Last year, I bought a 3D printer. Since then, 3d printing has become a bit of an obsession. I’ve owned quite a few printers over the last year and I figured it’s time to do a run-down and some recommendations. In this post, I’m looking at the Monoprice Mini Delta.

Summary: A great printer if you are lucky (or persistent)

At $180, it’s an affordable printer and by far the cheapest delta printer on the market. With a resolution of 0.05mm and print speed up to 150mm/s, the Mini Delta is capable of amazing prints with quality rivaling printers two or three times the cost. It has a very sturdy metal chassis, linear rail system that moves very smoothly, and accepts a standard E3D style nozzle.

Overall, it’s a great little printer. There are, however, some caveats. I mentioned in the summary that one needs to be lucky with this printer. Many folks I know have no problems with their Mini Delta. Sadly, I have not had that experience. When it works, my Mini Delta is brilliant and it was a fantastic introduction to the hobby. Physically, I’ve had a few problems. First, let’s cover the issues that exist for all Mini Deltas, lucky or not.

Design Issues

In all Mini Deltas, there is a design issue between the firmware and power supply. The default power supply is an itty-bitty thing without much juice. To keep the power usage below the supply’s rating, the firmware prevents the bed heater and the nozzle heater from running at the same time, prefering the nozzle heater. As such, you can’t sensible issue commands to heat the bed and the nozzle at the same time. It will heat the nozzle and then only have a bit of power to warm the bed, while trying to keep the nozzle temperature stable. The bed never, in the span of my patience, gets to the proper temperature. If you instead heat the bed and then heat the nozzle, the temperature of the bed will plummet, typically to 40C or less, while the nozzle is heating. The bed will very slowly come back up to temperature. It’s possible to buy a bigger power supply as the Mini Delta uses a standard barrel plug. The limitation however is locked into the firmware and cannot be removed by the user.

Next up, the bed is documented as being able to reach 60C. I’ve never seen that happen. I’m not sure it’s possible. In practice, I can just barely get the bed to 55C. If the nozzle is hot, the bed stabilizes for me around 50C no matter how hot I requested. This is true of all Mini Deltas, as far as I am aware.

The build plate on the Mini Delta, by default, is a BuildTak-like surface. Unfortunately, the surface also features the logo of the original manufacturer of the printer, IIIP. This logo appears as gaps in the BuildTak, leaving the print bed with an inconsistent surface and variable grip. The gaps also provides a vector for scratching or even ripping off bits of the BuildTak if one uses metal tools to remove the print. This can all be countered by putting blue painters tape over the bed.

Those issues all sound bad but functionally, they’re not a huge problem. The Mini Delta is a PLA-focused printer so a cool bed, or an inconsistent/blue-tape surface aren’t show stoppers. In the day-to-day, as long as one is aware of the issues, they can be worked around with minimal fuss.

Feeling Lucky?

These issues are a bit more of a dice roll. Not all Mini Deltas have them but, of course, mine has them all.

The first problem is minor. In many Mini Deltas, the “front” of the build environment is rotated so the print “faces” out the back left. This can be fixed by switching some wires in the chassis, rotating the model in the slicer, or just accepting the issue and moving on with life. It’s purely a cosmetic issue.

The big major all-bad issue involves the control board. After about six months of service, my Mini Delta, for lack of a better phrase, lost its mind. Whenever I requested a movement on any axis, the head would either dive for the bed or shoot off to the side to the maxiumum physical edge and attempt to keep going. The printer was completely unusable. I ended up replacing the control board entirely. I have heard of this behavior occurring momentarily in other Mini Deltas. The theory from those folks is that some data corruption occurred and the board couldn’t handle it. In those cases, the person rebooted their printer and all was well.

Vendor Support

Monoprice has, in general, decent support. They are available via text chat, email, or phone. They tend to be good people and I’ve never had a negative interaction with a support agent. That said, the 3d printer support folks are in a tough spot. See, Monoprice doesn’t make any of its products. They are rebranded units from other manufacturers. In the case of the Mini Delta, the source manufacturer is IIIP. Since they don’t build the printers, their support staff receives no special training and has no special knowledge or access. Their department “buys” new printers the same way we do and they sit down and play with them, just like we do. They will try and help you but sometimes it’s clear they’re reading the same Reddit posts you are. So in terms of getting help making your printer work, they’re not a huge force multiplier.

Where Monoprice’s support truly wins out is their ability to authorize an RMA. I stupidly never tried to RMA my first Mini Delta even once it developed serious problems. At one point, I bought a second Mini Delta hoping to receive an un-cursed unit. That didn’t go so well and the Monoprice support issued a refund RMA very quickly and without fuss.

Summary

I recognize that I just dumped out a lot of issues with this printer but also said it’s a great printer. I stand by both. When the Mini Delta is working, which is most of the time, it is a brilliant little printer, particularly in its price point. If you want a small, cheap, PLA-focused printer, this is a very compelling device. All the issues I’m aware of can be worked around or fixed with a warranty hardware replacement. My Mini Delta is still humming over a year later. (I’ve done a lot of upgrades but that’s a subject of a different post.)

A lot more information, including possible upgrades and replacement parts, can be found at the unofficial wiki.