MATERIAL SHEAR TIPS -
OVERVIEW

1) Do not trust the ruler.

2) Do not trust it to be square.

3) There is a major difference between a metal shear and a
flex shear.

4) Unisub FR may be shear cut under certain conditions.

TIPS

1) Unless the ruler is engraved it is
made of a plastic material pressed onto metal. It
streaches when pressed. I have 2 trimmers and both rulers are off
in different places. It may be perfect at 2" and 8" but
can be 1/16" off at 6". Cut flex strips about 1"
to 2" wide of precise lengths that you use by setting the
stop with a metal ruler and then verifing the length. This will
be the lengths that you will cut in the future so be precise (or
the faintest bit under to guarantee not being 1/32" short in
the last cut of a section of a sheet). Carefully bond them
together (using Res-N-Bond or equivalent) going from the longest
to the shortest to make a pile. Be sure that the common edge is
even. This block can be placed easily against the blad at the
length that you want while you set the stop. Due to there being a
longer strip on top of the length that you want it is easy to
hold in place. I Score lines on the surface to show exactly there
the under strips are and mark them to make it super to place in
the proper place. If you use many lengths better to make a few
blocks than to go over 1/4" total thickness. I have one for
1/4 & 3/4 markings and another for 1/2 and even inch
markings, plus some for oddball lengths that I commonly use.

2) Invest a very small amount in a
machinists square. It is an L shaped picec of steel one
foot by eight inches. It is thick enough to remain square. Align
your ruler/guide with this. After aligning you can test by
cutting a 6 x 6 piece of material by shearing each side in a
clockwise progression. You will never get it perfectly square but
you can see how far off it can become, shoot for very little. Cut
a piece of scrap about 9 x 9 (hopefully you do not have many of
this size scrap) mark the corner of the last cut and side that
was against the guide. This makes an excellant push/align guide
for last pieces of a set of cuts. When you buy flex have it split
lengthwise unless you have a 48" shear or need things bigger
than 12" in both directions, which needs hand cutting.

3) The shape of the blade is critical
for the material being cut. Plastic ain't metal. A plastic
blade is very sharp so as to cut into the plastic as it shears. A
metal blade is much blunter to tear the metal apart at the cut.
Metal will easily chip a hardened plastic cutting blade. (I
believe that the bottom blade is the same.)

4) Yes Unisub FR can be shear cut
somewhat. You must use a metal shear, the fiberglass
reinforcement may microchip the plastic blade. The trick is to
have the material at 80 to 90 degrees Farenheit. Too cold and you
get bad chipping and a very rough edge. Too warm and you may put
a crack at the edge of the surface at the cut. Too hot and the
plastic will powder at the edge from being torn by the fiberglass
as it is being sheared. If you need a perfect edge for a badge
you will have to quick sand the edge.

Philadelphia, PA (Really Bensalem)

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