>Hopefully layups start this weekend - so I guess I better get a Dremel
Some time back, before I actually started doing my own layups on the
aircraft parts, I mentioned the use of a diamond wheel on a 115mm
angle grinder for trimming fibreglass (I'd been using one to trim the
heavy chopped-strand mat polyester-resin layups on my covered
trailer). This was comprehensively pooh-poohed by all and sundry as
much too heavy and unnecessary, and I retired into my corner again.
However, being a stubborn animal, I have since tried trimming my
layups with both the Dremel (with a Perma-Grit wheel) and the
aforementioned 115mm angle-grinder & diamond wheel. I find the
angle-grinder much easier to control (I feel I'd do better with the
Dremel if its wheel ran at right angles to the body, too), and it
goes through with pretty much undetectable effort. Of course, care is
needed to avoid cutting where I don't want to cut, but that applies
generally. The dust seems finer than with the Dremel, but there also
sems to be less of it. Of course I wear a mask and a suit, and have
the big workshop filter running during and for some time afterwards
to clean up the air. I shine a bright light through the glass from
the foam side and can cut with pleasing precision, needing only a rub
with a tungsten carbide file or the loooong Perma-Grit sander to get
(eg) trailing edges straight and in the right place.
The Dremel is, of course, valuable for many other things.
I don't feel happy about knife trimming, quite apart from the other
things I could be doing instead of watching and waiting for it to
reach the critical stage. When it gets to that stiff condition,
intermolecular bonds are forming. I can't see that fiddling about
with it at that point is going to help matters any. There is going to
be all sorts of small stresses and strains happening where the knife
is working or the other hand is holding the edge, and that could
damage the quality of the bonding locally. On the other hand, it
_may_ not do any harm, but as I can't think of any mechanism by which
knife trimming can be imparting improvement, I'm very happy to wait
until the layup is fully cured and use the diamond wheel next time
I'm awake.
My experience - your mileage may vary ...
regards
Rowland
| PFA 16532 EAA 168386 Young Eagles Flight Leader 017623
| Europa builder #435 G-ROWI
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