Electrolysis of cast iron?
 

I've got an idea for mounting a folding extension table off the back of
my table saw which starts with bolting an aluminum angle to the cast
iron top. Do I need to worry about electrolysis between the aluminum
and the cast iron?

"Roy Smith" wrote in message
...
I've got an idea for mounting a folding extension table off the back of
my table saw which starts with bolting an aluminum angle to the cast
iron top. Do I need to worry about electrolysis between the aluminum
and the cast iron?

I don't think so. First, for galvanic corrosion to take place, there has to
be the prescence of an electrolyte, usually water. Second, there's not a
large potential difference between cast iron and aluminum alloys. Even if
it did happen somehow, since aluminum is less noble than cast iron, the
aluminum (aluminium for our friends across the pond) angle would be the
anode and would sacrafice itself, so the table saw top would be protected.

todd

"Todd Fatheree" wrote in message
...
"Roy Smith" wrote in message
...
I've got an idea for mounting a folding extension table off the back of
my table saw which starts with bolting an aluminum angle to the cast
iron top. Do I need to worry about electrolysis between the aluminum
and the cast iron?

I don't think so. First, for galvanic corrosion to take place, there has
to
be the prescence of an electrolyte, usually water. Second, there's not a
large potential difference between cast iron and aluminum alloys. Even if
it did happen somehow, since aluminum is less noble than cast iron, the
aluminum (aluminium for our friends across the pond) angle would be the
anode and would sacrafice itself, so the table saw top would be protected.

todd

For ordinary thicknesses, ok for years. Environment matters, eg. if near
ocean, might be bad if the parts are thin. In dry area, no problem.

Roy Smith wrote:

I've got an idea for mounting a folding extension table off
the back of my table saw which starts with bolting an aluminum
angle to the cast iron top. Do I need to worry about
electrolysis between the aluminum and the cast iron?

Roy...

I've been using the same aluminum [aluminium] insert in my cast
iron table top since 1975 and haven't detected any ill effects.
It's probably something not much worth worrying about.

I recently added an outfeed table to my saw - also starting by
attaching an aluminum angle - that you can look over at
http://www.iedu.com/DeSoto/outfeed.html. It seems to be
surviving fairly well (and will probably outlast me!)

--
Morris Dovey
DeSoto Solar
DeSoto, Iowa USA
http://www.iedu.com/DeSoto/solar.html

On Tue, 21 Dec 2004 23:04:52 -0500, Roy Smith wrote:

Do I need to worry about electrolysis between the aluminum
and the cast iron?

Aluminium extrusion is often anodised, which is some of the best
electrolytic protection you could get.

As to the rest, then if it's going to get wet, then you should worry
(there are primers to deal with this). For a saw part in a normal
workshop though, it's no problem.

--
Smert' spamionam

On Tue, 21 Dec 2004 23:04:52 -0500, Roy Smith wrote:

I've got an idea for mounting a folding extension table off the back of
my table saw which starts with bolting an aluminum angle to the cast
iron top. Do I need to worry about electrolysis between the aluminum
and the cast iron?

No. But if still worried, use a plastic shim.

On Tue, 21 Dec 2004 23:04:52 -0500, Roy Smith wrote:

I've got an idea for mounting a folding extension table off the back of
my table saw which starts with bolting an aluminum angle to the cast
iron top. Do I need to worry about electrolysis between the aluminum
and the cast iron?


the big offender is aluminum to copper.

if you're worried about it, slip a sheet of paper between.