Printing MK4 gcode files on a MK3.9
I've just ordered a MK3.9 kit. I also have a MK4, so I figured I could compare the output of both to decide whether the 0.9 degree stepper motors are important to me. *
It would be convenient to be able to slice once and then print the same (b)gcode on either printer. Prusa CS said this would probably work, but he suspected that the quality might not be as good as a file that was sliced for a MK3.9 directly. **
Does anyone have experience of printing MK4 files on a Mk3.9? a) Is it possible, and b) how does the quality compare to a print that was sliced for a MK3.9?
* I should have checked the availability of suitable 0.9 degree motors before ordering the MK3.9
** Another reason that the full MK4 upgrade might have been a better choice for me. By the time I'd figured this out, my MK3.9 order had already shipped!
RE:
My MK3.9 kit arrived, and I've built it. I can now provide answers to my own questions, and I thought they might be useful to others. I made a test print with a curved face and a few straight faces, which I oriented so that the straight faces were at 45 degrees the the X and Y axes, so that any VFAs would be highlighted. I sliced the model for both a MK4 and a MK3.9, and I printed both bgcodes on both printers.
I can now say that:
1) A MK3.9 can print files that are sliced for a MK4, and vice versa.
2) On either printer, I see no difference between files sliced for a MK3.9 and files sliced for a MK4.
So far, so good - 'slice once, print on either'.
However:
3) I do see a difference between the 1.8° stepper motors of the MK3.9 and the 0.9° stepper motors of the MK4.
A couple of photos should show this. In both photos, the order of the prints from top to bottom is:
- MK4 printer, model sliced for MK4
- MK4 printer, model sliced for MK3.9
- MK3.9 printer, model sliced for MK4
- MK3.9 printer, model sliced for MK3.9
It's not easy to capture everything on a photo, but essentially the VFAs on the bottom two prints (MK3.9 printer) are indistinguishable from each other, and are much more noticeable than on the top two prints. Equally, the VFAs on the top two prints (MK4 printer) are indistinguishable from each other.
On the basis of this test I've decided it probably is worth updating the stepper motors on my MK3.9 to the 0.9° models. They're not yet available in Prusa's Eshop, but according to this thread they are apparently the LDO-42STH40-1684MAC motors. I've ordered some for a good price from Filastruder in the US (link) - I'm in the UK, so it'll be some days yet before I can test them.
RE: Printing MK4 gcode files on a MK3.9
In case anyone searches and finds this, like I did, I can affirm the same is true of the MK3.9S and MK4S.
I cross-compared some non-binary GCODE and the differences were:
- The generation timestamp
- The thumbnail
- The printer model check name (M862.3 P "MK3.9S" vs M862.3 P "MK4S")
- The printer model name (MK3.9S vs MK4S)
- The printer settings ID (Original Prusa MK3.9S HF0.4 nozzle vs Original Prusa MK4S HF0.4 nozzle)
The actual generated instructions are otherwise identical, and this MK3.9S does not at all refuse or error on MK4S-tagged GCODE as of firmware 6.1.3.
RE: Printing MK4 gcode files on a MK3.9
I used the mk4 profile on my mk3.5 in another slicer and it worked also.