Thermoplast Extruder Variations
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This Page Contains multiple RepRap development projects and should be split up. Each individual project/design/improvement should have its own development page within an encompassing category.
Release status: Unknown
| Description | |
| License | unknown
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| Author | unknown
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| Contributors | |
| Based-on | |
| Categories | Thermoplastic Extruder 1.0
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| CAD Models | |
| External Link |
Contents
Design
- Direct Drive -Does not use flexible steel cable
- No-support gear bush holder
- High-temperature heater design
- Very simple nozzle
- Nozzle valve
- Embedded bearings
- Hardware Store (HS) Extruder
- Geared - Goes slower, but provide more control on the amount extruded
- Grub Screw in lower end of PTFE Insulator to help hold the brass barrel when using higher temperatures
- Drive screw can be smooth for most of it's length. It reportedly only needs about 7 complete threads to dig in, the rest just add friction.
- Quick and dirty design - Needs more work
- Welding tip nozzle v2
- Welding tip nozzle v3
- Simple star screwdriver drive - works OK, needs refinement
- Coach Bolt Drive hack
Materials
Barrel
- Machined out of a brass bolt.
- Aluminum has been used successfully.
- Combination of stiff copper tubing and copper plate brazed together was used by Forrest Higgs.
Orifice
- Mechanical pencil tip was reported to have heating problems.
- 0.6mm MigMate Welding tips from Halfords (5 for 4.99) - work ok when drilled out to 3mm, premade 0.6mm nozzle with m5 thread
Barrel dielectric material
- Furnace cement is now the officially recommended material.
- Both High-Temp JB weld and bar-b-que paint degrade after a hundred hours or so.
Pump
- Piston Pump
This could handle a liquid, slurry or paste, and even small pellets. Pistons can be either single acting, pushing material through a one-way-valve only on the out stroke, or double acting, having one-way-valves on each side and pumping on both the out and in strokes. There can be 2 or more valves working in sequence to provide a more consistent pressure and rate of delivery. For liquids or pastes, the feed to the piston would also be a one-way-valve, such as a flapper valve. For pellets, it would be easiest to use single acting pistons with an opening on the top at the end of the pull back stroke so that fresh pellets could fall into the now empty piston chamber. Depending on the amount of pressure exerted, heat would also need to be applied.
- Gear Positive Displacement Pump
Two identical gears in a figure 8 shaped cavity expel all the liquid (or particles) between the gear teeth when they mesh, but move the material around the outside in the small cavities between the gear teeth and the sides of the chamber. Automotive oil pumps work this way to push the oil out under high pressure to squeeze through the entire engine.
Insulator
- Originally designed to be made from PTFE (Teflon
- PEEK (w/o fiberglass reinforcement is reported to work) Make Thermal Barrier With Drill Press
- Concrete has been reported not to work (tried by vik, who still hasn't supplied details)
- Drywall mud (shrinks and cracks horribly, tried by John Gilmore)
- wood - apparently university of washing ME department is using it successfully
