Bill of Materials (BOM)
Carefully read the specifications to order the correct component.
Hardware
| Component | Qty | Qty for Double Chain Axe | Specification | Where to Buy |
|---|---|---|---|---|
| Hex socket screw set | 1 set | 1 set | M3 / M4 / M5 assortment, stainless steel | AliExpress · Amazon |
| Countersunk screws | 2 pcs | 4 pcs | M3 × 5mm, flat head, stainless | AliExpress · Amazon |
| Hexagon Socket Allen screw | 2 pcs | 4 pcs | M4 5mm It’s often available as a spare part for printers (check before buying—you may already have them). It’s used to secure the heat break as well as pulleys on shafts. | AliExpress |
| Bearing | 5 pcs | 10 pcs | 4 × 12 × 4 mm 604ZZ | AliExpress |
| Spring | 1 pc | 2 pcs | 0.6mm wire, 40mm length, 6mm OD | AliExpress |
| Aluminum tube | 1 pc | 1 pc | 35mm OD × 32mm ID × 700mm length Can substitute fiberglass, carbon fiber, PVC, or steel (heavier). Usually cheaper at local hardware stores. | Amazon |
| M4×20 screw | 0 | 20 pcs | M4 × 20mm The standard hex socket screw set does not include enough M4×20 screws for the Double Chain Axe build — purchase these separately. | AliExpress |
Battery Compartment
| Component | Qty | Specification | Where to Buy |
|---|---|---|---|
| AWG wire | 5 m | 26 AWG wire (black + white) | AliExpress |
| Battery Shrapnel | 2 pcs | Battery contacts | AliExpress |
| Battery Holder | 3 | Battery Holder for 3 x 1.5V AAA | AliExpress |
Main electronics
| Component | Qty | Qty for Double Chain Axe | Specification | Where to Buy |
|---|---|---|---|---|
| Motor | 1 pc | 2 pcs | JGA25-370 12V 399 or 620 RPM | AliExpress |
| Speakers (pair) | 2 pcs | 2 pcs | 40mm, 5W, 4Ω | AliExpress |
| Switch ON-OFF | 1 pc | 1 pc | MTS-102 | AliExpress |
| Tactile button | 2 pcs | 2 pcs | 6×6×6mm | AliExpress |
| MP3 player board | 1 pc | 1 pc | DY-HV20T | AliExpress |
| MOSFET | 1 pc | 1 pc | FR120N | AliExpress |
| Resistor | 1 pc | 1 pc | 1kΩ | AliExpress |
| Micro SD card | 1 pc | 1 pc | Any size — stores audio files | — |
Printing
All parts are designed to print without supports — where supports are needed, they are already integrated into the model and will need to be removed during assembly (more on this in the Assembly section).
A ready-to-print Bambu Lab project file is provided with all parts pre-arranged on build plates. Each plate is named after the assembly it belongs to: Handle, Blade, Body, etc. The parts are already oriented in the correct printing position — just slice and print.
Print Settings
Minimum settings for all parts: 2 walls, 10% infill.
Exception — Chainax_Body part: print with minimum 3 walls and 30% infill. This part bears higher mechanical loads from the motor and gearbox.
Material
Any common filament will work: PLA, PETG, or ABS. There is no significant difference in performance for this project — choose whatever you are most comfortable printing with.
You’ll need at least 2 kg of filament for printing; it’s better to take extra in case of defects.
Where more than one copy of a part is needed, the quantity is indicated in the file name.
⚠ CHAIN ELEMENT COUNT
Demon Axe style: 37 chain elements
Viking Axe style: 38 chain elements
Prepare these parts before assembly.
For a better understanding of the next three steps of soldering the wires, I will provide the final wiring diagram of the entire electronics setup.
Speakers
You will need approximately 20 cm of wire and a short 5 cm jumper wire. The speakers must be connected in series, since the amplifier is designed for 8Ω impedance and each speaker is rated at 4Ω. Wiring them in series gives the required 8Ω total. If you find 8Ω speakers of the same size, you can connect them in parallel instead.
Prepare these parts before assembly.
Motor wiring
You will need approximately 40 cm of wire for the motor connection. Solder the black wire to the motor terminal marked with a red dot — this ensures correct polarity. If the chain rotates in the wrong direction after assembly, simply swap the two wires either at the motor terminals or at the FR120N board.
Trigger buttons
You will need two wires: one 24 cm and one 50 cm. If you only want a single trigger, you need only the 50 cm wire. Solder the wires to the buttons in sequence.
Battery Compartment Assembly
The battery compartment holds nine 9 AAA batteries in series (9-13.5V). All parts for this section should already be 3D-printed. You will need a soldering iron, 22AWG dual wire (red + black), heat shrink tubing, on/off switch and a hot glue gun (optional).
To enlarge the images in the instructions, simply click on them.
01 Install the positive contact
Take the positive (+) battery contact and insert it into the 3D-printed battery compartment body with the convex side facing inward (toward where the battery will sit). Push it all the way in until it seats firmly.
02 Install the negative contact
Take the negative (−) spring contact. Insert it with the spring side facing inward (toward the battery). Push it firmly into its mounting slot until fully seated.
03 Prepare the power wire with switch
Take a dual wire (red + black), 115 cm long, 22AWG (you can also use 20AWG or 18AWG — but not thicker). On one end, cut the black wire only, leaving a 150 mm offset from the end. Slide heat shrink tubing onto both cut ends of the black wire before soldering.
Solder the power switch into the break in the black wire: one lead to the center terminal, the other to either side terminal (left or right — doesn't matter, both will work as on/off). Once soldered, slide the heat shrink tubing over the joints and shrink it with a heat gun or lighter.
04 Route the positive wire
On the other end of the dual wire, separate the red and black wires. Take the red (positive) wire and thread it through the compartment body as shown in the photo — first through the larger rectangular channel, then through the small hole, routing it along the full length of the battery compartment. Strip the tip and solder it to the positive contact. Then lay the wire flat into the built-in cable channel.
05 Connect the negative wire
Lay the wire out straight to determine the correct length. Trim the excess black (negative) wire, leaving about 10 mm of stripped wire to solder. Thread it through the rectangular channel (same as the red wire) and solder it to the negative contact.
06 Secure with hot glue (optional)
For extra reliability, fill the rectangular wire channel with hot glue. This serves two purposes: it insulates the solder joints and prevents the wires from being pulled loose during handling.Lay the wire out straight to determine the correct length.
Caution: Make sure the hot glue does not flow into the battery compartment itself. If glue reaches the spring contacts, it can interfere with battery contact and affect the circuit. Keep the glue contained within the wire channel only.
Parts Assembly
I also have an assembly video; some steps are outdated, but it may help you with the build. Youtube video
Gearbox Assembly
The gearbox is the mechanical heart of the chainaxe — it transfers motor power to the chain. Take your time with this section and make sure all gears spin freely before moving on.
01 Prepare the gears
Remove any support material or debris from the bearing seats on each gear. The bearing pockets must be clean for the bearings to seat properly.
02 Install the bearings
Press the bearings into each gear — two bearings per gear, one on each side. If they don't slide in easily, use a flat surface or a clamp to press them in evenly. Do not hammer them — apply steady, even pressure. Total: 4 bearings across 2 gears.
03 Attach the small gear to the motor
Look at the motor shaft — you will see a flat section (a "D-cut" or flat). The small gear has a matching flat inside its bore. Align the flat on the shaft with the flat inside the gear and press the gear all the way down onto the shaft. The gear also has two holes on its face — insert M4 grub screws into these holes and tighten them fully. This locks the gear to the shaft.
04 Mount the motor to the body
Insert the screw with threadlocker and fasten the motor to the body. On the opposite side, there is a window for the second mounting screw — insert the screw through this window. There is also an access hole in the body to reach it with an Allen key. Tighten the second screw through this hole.
05 Install the M4 nuts
Insert two M4 press-fit nuts into the dedicated slots on the body. Push them in firmly until they sit flush.
06 Install the large gears
Place the two gears into their slots on the body, oriented as shown in the photo. Insert the screws M4x20 through the gears and into the M4 nuts, then tighten.
Do not overtighten. Check that all gears spin freely by hand. They will feel slightly stiff because you are also turning the motor through the gear train — this is normal. But they must be able to rotate when turned by hand.
07 Install additional nuts for the cover
On the body, there are two additional slots for M4 nuts, one on each side. Press the nuts into these slots until the thread is visible through the screw hole. These will be used later to secure the gearbox cover.
Tensioner Assembly
01 Install the bearing into the tensioner gear
Press the bearing into the tensioner gear. Push it all the way in until it is fully seated.
02 Insert the M4 nut into the tensioner body
Take the tensioner body and press an M4 nut into the dedicated slot. Push it in until the thread is visible through the hole on the other side.
03 Insert the M4 nut into the tensioner tip
Insert a second M4 nut into the slot at the end (tip) of the tensioner body.
04 Mount the gear onto the tensioner
Place the gear with the bearing onto the rotation axis of the tensioner. Apply threadlocker to an M4x20 screw and drive it through the gear into the tensioner axis, as shown in the photo. Do not overtighten — the gear must spin freely on the bearing.
Blade Assembly
This section has style-specific steps. Follow the instructions for your blade style, then continue with the common steps at the end.
— DEMON AXE STYLE —
01 Route the motor wires
Thread the motor wires through the hole at the bottom of the blade.
02 Insert the gearbox
Insert the gearbox into the blade from the top, aligning the mounting holes on the gearbox with the holes on the blade. Be careful not to pinch the motor wires where the motor enters the hole — gently pull the wires through from below as you push the gearbox in.
03 Secure the gearbox
Fasten the gearbox to the blade with two M4x8 screws.
04 Route the motor cable
Push the motor wire into the cable channel inside the blade. Thread it all the way through and pull it out the other end completely. Tuck the wire neatly into the channel so it does not hang loose.
05 Install decorative overlays
Insert two M4 nuts into the slots on one side of the blade, and two more M4 nuts into the slots on the opposite side. Attach the rear decorative overlay with two M4x20 screws. Attach the front decorative overlay with two M4x20 screws.
— Viking AXE STYLE —
01 Insert the gearbox
Insert the gearbox from the bottom side of the blade, aligning the mounting holes on the gearbox with the holes on the blade.
02 Secure the gearbox
Fasten the gearbox to the blade with four M4x8 screws.
03 Prepare the wolf head overlay
The wolf teeth are printed as separate pieces for better print quality. Glue the teeth onto the wolf head first. You can then glue the completed wolf head onto the blade now, or leave it for later — it is easier to paint the blade and the wolf head separately before gluing them together.
— ALL STYLES — COMMON STEPS —
06 Install nuts in the upper blade half
Insert three M4 nuts into the upper blade half. Push them in until the thread is visible through the screw holes.
07 Install nuts in the lower blade half
Insert two M4 nuts into the lower blade half, pushing them in fully.
08 Install the tensioner nut
Inside the lower blade half, there is a slot for an M4 nut that secures the tensioner. Insert the M4 nut and tighten it fully.
09 Install the tensioner
Insert the tensioner assembly into the lower blade half, pushing it all the way in.
10 Install the tensioner spring
Thread an M4x8 screw through the spring, then guide the spring end into the mounting hole on the tensioner. Begin tightening the screw, but do not tighten it fully yet — you need to redirect the spring inward first by rotating it into position. Once the spring is turned inward, align the spring loop with the spring mounting hole in the blade body.
Insert an M4x16 screw through the hole and the spring loop, then begin tightening. If the spring starts to bend or shift, hold it in place with your finger while tightening. Tighten both screws fully so the spring sits straight, as shown in the photo.
11 Join the blade halves
Bring the upper and lower blade halves together, aligning them carefully. Secure with two M4x20 screws — one at the front and one at the rear of the blade.
The blade assembly is now complete and ready for installation onto the handle.
Handle Assembly
Use slow-drying glue for all gluing steps in this section — this gives you time to adjust parts and disassemble if needed.
01 Remove integrated supports
Remove the built-in print supports from the button slots on the handle parts. Use flush cutters or simply snap them off by hand. One of the handle parts also has supports for the decorative elements — remove one from each side.
02 Install the first trigger button
Thread the button wire through the inside of the first handle part so that the second button (if you are building the two-button option) comes out the other end. Press the button into its slot. You can use a screwdriver to push it in, or use flush cutters — gently squeeze from both sides to press the button evenly into the slot. Be careful not to cut the button itself.
03 Route the wire and join the second handle part
Inside the first handle part, lay the wire into the cable channel. Apply glue to the second handle part and carefully fit it onto the first part. Thread the second button through the opening — there is a small window to guide the button into position. Press the second button into its slot.
04 Route the cable with the tube
Push the wire into the cable channel. If the wire is difficult to route, use the aluminum tube to help — gently insert the tube into the handle and use its edge to nudge the wire into the channel.
05 Install the lower trigger
Insert the lower trigger piece into its slot, then push the tube further in. The tube will lock the button in place.
06 Attach the third handle part
Apply glue to the third handle part and fit it onto the second part. After this, you can push the tube all the way in.
07 Install M3 nuts
Insert four M3 nuts into the slots around the first handle part — one in each slot around the perimeter. Push them in until seated.
08 Install the upper trigger
Take the upper trigger piece. There is a small window in the trigger where the button wire needs to pass through — thread the wire through it. Once threaded, position the button in its slot as shown in the photo.
09 Attach the final handle part
Take the last handle part and route the button wire through its cable channel. Slide this part onto the tube. Align the flat on the tube with the corresponding flat on both the last handle part and the first handle part so they match up. Push the parts together and secure with four M3x8 screws around the perimeter of the handle.
The photo shows the fully assembled handle.
Note: The handle assembly for the Viking axe style is identical.
Main Body Assembly
01 Prepare the speaker housing
Take the speaker housing. Insert an M4 nut into the bottom slot and press it in until the thread is visible through the hole. Insert two more M4 nuts into the edge slots, one on each side, and press them in fully.
02 Install the speakers
Place the speakers into the housing with the wires facing upward. Insert the locking wedge and secure it with one M4x20 screw.
03 Attach the speaker housing to the main body
Thread the speaker wires through the holes in the main body. Attach the speaker housing to the main body using M4x20 screws. Note that the holes are not symmetrical — if they do not line up, rotate the speaker housing 180 degrees.
04 Install M4 nuts in the main body
Insert two M4 nuts into the slots on the top side of the main body. Flip the body over and insert two more M4 nuts into the slots on the bottom side. Press all nuts in fully.
05 Install M5 nuts along the tube opening
Insert four M5 nuts along the rounded slot on the main body, as shown in the photo. These will secure the tube brackets later.
06 Install the display (if applicable)
If your build option includes a display, thread the display cable through the window in the body and seat the display into its dedicated slot.
07 Install the handle into the main body
Thread the button wire from the handle through the cable channel inside the main body. Pull the wire out through the small window at the end of the body — use tweezers or your fingers to grab the wire end. Then push the tube with the handle all the way in.
Main Body Assembly — Double Chain Axe
The assembly process is very similar to the single-blade version, with a few differences specific to the dual-blade configuration.
The trigger button cable channel is rotated 90 degrees compared to the single-blade version, because the handle itself is rotated 90 degrees in this setup.
Thread the trigger button wire through the cable channel and pull it out from the other side. When inserting the handle tube into the main body, gradually pull the wire through at the same time — this prevents the wire from getting pinched between the handle and the body.
The rest of the assembly follows the same steps as the single-blade version.
08 Secure the handle
Fasten the handle to the body with four M4x20 screws around the handle flange, as shown in the photo.
09 Prepare the tube brackets
Take the two tube brackets. Insert two M3 nuts into each bracket
10 Install the tube brackets
Place the brackets onto the tube with the nut holes facing toward the speaker housing. Secure the brackets with M5x20 screws. Tighten the screws gradually, alternating between left and right — a little on the left, a little on the right, back to the left, back to the right. Do not fully tighten one side first, as this will cause the brackets to sit unevenly.
Blade Assembly
Install the chain
Insert the assembled chain elements into the blade guide, teeth facing outward. Push the chain forward until it reaches about halfway around the blade.
Then tilt the axe with the blade pointing downward at a slight angle to the horizon — this lets gravity pull the chain along the guide rails. Keep pushing until the chain comes out and advances along the lower part of the guide. Once it emerges, use your hand to pull it the rest of the way around to the bottom edge of the blade.
To close the chain loop, press it against the tensioner to create enough slack, then connect the two ends by snapping the chain links together. Press firmly on the link until it clicks into place.
Install the blade
Thread the motor wire through the main body so it comes out the other side. Seat the blade into the body and secure it with four M4x20 screws — two on each side.
Install the Dual blade
The Double Chain Axe assembly is almost identical to the single-blade version, but you will need to install two blades.
Thread the motor wire of the first blade through the cable channel in the main body. Reach inside the body to grab the wire end and pull it through. Seat the first blade into the body and secure it with four M4×20 screws — two on each side.
Repeat the same procedure for the second blade
MP3 Setup Wiring
01 Place boards on board holder
Secure the DY-HV20T MP3 board board to the mounting bracket using four M3×8 screws. Simply insert the FR120N board into the slot above the MP3 board.
02 Configure the MP3 board switches
On the DY-HV20T MP3 board, set the DIP switches to the following positions:
- Switch 1: OFF
- Switch 2: ON
- Switch 3: OFF
Refer to the photo for the correct switch positions.
Audio files
To make the MP3 board work, write the following files to the Micro SD card: WAV 01 — Download WAV 02 — Download
03 Place board holder into main body
Install the board holder with the boards into the main body and secure it with M3×16 screws.
04 Connect all wiring
Solder all wires according to the wiring diagram shown below. For the Double Chain Axe build, simply solder the second motor wires to the same contacts as the first motor — both motors run in parallel from a single output. Double-check each connection before powering on.
05 Prepare the SD card and insert the board
Write the audio files to the Micro SD card, insert the card into the DY-HV20T board
Basic operation
01 Insert batteries and power on
Take three standard AA battery holders. Insert the batteries with the negative (−) end on the spring and the positive (+) end on the flat contact — the same way you would insert batteries into any device. Assemble three holders with three batteries each.
Insert the battery holders into the battery compartment as shown in the photo, with the spring (positive) side facing toward the positive (+) contact of the compartment. Insert all three, then slide the battery compartment into the handle and secure the end cap.
02 Test the device
Turn on the device using the power switch shown in the photo. You can now control the motor by pressing either the upper or lower trigger button — both will activate the chain. If you built the single-button option, only the upper trigger will function.
Painting
This section is currently under development. A more detailed painting guide may be added in the future. Below are the key points to keep in mind when painting your axe.
⚠ Important — protect moving parts
Do not apply primer or paint to the chain, chain guides, or any moving surfaces. Paint is a sticky substance — if it gets on the guide rails, the chain will stick or rotate poorly due to increased friction between the links. This can lead to motor overheating and potential electronics failure.
Before painting, cover all internal surfaces and guide rails with masking tape. If paint accidentally gets on the guides or chain, make sure to thoroughly clean it off. The chain must rotate freely and slide along the guides without resistance.
Painting the chain
Paint the chain elements either separately before installation, or very carefully while installed — making sure that primer and paint do not get inside the links where they slide against each other.
Surface preparation
Sand the plastic surface before painting to improve adhesion. You can then apply a filler primer or automotive putty to smooth out layer lines.
An excellent alternative for smoothing print layers is UV resin. Apply a thin coat of photopolymer resin to the surface, then gently heat it with a heat gun or torch to remove air bubbles. Cure it under a UV lamp. Sand away any drips or uneven spots, then apply primer followed by paint.
Paint options
You can use acrylic craft paints or automotive spray paints. I typically use FolkArt acrylic paints — they come in larger bottles compared to modeling paints, making them a good option in terms of both price and quality. Spray cans also work well, especially for base coats and large surfaces.
Always apply primer before painting, regardless of which paint type you choose.