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Centrifugal magnetic finisher


#1

Glacier I’d like to know if any of you have experience using the
centrifugal magnetic finishers? We just purchased a Raytech
centrifugal magnetic finisher model cmf-400.

My husband just did the first batch of 6 small 14k gold pendants. He
did the cycle according to directions and the finish is really poor.
He removed the sprues, filed, and then filed again with a very fine
escapement file to get the surfaces uniform, then did the magnetic
cycle for 40 minutes. At this point it seems the finisher is doing
more harm than good.

We do very limited casting production and would like to do more, but
up to this point we have been hand-finishing everything and that
really eats up the time. I’m pretty fanatical about the perfect
finish and all this stuff goes directly into a showcase at the AGS
store where I work, so it has to be and look quality.

I’m ready to pack this stuff up and send it back but I’m impatient,
and thought perhaps some of you may have advice about this product.
I thought I was buying state of the art but perhaps I was just sold!
Any advice, at all, would be appreciated.

Barbara Gillis
@Chris


#2

I use one of the magnetic tumblers sold by Gesswein. We use it as a
preliminary step and still hand polish the pieces. It definitely helps
on sterling castings, but it is not a final finish.


#3

Barbara, The magnetic finisher it the last step in the finishing
process. It will not take a raw casting and produce a final finish.
You must either hand or tumble finish to a pre polish state then put
the work in the magnetic tumbler. It produces a good finish on
detailed and high texture surfaces but the finish tends to look
frosted on large smooth areas.

Jim


@jbin
James Binnion Metal Arts
4701 San Leandro St #18
Oakland, CA 94601
510-533-5108


#4

Hello Barbara The magnetic finisher is only a part of a complete
automatic finishing process.

First the items should be (preferably) vibratory finished in cutting
media for between 3 to 12 hours depending on the load, media used,
steps used. Time and steps depends on many factors and the complexity
of an item. We would then use the magnetic finisher on gold for no
more than 5 to 10 minutes, depending on the load to brighten the inner
surfaces of rings and pendants where our polishing compounds or other
types of polishing cannot reach.

Primarily, the magnetic finisher has eliminated the neccesity to “
bomb” in cyanide/hydrogen peroxide… provided that your castings
have not been overheated while soldering or incorrectly cast.

After having used the magnetic finisher to brighten the interior of
your items, you will find that you can easily handpolish the exterior
of the item without a problem…unless you left the gold items in for
too long and pitted the gold. However, it will not harden the surface
of your metal as steel shot will do.

If everything has been done correctly, you may be able to finish the
polishing job in treated walnut shell or treated corn cob to give the
item a high luster. This can add another 6 to 12 hours of finishing
time. We do our large casting jobs this way (1000 -10,000) pieces and
then , if we need to touch up items, it will take 1 man polishing
only a very short time to get excellent polished goods. Our
vibratory machines are large enough to handle 1000 + pieces on an
overnight basis.

There are also high speed rotovibes that start at about $2000 to
$45,000 which will do what my vibe does in 12 hours in about 2 hours.
The problem with these powerful machines is that they will damage
and break/bend small, dainty pieces if you are not extremely careful
selecting your media,timecycles etc…

I must say that what i have seen in the industry is that most people
don’t vibratory their items long enough and then run them too long in
steel shot or magnetic pin polishers.

Something to say about Raytech magnetic finishers is that often , the
recomended cycle time suggested is way to long. The amount of items in
the machine get less damage if their is at least twice as many items
in the bowl… as this will slow the movement down and cut down on
hard impingement caused by the items flying around at some 600
revolutions / minute. The raytech machines are more powerful than many
of the more expensive machines and do a better job. We have 1 raytech
machine that cost us $950 and 1 large machine (not raytech) that cost
$4000. …Guess which one has never broken and does twice the work.
No, I don’t own any of their stock , but i wish i did. :slight_smile: Daniel
Grandi

http://www.racecajewelry.com model making, mold making, casting ,
finishing in gold, Silver. Bronze and pewter for designers and stores.


#5

Hi:

I use the centrifugal magnetic finisher with good results. Keep in
mind that this kind of machine is not intended to be used as the last
step in finishing pieces.

It will reach as much as the 70 percent of the polish process, but
you can put many pieces to be treated. I use it as a pre-treatment
before the final polish process, which would be easier. Some pieces
require as little as 5 minutes and others requires 20-30 minutes to
obtain the maximum benefit. No aditional benefits occurs if I leave
pieces during one hour or more. It has its own limit and the best
finish is obtained one by one with the old and well known method,
despite I saw a machine that uses nut husk sawdust, pieces are rotated
very slowly and the results I�ve seen were excellent as the final
process in polishing. It is very important that the liquid you use,
remains clean, only use the additive that comes with the machine, a
good dish detergent could also be used with good results (100
milliters per liter of water) as alternative. No solid particles there
must be in the recipient, dust, sand, carbonates. I hope this can help
you, write me if you have more questions.

Regards
from Daniel Mischelejis
Buenos Aires, Argentina
email: @Daniel_Mischelejis
web page: http://www.mischelejis.com


#6

Barbara - This machine only burnishes, it doesn’t polish like you do
with a buff. It is good for burnishing pieces that are very
detailed, like filagree (which you wouldn’t buff) or pieces with
stones cast in place. The finish on pieces with smooth sections will
be kind of orange peel from the little pins hitting on end.

To get an acceptable finish for pieces that you would normally buff,
you need a tumbler that would do cutdown, and then maybe burnish and
finish with a dry buff charged with some compound. I use a TV 25
Raytech vibratory tumbler (about 6 quart) and run grey Hone (Rio) for
6 hours, followed by green Hone for 6 hours. Both are run with a flow
thru system. Then to refine the finish, I run Dri shine III charged
with Simichrome for at least 12 hours, better at 24 hours. I usually
skip the rotary tumbler with steel when finishing gold. If
burnishing is required, ceramic beads or cylinders are preferable for
gold.

Judy Hoch


#7

Hello Chris and Babara,

I’ve the same machnetic tumbler as you have.It works fine for what I
use it,but forget the idea of using this equipment as the last final
touch(as far as I know).On smaller pieces it will work readable but
bigger pieces will have a matt finish.To get this perfect mirror like
finish,you beter check-out for stripping or plating procedures or
…handwork.

Stripping or plating is the very last point of perfection,but get
informed first before you buy it.I’m feeling fine with the one I
have,but I use it as a prefinish rather then the ultimate touch.
Regards Pedro Palonso@t-online.de


#8
   I'm pretty fanatical about the perfect finish and all this stuff
goes directly into a showcase...

From what I’ve seen, the magnetic finishers are wonderful and fast
for that final all-over polish. They aren’t going to take rough
castings down to smooth, though. They’ll just shiny up the lumpy
parts.

Have you tried a vibratory tumbler? I’m also picky about my finish.
I grind, file and sand imperfections down to 600 grit paper, then put
the pieces in to tumble for a day or two in heavy cut-down media.
Then switch them to a prepolish media for another day or two. Then I
tumble them in stainless shot for a few hours. Sometimes they
require a little hand finishing at the end to bring them up to snuff,
but not a whole lot. I do this with fabricated and also cast pieces.
My product is fairly substantial, by the way, not delicate. -Dana