In my previous post, I looked at the 3Doodler V2 pen, it's a great little product, both myself and my kids continue to have great fun using it to be crafty and creative.
The topic of more colours and materials soon came up as we continued to use up all the supplied plastic, this got me thinking about how to make my own straight strands of 3Doodling filament.
Making your own 3Doodling plastic:
On a practical note, the filament used for 3D pens like the 3Doodler does need to be straight. You may think that you can just use a normal coil of 3D printing filament, please don't do that, it will not allow the filament to rotate and so will put a lot more strain on the drive gear, basically killing it way before it's time. Without rotation the lifetime of the pen motor will drastically reduce, so if you want the pen to work well and for long enough to enjoy using it, then use straight sections of filament, specially designed for pens or alternatively make them yourself.
You can easily straighten out any 3D printing filament yourself, just follow these easy steps and you can experiment with other materials and suppliers. Please do this at your own risk, if you block up your pen or use a strange material that's up to you, if in doubt just buy the 3Doodler pen refill packs and play it safe.
Take a section of 3mm (2.85mm) PLA or ABS 3D Printing filament under 30cm long. I like to use two glass chopping boards for this next step. Hold the section of PLA by the end and heat it up with a hair-dryer or hot-air gun, about 5-10 seconds is all it needs to become soft. Then lay on the glass cutting board and place another glass cutting board over the top, roll the filament for a few seconds back and forth, it will be straight, round and cooled down, ready to use or cut into shorter sections if required.
"One of the reasons I have taken this apart is also to demonstrate how complicated the design and assembly of units like this are."
The top of the image above shows standard 3D printing filament sections cut to length, in the middle we have heat straightened sections compared to official 3Doodler packs.
Don't go too long, I know it's tempting to straighten a really long section, but it's easier and better for the pen to use sections under 30cm.
And do make sure you only roll one strand at a time, if you try to do multiple strands, they will stick together as shown above.
One question I have been asked is 'can you plastic-weld with it?' - Not really, thermoplastic cools quite fast, you can stick in the nozzle to help melt and fuse sections together, but it's not an ideal way to bond together two plastic parts. It's certainly not a repair tool for 3D printed parts.
Tear-down and hacking the 3Doodler:
As an engineer I needed to get inside the pen. Some time later... after my kids had gone to bed. I opened it up to take a look inside... But I don't want to break it - my kids would not be pleased.
Oh the joy of such master craftsmanship inside. This is an astonishing piece of engineering.
(NB: Open up your 3Doodler at your own risk).
There is a secret little cover on the 3Doodler V2 - take it off and you get access to some extra hidden pins for experimentation.
If you pop off the side hatch, you can see two rows of holes, the lower set is for remote control. You can connect up the 3Doodler foot pedal, make your own or use some other interface to control your 3Doodler pen.
You don't have to take the pen apart to connect to these pins, but I wanted to see how everything was assembled. The image above shows two 0.1" Molex KK pin headers, you can insert these (remove one pin) and start hacking your 3Doodler. The top row of pins is connected to the microcontroller, I didn't have time to debug exactly what they were doing, but it's most likely a serial communication port for programming, testing or running the pen in other modes.
Push in the pin headers and away you go.
Before you can get inside the 3Doodler V2, you need to remove the service hatch and also the rubber hot-end and button cover assembly. These just pull out, carefully.
It's well designed with nice touches like a good light guide that add to the quality of the 3Doodler over alternative 3D Pens.
After you also remove the plastic back plate, you can then just slide out the electronics assembly from the back, the aluminium cover fits perfectly with only microns of space to spare.
It's an incredible use of space inside that little pen. My only surprise was that the filament path is in a square channel, it has no liner. The filament does need to rotate, but I did wonder if a thin PTFE liner would help - maybe that'll be an enhancement I'll try at some point. It will need to be well fixed inside the case as it can't be allowed to get near the drive screw.
The motor gearing unit is astonishing, driving a tapered worm screw to feed the filament to the hot-end. It's interesting to watch the drive system running, after every button press a nice reversal move draws the filament back into the unit, minimizing ooze. That's the sound you can hear after you release the button. It's also a longer reversal than a quick press, so if you just keep on pressing the button quickly the filament will be reversed out completely. You can just press both buttons to reverse, but this seems to take longer.
The hot-end is also a well engineered design, limiting heat into the rest of the unit and using a very small kapton heater assembly with integrated NTC thermistor.
It goes back together easily, just take your time and insert gently back into the aluminium case. I'll appreciate the design even more now, just don't tell my kids.
I measured the operating temperature with a calibrated thermocouple sensor, because I really wanted to know why the ABS was not feeding consistently well.
High setting is for ABS and FLEXY:
Setting High and temperature adjustment turned down - 188 ˚C
Setting High and temperature adjustment turned up - 195 ˚C
This is quite low for ABS, and may explain some of the difficulties. Also note you have quite fine control with the temperature adjustment, I think it would be interesting to know if people actually use it.
Low setting is for PLA"
Setting Low and temperature adjustment turned down - 156 ˚C
Setting Low and temperature adjustment turned up - 169 ˚C
This may look low but is fine for most PLA. And it actually helps to keep it a little more solid, and cool quicker. PLA turns to the consistency of honey at over 200 ˚C and starts to break down quickly after 215+ ˚C.
I could see by the heater output, it is using bang-bang heating control rather than PWM. But it seems to stay stable enough for long time doodling.
I was delighted to see the use of an 8bit 8051 based microcontroller in the 3Doodler. It's a micro that I have used countless times in products for all sorts of industries.
This one is a N79E8132 from nuvoton and it's only available to the Chinese market. In my experience that means it's cost is going to be around $0.20. The rest of the design is wonderfully simple, no over-complicated or dedicated components for driving the motor, just old-school electronics design using more modern components. A big thumbs up from me.
One of the reasons I have taken this apart is also to demonstrate how complicated the design and assembly of units like this are. Often in the media we see 3D printing being talked about as making manufacturing processes obsolete; electronics, mobile phones and cars are all often linked to 3D printing, but the reality is that electronic components are millions of times more complex than any 3D printer can make. Injection moulded parts are thousands of times more accurate and faster than 3D printers produce. And any sort of magic material additive - like Graphene for example, will be used first to improve current manufacturing of electronics before it becomes even slightly useful for 3D printers.
So next time you read in the news: 'The world's first 3D printed car / plane / drill / air conditioner / mobile phone / etc.????" just ask yourself if it's really 3D printed? or is it just a 3D printed plastic case with conventional parts inside. It's going to take decades before 3D printers can produce complicated electronics and assemblies. It may never be viable to use 3D printers for such purposes.
Stay excited about 3D printing technologies, just don't always believe the media hype.
Please drop me a line on Twitter if you want to talk about this or anything else @RichRap3D