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As those of you following this blog may be aware of, I’ve been experimenting extensively with 3D printed models for use in robotics, UAVs etc. To facilitate experimenting I recently got a low-cost 3D printer, the Wanhao Duplicator i3 Mini. As of this point I’ve used the i3 Mini for about a dozen prints so I would like to share my experience so far.
Overall my impression of this printer is mixed. I feel that there are a lot of great features and the potential to be a truly great product. On the other hand there are a few really serious problems that in some cases can ruin the whole experience. Let’s get to it.
The printer comes in a sturdy cardboard box with plenty of EPP foam to keep it in place. Removing the contents we find the printer, a sample quantity of PLA material, a 1Gb SD card with some ready to print models and a number of accessories. The most important accessory is the spool holder which you will have to assemble on the special spot on the printer. There is also a scraper for removing prints from the print bed, a Buildtak-like pad cut in the printer bed dimensions, a needle for unclogging the print head and a few hex keys that fit the printer’s screws.
The i3 Mini Printer: Overview
The i3 Mini is an Fused filament fabrication (FFF) printer with a print surface that measures 110mm by 135mm (4.33 x 5.31 inch). It comes with a 0.4mm brass nozzle and can reach temperatures up to 275ºC (527ºF). Stainless steel nozzles are also available for purchase. The extruder block is of the E3D V6 type. The printer accepts 1.75mm filament that is fed to the extruder through a bowden tube. The extruder driver motor is placed on a convenient location and the clamp is easily serviceable. The electronics are placed on the lower part of the printer which also serves as the horizontal part of the frame. The printer does not include an enclosure.
One thing that surprised me is the presence of a single fan for cooling the extruder and blowing air on the part. This fan is always on from the moment the machine is turned on, and there is no way to control it from software.
The printer interface is laid out on a monochrome LCD screen of rather low quality, but acceptable for this price range. A rotating knob helps navigate the printer menus and select items.
The screen displays basic information during printing such as elapsed time, percent complete, nozzle temperature and print speed multiplier. The only options allowed to change during a print are the nozzle temperature and the print speed multiplier.
It is also noteworthy that while on many sites this printer is advertised as being able to print many different materials, among which PLA, ABS and PETG. However, the manufacturer clearly states in the manual that the printer is designed to work only with PLA and nothing else. I haven’t tested it on other materials so I don’t have an opinion on the matter.
The printer itself is a sturdy device with a clean and professional look to it. The chassis is made out of 2mm sheet steel. The z-axis is on a lead screw and the x and y axes are belt driven. The x axis moves the extruder and the y axis moves the print table. The extruder moves on two linear bearings that are sturdy and well oiled. The x axis belt has a tensioner on it to keep it in tension. The print bed is also belt-driven and moves on two linear bearings, which while for the extruder is ok, it is not sufficient for the bed and may lead to oscillations as we will see later on.
Unfortunately there are several issues with this printer that overall ruin the experience. Below I’m listing a handful of the most important one I’ve come across.
I have to ask, seriously, what is with Wanhao and rotary knobs??? The rotary knob on the i3 Mini is completely unusable! The rate of user interface advance is completely irrelevant to the knob “clicks”, so it boils down to guesswork when your menu item will change. Not only that, but the knob often skips at the very last moment when you are clicking thus selecting the option above or below what you intended to select. I’ve found myself countless times clicking on something and the printer registering the “back” item instead. A few times I’ve even selected and printed the wrong file (!) using this dreaded knob. It is so bad it is just unacceptable and I really wish they would change it for anything else. Just slap some arrow keys instead, I’m sure it’ll work better!
Stopping the print
Stopping the print has as a result that the head just freezes over the last point it was while printing. This is terrible, as it means that a. your print will gain a huge blob of molten plastic and b. you’ll have to move the it anyway if you want to remove the print. To avoid this you have to race through the menus (with the poor knob described above), enter the manual move menu and move the head up. Caveat: If you accidentally move the head down, you will end up with a cone in your print and a print head that’s messed up in plastic. I learned my lesson and remember by hard that up is RIGHT for the Z axis!!
Extruder temperature issues
I am not sure if this is my machine only or a general issue but I found that PLA prints print well above 220ºC (428ºF) on this machine. PLA printing temps being around 200ºC (392ºF), this led me to suspect that the temperature at the nozzle is off by around 10 degrees. Printing at 210ºC (410ºF) leads to underextrusion and all sorts of issues. I’ve tested this with two different brands of PLA material, so I suspect it is not material related. This issue could arise either due to faulty probe readings, or difference in temperature between where it is measured and the nozzle. In any case, i do get good PLA prints by printing around 224-230ºC.
I’ve noticed on more than one occasion that while moving fast (>80mm/sec) on the Y axis, the bed oscillates. It actually doesn’t sound very good and got me worried more than once that something is experiencing stress. Reducing print head moving speed helps a little, but it is still observable in large moves. I can imagine that this is caused by the print surface being supported by just two linear bearings, which eventually leave little resistance to bending moments.
The bed moves around!
This has been a real show-stopper for me. On several occasions I’ve had the top plate of the print bed move around slightly during a print, which was enough to ruin the print completely. I located the problem at the adjustment screws being quite smaller in diameter than the holes they fit into. The top plate rests on these screws and there is nothing securing the platform laterally (in the XY plane). Therefore the bed is almost free to move around, which often happens either due to nozzle resistance, or due to abrupt bed accelerations. I’m clueless as to how such a major flaw passed QA or even design inspection on such a mainstream product!!
Last but not least, I’m presenting here a handful of sample prints to highlight print quality.
My impression from the Duplicator i3 Mini is that it has the potential to be a great product, but has some very serious flaws that unfortunately ruin the big picture. It is really a pity because the product has the potential to stand out above it’s class if only Wanhao addresses these issues. Hopefully we will be seeing upgrades to this model in the near future that does so.
I would suggest the i3 Mini if you have some 3D printing experience and want an affordable 3D printer that you can play around with. You can get some solid 3D prints out of this printer for sure. However, I would not suggest it to an absolute beginner as it is not always trivial to deal with the issues mentioned earlier.
What is your experience with the Wanhao Duplicator i3 Mini? Be sure to share in the comments below!