• aditya mehrotra.

filament updates: making parts of the frame, installing the motor, and printing some parts [updates]

So today after work, I started working on getting the filament extruder through the first initial stages of its build. This includes taking the wheel motor off of the old pathfinder robot platform, mounting it to the base of the wooden frame from science olympiad competitions in high school using some squaring technique at least.

But here's the deal/the plan. What we're going to do is - little by little, put together a prototype of the filament extruder based off of the RepRap recyclebot but not exactly based off of that. It uses a lot of similar parts - and we aren't logging the build too much in detail because if you want to make one or if we want to remake one, there's the reprap instructions. Basically, right now what we have is a 3/4" metal tube with Kapton Tape around it and a bunch of nichrome wire wound around it as well, then another layer of Kapton Tape. We have the auger we're supposed to use which is a 3/4" auger. We 3D printed a coupler between the motor and the auger and now we're working on 3D printing some of the rep-rap recyclebot parts out of ABS.

So here's the plan. We're going to start with mostly RepRap 3D printed parts and design - the code we're going to do ourselves. But the general idea is that we'll start with the RepRap and then as we get the extruder working we can start to generate our own designs, extend the hopper, and etc.

The other components we're going to add are a large fabric hopper to hold the tiny plastic pellets. We're going to use a shredder for now, like a normal paper shredder to put the plastic into little pieces.

So let's list out the next steps for what we're going to do:

(1) Go to Home Depot, and get a Dremel bit to cut off the end of the auger and some fiberglass insulation, and an angle bracket. 
(2) We need to wait for the 3D prints to finish and for the rest of the amazon packages to show up.
(3) Then we need to finish assembling the extruder nozzle.
(4) Put together the 3D printed parts to assemble the hopper and the rest of the system.
(5) Then we need to do the electronics and start working on the programming.

So here's the initial idea for the programming. I'm thinking about just USB-ing an arduino to my desktop computer and from there we'll just use pyfirmata and arduino firmata to code everything. Then we'll make a python GUI app that runs the right speed and temperature of the extruder - just based on selecting the type of material we're feeding into the system.

That last package should show up today so we won't be waiting on anything anymore. WE also want to go check the TORQUE rating of this motor just to make sure we likely won't burn it out. So the rated torque of the motor is 10kgcm which is about 1 Nm - which means 1kg weight at 1 meter away - I think that should be more than enough torque? I guess we will find out.

I'm also in the process of collecting the electronics I need to do this. It it also possible we'll need more winds of nichrome around the thing we've made - we didn't measure them right now. But we shall try and see what happens.

The other thing I'm doing is drawing some basic circuit diagrams. That's how the heating system and the relay will play into the circuit. There will be a motor controller, arduino, thermistor, and a few other components as well. But all-in-all this is not a very complicated design. And to control the temperature we'll probably use bang bang control, and for the motor speed, we'll probably use PID. We just need to find like a 10-20A 12v power supply and we have to have one lying around (or we'll use a battery).

#updates #omgrobots #filament

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