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    element14's The Ben Heck Show

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    Super Glue Gun
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    The team at the Ben Heck Show values Community input. Here is the current plan for the super glue gun project. Leave any questions, comments, or recommendations in the comments below.

     

    Overall Design:

    Features:

    • Heats up quickly
    • Anti-drip retraction
    • Motorized extrusion w/ analog speed control
    • Automatic stand

     

    Other Design Factors

    • Target audience: Serious crafters, makers, and craftsmen with LOTS of hot gluing to do.
    • COST: We are aiming for the sale cost of the glue gun to be around $99. This means that all parts should come to a cost of under about $30.

     

    Components

    Hot End Extruder

    • Design restrictions/considerations:
      • Needs to reach a certain temperature (Low-temperature glue guns operate at approximately 120 °C (248 °F) and are well suited when high temperatures are undesirable, such as gluing lace and cloth. High-temperature guns operate at approximately 190–210 °C (374–410 °F) and produce a stronger bond.)
      • Temperature falloffs
      • Safety limitations
    • Ideas:
      • Repurpose from another gun
      • Find a stock part we can use
      • Make our own? 3D printer parts?
      • This is certainly something we could use help with.

    Extruder Motor

    • Design restrictions/considerations:
      • Size: must fit in case without inhibiting a comfortable grip.
      • Power consumption limits
      • Force required to extrude glue
    • Progress:
      • We found a pancake shaped motor that runs at 50 RPM and 12 volts with a 5mm shaft.
      • It has enough torque to extrude hot glue even at full speed.
      • It's smaller so we could mount it sideways (not through the handle) giving us more room inside the handle for power supply, electronics and trigger.

    Microcontroller

    • Design restrictions/considerations:
      • Cheap
      • Small
      • Robust
      • Fast boot
    • Progress
      • Did much testing with Atmel ATTINY20
      • It has plenty of IO including many ADC's for sensing temperature, control dials and trigger.
      • Developing code with Atmel Studio.
      • Using low-level hardware timer to drive PWM for motor.
      • Could possibly use a pair of timers to control motor speeds in both directions.
      • Decent amount of flash for program (a whopping kilobyte!) so we could include many speed and temp options.
      • MCU allows us to use a cheaper/simpler motor controller, perhaps our own h-bridge if that's less than a dedicated IC.

    Power Supply - THIS IS THE NEXT STEP

    • Design restrictions/considerations:
      • 120VAC to 12VDC (motor) and 5VCD (logic)
      • Should have an option to work at 220V 50Hz as well
      • Must fit inside handle
      • Must be cheap.
    • Ideas
      • We have some sample packages with 5 and 12 volt lines, but the 12 volt current capacity is a bit under our spec and exceeding it browns out the 5VDC causing a MCU reset.
      • Ultimately we want a single PCB in the handle with everything, but we can use existing supplies to mock up a target spec.

    Trigger/controls

    • Design restrictions/considerations:
      • Manufacturable. Final product will not be 3D printed.
      • Capacitive touch to activate stand retraction
      • Force required to extrude glue
    • Ideas
      • TBD

     

    Automatic Stand

    • Design restrictions/considerations:
      • Need room for motor inside case
    • Ideas
      • TBD

    Case Design

    • Design restrictions/considerations:
      • Ergonomic/comfortable to hold
    • Ideas
      • Test design on 3D Printer
      • Final product Injection molded