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Home grown magnetic pin finisher


#1

I have always liked the fast and efficient performance of magnetic
pin finishers but as a not for profit (amateur) jeweler I could
hardly justify the expense.

The solution, build it myself.

Disclaimer:

Motors are dangerous! Strong magnets are dangerous! 110 volt power
is dangerous! And properly many other aspects of this project are
too. I’m not telling anyone to do this, but it worked great and I now
have a cool magnetic pin finishers!

I found almost no on the web so resorted to trial and
error. I mocked up motor, plate, magnets and chamber. Using 0.5mm X
5mm media the system seamed to work under a surprisingly wide range
of speeds and geometry but required a strong motor. I’m using 1/16
hp.

I decided to omit the motor speed controller but the gap between the
magnetic disk and parts chamber was critical and required exact
adjustment to get the right frenzied pin dance.

Chamber: I used 6" diameter polycarbonate tube glued to a square
base but other materials could be used.

Large diameter PVC or ABS would work fine and are cheep. Downside
they are not transparent.

Other containers with flat bottoms most likely would work too.

I stuck a piece of material in the center so parts don’t park in the
eye of the storm.

I kept the bottom square with some holes to keep it located over the
magnetic plate.

Max working Capacity: 1 Ltr. water 200 grams media. Total volume 2
Ltr.

Magnetic plate. The 6 magnets I used were rectangles ~.8" X 1.25"
X.45" I turned the aluminum plate to 6" diameter and bored 6 holes
symmetrically spaced in a radial sweeping formation. (This was not
based on any scientific basis but just looked cool!)

The center is bored to fit the motors shaft. Two set screws to fix
it.

The magnets were potted in the pockets with epoxy poles alternating.

The rest is just a box. It spins quite fast and vibrates a little so
I made a box with good stance. I used 4 X 1/4-20 stainless threaded
rods with counter locking nuts to support and adjust the top support
plate. Wire up with a timer switch and away you go.

Works like a charm… So let’s make it better!

I noticed that it gets very dirty. The dirt is magnetic dust from
the media and debris from parts. Even with extensive rinsing it
sticks to the media.

To address this I added a 3/8" drain port about 1" above the normal
water line and a clean water supply that clips onto the side of the
chamber directing water to the center of the vortex. I add a little
burnishing compound and for the last three minutes of the cycle run
the water

This quickly flushed the chamber totally clean. I have bright parts
and clean media.

Material:

6" Polycarbonate tubing $30.00
1/16 hp surplus motor $10.00
Timer 0-6 hour $20.00
Magnets Surplus 6@ $2 $12.00
1/2 Aluminum plate for disk $8.00
http://shorinternational.com/TumblingMedia.htm $50.00/lb.
Wood paint and other stuff ~ $20.00
Total ~ $150.00

Mark


#2

Hi Mark, Sounds pretty nifty! What are the odds for a picture?


#3
Sounds pretty nifty! What are the odds for a picture?