June 3, 2026
Description
Easy, convenient, and FAST filament loading for your Genuine Prusa XL! Just insert the filament into the sensor and past the loading gears then press the associated paddle to simultaneously provide clamping force on the filament and trigger the power switch! Installs quickly and easily, without any need to change the OEM sensor set up! No more slowly pushing filament a couple inches at a time. No more having to figure out the correct orientation, lining up the teeth on the Bowden Speed Loader, and holding steady while loading.
Although I did have a lot of requests for this, it wasn't until I came up with a way to have one motor, battery, switch, and gear for all three filaments, on the side of the XL, in a way that will fit on the side, that I decided to start working on it. I also wanted to use as many of the same parts from the Bowden Speed Loader as possible. Unfortunately, there are still many new parts to get.
The design goals for this project changed over time, but my main priority was to avoid having to change the OEM hardware in any significant way. This also included being able to install and remove it without dismantling, even unplugging, the filament sensors. Since it was to be battery powered, the battery needed to be easy to change in situ. It also had to be securely mounted to the frame of the XL. I was able to keep the GA12-N20 gearmotor, but also designed a version for a motor with a bit more speed and torque.
Some people may wish that it were more automated. I don't have the skills, nor the desire to learn them, to design the electronics and code needed to do something like that. Maybe someone will remix my design into something like that, but powering from an external supply rather than a battery is fairly simple, with some additional 9v battery clips and an appropriate power supply.
STL, STEP, and Fusion360 files are all provided so that the design can be more easily adapted to other size parts. Specifically, I've parameterized the gears, in case you have another set of gears you want to try. A Bondtech style drive gear, as on the BSL, can be used, but then a different spur gear will be needed, and the mesh distance may change, so be sure your gears mesh properly before adjusting the CAD. The gears in the CAD are only representative, and should NOT be printed, because they won't work properly, if at all.
As per the license, I'd really appreciate credit to me for the basic concept of this design on any remixes. My Fusion360 skills are intermediate at best, so expect to have to do more editing after changing any gear specs.
To use, simply insert the filament through the filament sensor and ensure that it goes into the gears of the SideKick. Press the paddle that aligns with the filament you just loaded. There is no need to fold the other paddles back, but if you prefer to do so, they will fold all the way back and out of the way. As long as you don't apply pressure to the other paddles, all will be well.
To unload filament, since the spool needs to be rotated backward, I usually just remove the spool and rewind it manually, taking care not to let the end of the filament loose once it leaves the XL sensors. The SideKick is NOT an unloading tool for that reason.
There are two build options. You then have the option of powering it with a 9v battery, alkaline or rechargeable, or use an external 9v or 12v power supply. Batteries are convenient, but a little slower and slow down more at the end as the load increases, and need to be replaced or recharged occasionally. External power is great, but more expensive and complex to install.
This is a slightly larger version because it uses a slightly larger gearmotor that is directly connected to the extruder gears, as it would not easily fit in the same space the smaller gearmotor does. Also, this design does not give up any speed/energy to yet another set of gears. This is the better option if you need to buy the gearmotor anyway. The added cost of the bigger motor is offset by the lower cost of a simple shaft coupler in place of the two gears needed for the compact drive version.
This is the original design with the same GA12-N20 gearmotor as used on the Bowden Speed Loader. If you already have extra motors, then this might be the option for you. You'll need to source the two gears that connect the motor to the drive gears in addition to the rest of the parts, but this is a more compact solution than the direct drive version. The main downside to this version is that those little gearmotors are not known for being robust and long lasting.
Each option is designed to be powered by a simple 9v battery. Alkaline seem to offer better power from start to finish of loading, but are a continuing expense to replace them. Rechargeables are nice in that they can be recharged but seem to lack a little oomph as compared to Alkaline. Though, maybe that's just the batteries I have.
If you prefer, power can be easily provided by a low cost variable voltage power supply and some additional 9v battery clips. Look for the brick style adjustable supplies that come with a variety of connectors, specifically the one with screw terminals to easily connect to lead wires. Loading speed will be much better from beginning to end, and you never have to recharge or replace the batteries! I'm not going to link a specific model, but just search for "12v adjustable universal power supply" and you'll get many similar results. Check out the remixes for a model that you can print to install a DC jack in place of the battery!
You could absolutely do this if you know what you're doing. With an appropriate voltage/buck converter and the right connections to the XL power supply, the SideKick could easily be powered by the XL itself. I'm not going to suggest that or show people how, because I don't want to get it wrong, or have people blame me if THEY do it wrong. But, if you know what you're doing, I'm pretty sure you can figure it out. ;)
I look forward to all the cool ideas people come up with in their remixes! USB power? Power from the XL PSU? Something with logic? GO FOR IT!
Quantities are for one SideKick. Double if making a SideKick for both sides. Links are to Amazon and are NOT affiliate links.
Blourolls has agreed to make a complete hardware kit for the direct drive SideKick! Now you can easily source all the parts you need without buying extras you don't! Hit this link, and don't forget to post a make! :)
https://www.blurolls3d.com/products/sidekick-prusa-xl-filament-loader-designed-by-mrflippant
Three OD 11mm 5mm bore Extruder Gear for 3D Printer Compatible for Ender 3 et al
Six m3x16mm screws
One m5x50mm bolt and nut.
At least 53mm of 4mm OD x 2mm ID PTFE tube (cut to three 17.6mm sections)
A few inches of a small gauge wire (I used some 24g speaker wire)
A couple M3 T-nuts for 3030 extrusion
Three OD 11mm 5mm bore Extruder Gear for 3D Printer Compatible for Ender 3 et al
One 3mm Bore 16T Mod 0.5 Gear
Printable Pinion Gear available, but not recommended
One 5mm Bore 32T Mod 0.5 Gear
Printable Spur Gear available, but not recommended
Four m3x16mm screws
One m5x50mm bolt and nut
At least 53mm of 4mm OD x 2mm ID PTFE tube (cut to three 17.6mm sections)
A few inches of a small gauge wire (I used some 24g speaker wire)
Some grease for the gears. Superlube should work well enough.
A couple M3 T-nuts for 3030 extrusion
There are no special settings or materials needed for this build. All models should be printed in the provided orientation, and no supports should be needed. I designed this to be as easy to print and assemble as possible. If you decide to use something other than PLA, be sure to account for material shrinkage rates, even for PETG, as the tolerances for hardware are fairly tight, so if your prints shrink much, stuff might not fit or close up completely after assembly. Just download the set of files for the version you're printing, make sure you have the right number of spacers, and don't forget to print at least one PTFE jig, and send it!
Print all the parts in the orientation provided, though it needs FOUR spacers, not just two. There should be no need for supports, and PLA with default settings is fine. If you print in something else, be sure to account for any shrinkage of the material, even PETG. The "SideKick" text is separate bodies of the Top part. Just click the "split to parts" tool to easily assign a different color/tool to the text, rather than having to paint it.
For this project, the polarity to the motor is absolutely critical. A + indicator is not enough to go by, so a test with a battery directly to the motor tabs is good practice. For the Direct Drive version, on the LEFT (123) side, the motor shaft needs to spin clockwise when looking at the end of the motor shaft. For the Direct Drive version on the RIGHT (456) side, the motor should spin counter/anti-clockwise. Once you determine the correct polarity for the assembly, mark it on the motor with a marker of some kind.
The switch needs to be wired so that pressing the lever closes the circuit, so test your switch if you're not certain which tabs to use. For the switch I used, it's the two tabs at the hinge end of the lever.
Solder your wires to the switch. The other end of the wires should go to the negative tab (per Step #2) of the motor and the negative (black) lead of the 9v battery connector clip. Use some solder and insulation on the wire-to-wire connection. In my example below, I was able to wire the 9v clip leads directly to the switch and the motor, and only needed some wire to go from the other tab on the switch to the other tab on the motor.
Solder the positive (red) lead from the 9v battery connector to the positive tab (per Step #2) on the motor.
Test the system with a battery connected to ensure the switch works as expected, and the motor turns the correct direction (per step 2). Correct any errors now!
Insert the switch and 9v battery clip through the opening in the SideKick Middle part. The motor can then slot into its resting place for now.
With SideKick Bottom, channel the wires from the 9v battery clip into the battery compartment. Leave the clip outside of the assembly to ensure the battery leads do not get pinched in the assembly. Also channel the wiring to the switch into position, having the Wire Keeper at the ready.
Press the Wire Keeper into the wire channels to help keep the wiring in place while you proceed. It doesn't need to be pressed all the way down, only enough that it is not sticking up, and so that all the wires are held into their channels.
Slide the switch sideways back through it's opening in the SideKick Middle part, and place the Middle on top of the Bottom, lining them up.
Make sure none of the wires have been pinched by the two parts, and then press them together completely.
Assemble the gears to the D shaft in the below order and orientation. Incorrect orientation may result in poor action during filament loading. Leave the set screws slightly loose for now.
--Shaft Coupler, Spacer, Bearing, Spacer, Extruder Gear x3, Spacer, Bearing--
(and one more spacer if you use a 50mm bolt, between the last bearing and the bolt head.)
Slightly raising the shaft end of the motor, slide the shaft coupler onto the motor and then place the gear assembly into the channel, ensuring that all the parts fit snugly and without significant play along its axis. A 60mm rod or d-shaft is preferred, but another m5x50 bolt also works. Check the alignment of the extruder gears through the windows of SideKick Top placed carefully on the assembly.
Add or remove spacers as needed to adjust the fit. When you are satisfied with the fit, secure the set screws on all gears, making sure at least one set screw on each gear aligns with the flat of the D shaft.
Slide the switch through the opening in the SideKick Top part and align all the body parts.
Use your M3x16 screws to secure all the body parts together.
Orient the switch into its final position, with the hinge end of the switch closer to the center of the printed part and press it into the socket. The small steps in the SideKick Top will prevent it from being pushed into the assembly. If your switch is loose, you can use two M2x8mm screws through the holes to secure it. Or, add some thin tape or some glue to secure it.
Connect a 9v battery and test the motor again by pressing the switch by hand. You should see the extruder gears through the openings moving without excessive noise or vibration. If there is loud noise or strong vibrations, disassemble the SideKick and examine all parts for interference.
Insert one 3x7x3 bearing into the sockets on each of the paddle prints.
Use one m3x10mm set screw through the paddle print to hold the bearing in place in each paddle. The screw should be flush on both sides of the paddles, not sticking out at all.
The paddles nest into each other, and will only work when installed in the correct location.
Use the m5x50mm bolt through the paddle holes to secure them to the SideKick. Add a nut to the bottom to keep the bolt from creeping.
Pressing any paddle should activate the switch and provide clamping force to the filament. Install a battery and test it with some scrap filament now. If there is a problem, review your assembly so far for any errors.
Use the PTFE Jig to cut three pieces of PTFE to 17.6mm in length. Use a countersink bit if you have some, or a regular drill bit if necessary, to put a chamfer on the inner edge of the PTFE on at least one end, if not both.
Insert those PTFE "jumpers" into the holes at the front of the SideKick, where it will be interfacing with the Filament Sensor. Make sure the chamfered end is pointing out.
Print all the parts in the orientation provided. There should be no need for supports, and PLA with default settings is fine. If you print in something else, be sure to account for any shrinkage of the material, even PETG. The "SideKick" text is separate bodies of the Top part. Just click the "split to parts" tool to easily assign a different color/tool to the text, rather than having to paint it.
For this project, the polarity to the motor is absolutely critical. A + indicator is not enough to go by, so a test with a battery directly to the motor tabs is a good practice. For the Compact Drive version, on the LEFT (123) side, the motor shaft needs to spin counter/anti-clockwise when looking at the end of the motor shaft. For the Compact Drive version on the RIGHT (456) side, the motor should spin clockwise. Once you determine the correct polarity for the assembly, mark it on the motor with a marker of some kind.
The switch needs to be wired so that pressing the lever closes the circuit, so test your switch if you're not certain which tabs to use. For the switch I used, it's the two tabs at the hinge end of the lever.
Solder your wires to the switch. The other end of the wires should go to the negative tab (based on your testing from Step 2) of the motor and the negative (black) lead of the 9v battery connector clip. Use some solder and insulation on the wire-to-wire connection.
Solder the positive (red) lead from the 9v battery connector to the other tab on the motor.
Test the system with a battery connected to ensure the switch works as expected, and the motor turns the correct direction (see step 2). Correct any errors now!
If you choose to print the provided printable pinion, be sure to set seam to random to avoid weak spots. You will need to press the pinion on, so some kind if clamp or parallel pliers will be helpful to have on hand.
Put the pinion gear on the motor shaft as far down as it will go and secure the set screw to the flat of the motor shaft. In my case, the set screw interfered with the spur gear, so I had to grind the tip of the screw down a little bit for smooth gear mesh. If your assembly sounds like a box of rocks, this is probably what needs to be done.
Install the motor assembly into the SideKick Bottom part. The motor should fit snugly into the detent on the bottom of the motor compartment, and the pinion on the motor should not touch any of the print.
Insert the switch wire into the channel, leaving as much slack at the switch end as possible.
Channel the wires to the 9v battery clip through the opening and into the battery compartment. Leave the clip outside of the assembly to ensure the battery leads do not get pinched in the assembly.
If you choose to print the provided printable spur, be sure to set seam to random to avoid weak spots. You will need to press the pinion on, so some kind if clamp or parallel pliers will be helpful to have on hand.
Assemble the gears to the D shaft in the below order and orientation. Incorrect orientation may result in poor action during filament loading. Leave the set screws loose for now.
--Bearing, Spacer, Extruder Gear x3, Spur Gear, Spacer, Bearing--
Place the gear assembly into the channel on the SideKick Middle part, ensuring that all the parts fit snugly and without significant play along its axis. Add or remove spacers as needed to adjust the fit. When you are satisfied with the fit, secure the set screws on all gears, making sure at least one set screw on each gear aligns with the flat of the D shaft.
With the set screws all secured, the assembly should rotate easily with no resistance. Temporarily remove the gear assembly for the next step.
Slide the switch sideways through it's opening in the SideKick Middle part, then align the two printed parts, but do not install screws yet.
Put some grease on the teeth of the spur gear and try to spread it evenly around the gear. A little dab will do ya! :)
Replace the gear assembly. It should mesh with the pinion on the motor, and no longer spin easily, as doing so back-drives the motor.
Slide the switch through the opening in the SideKick Top part and align all the body parts.
Connect your battery and test the assembly by holding everything together by hand. The extruder gears should rotate away from the switch, and there should not be excessive noise or vibration.
Use your M3x16 screws to secure all the body parts together. Remember not to apply excessive force to the screwdriver to avoid stripping the plastic.
Orient the switch into its final position, with the hinge end of the switch closer to the center of the printed part and press it into the socket. The small steps in the SideKick Top will prevent it from being pushed into the assembly. If your switch is loose, you can use two M2x8mm screws (or some filament) through the holes to secure it. Or, add some thin tape or some glue to secure it.
Connect a 9v battery and test the motor again by pressing the switch by hand. You should see the extruder gears through the openings moving without excessive noise from the gearing. If there is loud noise or strong vibrations, disassemble the SideKick and examine all parts for interference. Again, you might need to grind down the tip of the pinion set screw to prevent interference with the gear mesh.
Insert one 3x7x3 bearing into the socket on each of the paddle prints.
Use one m3x10mm set screw through the paddle print to hold the bearing in place in each paddle. The set screws should be flush on both sides, not sticking out at all.
The paddles nest into each other, and will only work when installed in the correct location.
Use the m5x50mm bolt through the paddle holes to secure them to the SideKick. Add a nut to the bottom to keep the bolt from creeping. Do not overtighten! The paddles should rotate freely enough for the switch to push the paddles away.
Pressing any paddle should activate the switch and provide clamping force to the filament. Test it with some scrap filament now. If there is a problem, review your assembly so far for any errors.
Use the PTFE Jig to cut three pieces of PTFE to 17.6mm in length.
A countersink drill bit should be used to chamfer the inner edge of the ends of the PTFE sections, but a standard drill bit will work in a pinch. Without a chamfer, filament may not insert smoothly.
Insert those PTFE "jumpers" into the holes at the front of the SideKick, where it will be interfacing with the Filament Sensor.
When building one for the other side of the machine, everything is basically mirrored. The important thing is that the polarity of the motor should be the opposite of this one. When testing, the extruder gears should always appear to rotate AWAY from the switch. If your SideKick unloads filament, that just means you need to go swap the polarity at the motor.
Remove the PTFE from the back of the filament sensor.
Carefully (so you don't lose them) remove the collets.
Insert the collets into the back of the SideKick, being careful to get all the prongs into the holes.
Loosen the screw for the filament sensor, but do not remove it. You only need a few mm of space behind it.
Carefully slide the Sidekick into the back of the filament sensor, aligning the short PTFE tubes to the back of the filament sensor until there is no gap between the SideKick and the back of the sensor.
Tighten the screw to secure the filament sensor back to the frame of the XL, trying to keep it in it's original location, which should allow the SideKick mounting holes to line up with the extrusions above and below the filament sensor.
Insert T-nuts into the extrusions (printed ones are fine), then insert an m3 screw through the SideKick mounting holes and into the T-nuts to secure it.
Insert the PTFE from the extruders into the back of the SideKick.
2026/05/21 - By request, I added optional tops for the direct drive versions that take PC4M10x1 passthrough PTFE couplers rather than the collets.
2026/03/24 - By request, I added optional tops for the direct drive versions that take PC4M10x1.5 passthrough PTFE couplers rather than the collets.
2026/03/17 - Added printing instructions, such as they are, as well as link to Blurolls hardware kit.
2026/02/16 - Updated Direct Drive models to allow for full 60mm rod or D-shaft.
2026/02/15 - Added printable pinion and spur for the compact drive version. These are NOT recommended, but will do in a pinch. The gear pitch had to be much larger to make it printable on a 0.4mm nozzle. They will need to be pressed onto the motor shaft and rod/d-shaft/bolt, so having a clamp or parallel pliers is advised.
License:
Creative Commons — Attribution — Noncommercial — Share Alike
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MrFlippant
