Objectives

1. Print with 2.85/3.00mm filament as it is becoming quite cheap and can be used when 1.75mm filament is out of stock
2. Reduce overall noise level during printing - the noise level must be (subjectively) negligible when beside the printer
3. Minimize cost by using stock components when possible

Evaluation

Objective 1: Print with 2.85mm/3.0mm filament

• Issue: The stock extruder is not able to print using 2.85mm filament
  • Solution 01: Design and 3D print an alternate bowden extruder as a drop-in replacement
    • Issue: The minimum bend radius of the PTFE tube and larger filament cannot be met given the stock position of the extruder
    • Issue: Alternate positions on the printer do not meet the minimum bend radii
  • Solution 02: Use a 'flying extruder' similar to some delta-style 3D printers
    • Issue: The cantilevered X-axis gantry and enclosed Z-axis tower present challenges regarding the deflection and mounting of this style of extruder
  • Solution 03: Use a flex-drive style extruder such as the Flex3Drive
    • Issue: The minimum length of flexible shaft for this extruder is relatively long compared to the size of this printer.
    • Issue: Anecdotal reviews of flex drive extruders are not overwhelmingly positive, but are generally positive.
    • Issue: Most extruders of this style are designed for 1.75mm filament, so a redesign would be required.
  • Solution 04: Direct Drive Extruder
    • Issue: NEMA 17-driven extruders are relatively heavy, even with very short 'pancake' motors
      • Solution: Use a 'featherweight' extruder: https://hackaday.com/2020/11/05/a-featherweight-direct-drive-extruder-in-a-class-of-its-own/
        • Issue:  Tests for deflection and useability on MPSM printers are non-existent or difficult to find.

Objective 2: Reduce overall noise

• Issue: The stock A4988 drivers produce motor whine that is quite distinct and noticeable within a room
  • Solution 01: Replace the stock stepper drivers with quieter drivers, such as the TMC2208 or TMC2209 chips in stealthchop or legacy mode
    • Issue: Replacing the chips requires sufficient soldering skill and may be too 'complicated' for less experience individuals
    • Issue: Additional supplies would need to be purchased to properly and cleanly replace the onboard A4988 chips
  • Solution 02: Replace the stock mainboard and use 'plug-in' stepper drivers
    • Issue: A replacement mainboard can be expensive, relative to the low MSRP of the printer
      • Solution: A low-cost board(s) such as the RAMPS/Mega combination is sufficient for basic printer operation, and is well documented
      • Solution: Alternate 8-bit board - Low cost, but less documentation than the RAMPS board
      • Solution: SKR board - these boards are not particularly expensive, but the higher cost will likely not yield noticeable benefit on this printer
      • Solution: Alternate 32-bit board - see SKR board justification above.
      • Solution: Gigdigit 'quiet' replacement board - An easy and straightforward solution, but regularly out-of-stock.
    • Issue: the stock LCD screen is not compatible with most mainboards not specifically designed for the MPSM
      • Solution: Use a cheap, common LCD such as the 12864 LCD screen
        • Issue: The monochrome screen is not as attractive as the stock full colour LCD
      • Solution: Reverse-engineer the stock screen to work with an alternate mainboard
        • Issue: The effort and equipment required to reverse-engineer the pinouts is likely not worth the time and effort
    • Issue: The stepper driver vrefs and/or current values are not officially published
      • Solution: Gigdigit has published stepper currents for the motors, based on their quiet board.
• Issue: The stock 30mm hotend fan can become loud when part cooling is set to a high level
  • Solution 01 : Use a 40mm fan with similar static pressure and airflow properties.  The fan can spin at a lower rpm, to achieve the same cooling, which will result in lower sound
    • Issue: The stock hotend and E3D v6 style hotend fan shrouds are not designed for 40mm fans
      • Solution: 3D print an adapter
      • Solution: 3D print an alternate 40mm compatible shroud
  • Solution02: Use a 50mm fan with similar static pressure and airflow properties.  The fan can spin
    at a lower rpm, to achieve the same cooling, which will result in lower sound.
    • Issue: The stock hotend and E3D v6 style hotend fan shrouds are not designed for 50mm fans
      • Solution: 3D print an adapter
      • Solution: 3D print an alternate 50mm compatible shroud
• Issue: The stock 40mm case fan runs relatively loud during printing (and homing sequences)
  • Solution 01 : Use a 50mm fan with similar static pressure and airflow
    properties.  The fan can spin at a lower rpm, to achieve the same cooling, which will result in lower sound
    • Issue: The case is not designed for a 50mm fan
      • Solution: Cut/drill an opening and mounting holes for a 50mm fan
      • Solution: 3D print an adapter

  • Solution 02: Use a 'quiet' 40mm fan such as a Noctua fan
    

Objective 3: Minimize cost

• Issue: Hardware upgrades can be expensive
  • Solution 01: Use stock hardware when possible, upgrade only if required
  • Solution 02: Use low cost components for upgrades/modifications
    • Issue: Low cost components can be of lower quality, and may fail prematurely.
  • Solution 03: Use components on hand/in inventory