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Pin Finishing


#1

After rummaging through my “spare parts” heap, I find that I have
all of the components necessary to make a magnetic pin finisher
except the magnets - so making one would be a piece of cake. However,
I’m struggling with what would be gained by doing so since I already
have a tumbler setup with steel shot, Do I have it right that the
marginal gain of the magnetic finisher is in the time it takes to
burnish a piece? Is there any other advantage? Does tumbling do
anything better?

I have a small shop. I’m wondering if there’s sufficient reason to
warrant giving up the space to another machine.

Jim Baird


#2

a friend of mine threw a few ceramic magnets in with his steel shot,
to see what would happen and it worked faster, that was about it…It
also didn’t wreck the polarity of the motor (a 12V brushless non
wirewound motor). Make magazine has the instructable though should
you want to make one yourself…rer


#3
Do I have it right that the marginal gain of the magnetic finisher
is in the time it takes to burnish a piece? Is there any other
advantage? Does tumbling do anything better? 

The advantage of the magnetic tumbers is that they work much faster,
and get into extremely small details. Ordinary steel shot, which
isn’t all that slow either, but does take a bit longer, is better at
peening surfaces and burnishing them, sometimes helping with porosity
and tightening up surface pores. Shot can leave a better brighter
surface, but won’t get into the tiny details like the tiny pins in a
magnetic finisher. In essence, the two machines actually do fairly
different jobs. Both finish the metal, but the results are different.
Some items are better processed with shot, some better done with the
mag finisher, and some end up best processed first with the magnetic
finisher to get the fine details bright, and then run in shot to
improve the finish on broader more exposed surfaces. If your tumbling
things that will then get manually polished more, you don’t need the
steel shot most of the time. But if you’re hoping for a final polish
on things, you might now and then want both.

Peter Rowe


#4

Hey Jim, I have both steel shot tumbler and a pin finisher, I
wouldn’t be without either. Many times pieces get run through both
machines.

Considering you have the spare parts in “the heap” I’d definitely
build it… Four magnets will cost you about 50$ I used 1"x1"x1/2"
n52 magnets

Pins are available at Rio and others around 30$. As far as comparing
it to burnishing I much prefer the pin finisher but that’s just
personal preference.

Build it, if it does’t work any better than your burnishing then
sell it.

Good luck, Jim Doherty


#5

If you do your own casting, the pin finisher is great at removing
the investment remaining on the casting. Spin the piece for 15-30
minute using plain water, drain, then use water with a burnishing
liquid added, then spin again. If a piece does not have any hard to
get at places, I prefer using a tumbler. It gives a “richer” finish.

Harvey Leshnick