My quick and dirty extruder

Hello all. I just found this 3d printing stuff by accident last week when surfing for something to do on the hack a day website. It got me interested right away and I would like to build a reprap for myself. I have plastics processing training from a college and worked in injection molding for about 7 years running a shop before I decided to try something new. So I have a working knowledge of the business and thought that maybe I could contribute by making feedstock for reprapers in exchange for parts to make my own unit.

I built this extruder in about 2 days so it needs a fair amount of refining. I did not want to spend a boatload of cash on a prototype. It uses a Hilti 3/4" masonary bit and a sched 80 pipe for a barrel. The screw motor is a windshield wiper motor. I got the idea from a fellow that made a similar unit for extruding plastic plant media. The feed area has a water jacket to stop bridging in the throat and the die is just a stainless pipe plug that was kicking around. I was able to run some HDPE with a melt index of 5 just this evening. There are a bunch of things that will need to be upgraded. I plan on changing the wiper motor to a direct drive hydraulic motor so I can control the speed or if I can find a servo motor that will do the same for less money. The heating coil on the barrel needs to be switched to a proper heater band X 2 or 3. I need to add thermocouple wells to the barrel between the bands and get a couple of temperature controllers to run the heat. Then make a cooling tank and a haul off unit so I can control the diameter of the filament.
If any of you are interested in testing out some of my material when I get this up and running let me know. I have some access to HDPE and ABS as well as coloring. Unfortunately this material is made for injection molding so it is pretty runny. I can probably source some lower melt index material but I need to know what you are using currently.
Loren

Whoops just noticed I posted that in the paste extrusion forum. If a moderator could please move the topic to the appropriate location please ..

Looks good! Can you resize that so it fits directly into the Darwin/Mendel/Huxley?

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Generation 7 Electronics	Teacup Firmware	RepRap DIY

I doubt it. Its for making the filament for the printers not for the printer itself. I have changed it to a hydraulic motor and switched over to heater bands with a proper controller now. I ran some abs and hdpe yesterday. It seems to be working good now. Today I plan on building the cooling tank and the take off unit that pulls the plastic rod to make it the proper diameter. The winder is going to be the difficult part. The problem is as you wind the roll, the filament will get pulled faster and faster after each layer and that will cause problems with the diameter of the filament.

Hey Loren

Perhaps the winder can work on a tension base? ie - keep the tension of the winding constant which will keep the tension on the plastic constant.

just a thought

Could work if I had something like that after a take up unit that sized it to begin with. As the extruded material comes out of the nozzle it is so weak that it takes barely any tension to change the thickness. That might change once I get the proper material to begin with.

I will post a video once I get it running good - not sure if this site will allow a quick video (size wise) but ill figure that out when I get there. I have attached a pic with updated stuff. Might be a bit hard to make it out. The iphone has a crappy camera on it.

The green pump hanging off the side is from a john deere swather, I got the hyd motor from local princess auto (harbour freight-like store), the heater bands and controller are from a local shop that specializes in electric heat. My total build cost was about $50 using stuff kicking around the shop/farm until I changed over to the proper heaters, controller, and hydraulic motor with speed control. Now its over $600. So hopefully I can recoup the costs once I begin running the filament.

My side business is manufacturing hobby greenhouses and I have lots of scrap lexan polycarbonate sheeting that I'd like to try and recycle into filament. Its pretty dry here where I live so I am hoping I do not have to dry the material before processing it but if I do then I have some ideas for that too. Have any of you tried to run polycarbonate in the printers? All I have seen so far is hdpe, pla, abs, pp and pvc.
Loren

Had it running for about an hour today with my home-made take up unit. I managed to produce quite a pile of scrap filament. See pic. I need to rework the barrel and screw setup into one piece. The two separate halves are not perfectly aligned and cause a slight binding when the screw turns. This makes the plastic pulse ever so slightly and makes the line thick and thin as it runs.
Loren

Quote

keep the tension of the winding constant which will keep the tension on the plastic constant.

As the diameter of the spool increases as it fills, the force on the plastic will decrease. To get a constant force, you want something which grips the filament directly, similar to how the Mendel extruder does. With rubber wheels, as the required force is low, and you don't want to damage the fresh filament.

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Generation 7 Electronics	Teacup Firmware	RepRap DIY