3D Printing – using the Cocoon Create (Wanhao i3)

*** Note: some of the info presented here may void your warranty, opening  the control box exposes you to potentially lethal 110/240V connections Рplease take care and disconnect power before opening the unit. The following are not instructions, just descriptions of my work, I accept no responsibility on how you use his information ***

I don’t know why I bother keeping this site alive. ūüėõ If you do not understand any of the terms here try Googling them (maybe adding ‘3D’ to the search term).

Well, back in February 2016, I bought a Cocoon Create (http://www.cocooncreate.com.au/) from Aldi here in Australia. Yes Aldi does sell some strange stuff here on occasion.
It is, in fact, a re-branded Wanhao I3, and was a good price at A$499.
This is my first foray into 3D printing, although I have been tempted to have a go for a while. From the start I have been impressed with the quality of the prints from this gadget, I guess my expectations were rather low.

As I have had two of them for nearly a year, I’ll share my thoughts about owning them, pitfalls, urban myths, fun, frustration but thankfully no disillusionment – not yet.

This printer is really suitable for the tinkerer types who are not afraid to pickup a screwdriver and learn a bit. It is not plug and play (mostly) and requires some mechanical skill to deal with running the thing, even in its standard form before you might even consider improving it with mods.

The 3D community… well to paraphrase a Star Wars quote…¬†“3D Printing. You will never find a more wretched hive of scum and villainy”. No that’s not quite true. What is true is the usual clash of amateur learners with (not so) knowledgeable experienced users sprinkled with a few experts (with real engineering understanding).

3D printing covers a few areas of engineering – Mechanical/Electronic (Mechatronic), materials engineering (Plastics and their properties) and a sprinkling of thermodynamics. I’m quite adept at the electronics side of things, had some experience with the mechanics (bearings, stepper motors, etc) but I’m new to thermo-plastics, at least in the formation of objects.

Really simple 3D description: The 3D printer essentially moves a nozzle in 3D space, depositing a stream of plastic to create an object.¬†To do this lot’s of stuff moves and is heated up.

This 3D printer mostly works at a safe voltage (12V DC) for its electronics.

240/110 V comes in through a rear fused receptacle and is fed to a fan cooled switch mode power supply that produces 12 VDC at up to 20 Amps. This DC voltage primarily feeds the controller board (called a Melzi – an Arduino clone) and directly feeds two of the fans, the rear panel fan on the electronics box and the cooling heatsink fan on the hot end. These two fans are always on when the power switch is turned on ate the rear.

The Melzi board is the brains and controls the movement of all things that move – stepper motors for movement – X, Y, Z (2 motors) and the extruder. The Melzi comes pre-programmed with it’s own firmware (although you can re-flash it). It can talk to the outside world in two ways – via files on a micro SD memory card or through a USB serial port.

To print a 3D object, it needs to be ‘sliced’ into layers. Cura is the suggested package for doing this and a great tutorial to get you started on adjusting the settings for Cura in here.

Mods – modifications – here’s were you get your screwdriver fix!

I’ll list the ‘stuff’ I’ve done to my printer (with or without explanation!). Most of this has come from various sources on the internet.

The first thing everyone pretty much agrees on (rare in this hobby) is to print off some dials to replace the wing nuts on the platform levelling screws. I replaced the adjusting nuts with 3mm nyl-loc nuts and the bed adjustment stays pretty stable. Also lock those screws onto the bed with the same type of screws –¬†3mm ny-loc nuts, this stops them wobbling about.

I added gantry stabilisation (or “Z arm stabilisation”). Use this link from Thingiverse –¬†http://www.thingiverse.com/thing:921948. I profess, I didn’t do any before and after quality measurements but it does make the printer much more stable, especially if you feed your filament from a roll mounted up there. I did not use the full Y Brace bracket either, no particular reason not to.

Fan Noise – Fan Noise – Fan Noise.

Fans are the most intrusive noise from the printer (next to the noise from the Y stepper motor that’s amplified through the platform!). I rate the noise frome the fans as (loudest to quietest):¬†Fan on rear of control box (40mm), internal power supply fan (80mm), hot end (40mm) and extruder fan (30mm). All the fans are 12V.

I have installed a Noctua 40mm fan on the hot end. It runs slower and is designed for quiet operation. I have checked the thermal dissipation with this fan using a Flir thermal camera and it is quite acceptable. I could not see a great difference between this and the stock fan for cooling but the reduced noise was a real benefit.

I have replaced the rear panel of the control box to fit an 80mm fan Рsee here and added a 100 Ohm, 1 Watt resistor to the fan in the internal switch mode power supply. This again has reduced the fan noise considerably. There was no measurable difference on the Melzi board temperatures after the rear fan change and thermal measurements for the power supply have it running at 29 degrees C with a room temp of 25 after two hours doing a PLA print.

I have not changed the cooling fan for the extruder… yet. Although the fan and duct have been angled more to point at the nozzle now.

If the power supply ever fails, it will be replaced with a quiet PC power supply on standby for the job.

Electronics.

As noted above, I added a resistor to the power supply fan.I have also done the temperature stability mod for the hot end – see here. This does improve the endpoint stability by improving the grounding to the switching MOSFET for the hot-end.

The Vref for the current limits of¬†the stepper motors have been set to 0.684V for X,Y & Z steppers and 0.864V for the E (Extruder) stepper. The extruder stepper motor has a higher current rating. There are a few online guides for setting these, search for “Vref wanhao i3”.

I have also cabled 12V out of the electronics box to the platform area to run overhead 12V LED lighting.

Running the printer.

Initially I was sending files to the printer by loading them onto the micro SD card (supplied with the printer, by the way) on my PC and ‘sneaker net’ them to the printer – this quickly becomes a real pain.¬†Using Octopi,¬†¬†I have set up a Raspberry PI 2 with a ¬†Microsoft 3000 webcam and WiFi to wirelessly upload objects and to monitor the print process. Here is a good tutorial on how to set it up and if you do use it (it is great!) – then please consider supporting the author.

Filament – so far I have only printed in PLA. I have used the Cocoon filament (blue, green, grey and black), 3D Fuel (Orange and Red), miscellaneous EBay PLA – white, transparent, Bilby glow in the dark, Jaycar wood filament. I have copper and ABS clear to try but I’m wanting to convert the hot end to a Micro-Swiss one first as the ABS runs hotter and the copper/glow/wood might be abrasive.

Repairs and bits…

I have already replaced one of the platform linear bearings. This might be because I used fine machine oil and it *may* to have gelled the grease in the bearings.

Grease – bearings seem to run dry but I think it is the quality of the bearing here. I find a few drops of Singer Machine oil helps if you start getting odd noises when things are moving.

Links:

Google Wanhao Group, Google OctoPrint Group