I did a rough cast manifold once, and I will never polish a rough casting
again. I started out with a die grinder and sandpaper drums to remove the
parting lines and start smoothing out the casting pits. For me what worked
best for getting the surface smooth enough to start polishing was ALOT of
hand sanding with progressively finer grits. I did do all the tight spots
that I could with some finer grit tapered sandpaper drums on the die
grinder.
When it came to the buffing and polishing, because of the complex surfaces I
could not use the wheel on the bench grinder effectively, so I used a 4"
buffing wheel on the die grinder for the larger surfaces and an assortment
of small felt bobs on a dremel tool and 1/8" die grinder for the tight
areas. I would highly recommend the 1/8" die grinder over the dremel - about
twice the RPMs.
This took me MANY, MANY hours, but the results were beautiful. Unfortunately
I don't have a website right now, but I put together a page showing the
progression of the smoothing and polishing. If I get some web space again I
will post the page and provide a link.
As I mentioned, I doubt I will tackle a rough casting again. Sending it out
to a professional polisher will save you lots of time and get nice results,
but you will pay for it, especially on a rough piece. :)
One last recommendation...the manifold I did had several unneeded screw
bosses, vacuum ports, smog fittings, etc. I cut everything off that I didn't
need, had the holes welded up, and smoothed them over. You wind up with a
really clean presentation without a bunch of blocked off fittings.
Brian
-----Original Message-----
From: owner-datsun-roadsters@autox.team.net
[mailto:owner-datsun-roadsters@autox.team.net]On Behalf Of
JOHNSOF@aol.com
Sent: Tuesday, December 03, 2002 7:01 PM
To: datsun-roadsters@autox.team.net
Subject: aluminum polishing
I know this subject was covered at length some months back, but...
The cast aluminum parts - thermostat outlet, valve cover, etc - are so full
of "flaws" from the casting process that I can't seem to polish them very
well. The stamped aluminum parts, like the Solex air filter cover, polish
up
very easily. Are the cast parts going to require sanding first? Starting
with 80 or 160 grit, and then progressing to polishing compounds and finally
rouge? Or what am I missing?
Thanks in advance.
Fred J.
'69 SRL
WI
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