Mk4 early days questions - adjusting belts, heatbed temp, prints lifting, and socks
hello all,
I just got a Prusa Mk4 kit, which I finished building a few days ago. This is my first Prusa, but I have been printing for a few years now with Anycubic's FDM printers.
- Poor bed adhesion: My first test benchy came out great. However, my next print - which was a fairly large speaker grille, almost the entire length of the PEI sheet, popped off mid-print and failed despite me cleaning it beforehand with IPA. I took off the sheet, washed it with dawn, dried it, and re-cleaned with IPA. I also added a brim. While the print is in progress and I think it's going to be OK, I do see that it's lifting a little at the ends of the print. I am using prusament PLA, print bed is 60c, and the fan is at 100%. Any additional suggestions? I know I can glue stick it but... should that be necessary for PLA?
- Tying very nicely into the previous point: while the prusa slicer shows 60c, and prusa connect shows a flat 60c on the bed, an infrared thermometer pointed at the bed shows... 46c. Is this normal?
- Do you recommend a silicone sock for the nozzle/heating block?
- I had a hell of a time tensioning the belts with the phone app - I tried a pair of galaxy s9s and a pixel 7. The Y belt was fine, but the X belt seems to fly between "too loose" and "too tight" regardless of how loose or tight the belt is. I assume I am strumming it wrong, although I did watch the video. Any other tools or suggestions for this?
Thank you!
RE: Mk4 early days questions - adjusting belts, heatbed temp, prints lifting, and socks
Try the android app "Spectroid" for tensioning the belts.
RE: Mk4 early days questions - adjusting belts, heatbed temp, prints lifting, and socks
I just recently got my MK4 also. As for the belts, I too had the same problem till I found out my phones microphone was actually on the top!! Once I turned over the phone the tuning was much easier. I naturally assumed it was on the bottom ..go figure.
Warping and lifting is often a result of cool air, drafts or aircon outlets, blowing over the print and messing with the cooling ... intermittent drafts (doors opening?) are hardest to track down.
I have never used a silicine sock and never felt the need - others experience may vary.
Cheerio,
RE: Mk4 early days questions - adjusting belts, heatbed temp, prints lifting, and socks
I like the sock. I have run an MK3 for years without a sock. I now use a sock on the MK3 and my MK4. One nozzle change with excess filament residue all over it and I immediately went to a sock. Also saves you from the occasional blob. There is a setting on the MK4 for a Sock that needs to be set when a sock is added.
I am using a satin plate for PLA/PETG, tends to adhere better. I was regularly using an adhesive on the PEI plate, nothing on the satin.
Large rectangular parts tend to have corners that pull up. Brim or rafting may be needed.
4
RE: Mk4 early days questions - adjusting belts, heatbed temp, prints lifting, and socks
I had great repeatable results with the Belt Tension app on my iPhone 13Pro in a quiet room.
I held the phone’s microphone about an inch away from the belt and used a light plucking action.
The results agreed with my petg printed tension gauge. The “just right” from the app fell at the upper ok limit on the gauge.
RE: Mk4 early days questions - adjusting belts, heatbed temp, prints lifting, and socks
Thank you all for the assistance, I really appreciate it (at least 4 of you really helped me out here!)
RE:
- Bed adhesion - PLA shouldn't have any issues except in extreme geometries... which it sounds like you're dealing with. Corner lifting is expected for large area prints. It can be mitigated by using gyoid infill, and adding a brim. Gluestick should not be necessary for PLA.
- Bed temperature - trust the thermistor. An infrared thermometer will be subject to the reflectiveness of the build plate (it's infrared light after all). I didn't realize this until I got my FLIR just a few days ago -- you can actually see the reflection of the room in the build plate, meaning you're seeing room ambient affect the measured temperature. The thermistor is a contact thermocouple -- that's the reliable reading.
- Silicone sock - personal preference. It's the great debate.
RE: Mk4 early days questions - adjusting belts, heatbed temp, prints lifting, and socks
oh cool, thanks - I had not used gyroid infill before.