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Esta página faz parte de um projeto internacional para usar a impressão 3-D RepRap para fazer OSAT para o desenvolvimento sustentável . Saiba mais .

Pesquisa: Impressão 3D de código aberto de OSATRecycleBotLCA de reciclagem domésticaReciclagem distribuída verdeFilamento éticoLCA de fabricação distribuídaRepRap LCA Energia e CO 2RepRaps movidos a energia solarrecyclebot movido a energia solarCentro de viabilidadeMecânica testesProtocolo de impressão RepRap: MOSTLições aprendidasMOST RepRap BuildMOST Prusa BuildMOST HS RepRap buildServidor de Impressão RepRap

Faça-me: Quer construir um REPrap MAIS? - Começa aqui! Visão geral da construção Delta:MOSTVisão geral da construção AthenaImpressora 3D de metal MOSTImpressora 3D de resposta humanitária a crises



Progresso técnico no prototipador rápido auto-replicante de código aberto ( RepRap) permitiu que uma forma distribuída de manufatura aditiva se expandisse rapidamente usando materiais à base de polímeros. No entanto, a falta de uma alternativa de metal de código aberto e os altos custos de capital e baixo rendimento de impressoras 3D de metal comercializadas proprietárias restringiram severamente sua implantação. As aplicações das impressoras 3D de metal comercializadas são limitadas apenas a prototipagem rápida e produtos acabados caros. Isso restringe severamente o acesso da tecnologia para pequenas e médias empresas, o mundo em desenvolvimento e para uso em laboratórios. Este artigo relata o desenvolvimento de uma impressora 3D de metal de código aberto de menos de US$ 2.000. A impressora 3D de metal é controlada por um microcontrolador de código aberto e é uma combinação de um soldador MIG comercial de gás e metal de baixo custo e um derivado do Rostock, um deltabot RepRap. A lista de materiais, esquemas de projeto elétrico e mecânico e procedimentos básicos de construção e operação são fornecidos. Uma análise técnica preliminar das propriedades da impressora 3-D e dos produtos de aço resultantes é realizada. Os resultados da impressão de peças metálicas funcionais personalizadas são discutidos e são tiradas conclusões sobre o potencial da tecnologia e o trabalho futuro necessário para a distribuição em massa dessa tecnologia.

Para a mais recente impressora 3D RepRap de metal MOST, veja isto

Novo software: Slicer e melhorias de processo para impressão 3D de metal baseada em GMAW de código aberto

Fonte

Gerald C. Anzalone, Chenlong Zhang, Bas Wijnen, Paul G. Sanders e Joshua M. Pearce, " Impressão de metal 3D de código aberto de baixo custo " IEEE Access , 1, pp.803-810, (2013). doi: 10.1109/ACCESS.2013.2293018 preprint de acesso aberto

Bill of Materials

ItemNúmeroCusto(USD)Fonte
Todas as 12 peças impressas a $ 40/kg$12.00RepRap local
Todos os Fixadores$2.00http://www.mcmaster.com/
Porca M390
Parafuso M3x10 mm12
Parafuso M3x12mm48
Parafuso M3x20mm12
Parafuso de fixação M3x8mm6
M3washer102
Porcas M86
Parafuso M8set3
Isolamento cerâmico de 152 mm x 152 mm1$ 4.00
Rods,bearings and tieshttp://www.amazon.com/
300mm x 8mm smooth rod6$25.00
304.8mm carbon fiber rod6$6.00
608zz bearings6$2.40
LM8UUbearings6$6.00
Small wire ties3$0.50
Tie rod end24$ 8.00
600mm T5 belt3$ 5.90http://www.polytechdesign.com/
241mm x 51mm x 4mm Aluminum plate3$114.00Local machine shop
NEMA17 Stepper motor (1.8 deg.,5.5kg-cm holding torque, 750mm wire)3$39.00http://www.kysanelectronics.com/
Mechanical limit switch3$3.33http://www.digikey.com/
Melzi Microcontroller board1$120.00http://web.archive.org/web/20160304170259/http://matterfy.com/
Millermatic 140 Auto-set MIG Welder with Cart1$836.00http://www.millerwelds.com/
Power supply1$8.00(Recycled)/Internet
Wires1$ 2.00(Recycled)/Internet
Total$1,194.13

Printed Parts

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Print these STL files on any flavor of RepRap. The red parts in the image on the right are the printed parts. The SCAD if you need it.

Construction

Note to Makers

If you have made a RepRap before this will be easy -- if you are not familiar with RepRaps or Deltabots like the Rostock - more detailed build instructions are available at the MOST Prusa RepRap build page and the Delta Build Overview:MOST. Those links will give details on how, for example, you can braid the wires or configure the Melzi/Arduino microcontroller.This concept, however, is not limited to this specific design and should of course work for most RepRap printers -- you just need the fire proofing and your own welder...good luck! If you get it to work - please drop us a line.

Initial Prep

  1. Prepare all the materials listed in BOM
  2. Print all plastic components on a RepRap
  3. Ream the M3 screw holes in each plastic part and clean out nut traps with a sharp knife, make it fit for all M3 screws and nuts

Single pillar build

Detail of bottom inside, showing placement of limit switch
Detail of bottom outside
Detail top
  1. Attach the motor and the base plastic with M3 X 10mm screws with washers. Insert two M3 nuts into the set screw nut traps in the pulley, loosely insert two M3 X 8mm set screws into the pulley. Push the pulley through the motor rods and fasten all screws.
  2. Attach the limit switch to its holder on the base plastic using M2 X 10mm screws. Add some epoxy to make sure the switch doesn't move. Ensure that the screw in the carriage engages the switch arm. Adjust this screw to set the position where the carriage engages the limit switch.
  3. Use drill or knife to clean the rod openings, insert 2 parallel 300mm smooth rods into the holes in base plastic, use M3 X 12mm screw with washers to fasten all the rod to immobilize the both rods.
  4. Emerge the LM8UU bearings into oil for lubrication, insert 2 LM8UU bearings into the slots in the plastic shuttle, and firmly tighten each bearing with two small wire ties. Slide the LM8UU bearings with the plastic shuttles onto each rods.
  5. Fasten the top end of the parallel rods into the top plastics with M3 X 12mm screws with washers. Use the M8 set screw and M8 nut to fix two 608zz bearings into the center holes in the top plastic.
  6. Pass one end of the T5 belt through and around one belt terminator and pull the tail of the belt through other terminator. Loop the end of the belt around the pulley. Loop the other end of the belt around the 608zz bearings. Attach one terminator to the plastic shuttle with LM8UU bearings with an M3 X 10mm screw with washer. Firmly fasten the terminators with a small wire tie.

3X

This ends the single pillar build. 3 pillars should be built in parallel. 241mm X 51mm aluminum plates are attached to both bottom and top plastics to make the frame a triangular prism shape.

Platform build

  1. Epoxy the tie wire ends to carbon fiber rods in both ends. M3 X 12mm screw and nut set is used to fasten the tie wire ends to the plastic shuttles. The other end is fastened to the plastic stage holder.
  2. Ensure the M3 screws are loosely thread through the hole in the tie wire ends so that it allows each carbon fiber arm to shift in all direction freely.
  3. 3 5cm long nails are thread into the plastic platform holder for supporting the 152mm X 152mm ceramic tray.

Electronics

Fig. 2 Wiring Diagram
  • For the wiring diagram see Fig. 2
  • Step motors and limit switches are wired to corresponding terminals on the microcontroller board, which is connected to Linux computer with a USB cable.
  • The board is powered with a recycled computer power supply.
  • To control the welder we use one of these relays attached to the RAMPS auxiliary i/o and power pins. Changing the state of the pins to which the board is attached changes the state of the relay assigned to the activated pin. The relay contacts are then wired in parallel with the trigger switch in the handle of the welding gun. Toggling the handle trigger or the relay will toggle the welder. This way the welder can still be used as it normally would when not attached to the printer...

Safety

  • Safety equipment is based off of standard MIG welding safety protocols

Work Area

  • Use your metal 3D printer on a flat surface isolated from water and flammable materials.
  • Verify that you have proper grounding with a metal on metal connection to your substrate.
  • Ensure your gas cylinder is secured to an upright support or cart at all times and only use gas hoses designed for welding.
  • Eliminate clutter from the work area as you will be raining sparks everywhere. Minimize the number of cables underfoot to avoid tripping.
  • Examine hoses regularly for leaks, wear and loose connections and replace faulty lines. Spray with a soap and water mixture. Bubbles will show leaks.
  • Ensure proper ventilation of work area. Welding fumes are hazardous. In a home garage leave a door or window open and run a box fan as an exhaust to remove fumes from your breathing area. We have also used masks.

Safety gear

  • Wear safety glasses at all times while in the lab.
  • When printing and/looking at the printer while printing wear a welders mask/welding helmet (auto-darkening or flip-shade with current ANSI certification) or look at it using a webcam. Do not watch the printer with unprotected eyes!
  • Use pliers to pick up the substrate after printing or thick leather gloves
  • Always wear flame-resistant lab coat and heavy duty leather gloves when handling the printed parts
  • Wear leather shoes - high-tops (steel-toes are a bonus).

Metal 3D printing exposes you to welding for longer periods of time than is normal for routine welding. You should ensure that all of your skin is covered by something to avoid "sun burns".

Operation

The stage is controlled like a regular RepRap Delta 3-D printer. For a primer on the nomenclature try this. Download Repetier firmware and host software, use Arduino to upload the firmware to the stage, and set up Cura on the host. This will work on any type of computer but we recommend the free and open source Debian.Models can be created and modified with any 3-D editor, such as OpenSCAD, Blender or a CAD application like FreeCAD (for a more detailed list of free open source CAD programs go here. The model should be exported as an STL file. That is loaded into Cura and sliced to a toolpath. It may take a few tries to get all the settings right. The GCode is saved to disk and opened with Repetier Host, which sends it to the stage. When the platform reaches the welding gun, switch on the welder by plugging in cable leading to the switch (which is to be held pressed with a wire tie).While the print is going, pay attention to the distance between the gun and the object. This should start out at approximately 7 mm and remain the same. If it increases, either decrease the layer height, or slow down the movement (this can be done during the print with Repetier Host). If it decreases, do the opposite.

Experimental features

While the whole setup is still highly experimental, some parts are more experimental than others. Some features are listed here that are being tested with various levels of success.Cura will attempt to adjust the "line width" of the deposited filament by changing its feedrate. Currently the welder does not support any such adjustment, so some parts get more material than they should, while others get less. To solve this, a plugin for Cura was developed which converts these feedrate changes into nozzle speed changes. The plugin can be found with the scad file on github.This plugin also supports adding in custom commands when travel ends or starts. This can be used to activate a relay for switching the welder power.

See also

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  • 3D printing of metal, open source and peanuts - Tom's Hardware

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