For years I've been trying to find a
way to cut Printed Circuit Boards (PCB) for both through hole and
Surface Mount Technology work. A scroll saw
mounted under a work bench works but it has about a 1/16" saw kerf
that's wasting expensive PCB material. A scribe used on both
sides of the board (making "V" grooves) takes a lot of time and hurts
the fingers. The
8" Mini Shear Break
worked a small fraction of the time.
Tin
Snips work but have a very short cut distance so even when going
from each side are very limited. They also bend the PCB material
to the point where it might be overstressed. The Harbor Freight
67256 Multi-Function Tool cuts very slowly with the 67264 diamond
blade.
A foot operated sheet metal shear that's about five feet long works but
takes up a lot of space and is expensive.
The
Enco
130-5700
12" Bench Top Hand Shear cuts 1/16" PCB material like a
knife through hot butter and is very easy to control. The 5"
($67) , 6"
or 8" versions may also work well, but I got the 12" ($120) to error on
the
safe side. If you know how the smaller units work for cutting
1/6" PCB material please
let me know.
The 12" shear will not stand up by
itself. The factory intended for it to be anchored to something
very substantial so leverage could be applied to the handle but it
takes a very small amount of force to cut PCB material since the shear
uses a compound linkage. So it does not need to be anchored for
leverage but does need to be mounted to keep from falling over.
You also need to have good lighting to see the PCB cut lines and the
blade. The plan is to mount it on a two foot square piece of
heave plywood.
With the shear sitting on the floor and a table lamp on the left side
and the back leaning against a cardboard box to keep it from falling
over I separated a 2.5" x 3.8" ExpressPCB "Mini Board" into 63 (6 by
9) smaller boards in about 5 minutes. Note that after
making 6 cuts then each strip needs 9 more cuts so 63 cuts for 63
parts. Note that there is no fiberglass dust like with a saw.
Tried the shear of a stack of paper about 1/2" think and although it
cuts the paper easily it does not cut straight.
Sheet-metal will be another test. Both Brass and Phosphor Bronze.
The "Wheel" shown in
Fig 1 can be adjusted up and
down and is there to keep a steel plate from lifting when it's
cut. But the wheel is not needed for PCB matgerial.
11 Feb 2010 - I'm now thinking to mount it on my work bench using the
thumb nuts so that it can be moved to the back when not being
used. But will need help to lift it.
I tried to get the shadow of the blade to act as an optical guide for
cutting, but the lamp is too wide of a light source. Something
like a single LED may work. Because of parallax the apparant
position of the PCB needs to be offset a little to get the cut on top
of the 0.006" wide cut lines. If you know a good way of
positioning the PCB
let me know.
The Handle is a little over 34 inches
long and the distance between the handle pivot bolt connecting link top
is 2 inches for a 17:1 advantage. If a PCB is inserted at the
back of the shear there is about a 2:1 advantage for a total of
34:1. But even if a PCB is inserted at the very front it still
cuts with very little force on the handle.
