Introduction
Before upgrading your Prusa Mini with the Revo Micro please read the following safety cautions
After requests for a mounting option using the original fan, we’ve created a second edition of our Prusa Mini upgrade guide that retains the original Prusa HotEnd fan. We recommend using edition 2 as it passes Prusa's self-test. It can be found here.
This is a complete upgrade guide suitable for an original Prusa MINI+ and Revo Micro. Please note, your printer may vary from the one illustrated in this guide, depending on the model and your own upgrade choices.
You should read through the whole guide before attempting the upgrade to ensure you understand exactly what is required to successfully complete it. The upgrade should take approximately 1 hour & 20 minutes.
The upgrade has been carefully designed to reuse the existing fixings on your Mini. This means you will not need to buy any additional nuts and bolts to complete it.
No Firmware changes are required for this upgrade.
Preparation
To begin, you need to make sure you have a part printed in advance:
Do not begin disassembling your printer until you have printed this part or you risk being unable to complete the upgrade.
A 3D printed bracket for mounting your Revo Micro:
In order to make the upgrade as straightforward as possible, the part is attached by threading directly into the plastic. In testing, this was found to be sufficiently strong and it means you will not need any additional fixings. This version is shown in the illustrations and is the default option. Alternatively, if you want a stronger connection, an extra STL is provided with slots for M3 square nuts.
Models available here: https://www.prusaprinters.org/prints/117149-revo-micro-prusa-mini-upgrade
You can find a multimaterial version of the mount here. Courtesy of @de3dprintman!
Make sure you check the tolerances of the printed part before beginning the upgrade. The M3 screws should easily thread into the plastic and (if you are using them) the square nuts should slide into place.
Recommended materials: PETG, ABS, ASA, Nylon, PC blends, etc. are all good. Avoid using PLA!
Good part cooling will be needed!
Print with mounting side face down on the bed as shown
0.4mm nozzle, 0.2mm layer height
40% infill
3 perimeters (walls)
5 top/bottom layers
Using a brim is recommended
There's no need to use supports as they are designed straight into the model. Simply break these off once printed! (Models without support are also provided just in case you want to add your own).
You will also be needing the cable management arm on your existing Prusa Mini. If you need a replacement or want to reprint it in another colour scheme, you can find the original STL here: https://www.prusaprinters.org/prints/57214-mini-printable-parts/files
If you have an early release of the Mini, you may find that yours doesn't use the cable management arm or potentially has the older version of the Minda holder. MINI+ superseded the MINI, but the printed parts are reverse-compatible. Just download and print them from the link above. The files are named fan-spacer-clip and minda-holder.
To undertake this upgrade you will need:
- 2.5mm hex key
- Flush cutters/cutting pliers
- Adjustable wrench/large pliers
- Utility knife/tube cutter
- Small flathead screwdriver
- A handful of cable ties
- Your 3D printed bracket
- Your existing Prusa Mini
- Revo Micro 24V variation (Please double check your own voltage, all original Prusa Mini's are 24V).
- (Optional) 2 x M3 square nuts
Check out our blog if you are unsure on whether you need a 12 or 24V Revo Micro: https://e3d-online.com/blogs/news/12v-vs-24v
Before starting disassembly, you should make sure your Mini is on the latest firmware from Prusa.
Please see: https://help.prusa3d.com/en/downloads/
Disassembly instructions
Move your extruder to roughly the centre of your bed and around 100mm above the build plate before starting this upgrade, this will give you easier access to the extruder.
You should also ensure there is no filament loaded and that the printer is unplugged from the power source before starting.
You should also place a cloth or piece of fabric over your heat bed to give it some protection in case you drop something onto it.
1. Use the 2.5mm hex key to remove the screw holding the part cooling fan in place and then carefully twist the fan upwards as you remove it. This will help ensure you do not strain the wires.
It is a good idea to keep your screws in a small container while you are working on the printer so that you don't lose them!
2. Loosen the upper fitting and remove the Bowden tube from the HotEnd. You may have to use pliers or a wrench to get a good enough grip on the fitting.
3. Remove the screw that holds the cable management arm in place. Remove the arm and set it aside, you will need it later.
4. Remove the screw that connects the pinda arm to the heatsink.
5. Remove the screw that sits underneath the fan.
6. Remove the screw above the fan which holds the heatsink.
The whole HotEnd assembly will now be loose, so be careful.
7. Unwrap some of the cable sleeve and place the Prusa HotEnd on the heatbed for now, we will deal with the rest of the wiring later. You should cut the cable ties holding the sleeve to the x-axis now.
Assembly instructions
8. With the Prusa Mini HotEnd successfully disassembled, you are now ready to add the new mount.
Prepare your printed part: Make sure any support material has been removed.
Pliers can be helpful here!
If you are using the square nut version of the STL, you should add these now!
9. If you haven't done so already, thread the screws into the printed part and then back out. At least once for each hole on the part. This will physically create the threads and make the part easier to attach to the carriage.
It should be easy to screw them in and out, if you're finding it difficult, the hole is probably too small and your printer may be over extruding.
10. Position the printed part so that it lines up with the holes on the carriage.
11. Secure the printed part with three M3x20 screws.
Do not overtighten or you will break the plastic threads you just created. Be aware that if you over-thread the lower screw at the back, it may clash with the Revo Micro's heatsink.
12. Unscrew the M12 Nut from your Revo Micro.
13. Position the Revo Micro in the mount.
You should position the HeaterCore sleeve towards the slot in the Pinda arm from the previous wiring. You can leave the wires as they are for now. You can route them into the wiring loom later.
You should avoid bending the stain relief. Repeatedly bending it can lead to damage.
14. Secure the M12 Nut using your fingers, making sure the HeaterCore's sleeve stays in the correct position as you tighten.
Tightening the M12 nut as much as you can using your fingers should be sufficient. If it still feels loose, you can use an appropriately sized wrench/spanner.
15. Remove the brass olive (compression fitting) from the Bowden tube. You will find it easiest to cut it off. Make sure to cut as close to the brass olive as possible. Otherwise, you risk shortening the tube too much.
If you find that the tube is a little short, you can get a new piece of Bowden tube, about 20 to 25mm longer than the existing tube, (300mm total) and add a new brass olive from your spares bag to one end.
Try to cut into the tube as straight as possible and make sure the tip of the tube is circular and not squashed. Rework it back into shape if needed. You can use a scrap of filament to make sure it isn't squashed. The filament should pass through easily.
16. Remove the collet clip and feed the Bowden tube into the top of your Revo Micro. Replace the collet clip once the tube is in place.
Wiring
17. Now you just need to swap over the heater, thermistor, and fan wires.
Start by plugging in your extension cables as follows:
The longer cable coming from the HeaterCore (the lower of the two cables) is the heater cable.
18. Remove the screw holding the mainboard housing together and remove the top covers.
19. Remove the old wires from the sleeve all the way down to the board.
Then route the new extension cables through the sleeve all the way to the board
We recommend that you keep the serial number tag visible (rather than hidden in the wiring loom). It will be found on your Revo Micro's heater/thermistor wires
20. Next you need to swap over the heater, thermistor, and HotEnd fan.
At this point, you should still have the old heater, thermistor and fan plugged into the board.
The illustration below shows the location of the terminals but if in doubt please refer to Prusa's documentation.
Unplug the HotEnd Heater first. The whole terminal should pull away.
Unscrew the Heater connections from the terminal using a small flathead screwdriver and replace them with the Revo Heater extension cable (black with red ferrules). Then plug the terminal back into the board.
Don't worry about mixing up the heater wires, heaters don't have a polarity.
Next, unplug the thermistor. You will need to press on the small tab on the side as you pull to release it. Replace it with the Revo thermistor.
The thermistor extension cable doesn't have the same orientation tab as the original cable. Thermistors do not have a polarity though, so you can plug it in either way around.
Finally, you need to replace the HotEnd Fan. You will only be making use of 2 of the 3 pins.
The red wire in the middle and the black and red wire on the outside closest to the heat bed. Prusa actually under volts the HotEnd fan,
The fan has polarity so make sure you wire it correctly or you risk damaging the fan
You will not need the supplied step-down board for this upgrade because the Prusa Mini fans run off a 5V supply already.
21. Tidy up any excess cable using cable ties and close the housing.
22. Slide the cable management arm into position over the wiring loom and secure it using an M3x20mm screw.
Make sure the wiring isn't obstructing the carriage when at max position on the X-axis (180mm).
23. Move the Toolhead to the end of the X-axis and make sure there is sufficient length in your wiring loom and bowden tube.
24. If there is sufficient slack, reattach the wiring loom to the gantry with some cable ties.
25. Reposition the fan and secure it with the remaining M3 x 20 screw.
Final calibration
Please note: As you have swapped from a 3 pin to a 2 pin HotEnd Fan, if you use the self-test function on your Prusa Mini, you will notice that the HotEnd fan fails. Don't worry, this does not affect the functionality of the printer.
26. Plug in and turn on your Prusa Mini. Click on 'Calibration', then go to 'Test Heaters'.
Please note, when heating up your Revo for the first time, you may notice small amounts of smoke coming from the nozzle. This is just residue burning off and is nothing to worry about.
Wait for the test to finish. Check to see if the HotEnd fan come on once the heater gets past 50 degrees. If it doesn't come on, shut off the test and check your wiring again.
If this test fails, it is likely that your heater/thermistor connection is loose/faulty
27. If the test is successful, head over to 'Calibration' and click on 'First Layer Calibration'.
Run through the calibration.
When prompted, make sure you select 'NO' and use the default value (0mm). Your old offset could cause the nozzle to collide with the bed. You may need to adjust the physical height of the Pinda Probe if you find that the nozzle is still too high when at -2mm on 'adjusted z height'.
If you are struggling to get a consistent first layer. You should rerun your mesh bed levelling in the calibration menu.
PID tuning the Mini
Prusa recommends not to PID tune the Mini (Source here) and the auto PID tune command that is present on the MK3 is not available. Without custom firmware, you are also unable to save to EEPROM.
If you feel the need to PID tune your Mini you can use pronterface and then add your generated PID values to the start G-code of your slicer.
That's it! Your Prusa Mini is now upgraded to Revo.
With the upgrade complete, why not print a fancy holder for your new Revo Nozzles?
https://www.prusaprinters.org/social/193579-e3d/prints
