Tumbler problems

my dilemna is that one of the barrels bursts open - on average -
once an hour.  

Catherine, I have that problem with my Lortone 45C and got some good
advice from the Tech. Dept. at Rio, which I incorporated into my
article on tumble-polishing metal jewelry, published in Lapidary
Journal, July 1999, pp. 75-77. Assuming you may not have that on
hand, here’s what I do.

First, I set up my whole assembly on wood blocks (about half an inch
thick), inside an old, large aluminum cake-pan, so that the mess
produced when the cover spontaneously comes off, stays inside the
pan. The blocks keep liquid from getting into the motor.

Also, (this was the advice from Rio), I take a short, thick, blunt
piece of wood and place it under the center of the barrel after it
is loaded, then gently push the barrel downward so that its
bottom is slightly arched up upward. Holding the barrel in this
position, put on the flat inner lid and the upper metal lid, then
tighten the knurled knob. The bottom should remain slightly
indented, and the positive air pressure outside the barrel will
help keep the lid in place.

It’s not 100% foolproof for me, because I tumble heavier things,
but it may be fine for you.

HTH (hope this helps)
Judy Bjorkman

Rotary is a must, as I need the work-hardening action that the
rotary tumblers provide.  And I am using stainless steel shot. 

Catherine, in my earlier post, I neglected to mention that stainless
steel shot (in the usual amount) is too heavy for the Lortone tumbler
(at least, for mine). That’s why I use ceramic media, my favorite
being Cerambits, available through Kingsley North (but you have to
ask them to order it elsewhere; it’s not in their catalog).
Otherwise, try using a lot less stainless steel shot and see how
that works. Once, when I half-filled my Lortone 45C with the steel
shot, the motor really wouldn’t even turn it. My guess is, that’s
why your motor burned out.

All the best,
Judy Bjorkman

A lot has been said about this problem and apparently this thread
will keep on appearing from time to time. I am indicating a useful
web-page from SHOR International which may help quite a few to
understand better the process of vib tumbling and the appropriate
use of different media. Hope this helps!
http://www.shorinternational.com/VibratoryInstruct.htm

From Sunny to a dismal weather covering Malta!
Joseph Tanti
http://jostanti.cjb.net