Thanks for the tip. I will look for it and buy a couple.

I have read a couple books about this. Seem like the pros uses both a
grinder or a rotary sander with disc pad. They don't explain why they
use the grinder instead of the rotary sander in one occasion and then
use the rotary sander in another occasion. I have a feeling that this
may have something to do with the width of the bevel edge that they
want to make. I "guess" if the bevel edge is only 1.5", a grinder with
a 4" wheel is more suitable; on the other hand, if the bevel edge is 3"
wide, a rotary sander with a large 6" or 7" plywood pad is probably
more suitable than a 4" grinder. In my case, the fiberglass skin is
1/8"; this means the bevel edge should be only 1.5"; this also means
that I should use a grinder as what you have recommended. Thanks.

Jay Chan

Jim Conlin wrote:
Get several. They're a buck or so. Start with a fine one and escalate as
you feel more aggressive..


wrote in message
oups.com...
I see. This means if I use a random orbital sander to sand the bevel
edge, I may risk damaging the sanding pad, and I will take a long time
to get the job done.

If I use an angle grinder with 36-grit fiber disc (that I assume has
some give), I may find that it may not sand as aggressive as I
originally thought -- I thought it was being used like it had a metal
cutting wheel; that's why I said it might sand too aggressive; I didn't
know that I can put a fiber disc on it.

This sounds good. I already has an angle grinder, I just need to get
the 36-grit fiber disc to find out if it is the right tool.

Thanks for the info. I appreciate that.

Jay Chan


Jim Conlin wrote:
The sanding discs for that tool are of middling light paper(D or E wt.)
and
available from maybe 60 grit up. The pad is a firm sponge. The #60
will
take forever to shape a bevel and the sharp edge of a glass skin will
tear
up the paper and the pad. Use as fine a grit as you like on the
minigrinder
and be careful.. It doesn't need to be pretty. You'll be adding glass
back
into the bevels.
You will need the RO sander, but not for this.



wrote in message
oups.com...
Please explain the reason why you think the 7424 random-orbit sander
is
not a good tool for beveling a tapered edge along the edge of a
fiberglass skin. I am not questioning you; I know that you must have
a
lot of experience about this. I am asking this just trying to figure
out which features of a sander that work for beveling and which don't.

I already have a low cost angle-grinder. But I have a feeling that it
is a bit aggressive for fiberglass skin. People who have the right
touch probably can use it just fine. I probably will do more damage
than good using it. Therefore, I am looking for a sander that comes
with a pad.

Jay Chan


Jim Conlin wrote:
The Porter-Cable 7224 looks like a Porter-Cable 7336 with a
different
pad.
Same amps, same rpm's. That series (733x) comes with both 5" and 6"
pads,
both PSA and Hook&loop. I have both and use the 6" more in my work.
YMMV.
There's a counterweight that's calibrated to the weight of the pad,
so
you'll have to change that, too.

As useful as thePorter-Cable random-orbit sander is, it's probably
not
going
to be effective at grinding teh bevel in your glass deck skins. For
that
job, a low-cost choice would be a 4-1/2" mini-grinder such as the
Porter-Cable #7430 with a #36 disc. Wear protective gear.

You will want the R-O sander for cleaning up your skins and for
subsequent
finishing.


wrote in message
oups.com...
I am interested in a Porter-Cable random orbital 6" polisher 7424
(6
speeds). By switching the 6" backing pad with a 13700 5" sanding
pad,
I can convert it into a 5" random orbital sander. By the look of
its
picture with the sanding pad, it surely looks just like any other
angle
sander. I am wondering whether I can use it to sand down a
fiberglass
skin to taper its edge. Any idea?

Let me explain what I am trying to use the sander for:
I am going to lift the fiberglass skin of a deck, and then
replace
the core material. After this, I need to put the fiberglass skin
back
in place, and I am supposed to use fiberglass cloth and epoxy to
bridge
the cut on the fiberglass skin. I need to sand and taper the two
edges
along the cut in order to level the patch with the rest of the
fiberglass skin, and that is what I intend to use the sander for.

Of course, I also want to use it as a random orbital polisher. I
just
want to know if I can also use it as a sander in the way that I
have
described above.

Thanks in advance for any info.

Jay Chan