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Homemade All Metal Extruder

Posted by chuttney1 
Homemade All Metal Extruder
January 10, 2015 04:17AM

Some information on my printer. A prusa i2 with the arduino and ramps board. Fans on the X,Y, filament motor, and hotend barrel for cooling. Power by a 12V 30amp power supply. Using a 12V heater cartridge and a thermistor. I also have a milling machine and a lathe. Using 1.75mm filament.
Some information about the homemade barrel and hotend. Used E3D design for the barrel. Brass hotend barrel with nut and brass nozzle. Contains a PTFE liner from the top going in an half inch. Brass hotend barrel and PTFE liner is separated by a 2mm aluminum wall to butt the hotend barrel to the aluminum barrel for a tight fit.
My goal with this is to print all the high temperature plastic such as ABS and nylon.

A few weeks ago, I finished building an all metal extruder using the barrel design from E3D. I try to use as much of the existing parts from my prusa i2. Before this, peek barrel started to fail by bulging one side. I am currently testing with PLA filament and it's not going well. Filament gets soft while inside the barrel. Most recent test is with fans, but I am having a power issue using the fans and the heater cartridge at the same time. This limits the fan speed to all fans, but I do like to keep control over this while running my printer. My decision to use an aluminum barrel is base on its specific heat capacity which means it can take and give off more heat than other metals such as brass, steel, and copper. For now, I will rewire the fans to just have only one fan on the aluminum barrel and put the other on a sealed-SLA with a trim pot. I know there isn't the best material for a barrel, but the use of aluminum is giving me second thoughts because of the property I want is giving me a problem.

I have a few questions.
1. Any difference between using aluminum, steel, copper, brass for all metal hotends? How about PEEK and PTFE?
2. Any 24V controller recommendation?

Edited 1 time(s). Last edit at 01/10/2015 04:24AM by chuttney1.
Re: Homemade All Metal Extruder
January 11, 2015 03:09AM
1) Aluminum is best for the heatsink and heater block because it is light and has high thermal conductivity. The alloys you use matter too, stick with 6061, 6063, or 7068.
PTFE is a good liner for the barrel because it lowers the friction force on the filament. Don't run the PTFE into the hot zone, though, because it degrades at around 250C.
PEEK is expensive and kind of useless.
Brass is good for the nozzle, nothing else.

2) You can use a smoothieboard for 24V operation, I have one on my Rostock Max and it works great. You can also use 12V parts, and 12V parts work with 24V controllers (changes in firmware needed) but not the other way around.

Your design looks pretty good except for the part between the finned heat sink and the heater block. It should have low thermal conductivity and thin walls.
Also, it is preferable to use a smaller heater block. My hotends use a minimal heater block for very fast heat up times.
Re: Homemade All Metal Extruder
January 12, 2015 05:25AM
was discussed before ..

groove or grooveless hotend
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