Loctite makes a bewildering array
of products. Table 2 lists some of the
most suitable types for robots. My top
recommendations are highlighted;
they provide the best combination of
features you need in a combat bot.
Make sure that both parts are
as clean and de-greased as possible.
Cleaning with isopropyl alcohol or a
similar solvent makes a huge
difference, even with the grease-tolerant products like 243.
For screws secured with a nut,
you only need to apply Loctite to
the screw where the nut will be
tightened. I like to assemble the
screw in the part first so that I can
see exactly where to apply the Loctite.
This helps prevent the screw hole
from gumming up with old Loctite.
For screws that are inserted in
blind threaded holes, you need to
apply Loctite to both the screw and
the hole. Otherwise, air pressure will
force much of the Loctite out of the
hole as the screw is inserted. I find
the end of a cable tie is perfect for
distributing Loctite in small holes.
For fasteners where BOTH parts
are made of inactive metals such as
aluminum, stainless steel, magnesium,
zinc, black oxide, cadmium, or
titanium, you need to use Loctite
7649 spray or liquid primer. The primer
will reduce curing time and provide
more holding power. For surfaces
where one of the areas is brass,
copper, bronze, iron, steel, or nickel,
you don’t need to use primer unless
a short curing time is important.
Parts with low and medium
strength Loctite generally only need
leverage to remove them. Parts with
high strength Loctite are hard to shift.
The recommended procedure is to
heat the parts to 480°F for several
minutes before trying to separate them.
Once the screw is removed, you
can reuse it simply by scraping off
the hardened Loctite and applying a
fresh coat. The old Loctite can be
tough to remove (if it isn’t, you are
doing something wrong!). A wire
brush will get most of the material
off, while a small triangular file will
clean up tough spots. If you are really
pressed for time in the pits, apply a
small amount of Loctite over the
hardened material; it is usually enough
to get you through one more match
and because the fresh Loctite is in a
thin layer, it will cure faster.
Tips and Tricks
Clean new screws. Almost all
new nuts and screws have oil
residue on them. A quick wipe with
solvent makes a huge difference to
Loctite’s holding power!
If you want to know more about
threaded joints, these two links will
provide more than enough info:
Completed and Upcoming Events
Jan 10 to Feb 10, 2010
Kilobots XVI SPECTRUM was held
January 16th in
Upcoming Events for
April and May
RoboGames 2010 will be held April 23rd — 25th in San Mateo,
HORD Spring 2010 will be held on May 15th in Brecksville,
Ohio, presented by
the Ohio Robot
32 SERVO 04.2010