Mk2.5s to Mk3s+ upgrade in 2021. Is it worth it?  

RE: Mk2.5s to Mk3s+ upgrade in 2021. Is it worth it?

Posted by: @chicago-keri

OK, so my poor old Prusa MK2.5s is working just fine with many modifications.  Other than a Mosquito hotend, I've drilled the MK2s frame for the MK3 extrusions and endplates (along with Einsy box holes), came up with end limit switch mounts for the MK3 type X and Y axes, installed a SuperPinda, mounted a later type front panel with a black LCD, obtained highest quality linear rods and bearings and it's been running happily for some time now.

But, I've been accumulating spare MK3 parts, notably a broken Einsy Rambo (shorted 3.3v regulator U11), a 24v PSU, a 24v hotend heater element, 5v parts fan, and was thinking,  my machine is largely a MK3 already! After all, the extruder and X axis are already there, the Y axis is almost there and the Z isn't that different to begin with.  How hard could it be?

So after diagnosing and repairing the Einsy, I figured that all I needed to move up to Mk3S+ was the Y carriage and 24v heated bed along with a bunch of printed parts.  So, I ordered up the heated bed and a  Y-carriage including the Mk3 type frame, even though I had already drilled out all of the MK3 holes on my MK2s frame.... Yes, I could have used the old frame but it is time to move on.

The package got here, Chicago, from Prusa in record time.  Stripping down the Mk2.5 went quickly and in no time I had the frame set up with the already completed and running X axis and extruder mounted, along with a huge box of discarded black and orange Mk2s parts.

Now comes the interesting parts: The harness for the filament sensor is subtly different. One wire has to be moved. Also, the Y-connectors for the 5v hotend fan and the Super Pinda are discarded.  As I had eliminated these Y-connectors by modifying the cabling directly, I had to de-modify them.   Busted out the 12v hotend heater and replaced with the 24v one. 

Wired it all up and.... It just works. Completed the initial setup wizard without issue.  How boring!  To alleviate my boredom, the SD card refused to work.  A quick inspection reveals that I somehow managed to break one of the ribbon cables, an easy fix.

Is it worth having a MK3s+? Absolutely!   Even though the Mk2.5s runs the same firmware, many of the features are incapable of running on the older MiniRambo hardware.  It's quieter, the steppers have finer resolution, the 24v electronics run at much lower currents, Power Panic can save an excruciatingly long print from power failures, no more answering the "are both Z axes full up?" question and PrusaSlicer seems to think a 3 hour print can be done a little bit faster than previously.

But, now that the MK2s > Mk3s upgrade kit is no longer available, which was almost the cost of a Mk3s anyway,  is it worth upgrading your Mk2.5s to Mk3s?  

No! Absolutely not.  It would have been much faster and cheaper to just buy a new Mk3s+ kit and start over. Additionally, it would be a better machine with warranty support.  And  the Mk2.5s would still be in one piece to be used, sold or given away.

Why would you want to do this "the hard way" as I have done?  Well, as was the case when I went from Mk2s > Mk2.5s, sometimes getting the kit from Prusa can have a long lead time.   I went from a running Mk2.5S to a running Mk3s+  in under two weeks including shipping time, at a time when a new Mk3s+ kit would be expected to arrive in 5-6 weeks.  Also, if you enjoy the learning experience and troubleshooting, this can help you with that. Keep in mind though, that my machine was already "mostly there" with many Mk3s parts already installed... to do this from a standard Mk2.5s  would take longer and require more parts.

Yes of course. it's worth.