Hello Orchidians - I have a small, hobby tumbler which convinces me
that tumbling will round off the corners of stones and polish to a
small degree and I am thinking of investing in a high quality
lapidary model. Could you please share your experiences? In
particular, these Qs came to mind:
When I am prospecting, I see many river stones, all rounded and
polished to a degree by this natural tumbler. How far can the best of
tumblers go toward both criteria (1) rounding - can a tumbler
substitute for a bead machine; (2) polishing - can a tumbler
substitute for hand polishing?
BTW, when I worked in gold mining and milling in NWT we used huge
ball mills which are tumblers, but the purpose is grinding up the
ore. If you were to use round (hardened) steel balls in a lapidary
tumbler would it not produce spherical beads?
We use Lorotones at the Rock club I belong to. We’ve had no
problems. If you put silver pieces in a clean tumbler with some steel
shot of assorted shapes you can get a decent polish. Don’t try using
them for bead mills though. Its more trouble than its worth. Sheri
There are beading machines, and sphere machines that are separate
from tumblers. Some of these can be quite expensive. My tumbling
experience is limited, but I have been a lapidary for 40+ years, and
know that you get rocks that are rounded and tend to break down
where fractured, and do get sort of a river rock look. You can polish
your metal in either a vibratory, or rolling barrel type tumbler. You
can tumble, say turquoise nuggets, gently in a vibratory tumbler,
leaving them very much natural, only shiny (then drill for beads).
But, if I understand your question, no to most of it. There is always
Google, and rock clubs that have many types of tumblers going all the
time. with many people trying different stuff, you might be able to
access locally. I know that you can medium grind cabochons, and then
put them in a vibratory tumbler to finish polish. That is how much of
the commercial stone is cabbed so cheaply. I carve my fire agates to
a pre-polish (1200), then finish to a brilliant shine in a vibratory
tumbler. I’ll be interested to see what the group has to say.
There are beading machines, and sphere machines that are separate
from tumblers............. [snip] .......... I'll be interested
to see what the group has to say.
Thank you for the advise. I may just contact Lortone and buy one of
their machines as Sheri suggested since I am very pleased with the
slabbing saw they sent me.
I read Professor Warwick’s book “March of the Machines” and one of
his maxims is that if there is a SPECIFIC job a human can do, chances
are a robot can be made to substitute for the human. I wonder if
anyone knows whether cubic stone blocks as I can cut could be put
into such a specialized bead machine and come out round? I have never
seen a perfect sphere in a river stone but some come close. My guess
is that if you put 100 perfect cubes into a machine, because of
varying rock strength around the surface maybe 10 would come out as
perfect spheres. But what if it is 100:1 instead of 10:1?
That being so, it would get down to cost-effectiness and hand bead
making being cheapest. Even so, lapidary tumblers seem to have $1,000
as maximum cost. What if you want to spend $10,000 on a bead machine?
Could it be that the ratio above is so low (in producing spheres from
cubes) that the ratio it be 100 or 1,000:1 and Warwick is right about
the machine maxim but not the economics? Any other guesses on what
the ratio would be?
Suppose you go to the other end of the scale, Dr Rasmussen. What is
the Rolls Royce of tumblers?
For that matter, what is the best of the best in grit sequence for
polishing? I note from my river stone prospecting that the jade
cobbles/floats are hard to spot because of the surface “skin” no
matter how much tumbled they are. Do you think you could put a gloss
on jade with a Lortone tumbler to rival hand polishing?
I will cc Lortone to invite their reply as well. Orchid moderators
of course may moderate out sales promotional posts but I think
education is welcomed.
My C&M Topline tumbler is excellent. It cost me, but paid for itself
in a month. Double barrel space, heavy duty and after years of use
I’m glad I went for the best. RMP
There are two types of rock tumblers on the market, rotary and
vibratory. Each polish stones, but gives a different result as to the
shape of the finished stone. The coat of the tumbler has little
effect on the final polish, but to the size of load and durability of
the machine. What kind of stones you plan to polish, along with size,
quantity and end use should be your guide to how much you want to
spend on a tumbler. Many factors go into creating a high polished
stone and most, if not all, has anything to do with the machine. I
know of a commercial lapidary who produced large quantities of
polished stone to sell wholesale to gift shops, in an open cement
mixer. The secret to ending with a great polish is like with a
computer, garbage in, garbage out. Stone must be matched for size and
hardness, and carefully checked cracks and flaws. A hard stone
breaking in a final polish can ruin the run and price of the tumbler
would have no effect. I recommend you visit rockumbler.com, the do
sell various tumbles and supplies, but also have a wealth of free
and instruction. Best of Luck
Lapidary tumbling machines are filled with stones, grit and water
and can be either rotary or vibratory. While the machines are
identical to those used in jewelry finishing, the materials are crazy
different. Lapidary finishing requires having enough stone material,
whether scrap or cut goods to rub against each other and the grit to
finish. It is a science all in itself.
Probably the best current book on lapidary finishing comes from the
Harmon’s in Montana who are known for their exquisite cutting and
finishing of patterned Montana agate.
Now to the comment about magnetic finishing from Mr. Anderson - a
magnetic tumbler is loaded lightly with steel pins, water and a small
amount of jewelry. It is totally the wrong machine for finishing
stone. Like many tools we use, it has very specific things that it
should be used for, rocks isn’t one of them. It isn’t the end-all for
jewelry finishing either, but useful for some processes.
For learning about lapidary processes, go to one of the lapidary
discussion groups, you will get better advice on finishing stones
there.
Judy Hoch
Author - Tumble Finishing for Handmade Jewelry.
I wonder if anyone knows whether cubic stone blocks as I can cut
could be put into such a specialized bead machine and come out
round?
I’m pretty darn sure they’ll come out as smaller cubes with rounded
edges and corners.
If you start with a big enough cube, and tumble long enough, I
suppose they might end up MOL spherical. I’m imagining, say, a 3"
cube ending up the size of a pea. I cannot believe anything
satisfactory can be achieved this way, especially since stones are
rarely perfectly consistent in hardness-- so they will not be perfect
spheres unless ground that way by a machine for that purpose.
If that is the result, Noel, I would be very pleased as long as the
cost of operating the machine to that stage was right.
I was examining a string of pearls today which was valuable and
smaller than pea size.
If there are machine sellers out there who can do this, make me an
offer.
As I have said many times, when I buy a machine I want PROOF that it
can do what it claims whether it is a bead machine, CNC, robotic
carver or whatever. Does anyone question my buyer behaviour?
The other day I was looking at a valuable string of baroque pearls,
smaller than pea size so this could be exactly what I need though I
would start with cubes smaller than 3 inches. All stones the same H
value.
I want to buy “the best of the best” in tumblers. What I am puzzled
by now is that there WERE two main types of tumblers, vibratory and
rotary but now there is also magnetic. And the advise I am getting on
whether magnetic is generally good for polishing or not is
conflicted.
Perhaps I could start with a rotary/vibratory machine and then
finish-polish the baroque beads with a magnetic tumbler. Would that
work?
Peter- A rotary tumbler is more than adequate to deliver an excellent
polish on materials such as garnet, amethyst, citrine, kunzite,
aquamarine, agate, jasper, etc. I was buying baroque nuggets like
these, all with mirror polish, 55 years ago. No need to fret over the
process or reinvent anything. It is a matter of the operator allowing
sufficient time at each stage, while proceeding in a logical
progression of ever finer grits up to the polishing stage. Polishing
may require a different polishing oxide (cerium, zirconium, chrome,
aluminum, depending on what you are tumbling) plus plastic or
masonite chips, plus segregation of stones by type. Consult a book
or an expert on the subject, or try it yourself and learn through
trial and error. Learning by doing may be the best approach for you.
It does require an investment in time and patience. especially time,
bcause you cannot rush tumbling! Good luck.
I personally own a magnetic tumbler. It gets into the small, places
and behind things that I can not get to by hand and brings it to a
fairly high polish in less then 25 minutes. then I hand polish my
pieces. Nothing puts a shine on a piece as hand polishing. Rotary
tumblers just take too much time for me personally.
Peter - there are many more than three types of tumblers. Magnetic
tumblers are a special version of burnishing machine. And they won’t
do a bit of good on your stone. What you need is many variations of
grit within a device that continuously rotates the stone in three
dimensions. To suggest that you could put blocks in a tumbler and get
globes is to suggest that if you had enough monkeys typing, they
would come up with Ulysses.
CIA