Archive | September 2012

Cleaned up the Prototype

We met up on Saturday and worked on cleaning up the concept 3 prototype. The front panel has the temp controller and the nob for controlling the spool motor. The screw motor is set to run at full power all the time.  A fan has been added to help cool the filament as it exits and will prevent the filament from stretching.  It looks much better now. All it needs is some paint and it would be slick.

HDPE filament

We made some HDPE filement on Sunday. We need to work on its consistency. But its a step in the right direction. Next step is to try printing with it!!

It works!!

We met on Sunday and did some testing.  We got the filament to extrude out at a good rate.  We initially had some issues with the power of the new motor we got. We let the extruder heat up and has to run the motor at a higher voltage than suggested.  Once we had some movement the voltage was set to 12V and it ran good. There are a few pictures below and a video of it working. Also, the video has some footage of the strength of the filament.

Things to do

  • Upgrade motor- we need a little bit more torque
  • Mount Fan- this will help the filament not stretch out
  • Clean up the prototype
  • Put the spool motor back on

Evolution of our design

Our design has evolved a lot of the past few months. We started with a 3″ pipe and plunger design and have ended up with a 1″ pipe and screw design. 

Left: The left most design in the picture above is our first design based on a melt flow index machine.  We would use a 3″ pipe as the cylinder and push the plastic through using a piston. We decided to use a pineapple during this design to help melt and mix the plastic. The initial pineapple was made from a huge threaded steel rod. It was hard to find any 3″ steel around and that was our only option.  We also had a valve in the design to turn on and off the flow of plastic. But we scrapped this later because the nozzle was not heating up.

Center: Our next design was still a piston cylinder design but with some adjustments. We actually broke the cnc mill we machined our first prototype on. We over extended the X axis and got it stuck. So this design our goal was to make the biggest piece fit within the area of the mill we would be machining everything on. The original height of the side pieces was 32″ (which is the limit we could machine), so we shortened it up by dropping the spool down and making the height of the pot lower.  This brought the height down to 28″, which was much safe for us to machine. The original had two smaller fans mounted to the side next to the nozzle. We went with one large fan located in the back. another big improvement was adding tabs to all the wooden pieces. This will help with the strength of the structure and simplicity of assembly. The first prototype is held together with wood glue and finish nails. Now we just need wood glue.

Right:  This is our current design and what our second prototype is based on.  This has the same height as the last revision but the extruder assembly is lower. This allows for the top section to be used as a hopper for plastic. The width of the side panels is an inch thinner due to the limits of the mill. The extruder assembly consist of a double threaded 1″ pipe, 2 caps, a 1″ wood auger, 12V dc motor,AL pineapple, and a nozzle. The design allows for the extruder assembly to be removes easily. This will allow the extruder Assembly to be designated to types of plastics or colors and changed out when switching plastics. A box was added to the side to house the electronics.

I am making a video to show the evolution of our design and point out the features that changed.

Twitter page

We have a twitter page now. So follow us and stay up to day on all the little things.

We are on twitter!!

We have a Twitter page now. Follow us and stay up to date on all the little stuff @OSPrinting

Small Poll on Materials

I just wanted to see what people might be interested in the future in terms of materials.