Side LED Light Bar Prusa i3 MK3

Side light bar for the Prusa i3 MK3/S/+. Attaches to the x-axis motor. Fits 9x17mm aluminum u-channel. Wire routes out the back and through the x-axis motor wire sleeve into the electronics box. Includes an opening to insert a power switch. The LED strip can be powered by the printer 24V power supply.

See below for assembly instructions.

This is the side light bar. Click below for my other light bar versions.

MK4 Light Bar

MK2/MK3 Dual Light
MK2/MK3 Dual MMU2 Light
MK2/MK3 Single Light
MK2/MK3 Bear Upgrade

MINI Light Bar
 

Files:
Side Light Bar: Standard version with power switch.

Side Light Bar - No Switch: Same as the standard version with no hole for power switch. Either use an external switch, connect to top mount light bar, or always have the light on with the printer.

Print instructions

Recommended Print Settings:
Print Settings: 0.20mm QUALITY
Layer Height: 0.20mm
Infill: 15% Gyroid
Supports: None
Open 3MF files in PrusaSlicer for preconfigured settings

Required hardware:
Aluminum u-channel (9x17mm)
24V LED strip
22 AWG Wire
Power switch (KCD11 10x15mm)
Qty: 1 - Thin M3 Square Nut (1.8mm thickness)
Screws:
Qty: 1 - M3 X 18mm Cap Head Screw
Qty: 1 - M3 X 5mm Countersunk Screws (Part is designed for countersunk screws but can also be replaced with M3x8 Cap Head screw)

Optional hardware:
Heat shrink tubing
Fork terminals

Hardware Kit
 

Purchase a hardware kit from my Etsy store at the link above.

Tools:
Wire stripper
Soldering tools
Hacksaw
2mm Hex key
2.5mm Hex key
Metal file (optional)
Wire crimper (optional)

Assembly Instructions

If you purchased a pre-assembled kit, scroll to the bottom for instructions on how to install and connect to power.

Cut Material to Length

If you purchased a hardware kit you can skip these steps as all material comes cut to the correct length.

1. Cut the u-channel to 68mm and and check that it slides into the housing. Use a metal file to round off any sharp edges to make it slide in easier.

2. Cut the LED strip at the designated cutting areas to fit the u-channel.

3. Cut the wire to 106cm (42").

Side light bar kit

Wiring diagram

Inserting Wire

1. Insert the red and black wire through the small hole in the back of the housing and out the switch hole. Insert the wire back through the switch hole and through to the front LED slot. Leave a small loop of wire sticking out the switch hole.

2. Feed the wire through until there is 5cm (2") of wire sticking out the front LED slot.

Wire inserted

Power Switch Wiring

1. Cut the red wire for the power switch. Be careful when cutting not to also cut through the back wire insulation. Pull back the red wire and strip off the ends.

2. Solder the power switch to the red wires. Verify switch orientation with picture below. If using heat shrink, place it over the wires before soldering the power switch. For best soldering results, tin the wires and switch terminals with solder first, then join together.

3. Insert the power switch into the opening. Pull the wire on either end to remove any slack. The power switch needs to be 10x15mm to fit in the provided opening.

Cut wire for switch

Solder switch

Heat Shrink

Insert switch

LED Strip Wiring

1. Cut the wire so that there is about 4cm (1.5") sticking out the end of the housing and strip about 5mm (~1/4") off the ends of the wires.

2. Solder the wires to the LED, red to + and black to -. For best soldering results, tin the LED pads and wires with solder first, then join together.

3. IMPORTANT: Make sure that the solder/wires are NOT touching the solder joints on the individual LED chip closest to the end and are only touching the designated solder pads on the strip. If the wire is touching the solder joints on the LED chip, once power is applied this could blow that single LED chip causing the whole segment to stop working.

4. Put the heat shrink in place and apply heat.

5. Remove the adhesive backing from the LED strip and stick it to the inside of the u-channel.

6. Attach the frosted cover to the u-channel and insert into the light bar housing. Fold the wire for easier insertion.

7. Insert the square nut into the slot in the printed cap and put it in place. Secure it with the countersunk screw. You can also use an M3 cap head screw up to 8mm here if you don't have countersunk screws. 

Strip LED wire

Solder LED strip

Heat shrink

Fold wire for easier insertion

Front LED installed

Cap

Countersunk Screw

Cap Head Screw (Fits up to 8mm)

Final Assembly

1. Determine where you are going to connect the wires to power and review the following options.

1a. If powering from the screw terminals in the electronics box (Power Option 1 below), proceed through steps 2-8.

1b. If powering from a top mount light bar (Power Option 2 below), skip steps 2-8 for now and proceed to the Power Option 2 section below.

2. Cut the wire sticking out the back of the housing to 60cm (23)" from the point it leaves the rear of the housing to the tip of the wire. If needed, temporarily install on the printer to verify the correct length.

3. Strip about 5mm (~1/4") off the ends of the wires.

4. Using a crimping tool, attach the fork terminals to the wires. 

5. Install the light bar onto the x-axis motor using the M3 x 18mm screw.

6. Partially loosen the 2 screws holding the electronics box to the frame. Pull the box to the side to release it from the screws.

7. Cut the zip tie from the x-axis motor wire sleeve and insert the wire into the sleeve all the way inside the electronics box. Reinstall a zip tie if desired.

8. Reinstall the electronics box and tighten the 2 screws. Make sure no wires are being pinched.

Strip power wires

Fork terminals

Completed assembly

Installed on printer

Wire run

Loosen top screw                                                                                  Photo Credit: Prusa Research

Loosen bottom screw                                                                           Photo Credit: Prusa Research

Release box from screws, feed wire through sleeve                         Photo Credit: Prusa Research

Power Connection

Power Option 1: Printer Power Supply

To power the LED strip with the MK3 printer power supply, connect the red and black wires to the first and second screw terminals respectively on the EINSY board.

1. Undo the screw terminals enough to insert the power and ground wires, stacking them with the wires coming from the printer power supply. 

2. Once in place, tighten the screw terminals snug.

3. Tug gently on the wires to ensure that they are secure.

NOTE: You can also use the third and fourth screws if you are already doubled up on the first pair from either the MMU2 or top mount light bar. Do NOT use the screws furthest to the right, those connect to the heat bed.

MK3 power supply connection                                                            Photo Credit: Prusa Research

Stack fork terminals                                                                             Photo Credit: Prusa Research

Power Option 2: Top Mount Light Bar

If you are using one of my top dual mount MK3 light bars, it is also possible to power the side light bar from the top light bar. The wires will connect to the tail end of the rear LED strip. This will mean that the power switch on the top light bar will also control the side light bar.

1. Feed the wire from the side light bar into the small hole on the left mount of the top light bar. Put a curl on the end of the wire to help direct it toward the rear opening of the mount. Use a smaller pull wire if you have trouble feeding it through.

NOTE: Earlier versions of the top mount light bars did not have a passageway to the rear opening of the mount. Print one of the newer versions if yours does not have this.

2. Feed the wire through the opening until there is approximately 64cm (25") from the point where the wire enters the side light bar to the point where it enters the top light bar. This is the distance of wire needed to route down to the electronics box and back up to the x-axis motor to attach the side light bar.

3. Cut any excess wire off the end sticking out the rear opening of the top mount. Strip about 5mm (~1/4") off the ends of the wires.

4. Place heat shrink on LED strip and solder the wires to the rear LED strip, red to + and black to -.

5. Apply heat to heat shrink.

6. Insert the rear u-channel into the mount to re-assemble top light bar.

7. Complete steps 5-8 from the Final Assembly section above.

8. Connect your combined top and side light bar to power using the steps in Power Option 1 above.

Wiring Diagram

Feed wire into top mount

Use pull wire if needed

Completed Assembly