Monoprice Mini Delta Review

For the last year or so, Monoprice has been teasing their follow-up to the fantastic $200 MP Select Mini. This is the $150 mini delta printer. We got a look at it last January at CES, it was on display at the Bay Area Maker Faire last May. Now there’s one on the Hackaday review desk.

Over the last few years, 3D printing has settled down into what most of us expected way back in 2010. No, not everyone wants, or arguably needs, a 3D printer on their desks. This is a far cry from the hype of a few years ago, leaving us with what we have today. 3D printers are just tools, much like a drill press or a laser cutter.

With that said, there still are some fantastic advances in 3D printing coming down from on high. Prusa will be shipping the 4-color multi-extruder add-on for the i3 Mk 2 shortly, and somehow or another we have infinite build volume printers. Still, there’s space to democratize 3D printing, and an opportunity for someone to release a very cheap, very good printer.

Monoprice was kind enough to send me a review unit of the MP Mini Delta before it officially hit their website. This is one of the first off the production line, alongside the few hundred pre ordered on an Indiegogo campaign earlier this year.  Does this printer live up to expectations? It sure does, and that’s not just because it’s a $150 printer.

This would be an excellent printer at three times the price, and evidence enough that 3D printing is changing from a weird hobbyist thing to a proper tool.

Specs and a Teardown

The MP Mini Delta is an all-metal 3D printer, with a 110mm diameter by 120mm height build volume. It includes a heated build platform with a BuildTak-like surface, auto bed leveling, a full-color display, and WiFi connectivity. This printer accepts PLA, and ABS, and I have run PETG through this printer for a few random objects. The power supply is 12VDC, so if you’re building a workshop in a van, here you go. In short, this is a minimum viable product that has a build volume just large enough to be a useful tool for prototyping.

This printer leans heavily on the innovative features found in the knock-out hit of last year, the Monoprice MP Select Mini. We loved this printer last year, and not because it only cost $200 shipped to our doorstep. The Select Mini was a sea change in what could be expected from bargain 3D printers. It had a 32-bit ARM controller board. This printer was technically WiFi-enabled. It had a reasonably large build volume, a full-color display, and a heated bed. The Mini Delta keeps the 32-bit ARM controller, has much better WiFi support, and the full color display looks even better.

With that said, how about a teardown?

To anyone who has taken apart Monoprice’s other inexpensive printer, this should seem very familiar. The electronics are divided up into two halves. The first is the controller board, responsible for moving the motors, reading thermistors, and sensing limit switches. This is a 32-bit ARM board based on the STM32F0. When this board appeared in the MP Select Mini, it was just slightly revolutionary. The other half of the electronics consists of a front panel controlled for the most part by an ESP8266. This chip handles the WiFi and drives the display. Apart from a slight reworking of the circuit and a vast improvement of the display’s UI, it doesn’t appear much has changed.

The mechanics of the printer are, of course, a delta platform, and not much needs to be said about that. The heated bed is a bit interesting; it literally sits on three tact switches. The bed leveling G-code simply taps the nozzle down onto the bed until the tact switches close. Simple, yet effective.

The extruder and hot end are again extremely similar to the MP Select Mini. This is a Bowden setup that does not feed the filament directly from the extruder to the nozzle. Instead, there is a break in the Bowden at the heatsink for the hot end. As with the MP Select Mini, this is the weak link of the entire system. This break in the Bowden tube between the extruder and hot end means flexible filaments are very hard to use. While this problem can be alleviated by re-engineering the hot end with 3D printed parts, it’s not a very big issue. However, if you’re buying a printer explicitly for the purpose of printing in Ninjaflex, I would look elsewhere.

One notable upgrade over the MP Select Mini is in the front panel. Instead of a rotary encoder, the Mini Delta features just a bright, crisp display and three buttons. A rotary knob is apparently more expensive than three buttons. The UI has been vastly improved and looks far more professional. The garish UI seemingly taken from a Windows 3.1-era application has been replaced with a sleek, modern skin. This isn’t a touch screen, but the three-button control makes sense.

WiFi

The printer as a web server. This is a simple server that allows you to set temperatures, upload g-code, and print items from across your network

While the Monoprice Select Mini had the hardware for WiFi connectivity, online printing wasn’t officially implemented at first. The Mini Delta comes with WiFi connectivity out of the box, and it’s actually easy to set up.

The web interface for this printer is simple — it’s just a place to drop G-code (which is then saved onto the SD card), a place to set temperatures for the hotend and bed, and two buttons to start and cancel a print. It’s not Octoprint and this is a very, very limited web interface, but then again all of this is running on an ESP8266. The future is awesome.

Configuring the web interface requires a mobile app, available in either the Play Store or iTunes, depending on your device preference. To use this app, simply enter the password to the WiFi network. Hold a button on the printer for a few seconds and WiFi magic happens. In less than a minute, the printer will be connected to the network, with the IP address displayed on the printer. From there, simply punch that IP address into any web browser and you’ll have access to your printer over the local network.

Again, this isn’t a full-featured web interface. For that, you’ll need a Raspberry Pi and Octoprint. This is a usable web interface, though, and a welcome addition to the standard feature set of consumer 3D printers.

Hacks and Mods

As with any 3D printer, I expect to see some hacks and mods to improve the performance of this little printer. We’ve already seen a few for the Monoprice Select Mini including something I did to adapt an E3D hot end, a few to increase the resolution of the printer, and some other mechanical escapades.

The end effector of the Mini Delta

The Mini Delta will surely be no different, and here I foresee two major hacks and mods. The first is improving or replacing the hot end, and the second is increasing the build volume of the printer.

I already mentioned the biggest weakness of the Mini Delta is at the hot end; the filament path is unconstrained at the heat break for the nozzle so printing in flexible filament is very difficult. This can be solved by completely replacing the hot end, keeping the filament contained for its trip through a Bowden tube.

While don’t plan to tackle this bit of engineering, the design of the Mini Delta is very amenable to hot end hacking. The platform, or end effector, or whatever we’re calling it, is just a piece of steel with upturned edges for the arms, and a central hole surrounded by a few holes for fasteners. It will be simple to engineer an adapter for an E3D hot end, and as with the MP Select Mini, we can reuse the heater cartridge and thermistor.

The second mod I have in mind for this printer is slightly less useful, even more absurd, and bordering on hilarious. One great feature of delta platforms is that extending the Z axis is much easier than with Cartesian platforms. I expect someone will mod the Mini Delta to have a build volume 110 mm in diameter and two meters tall by the next Midwest RepRap festival. This hack will require a metal brake to fabricate the three corners of the chassis, but apart from buying six pieces of two-meter long smooth rod, it will be a relatively easy build.

Well That’s Great, What About the Prints?

The first time anyone got a look at the prints produced by the MP Mini Delta were with the Hackaday coverage from the Bay Area Maker Faire. The default test print at Maker Faire and included on the printer’s SD card is a small Chinese cat print. The very large layer height used for the Maker Faire demo may have turned a few people off to the Mini Delta — there were visible layer lines that many 3D printing enthusiasts have confused with an inaccurate printer. This demo model was subtly changed in the production version; now, the default test print uses a 0.10 mm layer height. The print quality is amazing, and although the print time is nearly three hours no one will be disappointed by the plastic parts produced with this printer.

As always, a great benchmark for a filament-based 3D printer is the 3DBenchy, everyone’s favorite 3D printable tugboat. I was shocked by the quality of the Benchy produced by an un-tuned printer:

This Benchy was printed at 0.2 mm layer height, with some random PLA I had sitting around. No additional tuning was used for this print. This is the out of the box capability of the MP Mini Delta, and the results are phenomenal. The only issue with this print is a slight bit of sagging on the top of the pilot’s window. This is a bridging problem, and is one of the most difficult problems to troubleshoot.

By any measure, this is a phenomenal print. This would be an acceptable Benchy to come off a Lulzbot, Ultimaker, or Prusa i3. This is the out of the box settings, using the standard configuration for Cura. I am quite literally gobsmacked at the quality of parts this printer is able to produce. This isn’t just an excellent printer for the price — this is an excellent printer.

Market Segmentation is the Key

Over the last few years, the market for 3D printers has expanded enormously. Ten years ago, a 3D printer was only used in engineering firms, only for prototypes, and the machines themselves cost a small fortune. Now, there’s an actual market for 3D printers at all levels. If you have a budget, there’s a 3D printer for you.

The best metaphor for the 3D printer market is cars. If you have a few hundred dollars or a few hundred thousand, you have an opportunity to buy a car. In this metaphor, the metal sintering printers that build rocket engines are Maseratis, Lambos, and other cars with doors that go like this, not like this. These are, of course, far beyond the price range of the average consumer. Metal sintering, crazy huge build volumes, and other exotic technologies are coming down in price, but the top of the line in 3D printing is a lot like it was ten years ago.

But what about the high-end, prosumer printers? In the car metaphor, these printers would be a Lexus, a Jeep that has earned its nameplate, or a bitchin’ Camero. Here, there are plenty of options. Lulzbot makes a fantastic printer, as does Ultimaker. The Prusa Mk 2 is phenomenal with the multi-extruder add-on, it can print in multiple colors just like the Bugattis of the 3D printer world. In the high-end, prosumer space, we’re even getting infinite build volumes; the Printrbot Printrbelt is set to sell for $1500 USD.

Pick an auto manufacturer and look at the sales across product lines. Chevy is selling more Sonics than Corvettes, and Tesla will sell more Model 3s than any other model. You’ll always sell more econoboxes than muscle cars, and the same is true with 3D printers.

And so we have the Monoprice Mini Delta 3D printer. This is a printer that costs $150, shipped to your doorstep. I don’t even know if it’s possible for any manufacturer to build a less expensive 3D printer. By any account, this will probably be the most popular 3D printer of all time. Herein lies the problem of reviewing a printer designed to be the cheapest printer: you cannot criticize a Ford Fiesta for not being an F350. Likewise, I can’t criticize the Monoprice Mini Delta for a small build volume and inability to print in multiple colors. If that’s what you’re into, a Prusa i3 will do it, but it will also cost five times what you’ll pay for a Mini Delta.

With that said, the MP Mini Delta is an excellent printer. This printer was supposed to ship in April, but now we know what the delays were for. This is a high-quality printer that will find a home on many, many desktops. If you’re looking to get into 3D printing, if you’re looking for a new hobby, or that eager inventive 12-year-old cousin is showing an affinity for building stuff, this is the perfect printer. It’s cheap and well within impulse buy territory. It’s also a very well designed and extremely capable machine. I would recommend this machine to anybody, whether that’s someone who has never touched a 3D printed part before or someone setting up a bot farm to produce more parts faster.

This will be an exceptionally popular printer and we’re looking forward to the hacks that will turn this printer into something remarkable. If you have a useful hack for this tiny printer — or you turned it into a six foot tall monstrosity, be sure to send a writeup into the Hackaday tip line.

72 thoughts on “Monoprice Mini Delta Review

      1. Well that doesn’t answer the question, does it.

        If Monoprice was the exclusive distributor of a re-badged Malyan printer… “The MP Mini Delta”… then both statements are true.

        Now here’s a more important question that hasn’t been answered IMHO…
        Is it a tool? ..or… like most 3D printers.. a project?

  1. Since a few days I own one of these and I’m very happy with it. I’m completely new to the 3D printing business, but powering it up, loading the filament and printing the demo file was working like a charm. Nevertheless, there’s lots of questions to the newbie and I was searching for information specific to the MP Delta Mini which is scarce. It would be nice if we had a central place to discuss the printer and its peculiarities so I set up a forum. I hope it is not considered spam if I invite you to share your knowledge and discuss your questions there: http://www.mpminidelta.net/forum/

  2. Hm, it sounds like it might finally be time for an upgrade…

    It’s amazing that I can get something so, so much better than my trusty balsa wood Printrbot for half the cost! That Simple kit cost about $300 like 5 years ago, and I remember choosing it as one of the cheapest (and not likely to fall apart) commercial options available at the time.

    5 years, half the cost, far more features. Maybe I need to reconsider my favorite Bill Gates quote: “We always overestimate the change that will occur in the next two years and underestimate the change that will occur in the next ten. Don’t let yourself be lulled into inaction.”

    One year / five years?

  3. Unfortunately I’m not buying anything else directly from Monoprice. About a month ago I bought the gen 2 mini–the new black one with an e3d clone for a hotend. They knowingly shipped it with unfinished firmware that made the printer unusable. Out of the box, the part of the menu interface that’s used to move the head around was missing the x and y axis selections–you could literally only move the head up or down. That’s a bit of a problem when you need to move the platform around to level the bed… The small doc it came with was for the old, gen 1 interface on the original mini. I called their support and when I described the interface issue they said, ah, it looks like you have the new model, unfortunately we don’t have information on that yet to support it. So they knowingly shipped bad firmware, with the wrong doc, and their support staff couldn’t support it.
    It also came with faulty calibration, which got me an RMA; but they don’t pay for shipping, so I had to cough up $20 to send their mistake back to them.

    1. Knowingly? Your tale above doesn’t show that. It could be as simple as Monoprice ordering the old model and getting the new one. IOW it could be that their suppliers fucked up. It could be a lot of other small problems that actually do happen all over the world every day. But saying (without any proof) that it was intentional?

      Not reasonable. Not mature.

      1. “knowingly” is from my conversation with their support guy. He admitted that they were unprepared, from the support chat:
        [01:51 PM] : Unfortunately, we are not very versed in this firmware and are aware of the issues. I apologize for the inconvenience but we would not have any documentation for this setup yet.

    2. You can move the X-carriage and bed by hand to level the bed. The controls for moving X and Y are not really worth the trouble to use for bed leveling. X and Y controls were removed intentionally but now because of the few complaints there will be an updated GUI to bring the useless controls back.

      What part of the firmware was “bad”? Would you please also elaborate on the faulty calibration?

      1. the home position was almost off the bed, past the leveling screw. How are they useless? Yes, you can use repetier or whatever to move it around but with the new built in wifi I don’t expect to have to run a line to my computer… without those options the firmware was indeed “bad”, especially as the unit is marketed for complete newbs, and I don’t have the time to mess around with something more complex just to print project boxes. Without those two options their bed leveling instructions that come with the machine and are posted online can’t be followed.

        1. Errana – at this price point, you’re supposed to be impressed that it prints very well, not upset that you might have to hook it up via USB to calibrate it. Your expectations are inappropriate.

          1. my expectations were that the unit have the same level of functionality as the previous gen, which served me very well, with extra added features. Sorry, but I do not feel that to be inappropriate. I was expecting something my wife would be able to use and got the opposite, because of the dev’s oversimplifying. They removed basic features for the sake of simplicity. Same stereotypical complaint about Gnome (if you’re a linux person) and a number of other interfaces sacrificed to the UX gods.

        2. Level the bed by moving the X-carriage and the bed by hand. Just be sure you don’t touch the nozzle when doing so.
          This was done because they believe that the X/Y were not used often and cluttered the UI with useless menu items.

          I personally don’t use the X/Y controls much because it doesn’t have a way to move it specific increments. I either move the X-carriage and the bed by hand or if I want precision, I use a Web UI.

          Like I said already they are going to bring back the X and Y movement options in a UI Controller firmware update to give the users the option if for no reason other than making those users happy even if they will never use them.

          Monorprice video demonstrates how to level the bed using your hands. True the bed and nozzle should have been heated while leveling the bed.

          1. I’d say that seems hackish, but this is HackaDay, I’ll give it a shot. You seem to have a bit of inside knowledge: do you know if it’s possible to get me the new firmware to flash onto the esp8266 or is that out of the question?

        3. Send it back and don’t bother getting a replacement.

          3D Printing is obviously not ready for you since it’s not at the ‘reliable as a HP’ stage yet.

          Exactly as Matthew Upp described- all the controls and functionality were there but it didn’t work the way *you* thought of wanted it to work so *it* is broken and the company selling it is at fault because they deceived you.

          You know there’s laws against that right? You should talk to a lawyer… you can probably sue them for tricking you like that.

      2. Yes, you can do that at risk of blowing up your stepper drivers. The steppers generate voltage when moved manually… the only *correct* way to move them is from the UI period.

        Omitting this from the firmware is nonsense… its a trivial feature to begin with relative to the rest of it.

        1. Or… just disable the stepper drivers before you move them by hand… if the menu doesn’t have a “disable stepper” function, then that’s a problem… or you could, you know, just turn the printer off when you’re doing bed leveling, and then turn it on when you’re done… many ways to skin this cat.

  4. I’ve had mine for a few weeks now and it’s a solid little printer. It is louder than my Monoprice Maker Select Plus. Add additional lubricant to the rails to quiet the bearings down a bit. The lubricant they applied doesn’t do the job.

    This is a weird complaint, but the prints adhere to the build plate a little too well sometimes making it a pain to remove rafts and brims. Skirts are the way to go on this printer for sure.

    There are complaints of overheating causing drifts in the prints as the motors lag when overheating. One of my first prints was for 3 extended feet to keep the air flow clear even though it sits on a wire shelf.

    The web interface it a joke. It kept choking out uploading anything above 2mb so an Octoprint server was a must have for me since I don’t like running sd cards back and forth to the printer as I tune it.

    That said, this is pre-release firmware. Final release should be a little more stable.

    It’s become my quick prototype printer since I don’t have to worry about releveling like I do on my plus.

  5. I hope they secured the web interface. While the esp8266 may not be that powerful, and i’m sure rewriting the firmware remotely would be difficult, it would be awkward if your print was interrupted remotely and/or your gcode replaced by a troll. I’m sure they put in a failsafe against gcode damaging the system, but i’m sure it could still make a big mess if the gcode just had it extrude pla until it ran out. I think it more likely some kid would make someone else’s printer make wieners or 3d swear words.

    1. At the very worst they’d only be able to do any of that when the printer is left on and unattended (which isnt often) as there is no soft power control, only the manual power switch.

      Mostly the same concerns as with opening Octo up to external access- at worst, with the main printer power switch off, all they could really do is spy on you from the camera if you have one attached.

    2. Do you think people are seriously going to be looking for access to a particular 3D printer on someone’s home network? I don’t think there’s gonna be Stuxnet for MP Mini Delta coming any time soon. The printer would also need to be on for it to be an issue. I know I don’t leave my printer on randomly when I’m not using it, for safety reasons anyway.

      1. Question didn’t say *ON*, OP said *with*… I don’t know of a single printer that Octo will run *ON*.

        I dont know why Octo couldn’t drive this- essentially the same control board as the Mini (which Octo can drive) only in a delta configuration (which Octo can drive). There may not be a preset in Octo yet, but I imagine a default delta profile with MP delta specs copied over would do fine.

  6. the thing that runs ON the printer is the agent, and marlin is the main agent responder that octoprint talks to.

    there is no marlin on the monoprice, clearly; but I was asking if octoprint can talk to the arm code (whatever they are calling that pkg) on the monoprice?

    having one wifi interface to each printer – and each one using octoprint – really makes things much more consistent. the local UI on the new printer may be nice, but I would prefer to continue to use what I have been using, just with a new printer behind it.

    I also won’t buy the monoprice until the firmware can be replaced with opensource code of some kind.

    I’ve heard lots of issues with monoprice and I don’t want to be hobbled by their closed source firmware, even if octoprint does talk to its local agent.

  7. I have one of these. It’s not dimensionally accurate. It’s especially bad at the extremes of the print bed. Large squares are not square, and they definitely aren’t the right size.

    Surface finish and other aspects are great, though.

    1. Hackaday staff, why is dimensional accuracy not part of your review? It should be part of every delta printer review or at least mentioned. A 3D printer that can’t print parts that fit together is a bit of an issue if I was a user.

      You’ve described this as an excellent printer hackaday, and clearly it is not if dimensional accuracy is out by a lot as this user here has reported.

      Are you able to comment so that we can make our own judgement? Sorry I’m being a bit hard on you guys but a review like this should include important information such as this.

      1. It sounds like a weakness of the bed-leveling technique. The arms are probably not quite the right length on duckythescientist’s printer. The typical naive bed leveling technique can compensate for this imperfectly, introducing a kind of spherical distortion if the actual dimensions are very different than the expectedones. The fix would be to change the length of the arms to match the expectations of the firmware, or to update the firmware to expect different arm length. I have no idea if the MP printers have firmware open enough for this kind of thing to be practical, but that’s what I had to go through with my kit delta and marlin firmware. Anyways, the upshot is some printers will be better than others in this regard so maybe the hackaday specimen was lucky, or Brian didn’t test big squares.

          1. heh, if the arms are different lengths from eachother, yeah. there’s not much information to go by here. i’m curious about specific attributes of the distortion.

        1. OMG .. I listened to the Dead Milkmen recently, and rather than bringing back fond memories, it made me realize that the 80s were a little sad in some respects.

          Their accents grate on my ears .. and I’m from the Philly area. I can’t imagine how it sounds to someone not of this region.

  8. So, comparing the build areas, why go with the new delta rather than the current MP Select Mini? The latter has been around longer, has what I suspect is a simpler mechanism, has many already existing mods, etc.

    1. Currently no reason other than speed, you lose dimensional accuracy, and they haven’t learned that the end users need the ability to modify the firmware. So, I’d say buy a CR-10 instead, it has an open firmware, and prints well if not as fast as a delta and has a good community and lots of mods.

  9. Look at the prints coming off that machine, they are absolute sh/t compared to even a cheap prusa knock off. Now for $160 (no its not $150 quite understating it) yeah the printer works and it even comes mostly built out of the box but who cares of you cant get a clean print off.

    1. Actually, the prints that come off the MP Mini delta are the finest looking prints I have ever seen. Hands down better than any prints I have seen from a Prusa or any other big name FDM printer. The print surface quality is spectacular. There are other reviews online showing more detailed close-up images of prints from this machine. You should really check out some of them before forming an opinion based on a tiny picture of a cat and a benchy. The quality is really amazing.

  10. Shame it needs an app. Rather than, say, having the printer start it’s own wifi hotspot, and have you configure it through a simple web page. An app’s just another security hole / pain in the arse / waste of time / potential for Monoprice to sell your details / pain in the arse / security hole. And if it comes with ads, someone should 3D print a brick to put through their window.

    Really can’t understand the need for an app. I appreciate the user input speed is limited by the three buttons. But lots of other stuff throws up a preliminary wifi network for config. Even lightbulbs can do that.

    I want one, but then my brother in law got one a year or so ago. He’s printed a cat, some brackets for his 3D printer, and a nameplate for his 3D printer.

    1. The “MP 3D Printer WiFi Connect” mobile apps do not include any ads. It is a simple app for passing your wireless network SSID and password to the printer. None of the data is transferred to Monoprice or the developer.

      The mobile apps may be a waste of time for you but I used my own time to make them for the community free of charge. You don’t have to use them to connect the printer to WiFi if you choose to use it WiFi at all. There are many options to connect to WiFi and you can find them at https://www.mpminidelta.com/wifi/start

  11. You keep writing $150 printer.

    Unless they are charging less than they did during an Indiegogo campaign, the printer will be ~$170.

    Do you have information that the rest of us don’t have?

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