kind of grinder called a WEN wetstone (has a
water bath but it rotates flat like the grs) I got it at a yard sale
for ten dollars but it has a fairly coarse stone on it, there may be
other stones for it, they’re smaller in diameter than the grs diamond
hones. Its missing whatever holding fixtures came with it which
probably wouldn’t work for gravers anyway but you could probably
modify some thing like that if you could find a used one cheap. I’m
not sure how good or accurate it would be, I just use mine for rough
freehand grinding. Celeste