Fab@Home:Plastic Tool

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1 Plastic Tool System Part 1 of 5: The Plastic Tool
2 Assembly
- 2.1 Acrylic Body Assembly
- 2.2 Heater Assembly

Plastic Tool System Part 1 of 5: The Plastic Tool

In this part we will build the plastic tool itself. It will be wired up in part 3.

On Hand Assembly Tools and Parts for Plastic Tool

Soldering iron for Thermoplastic inserts and soldering
1.27mm Hex Driver
2.5mm Hex Driver
3mm Hex Driver
5/64" Hex Driver
Needle Nose Pliers
Loctite (Blue)
Wire Strippers
Multi-Meter
18 AWG wire
Drill Press/Cordless Drill
1/2" chamfer bit / 5/16" drill bit

Bill of Materials

Plastic Tool System BOM

NOTE: With the 1" wide Kapton tape, you may need to cut it down to 1/2" here sometimes to make things easier.

Acrylic Parts

You can download the DXF files for the Plastic Tool System here and cut them out on a laser cutter:

Plain DXF Files
Cut compensated for Epilog Helix 35W laser engraver DXF Files

You can also use Ponoko to cut out all of the acrylic parts for the Plastic Tool System for you here

SolidWorks 2009 assemblies and part files of the Fab@Home Model 2.0 with the Plastic Tool System
Also contains laser cutting layouts in Solidworks 2009 drawing files.

Fab@Home Model 2 CAD with Plastic Tool System in Parasolid Format

Assembly

Acrylic Body Assembly

Insert Thermoplastic Inserts with soldering iron in the same manner as the chassis inserts were inserted
1. Back plate: (Side in which inserts are inserted is important: see image)
  [4x] M4 Threaded Inserts
  [2x] #6-32 Threaded Inserts
2. Tool Mount Back plate:
  [2x] #6-32 Threaded Inserts
Press Fit Bearing: (Side in which bearing is press fit is important: see image)
[1x] 4mm Ball Bearing, 8mm O.D.
Use Pliers or a Vise with a piece of scrap acrylic so less pressure is put on the bearing
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Glue Idler Roller to Bearing
[1x] 4mm Ball Bearing, 13mm O.D.
Center the Acrylic halfway on the width of the pulley and glue along edges with Loctite. Use 3 washers stacked along the roller to space this out approximately.
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Secure the Back Plate to the Tool mount Back Plate via Tool Mount Spacer with #6-32 screws
[4x] #6-32 screws 1/2"
Use washers as necessary to keep the screws from protruding out the back of the tool mount back plate.
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Secure the SNAP motor to the Motor Plate with M2 screws
[1x] 62:1 SNAP motor
[4x] M2 screw 12mm
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Place the Motor Retainer Plate on top of the motor plate, with M4 screws holding it in place
[4x] M4 Screw 35mm
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Place a Retainer Plate on top of the motor retainer plate, with the M4 screws holding it in place
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Place a the smaller half of the filament guide Plate on top of the retainer plate, with the M4 screws holding it in place
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Put the pulley on the motor output shaft. Make the end of the pulley flush with the filament guide plate.
[1x] 4mm 17 tooth Pulley
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Carefully remove all plates, making sure to not move the pulley from its position. Once all plates are off, loctite and tighten set screws.
Put all the plates back on, per steps 6-8. This time including both halves of the filament guide plate
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Using an M4 screw, attach the idler roller with spacers
[1x] M4 screw 35mm
[2x] washer
Attach the parts in this order from the motor retainer plate: acrylic spacer, idler roller, acrylic spacer, washer, washer.
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Insert a M3 hex nut into the larger half of the filament guide plate. Place a Retainer Plate on top of the filament guide plate, with the M4 screws holding it in place
[1x] M3 Hex nut
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Insert the 4mm shaft into the pulley. Place the back plate on top of the retainer plate
[1x] 4mm shaft 25mm
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Insert a M3 hex nut into the back plate. Tighten an M4 nut on to the idler roller screw. Thread on a little bit the M4 nuts onto the four corner M4 screws. Attach the tool mount assembly from step 4, by tightening the corner M4 screws
[1x] M3 hex nut
[5x] M4 hex nut
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Insert a M3 hex nut into the motor plate. Insert the M3 30mm long screws into the insulator plate. Secure the insulator plate to the bottom of the assembly with the M3 14mm long screws
[3x] M3 screw 14mm
[2x] M3 screw 40mm
[1x] M3 hex nut
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Heater Assembly

Chamfer the untapped end (the 1/8" hole) with a 1/2" chamfer bit, or an equivalent drill bit (such as a 5/16") about a 12mm depth (.25"). You can use either a drill press or a cordless drill
[1x] PTFE Insulator
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Insert the insulator into the insulator plate with the threaded end facing out
[1x] PTFE Insulator
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Tighten the large washer against the insulator using the M3 hex nuts as pictured.
[1x] Large Washer
[4x] M3 hex nut
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Screw the brass heater barrel into the insulator, plain end first. Thread M6 thin hex nut on heater barrel up to the large washer. Thread on Nozzle
[1x] Brass M6 heater barrel
[1x] M6 Thin hex nut
[1x] 0.5mm brass nozzle
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Measure out a 30cm length of Nichrome wire. Strip each end and measure the resistance of the wire. We want 6 ohms, so cut down the wire in small increments down as necessary until this resistance is met plus/minus 0.10 ohms
[300mm] 30AWG Nichrome wire
[2x] crimp terminal
Crimp the ends of the Nichrome wire in the terminals with pliers as pictured
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Measure out two, 1 meter lengths of 18 AWG wire. Strip all ends. Crimp one end of each wire into a terminal on the end of the Nichrome wire
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Solder these terminals as shown and wrap in Kapton tape
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Cut a 5 foot length of K type thermocouple wire. Strip each end as shown. On one end twist the wires together to make a thermocouple
[5 ft] K type thermocouple
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Wrap the Nichrome wire around the Brass heater barrel starting from the nozzle as pictured. Wrap in 1/2" Kapton tape
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Tape the twisted end of the thermocouple wire to the nozzle as shown with 1/2" wide Kapton Tape. Then tape the wire to the barrel.
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From the roll of ceramic insulation, cut a 20mm by 150mm strip. Wrap this strip tightly around the heater barrel and shown with Kapton tape.
[1x] Roll of Ceramic Insulation
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Rout the wires through the gap between the back plate and the tool mount back plate. and secure with Kapton tape as shown
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