Prusa Core one top flap for improved chamber temperature retention and cooling (mod)

Prusa core one top flap

Should limit the convection currents when the fan is off and allow enough air to pass through when fans are active to maintain correct chamber temperature.

PRINT AT 0.2mm LAYER HEIGHT

v3 removed for serious flaw. recommended design is v4. It seems to work well when  printed in PETG I also tried ASA which i have more issues with, but many can be attributed to my filament which is of questionable quality.

DONT USE PLA

Print without supports, see the picture for recommended print orientation. 

Recommended print material PETG, PC, ASA or ABS (PETG recommended)

Installation insuctions

After removing the print from print bed, it might not sit perfectly flush, bend it carefuly such that the flap sits flush with the surface. Ensure the cooling grill is fully open before installation, insert the tabs of the flap through the cooling grill and make sure its full installed and there is no visible gap between the polycarbonate plate and the printed part. After installation make sure the flap sits flush with the top surface and can move freely.

Troubleshooting

• The flap doesnt close all the way
  • bend it backwards until it creates good enough seal
• The flap is not flexible enough
  • bend it back and forth until desired flexibility is achieved
• The flap is sagging in the middle
  • Print flap V5 (should be solved)

Performance evaluation

(all tests done on V2 of the flap)

Testing methodology:

1. Z axis moved to 170mm (about ⅔ down the print area)
2. Bed temp was set to 120C (print sheet removed)
3. cooling grill closed
4. wait about 20 min for temperature stabilization
5. collect chamber temp (datapoint 1)
6. open cooling grill and install prusa flap
7. wait about 20 min for temperature stabilization 
8. collect chamber temp (datapoint 2)
9. remove prusa flap, keep grill open
10. wait about 20 min for temperature stabilization 
11. collect chamber temp (datapoint 3)
12. set fans to 50% (keep bed heting on)
13. wait about 20 min for temperature stabilization
14. collect chamber temp (datapoint 4)
15. install prusa flap
16. wait about 20 min for temperature stabilization
17. collect chamber temp (datapoint 5)
18. remove prusa flap keep grill closed
19. wait about 20 min for temperature stabilization 
20. collect chamber temp (datapoint 6)

remark: During the entire test the bed temp was set to 120C (make sure to interact with the printer from time to time otherwise the heating element will timeout)

Testing results:

Data point 1:  45C (The temperature stabilized at about 45C with closed grill)

Data point 2: 45C (The temperature stabilized at about 45C with prusa flap, no heat retention loss)

Data point 3: 41C (The temperature stabilized at about 41C with open grill)

Data point 4: 37C (50% fan cooled down the chamber to 37C with grill open)

Data point 5: 36C (The temperature with Prusa flap installed and fans running did not cause any significant cooling suppression, disregard the 1C cooldown from previous test this is within margin of error)
Data point 6: 39C (The temperature is slightly higher when flap is removed and grill is closed)

remark: note that the model used for testing was printed with PLA, this material isnt recommended as it deforms under stress and even more so under increased temperature.

Conclusion

It appears the prusa flap is doing its job reasonably well, whatever airflow restriction it poses doesnt seem to influence the chamber temperature in a measurable way. It also provides quality of life improvement as this removes the necessity of actively having to adjust the grill position based on print material. Pac a pusu Vojta