What goes Wrong
Sample Sheet Metal Packs
Brooke's other Metal Working web pages
This is a combined 8" sheet
and an 8" bending break. It's sold by Harbor Freight as
and by Northern
+ Equipment as Item
. The Harbor Freight version is painted red
Northern Tool version is painted blue, but otherwise they seem
the same. The Micro-Mark 83213
is painted White and includes the cutoff guide (Missing
the other two versions). The Micro-Mark Manual
has some different information from the Harbor Freight manual.
This may also be called a pan and box break because it can
metal that already has prior bends. Also called a press
which is different than the folding type of break. The
Freight 18" break
is similar to a flat table top with a hinge. To use it
to trap the metal using the supplied bar with C clamps then
pull up on
the handles. But this type of break can not make a box
there has already been a prior bend.
This is made by Sieg, the same company that makes the Mini Machine Tools
There is a Profiform
version that comes in two widths called the 200 (8") or 320
(12"). It's manual
goes into some detail about setting the cutting tools.
properly set you can cut typing paper. This version has
accessories available that would also work on the Harbor
The 12" Bench Top Hand Shear
job I was trying to do with this product, i.e. cut Printed
Boards. Plus it can cut other things, like paper to make
The shear is at the top and
a horizontal top cutting bar and a sloped lower cutting
There is a gap in the top of the casting that's less than 2
0.079" deep that limits the thickness of material that you can
mm spec = 0.059"). 1/16" printed circuit board material
just fits and is easily cut. It would be better if the
was sanded to knock off the high spots (mainly paint but also
bumps). This was my application.
4 Jun 2007 - The shear will cut the ExpressPCB Mini boards
3.8") where typically the first cut is about 1.25" with no
problem. But if you're cutting a board that has 3 or
under the blade then it's very difficult. I've found
scribe to weaken the board on the top and bottom prior
shear it helps. For really large boards I still use the
saw that bolted under a table in the garage.
27 Oct 2007 - The Harbor Freight 38413
may be a better way to cut printed circuit
boards? If you have one let
A 3 foot floor mounted sheet metal shear that's foot operated
a 12" PCB like it was butter, but they are big and cost more
I want to spend for this.
I think the problem is the design of the mechanism that drives
blade. There's not enough leverage and with more
drive pins will snap. But I haven't done any
calculations to see
what the stresses are in the shear and frame. If they
are low for
say a 5" wide 1/16" double sided PCB then it would be worth
a better drive system, like a hydraulic ram.
Missing Accessory - Cutoff Length Guide
The Lower Blade Support Bar (Item 8) has a couple of 8 mm
holes in each
end and there are a couple of pinch bolts that are intended to
something. As of 16 Feb. 2006 I think the missing
accessory is a
right angle cutting guide. When installed the guide
you to align material on the guide and then make a cut 90
the guide. This would allow squaring up material that
with only one straight side. But I have not seen anyone
this useful accessory. As it is now if you cut out a
metal that's small enough to fit into this mini shear using
or a power sheet metal cutter (Harbor Freight 92148
electric sheet metal shear) it will not be square. So
missing guide you need to do layout and marking of the work
piece just to get it square. With the missing guide it
would be a
snap to square it up.
The main purpose is to both allow cutting the same length each
time. If care is used to set the stop bar parallel to
tool then it also allows the cut edge to be parallel to the
free end of
the material. It would make a nice accessory to have a
right angles to the cutting tool to allow squaring up a sheet
Guide (Item # 16)
has a couple of thumb screws that pinch on the two 8
mm rods coming out of the lower "V" groove die. The
the guide is to both set the length of metal to be bent and to
parallel to the bending line. The Guide has a lip that
positioned on the top side and facing the bending dies.
be wrong to feed the metal below the lip and above the rods
doing so would not allow the metal to move upwards as it's
So the tip of the lip must be the intended stop for the
But the amount of lip protrusion is only 4.83 mm
is about the length of the flat on top of the lower die, but
it is not
long enough to be over the bending line. If it was half
of the lower die width (15.71 mm or 0.622") then when
length of the material to be bent would be zero. If the
moved 0.25 inches away from the lower die the material that
would be 0.25" , etc. making setting the positon of the guide
BUT that's not the case. So was the guide made
or is there some reason for the strange lip protrusion
Also, how to determine which "V" goove in the lower die should
Shear Blades (9 & 10)
The blades are rectangular in
section so that they can be installed 4 different ways, each
presents a new cutting edge.
The break is at the bottom of
tool. It is of the type that has a lower die shaped
like a "V"
block and an upper die that has a 90 degree "v" point.
upper die is pressed down on sheet metal it's bent into a 90
angle if the die is pressed home.
The tool comes with an 8
inch wide top
die installed, but also supplied are four narrow dies of
allows setting up the break to bend a number of different
The lower die is a bar with
groove on the top side and another "V" groove on the
The grooves are of different depths to accommodate
thickness. Swaged into this die are a couple of 8 mm
extend back to a "Guide" that has a couple of thumb screws
it to the rods. This allows setting the length and
squares of the
metal prior to bending.
- Cutting Printed Circuit Boards - I received an email
the 8MSB they received would not cut a 1/16" PCB out of
I'm guessing this particular unit got mis-aligned during
and/or has a number of surfaces that are painted instead
of smooth and
- Making Zero
Gauss Chambers (mini boxes made from Mu-Metal)
- Prototype sheet metal work
- Learning what can easily be done and what's impossible
In the above photo the top 8 inch die
has been repositioned to the left and a couple of the small
have been installed on the right. The hope was to have
setup, but for a mini box that's 1 x 1 x 3 3/4" it did not
After some bends you need to remove the top dies to get
out of the break.
I'm making drawings and printing them at 1:1. Taping the
onto the metal and cutting the metal to the drawing.
Do not use scissors or shears to cut the notches. It
the metal to get bent (not flat). Do use a nibbler which
bend the metal then with a vise and file clean up the
tried using the 18 Gauge Electric Metal Shear 92148
but the thin metal was very distorted after cutting.
very similar to the one I have.
Maybe after a lot of practice my precision will improve, but
some tolerance needs to be part of the design. Even
better is to
make one half of the box, measure it then make the other
drawing to fit
the existing part (selective assembly was the norm before
8" Digital Calipers (Harbor Freight 47260
handy for design and layout of parts for this shear break.
Each time you use the 8MSB for cutting anything, cycle the
blade up and
down to be sure that it moves freely and that the blades do
The stock 8MSB has paint runs on the top surface of the frame
and these will keep a 1/16" from being positioned in some
spots and may
keep it out all together. Sand paper will get rid of the
spots. Still working on a good way to do this without
apart the top cutting blade.
What goes Wrong
- Yesterday I received a replacement 8MSB and cycled the
cutting blade up and down with nothing in there and it worked
fine. Then tried to cut a 3 3/4" wide PCB, but it would
so used sandpaper to knock off the paint runs. Then cut
up with no problem (this done without bolting it down).
means that the first 8MSB was put out of alignment by my wife
as an anvil. The hammering on the top blade clamp did
to the blade alignment.
When I get the new drive pins for the old one I'll learn how
to do the
blade alignment. This also means that you should not use
or other spacers to widen the gap since they may not be stable
to maintain the blade alignment.
April 2006 - Tried to cut a
panelized printed circuit board but it would not cut. I
have the shear break bolted down and in the past was able to
printed circuit boards that were narrower. So tried
force, but you can't use much when the shear is not bolted
Then without hearing or feeling anything unusual the lower
moving. After taking it apart is was clear that both
had sheared. Harbor freight offered "used" parts,
i.e. taken off another mini shear break that was not sellable,
opted to get new pins which will take 6 to 8 weeks.
After more inspection the following problems are apparent:
- Many surfaces where metal parts are rubbing against
parts are painted on one or both surfaces. The paint
needs to be
removed and replaced by grease.
- Where metal parts rub against each other there are burs
to be filed down.
- The Drive pins (Item # 19) are a poor design. The
hole extends to the narrow neck area making the neck very
0.1365 inch diameter hole through a metal part that's only
leaves only a 0.071 inch thick wall for an area of
inches. If the tapped hole was a little less deep
the area at the
neck would be 0.062 square inches or 130 percent
addition to the difference in area, the hole also acts as
further weakening the part. The tip of the drive pin
should be a
sphere, but these look more like a couple of chamfers were
approximate a sphere. There are shiny metal spots on
the edges of
the flat part.
I expect that between the paint and burs the sliding lower
assembly jammed on one side causing it to rotate and jam
Rotation would also tend to break off the drive pins. My
using this as an anvil, pounding on the top blade clamp with a
hammer and may have knocked the blade out of alignment.
A new mini shear break has arrived and is not being taken
Harbor Freight will take orders for spars parts, but it takes
months to get them (so for nothing has arrived). Micro
stocks cutting blades but will not order any other spare
On a few occasions I've been able to make a nice cut, but the
not. You would think it would work on the 10 mil
(see below or brass).
Maybe there needs to be another adjustment or fix. So
Lower Blade (9) sits on top of the Lower Blade Body
(6) and they both
ride in an open channel on the front of the
base. Any slop
between the moving parts and the base will result in a
the lower blade.
Lathes have gibs to adjust this slop but here there
Maybe offsetting each end of the blade relative to the
lower blade body
is the adjustment method?
|The base (1) has the
Holder (14) and the gear box parts:
30 Driving gear
27 Gear Shaft (with hole for Handle (31)
in front of the gear shaft you can see the end of
22 transfer gear shaft
23 transfer gear is out of sight.
The two gears have the same number of teeth and serve
to change the
direction of rotation.
The far end of the main shaft (20) rides directly on
the casting in the
open hole at the left of this photo. In a
similar manner the near
end rides on the casting.
The left open channel for the lower blade body (6) and
lower blade (9)
can be seen at the left of the photo at the front.
These are pending more work on
unit. Coming about June 2006.
- removing paint that's between metal to metal moving
replacing it with grease.
- polishing the drive pin ends into shiny spheres and
- Confirming that the slide assembly moves smoothly up and
without binding and greasing it.
- Remove the top cutting blade and it's support bar and
all the paint on the top. This is the bottom of the
the printed circuit board needs to fit and if the paint is
too thick or
has a run a 1/16" PCB will not fit. So this is
mainly to be sure
the board fits cleanly.
- Clean off the old waxy grease from the drive gear teeth
replace with fresh grease.
I expect that the new replacement parts will also have the
Sample Sheet Metal Packs
On Line Metals - offers a number of "Metal" packages offered
catagory sample packages but these packages only have rod stock
various metals. But they also have sheet metal sample
offered under each metal.
These sheet metal sample packs contain 4" x 4" samples in
thicknesses. Many of them are too thick to cut with the 8"
but many will work just fine.
Not shown is a sheet of Nickel Silver also from OLM.
On the left are the T-304 #4 and T-304 #2B Stainless
and Copper packs and on the top right the A569 Hot rolled steel
bottom right the 4130 cold rolled steel.
For making motor brushes for the Weeden
and the Small
(similar to the Gilbert Toy Motor) I've got a roll
phosphor bronze that's spring tempered.
A 6" strip can be cut off the roll with heavy scissors then
using the 8" MSB. But first the top cutting blade needed
adjusted. The first try just folded the 0.010" thick
It also would not cut a 3x5" paper card.
Loosen the top front clamping hex screws and finger tighten
Raise the lower cutting blade so it's past the top blade cutting
edge. Loosen the adjusting lock nuts and run the hex
screws forward with a small torque and lock the nuts. It
cut 3x5" card stock at any location across the blade.
necessary to get good paper cutting.
Now it does a good job on 6" wide metal.
To order a 3" x 3" x 0.009" piece of phosphor bronze see
the Phosphor Bronze Brush Kit
These are the Enco 891-5590
Straight. Cut 12.5" Wiss Tin Snips
I have had other kinds in flavors like left cutting, right
straight cutting that had serrated teeth on the blades.
Cutco heavy duty kitchen shears can cut a penny, but they too
cutting blades that leave a rough edge on the cut metal.
shears were chosen to cut the phosphor bronze and brass sheet
most if not all these cuts are straight.
25 Sep 2008 - these will easily cut 1/16" PCB material for about
an inch per squeeze. So to separate a 2.5" x 3.8"
ExpressPCB Mini board into three boards each 2.5" long (i.e. the
are 2.5" long) takes a couple of squeezes from each side.
replaced by the 12" shear
Brooke's other Metal Working web pages
Shanghai SIEG Industrial Co.
Micro Mark - 7x12
- also made by SIEG but much enhanced
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