Files "Bandsaw Sled - Big.jpg" and "Bandsaw Sled - Small.jpg"
show two sleds made for use on a metal-cutting bandsaw, the
intent being to force the bandsaw to cut straight.  This is accomplished
by clamping the stock to the sled, which in turn runs in the miter slot
of the bandsaw's table.  This was discussed at some length on RCM in the
thread titled "How to make a bandsaw cut straight" (May 2005).  The
original posting is reproduced here:

I recently [May 2005] acquired a bandsaw that will cut wood or metal (aluminium
at 3000 fpm and steel at ~100 fpm).  The saw is a Wilton 8201 and the blades are
Lenox (12-14 tpi) and Starrett (4-6 tpi).  It always cut at an angle with the
original cheapo blade.  Tightened and adjusted.  No dice.  Gave it a 5/8 inch
wide 10-12 tpi bimetal blade.  Much better, but still crooked.

The bandsaw books in effect say that this is to be expected, and describe
various ways to cope with the tendency, but I could not see why.

The mitre guage that came with the saw is pretty flimsy, but even that didn't
seem to explain the degree of crookedness.  Now, on table saws, the greatest
accuracy is obtained by use of a sled that carries the stock past the blade.

So, I made a sled out of a 3/8 by 3/4 by 12 inch cold rolled mild steel bar
(that slides in the mitre slot in the table), a piece of 1/4 inch 6061 T6
aluminium plate about 6x8 inches that I had laying around, and a piece of 3/8 by
3/4 inch aluminium bar (set vertical and accurately perpendicular to the steel
bar and thus mitre slot).   The pieces are held together with some large flat
head socket cap screws.  The sled reaches to within 1/16th inch of the blade, so
the stock is well supported.  (This is the Small Sled.)

In use, the stock is held in the sled against the aluminium bar, and the sled is
pushed past the blade.  On wood, this works quite well, but on metal it still
drifts a bit, the stock being held in the sled by hand. So I drilled another
hole in the sled to accept a 1/4-20 flathead socket cap screw, and attached a
small strap clamp.  This allows the metal to be clamped firmly to the sled. This
works: the cuts are now perpendicular.

So, the lesson seems to be that a significant cause of crooked cuts is the stock
drifting sideways while being cut.  I don't know the source of the sideways
force, but it cannot be that large.  It may be nothing more than the vibration
of the saw causing imperceptible walking.

Joe Gwinn