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Assembling Delta Effector:MOST
|By Michigan Tech's Open Sustainability Technology Lab.
Wanted: Students to make a distributed future with solar-powered open-source 3-D printing.
|This page is part of an international project to use RepRap 3-D printing to make OSAT for sustainable development. Learn more.
Research: Open source 3-D printing of OSAT • RecycleBot • LCA of home recycling • Green Distributed Recycling • Ethical Filament • LCA of distributed manufacturing • RepRap LCA Energy and CO2 • Solar-powered RepRaps • solar powered recyclebot • Feasibility hub • Mechanical testing • RepRap printing protocol: MOST• Lessons learned • MOST RepRap Build • MOST Prusa Build • MOST HS RepRap build • RepRap Print Server
Materials and Tools
The end effector is the part that moves the extruder hot end around the build volume. The printed end effector part is PLA, which if not cooled, will soften under the heat produced by the hot end. A 40mm square fan cools the end effector, the heat sink on the hot end and also the part being printed. The fan will run whenever the printer has powered applied, even when not printing, to ensure that no damage is done to the end effector.
The hot end must fit tightly in the end effector and getting it to seat can be difficult. Once seated, the hot end is kept from sliding by an M2 x 12mm screw - do not skip that step!
The extruder is a Bowden cable design in which the filament is constrained in a low friction PTFE (teflon) tube. Filament is pushed on one side by the extruder drive and only permitted to exit out the 0.5mm orifice in the hot end. The Bowden sheath (the teflon tube) has a 2mm inside diameter that permits the 1.75mm filament to slide through easily. When plastiforming threads in the teflon tube with the Bowden sheath retainer (M4 hex nuts), the inside diameter of the tube collapses, causing friction or outright blocking movement of the filament. It is imperative that you ream the tube (step detailed below) with a 2mm drill bit while plastiforming threads into the sheath. It is likewise imperative that any teflon chips that might be left in the tube after reaming be removed prior to inserting the tube in the hot end. Teflon doesn't melt, and chips left in the tube will block the hot end nozzle.
- Repeat with the opposite end of the Bowden sheath, except thread the nut just past the tapered portion of the tube and then cut that tapered end off flush with the M4 nut, leaving the nut in place.
- Carefully bend the thermistor and resistor leads on the hot end towards one side of the hot end.
- Feed the large conductor (heating resistor wire) through the large opening in the base of the effector and push it through the hole in the back of the effector so that it extends out the top of the effector. Remove any twist in the conductor. Pull the conductor from the top of the effector until the hot end is partially within the effector.
- Place the M4 nut in the pocket located in the top of the interior of the printed end effector.
- The slot for the hot end is purposefully tight-fitting; considerable force maybe required to fully insert the hot end in the slot. Be careful to minimize straining the conductors and assure that the retainer is not in the way of the hot end.
- Thread the 12mm-long threaded end of the Bowden sheath into the end effector. A full 12 to 14 revolutions will be required to thread the sheath into the hot end. Do not over-tighten the sheath or the end will be deformed, impeding the filament.
- Only two M3 x 12mm screws are required to affix the fan to the end effector: Place the fan over the opening with the wires exiting the fan towards the top of the effector and the fan spider facing the interior of the effector. Align the fan's mounting holes with the holes in the fan opening and plastiform M3 x 12mm screws into opposite corners of the fan.
- Secure the fan, thermistor and heating resistor wires to the Bowden sheath with a small wire tie immediately above the Bowden sheath opening.
|Tandem Build MOST Delta Navigation|
|Green indicate workshop tasks|
|Soldering and tinning|
|Assembling hot end|
|Drilling Pilot Holes|
|Person 1||Person 2|
|Tie Rods and Pulleys||Epoxying Magnets|
|Motor End Assembly||Idler End Assembly|
|Extruder Drive||Mount Bases|