Wanhao i3 Mini: Essential Mods & Printing More Materials

A few months ago I published my first impressions of the Wanhao Duplicator i3 Mini. At that time it was just a few weeks since I had bought the machine. However, since that time I’ve used it almost every day for the past months. I feel I’ve learned enough about the printer that it is a good time to provide a follow-up on that post with my experience. In particular, I’d like to focus on two areas: Using more printing materials with the i3 Mini, and mods to fix some of the issues it presents. So let’s get started.

The i3 Mini sitting in my printing closet
The i3 Mini sitting in my printing closet

As a general remark, the printer is still in good condition despite heavy use. I had to change the nozzle two times due to it getting clogged, and the fans are showing symptoms of long-term use. That is not to say that I haven’t had my fair share of issues with this machine, including failed prints and other mishaps. While some were my own fault, there are certainly things that Wanhao should improve should there be a v2 of this machine. In fact, it seems that many issue can be easily solved with a simple firmware update, but Wanhao has so far shown no intention of releasing one. This is a sad fact and gives the impression that this product is not supported. Ironically, and given these facts, if I was a buyer at this time, I would definitely avoid this printer.

Printing Alternative Materials

Wanhao claims that the i3 Mini can only print PLA. In my case in addition to PLA I’ve also printed TPU and PETG successfully without any issues. The only issue I’ve had was some slight warping in the case of printing PETG. However, this can be easily fixed with a generous amount of PVA glue.

Please keep in mind that the temperatures reported below take into consideration that in my printer there is an offset between reported and actual nozzle temperature.

I’ve experimented with PrimaSelect PETG, which prints fine with a bit higher temps than the PLA, at a reported 245ºC (473ºF). In reality this should be something around 225ºC. PETG has some issues adhering to the Wanhao-supplied print mat, but a generous amount of fresh PVA glue seems to fix this. TPU too requires elevated temperatures. In my case reported printer temp is 250ºC (482ºF) (maximum temp), which in reality is like 230ºC (446ºF). In addition to that, you will need to limit the volumetric flow of TPU to get a reliable print. This is because the default flow used in e.g. PLA results in the softer, more flexible TPU to create a kink right past the filament pusher and exit the filament path. I’ve got no picture of this but I show the point where the kink happens below.

Soft filaments like TPU tend to bend and leave path at this point at high feed rates.
Soft filaments like TPU tend to bend and leave path at this point at high feed rates (>1.2mm3/sec).

Thus, no more filament supply and print is ruined. To avoid this, you can either mod the pusher itself by providing a closed path for the filament to go through, or limit the volumetric rate in the gCode file. The latter proved an easy hack in my case. I’ve used PrimaFlex Black TPU, which printed fine with a max volumetric speed of 0.9mm3/s. This option can be found in Slic3r in Filament Settings>Overrides. In reality this does not limit the print speed so much for the overall print, just at those areas where the printer pushes out a lot of material, such as the first layer.

One could also experiment with cutting a short piece of PTFE tubing and inserting it between the bowden tube clamp and the filament clamp assembly. This would force the filament into a straight path, and since there are no other gaps between the pusher gear and the nozzle, it should theoretically stay in place.

Read also:  Build an Affordable Soldering Microscope using a Raspberry Pi

I’d like to try more materials and find out the limitations of the printer. If you’d like a material tested and reviewed, donations are always welcome.

Essential Printer Mods

In this section I’d like to discusss a few mods that made my life easier with this machine and helped fix the issues described in the original post.

Print Bed Slippage

In the previous post I mentioned print bed slipping issues due to poor fixture design. I used a simple zip-tie to fix this, tying it between the bed spring and a hole on the front side of the bed undercarriage. Image is worth a thousand words:

Print bed is held in place with a ziptie
Print bed is held in place with a ziptie

The zip-tie pulls the bed sideways so that it is always in tension. Slipping issues, begone!

Extruder & Mainboard Fans

Update: Commenter Jay pointed out that there are a bunch of items at thingiverse for improving the i3 Mini, among which also are bed stabilizers. They seem much more elegant so try these out before giving my solution a go!

Next is the fan. I got a 40x40x20mm 24V fan from Sunon to replace the original one as a more powerful extruder fan. I am not certain if I would recommend this mod though. On one hand, the airflow is good and I’ve noticed better quality prints overall, including less sagging on bridges and overhangs, which was my main goal with this mod. On the other hand, the fan itself draws more power. What’s more, it causes the heating element to draw more power as well to reach temperature. With this configuration, I’ve had the printer MCU crash a few times from what I suspect is insufficient power from the  PSU. This is most common when printing at temps above 230ºC (446ºF).

New fan with protection grille on the extruder
New fan with protection grille on the extruder

So I would only suggest this mod in combination with a new, more powerful PSU, which will probably be my next upgrade.

The mainboard fan is also one prime suspect for upgrade. The fan itself is annoyingly loud and quite inefficient. Even though I haven’t modded this yet, any plain old 40mm 24V fan should be a good replacement.

Another mod concerns covering the gap between the filament feeder and the bowden tube, at the top of the printer. I find this mod essential if you wish to print flexible materials reliably. Covering the gap will allow flexible filaments to stay inline with the bowden tube and not flex out of path due to feeder motor pressure.

SD Card

Not really a mod but in any case I’d suggest you do yourself a favor and stop using the SD card that came with the printer. Not only is it horrendously slow, it also has issues with mounting/unmounting (on a Mac at least), file corruption and more. Get yourself a decent 16Gb SD and never look back.

Conclusion

I’ve spent nearly six months using the Wanhao Duplicator i3 Mini and along the way I’ve fixed a few issues and learned a few ways to make it more reliable, and also print with a few alternative materials such as TPU and PETG. This post summed up the most important mods & tips that I’ve learned.

Are you an i3 Mini user? Do you feel like sharing a few tips or mods? Share your experience in the comments below!

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2 replies on “ Wanhao i3 Mini: Essential Mods & Printing More Materials ”
  1. Thanks for the tips. Regarding the zip tie mod for the print bed do you think this will cause issues with wear on the linear bearings due to the friction of the bed pulling to one side?

    I’ve had some issues with print layers not adhering together well with the i3 mini, I’m going to check it with an IR thermometer to see whether my nozzle temp reading is also higher than the actual temp.

    1. Thanks for the comment! The ziptie pulls the print plate against the undercarriage so there is no effect on the bearings whatsoever. It shouldn’t be attached directly to the rod that moves through the linear bearing though! I’ll try to make a diagram if I find some time.

      Regarding temperature, be sure to get a good IR thermometer and not an el-cheapo one. I have one that I bought for $10 and it wont show anything near the actual nozzle temperature. In the end, maybe it’s better to use a contact temp sensing method if all else fails…

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