Made of bicycle parts, some hardware, and a blade, this hacksaw belongs in any workshop.

1. IDIN Build-it: Bicycle Hacksaw
GOALS:
o Participants will have used a hacksaw, a drill and several hand tools, including a file,
and hammer, and a punch. Participants will also learn some basic welding.
o Participants will know how to properly use and tension a hacksaw
o Participants have made a working hacksaw
TIME:
1.5 hours
PREPARATION:
Collect materials and tools
Make sure to have enough materials and tools for your demonstration
Review and/or print Build-It instructions
Make a hacksaw yourself to discover what participants might find difficult
Organize the tools into sets to be distributed during the introduction
ROOM SET-UP:
This should be done in a workshop that is equipped with table space, vices, and welding
equipment. It would be useful to also have an open space where the instructor can
demonstrate steps to participants.

2. TOOLS MATERIALS
Item Amount Cost
Hacksaw Bicycle handlebar 1 $5
Vice Bicycle caliper 1 $3
Marker pen A large hex nut 1 minimal
Hand files
round and flat)
Threaded rod and
its hex nut
(between 2mm and
6mm wide)
150 mm
long
$1
2 pairs of pliers Hacksaw blade 1 $1
Spanners for
brake hardware
Total Cost $10
Hammer and
anvil
Punch
Welding
machine
Drill and bits

3. 1. What is a Build-It? (5 min)
A Build-It is a lesson where people make a small technology and learn some workshop skills.
Everyone will build together, step by step. As you build the technology, you will learn good
techniques for handling metal and wood. Each member will have an opportunity to learn these
hands-on skills by using some tools and materials. At the end of the Build-It, you will have had
some practice using tools and also have a technology for you to take home.
2. What is a bicycle hacksaw? (10 min)
Hacksaws are an important tool in any workshop. Today, you are not only going to use a
hacksaw, but you will build one. This project is building a hacksaw frame out of parts from a
bicycle handlebar and a bicycle caliper. It is made of two welded pieces from the metal
handlebars, two sections from a bicycle caliper, a threaded rod, a hacksaw blade, and some nuts
and bolts.
Review how the technology works by explaining how to use it and what the major parts are.
3. Setting up the Build-It (5 min)
ENCOURAGE PARTICIPANTS TO ENGAGE FULLY
• Ask, “Why?” “Where?” “What?” “How?” at any time during the session
• Engage everyone in the building activities and be sure that each person in the group can both
observe and participate in learning and doing all of the different techniques
(IF WORKING IN PAIRS/TEAMS OR STATIONS)
DIVIDE INTO PAIRS AND/OR INTRODUCE THE STATIONS
If working in teams, single-gender pairings often work best for allowing all members of the group
to participate evenly. Explain which tools need to be shared by the larger group, and where they
will be located.

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4. Preparing the hacksaw body (10 min)
Start with a bicycle handlebar. The hacksaw must be bent in only one plane, so the
handlebar must be cut so that it can be welded as a flat piece.
Tools Materials
Steps
1. Mark the handlebar before the curve of
the handle (as shown in the photo).
The long piece should only curve
downwards, in one direction.
2. Put the handlebar in a vice and cut the
handlebar in the desired places using a
hacksaw.
Be careful not to tighten the vise too
tight or you risk deforming the tube.
You now have three metal tubes. The long metal tube will be the body of the hacksaw
and one of the shorter tubes will be used as the hacksaw handle.
The second shorter tube is not required to build the hacksaw. However, it is useful to
keep hold of it so that if the first tube is damaged, you still have a spare to work with.
It also can be used to extend the body of the hacksaw if that variant of the hacksaw is
built.
3. Shorten the short tube to create the
handle.
The cut must be made so that the tube is
the correct length to allow the handle to
lie perpendicular to the alignment of the
hacksaw blade (see the picture in Step 5
to see what you are making).

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4. Using a hand file, smooth the sharp
edges of the cut tubes and shape the end
you just cut so that it fits with minimal
gaps.
5. You can now lay out the pieces to see the
hacksaw taking shape.
The spaces above the blade is where
sections of the caliper arm will go to
tension it.
5. Preparing the blade tensioner (20 min)
Tools Materials
Steps
Disassemble the caliper
1. Remove the nuts and bolts from the
caliper using a spanner.
2. Pull off the spring from the caliper using
pliers.
You should now be able to take the
caliper apart.
Preparing the front end tensioner
3. Take the Y-shaped caliper arm and align
it with the hacksaw handle. Once it’s in
place, draw a line about ½ to 1 inch
above the tip of the hacksaw frame so
that you know where to cut the caliper.
The caliper arm should be aligned so
that it matches the curve of the main bar.
The brake caliper and its
components
The two
caliper arms
and the spring

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4. Put the caliper arm in a vice and use a
hacksaw to cut it.
It may be easier to cut if it is positioned
vertically.
5. Flatten the end of the frame bar so that
the stirrup section can fit closely into the
bar, and be easily welded later.
You can flatten the end of the bar using
either a hammer or by squeezing the bar
gently using a vise.
6. Cut down the edges of the caliper arm so
that it can fit into the flattened tube.
Hacksaw the pointed sections off, and
then file until it fits closely in the bar.
Continuously check the fit between each
hacksawing and filing. These two parts
will be welded later.
The caliper arm section in
the flattened bar (after
hacksawing and filing the
edges of the arm section)

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There are a few variations of how to make a rear tensioner, each using different
parts of the bike.
Caliper version Brake handle version
(This Build-It) (another version)
Preparing the back end tensioner
7. Take the U-shaped caliper arm to make
the holder for the other end of the blade.
The section of the arm with the two holes
will be used to create a pivoting arm that
can hold the blade in place and be used
to keep the blade under tension.
8. First, flatten the end of the arm with a
hammer and an anvil.
9. Next, saw off the end of the arm which is
not required.
Tensioning system, as shown in
this Build-It using a caliper arm
Tensioning system, not shown in this Build-
It using a brake handle. This tensioning
system, discovered later, seems to be a
more robust design.
The
threaded
rod screws
onto this
nut
The threaded rod does
NOT screw into this
large nut. The rod
pushes against this
nut welded on the
caliper, which
tensions the blade
This is
pinned so
the arm
can pivot
The
threaded
rod screws
onto this
nut
The threaded rod
pushes against the
handle, which
tensions the blade.
This is
pinned so
the arm
can pivot
The parts in position so far

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10. Finally, use a file to smooth the edges of
the arm section so that it will be able to
move around smoothly inside the bar.
This will be done most easily if the arm
is held in a vise.
11. Like previously, you need to flatten the
other end of the main arm so that the
caliper arm section can fit inside the arm
and pivot freely.
Once the arm is flattened, check that the
caliper section fits, and file it more if
required.
6. Assembling the frame and tensioning system (20 min)
Tools Materials
Attaching the front end tensioner
1. Use a grinder or a file to grind the bar’s
chrome coating away in the areas where
you want to weld
You want to remove the chrome as it
gives off unpleasant gases if heated.
2. Weld the front caliper arm onto the main
bar
Tack in one place first, then check to
ensure it is in one plane
3. Weld the handle onto the main bar.
Again, tack it first, and keep checking
the alignment while you weld

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Fastening the blade
4. To fasten the blade, cut the two rings
from the spring using a hacksaw.
Put the put the spring in a vice, and
spread the spring open slightly to give
space to cut (however be careful as the
metal is a fairly high strength and would
be easy to break or deform).
Attaching the back end tensioner
5. Drill into the end of the main bar for a
bolt to attach the caliper arm and allow it
to pivot. Work out where the hole
should be and use a punch to create an
indentation in the correct position.
This indentation helps to position the
drill in the correct position.
6. Take the long screw from the section of
caliper parts and cut it in half to create
the pivot screw.
First, screw two bolts onto its middle.
Separate them slightly to expose the
middle of the bolt. Cut between the nuts
with a hacksaw to cut the bolt in half.
Having the nuts help guide the hacksaw
will prevent the bolt threads from getting
damaged.
Using the punch (note the position
of the hole in the main bar)

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7. Use a file to smooth the top of the cut
screw
7. Making the tensioning arm (20 min)
Tools Materials
Drill two holes in the hacksaw body to allow the tensioning rod to pass through. This
needs to be done very carefully.
1. Line up the filed rod with the hacksaw
body and mark the position of the holes
2. Mark the top hole with a punch, and then
drill it to ¼ inch.
3. Tilt the drill to make the hole oval, so
that the rod can slide through the hole at
the necessary angle.
4. Remove the blade and mark the position
of bottom hole with the punch.

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5. Like before, drill the hole with the ¼
inch bit, and then tilt drill to make it
oval.
6. Enlarge the top hole to ½ inch by
repeating the process with a ½ inch bit.
7. Put the small nut onto the threaded rod
and put the rod through the holes. It
should be placed where it will finally be.
8. Tack the small nut onto the main frame
of the hacksaw, by the bottom hole.
Once it is tacked, remove the threaded
rod and continue welding.
9. Put the threaded rod back on and weld
the large nut onto the caliper arm so that
the threaded rod rests inside.
If you would like, weld a washer onto the
threaded rod to make it easier to tension
the hacksaw.
Build-Its are published by IDIN. The
International Development Innovation
Network (IDIN) is a consortium funded
through USAID’s Higher Education
Solutions Network (HESN) that supports leading
universities to catalyze the development and
application of innovative science, technology,
and engineering approaches and tools to solve
some of the world’s most challenging
development problems.
The bicycle hacksaw featured here was designed created by Bernard Kiwia, an appropriate technology
teacher in Tanzania. The document was created by Benji Moncivaiz in collaboration with IDIN
representatives at UC-Davis and Olin College.
The two holes – note how the top hole
is larger than the bottom hole.