Yesterday I found myself cleaning up a bit of square tube in preparation
for welding and later paint. It was outside, but in SW Arizona, that
just means it has developed a small amount of protective rust over the
I started with an angle grinder and a flap disc. It made short work of
the light loose rust, but would hardly touch the mill scale. It also
showed some rust down "in the" the mill scale. I probably could have
stopped there, but I got carried away with myself. This stuff welds
really nice if you have bright shiny metal and takes a good paint coat
as well with an etching primer, and proper cure times.
I probably I could have just used extend or some other rust neutralizing
primer after knocking off the loose rust, but this construct will be
going into a humid environment.
I noticed a fresh flap disc stripped rust, and mill scale amazingly
fast. It did more work with less effort in the first minute or two than
it did in the next ten. Now the flap disc was still nearly new, but it
was performing like one that was half worn away. There was still plenty
of grit, but the edge was mostly the flaps rather than the grit, and the
face was the same, but also gummed up with mill scale.
I am NOT trying to get longer life out of a flap disc. I am trying to
get more time performing like the first minute or two of a new disc. I
don't care if the total life of the disc is less. Is there a practical
way to dress these so that you can expose more grit quickly. I tried
spinning it against a wire wheel on a bench grinder. The result was
less than amazing.
Sans the solution I am looking for is there a better disc for stripping
metal than an abbrasive flap disc? I can do the work with a grinding
wheel, but its much more skilled to avoid gouging the base metal and
doing damage. I tend to only use a grinding wheel to make the bevels
- posted 2 weeks ago