Ceci est une ancienne révision du document !
All of the previous stuff was pretty easy. This is where things start getting a bit more difficult.
Nozzle assembly
This is the heated nozzle that I spoke about earlier. During printing, this nozzle will be heated to about 200°C. Attached to the nozzle is a metal block with two holes through it. Through the small hole we will (later) be putting a temperature sensing component, and the larger hole will hold the heater.
Bowden Tube
The bowden tube is the tube that will connect the nozzle and the extruder. This is, quite probably, the most hair raising, and tricky, part of this assembly. You need to widen either end of this tube. You must use a slow drill, and a drill bit of exactly 2.5mm. Any other drill bit will mess this up. So it must be the right drill bit, and be done with a slow and steady hand. You drill about 10-15mm into the tube. The idea being that when you screw the tube into the nozzle, the internal diameter of the tube would shrink. Since it’s been drilled, it will shrink to the proper size. Same idea with the other end when you screw the little brass piece onto it.
Thermistor
The thermistor is used to sense the temperature as close to the nozzle as possible. Remember that hole in the metal block I mentioned? Well, we need to take some heatshrink, shrink it round the thermistor, and later we’ll put the thermistor into that hole in the block.
Hot End and Effector
With lots of other heat shrinking and what-not (I won’t bore you with every detail), it’s time to assemble the effector and heated nozzle.
This is where the thermistor goes into the small hole in the nozzle block, the nozzle gets pushed into the effector, the heater goes into the larger hole in the nozzle block, the supplied fan gets clipped, and screwed, onto the effector, and a cable tie or two to keep things neat.
Wiring
This is where things need to be double and triple checked. The wires from the heating element, the fan and the thermistor go to a small socket. The wires must be in the right sockets or there will be bad problems!
Now the effector can be mounted on the rods.
Electronics
Now it’s time to get cabling.
There are several cabling looms that we must run up the inside of (what I call) the back panel.
First, we need to microswitch the panel. Same as the other two.
Again, I won’t bore you with every detail, but several looms are cable-tied to the inside of the panel, the extruder is mounted to the top of the panel, and the panel is screwed to the printer.
Now, this is where I hit my first problem. The Duet board inlet/outlets didn’t match up with the holes in the panel. I ended up having to cut some pieces of rubber to make risers to have the Duet’s power, network, and card slots match the panel. Normally that wouldn’t be a problem, except only after I’d done a ton of wiring did I notice this. So, when you fit that last panel, check your Duet sockets before going further.
The looms are connected to the microswitches at the top, the bowden tube goes to the extruder, and the other ends of the looms go to the motors at the bottom.
The bed will sit on springs and touch screws that are on side pieces. These side piece screws are all linked together to form a loop, and when a screw on the bed is/isn’t touching the side piece screws, the printer knows where the bed is. After installing those wires, it’s time to fit the power jack and connect up everything to the Duet board.
The wiring diagram is an ominous sight, but be careful and you’ll be OK as most looms can only connect to one place. Worst case scenario here is that your X motor becomes Y and such like.
The bed of the printer is a plastic disc with a sheet that your hot filament will (hopefully!) adhere to.
As mentioned before, the bed sits on springs and has a screw in either corner to bring it into contact with the side pieces I also mentioned earlier.
There is a spigot to let you put the roll of filament onto the printer. I did attach this, but rarely have the spool on here. I usually leave the spool on the desk beside the printer. There’s also a top plate which I didn’t fit as I like to have my filament coming from above and down into the extruder.
Drive Belts
After fitting more, incredibly tiny, screws into the pulley wheels, they fit to the three base motors.
So how do the motors move the carriages? Drive belts. The drive belt is fed up through the carriage, up over the idler (at the top), down over the motor, and back into the carriage where it is wedged into place. But with a twist. No, not a plot twist, a twist in the drive belt.
With all that done. It’s time to commission and begin printing. But we’ll leave that for next month.