I paid for a MK3S but I think I got an MK3 instead. It won't work.

I paid for a MK3S but I think I got an MK3 instead. It won't work.  

New Member

I have been banging my head against a wall for over a year with endless calibrations, firmware flashing, replacement of X and Y motors. To top it off I even wasted money on new hot ends and wasted over two spools of PLA and PETG trying to get a single complete print off of my Prusa

I'm at my wit's end and think I found the problem. I even looked at my receipt and it clearly shows I purchased an MK3S model. The box that arrived over a year ago had MK3S on it as well. The problem is I turn on the Prusa printer, scroll down to support at the very bottom then further scroll to see what the firmware says. Firmware is 3.9.2 for the MK3S but the the support shows I have an MK3. Am I correct in thinking this is the problem? I honestly can't get this FFF printer to print anything to save my sanity and need to know what's wrong. If I've been flashing MK3S firmware for a board with MK3 firmware I think that could be the issue but I'm not sure if that is my problem anymore. I feel like I've just wasted a whole lot of money and turned something that was supposed to be fun into my own personal hell. I desperately need help on this. Did I really just waste a whole lot of money and time here? I still can't figure out why it won't print properly and have run every test I can think of and lurked all over this site. Could this be the issue or have I completely lost my mind already?

Posted : 02/01/2021 6:26 pm
Illustrious Member

The difference between the printers is pretty obvious. Check your part cooling fan. If it's slanted at a 45-degree angle, you got a Mk3s. If it's vertical at 90 degrees to the build plate, you got a Mk3. I've got a Mk3 and have no intention of "upgrading"!

I inadvertently flashed the Mk3s firmware to my Mk3 once and while it threw an error, I had no problem simply re-flashing the correct firmware back over it. A factory reset might be a good idea, followed by basic recalibration.

It sounds like you've thrown a lot of changes at the printer without fully getting the basics going. I would suggest starting out with the basics. Get a 75x75mm 1 layer square to print and adhere. That tests both your bed adhesion and Live-Z adjustment. These control the foundation that the rest of your print is -- literally -- built on top of. You need to get those right. If nothing else, start printing the Prusa logo and stop it after the first layer. Take some pics and post here and I'm sure we can get you going.

3D printing is more like cooking than engineering. There are lot of aspects to it that you learn by feel, and it's hard to convey the information exactly in written format. Just be patient and stick with it.

My notes and disclaimers on 3D printing and miscellaneous other tech projects
He is intelligent, but not experienced. His pattern indicates two dimensional thinking. -- Spock in Star Trek: The Wrath of Khan...
Posted : 02/01/2021 6:35 pm
dimprov liked
Reputable Member

I want to help avoid a potential problem here, both my MK3 printers came from the factory with the 45 degree slanted fans

Posted : 03/01/2021 3:37 am
Reputable Member

There was a short period of time between MK3 and MK3s that had a cooling upgrade sent out. I received two of those, what wasn't changed as far as I know what the extruder body and the filament intake at the top of the extruder, as bob mentioned if your lucky enough to have an MK3 don't change it, its the best, I don't even know why they changed the design. I'm trying to build another one, from ordered parts. but don't panic as bob also mentioned you can re-flash firmware if you find a problem.  you have not wasted your money, it just sounds like you need some community help, we're here. I also own an MK3S

This post was modified 2 months ago by Swiss_Cheese
Posted : 03/01/2021 3:53 am
Milos V.
Honorable Member

Except for extruder plastic parts there was one major change in MK3S. The filament sensor. MK3S has a new IR sensor. It is also written on the part. You can identify easily based on this. I believe this is also the only reason for different fw version. If you upload wrong one, the sensor and filament autoload will not work.

Posted : 03/01/2021 8:40 am
Reputable Member


You seem to have fallen into a very common morass of problems.  Unless you get basic printing working well first none of the many touted 'remedies' is going to do anything useful.  Of course most of the people who get eveything working well straight away don't visit the forums until much later when advanced issues arise.

Please restore the printer to something close to the original, flash it with the current MK3S firmware, thoroughly clean the bed with soap and hot water then print a test object; preferably one of the gcodes that came with the printer.  If it fails, post pictures of the print, top, side and especially the bottom.

When we see them there is a good chance that one of us will recognise the problem.

or have I completely lost my mind already?

I doubt we're competent to answer that one - let's stick with the printingg.


Posted : 03/01/2021 10:15 am

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