Part 2: Building Filament Extruder
In the first post, we discussed the viability of making filament at home. As much it’s to save money on filament but we also want to help local plastic recyclers who shred, wash, and convert the plastic scrap into pellets. We mostly print functional parts and rapid prototypes, 80% of the stuff we print ends up in the trash. This might help the environment if we managed to recycle it into filament again locally by mixing it with 30–40% virgin pellets.
Filament Extruder Line has 4 parts:
- Extruder
- Water Bath
- Puller
- Winder
So, let’s start building them one by one in future posts:
Extruder
Main components you require to build extruder are:
- Screw, Barrel, and Nozzle
- Motor, Gearbox and AC drive
- Band Heater, Thermocouple, Temperature controller
Screw, Barrel, and Nozzle
I am not a machinist so I had to buy this from a supplier. The local suppliers were quoting me a ridiculous price like $1000-$1500 for a screw/barrel set.
You’ll need a 25mm screw diameter with 400–500 lengths and a barrel. This is the most expensive part of the machine.
You can buy it from this website, they’ve provided me good quality screw/barrel. I also bought the nozzle from the same website.
Notice that the barrel has a slot there, we’ll mount a 3d printed Hopper there which will be made from PETG.
Cost: $350–400 (new)
Motor Sizing
1 HP motor per 5kg of ABS. I suggest starting with a 5kg/hour line.
3 phase 4 Pole AC induction motor.
How do you find this motor? 4 pole motor at 60hz, is 1800 rpm rated. So read the label of the motor if you find it in a junkyard. Or you can look for it on eBay or post an ad on a local classified website for a used motor. These motors are used in water pumps, shredder, etc… so you can find them anywhere.
Cost: $100 (new)
Gearbox
15:1 or 14:1, you can use worm gearbox as they are cheaper but Helical Inline Gearbox is more efficient and but they cost more.
While buying a gearbox make sure it’s rated for the power your motor is able to provide and that it has a suitable bore or shaft for your motor’s shaft.
Cost: $125 (new)
AC drive
This is used for motor speed control. Once we’ve geared the motor down, we’ll have a range of speed available from 0 rpm to <100 rpm, now if you want to select 30RPM that will be possible using AC drive. You just buy a 3 phase AC drive that’s rated for double the motor’s horsepower, I don’t have much experience with these but that’s what my friend suggested me.
Cost: $150 (new)
Band Heater, Thermocouple, Temperature controller
I bought mica band heaters. You’ll need 100–150W band heater and 3 of them for 5kg per/hr line.
The thermocouple you need is a standard K type thermocouple.
The temperature controller is the REX-C100 temperature controller.
Each controller/thermocouple set I found for $20.
Most DIY extruders use 3 zones for heating that means you’ll require 3 of each controller, thermocouple, and heater.
$20*3= $60 for 3 controller/thercomouple/SSR, and $15 for 3 heaters.
Cost: $75
Putting it all together
Notice the below unit has 4 heating zones, usually, 3 are enough. Notice the 3 display units, those are PID controllers REX C100. There you’ll set the temperature for melting ABS. We’ll talk about setting the temperature in future posts. The knobs below the controllers are used for setting temperature. And the knob at the end with markings is used for controlling motor/screw speed, it’s connected to the AC drive.
Barrel Insulation
The heaters heat the barrel wall, the barrel wall conducts heat to the plastic that is carried from the hopper by screw. We can reduce power consumption and reduce temperature fluctuations due to the rapid loss of heat by the insulating barrel.
You can buy fiberglass bandage roll and wrap it around the barrel several times, fold the long strips of aluminum foil multiple times to create a multilayered bandage, now wrap it around the fiberglass insulated barrel, finally tie it all down with a layer of Kapton tape.
You can use ceramic fiber, super wool, or cms wool — if it’s available where you like, I didn’t find it so I went with exhaust pipe insulation that I found at an automotive supplier.
Cost Saving
Buy heavy stuff like gearbox and motor locally, you can get them at 20% price if you buy them used.
But this is the most expensive part of this machine, puller/winder will not even cost $100 combined. That we’ll discuss in future posts.
