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Prusa MINI+ 3D Printer

This is not really a review of the Prusa MINI+ 3D Printer. There are plenty of full reviews out there. What this is though is a post about my own experience with the Prusa MINI+, at least the first week with it.

First, some background. I am not new to 3D printing. My first post about 3D printing was in 2011. (See them all!) I got my first RepRap working in 2012, and helped start the Milwaukee 3D Printing Meetup the same year. I was using printers at Milwaukee Makerspace, UWM, and other places around town (including at work) and in 2017 I replaced my ageing RepRap with a Monoprice Maker Select Plus. So I went about five years between printers, which is fitting, because it’s five years later and I just got another printer. (I’m not counting the Creality machine I gave to my daughter or the Maker Select v2 I just gave away to someone I know.) So yeah, I get 3D printing. ;)

So while the Maker Select Plus served me well (after a few upgrades) I wanted something a bit better in the quality department. Years ago I spec’d a Prusa i3 at work to replace an ageing (and often broken) MakerBot and I loved that machine. I basically told everyone I knew to get a Prusa if they could. (They got a whole bunch of them at Milwaukee Makerspace.) The experience was top notch for someone coming from the old RepRap/Pronterface world. Alas, I left that job and left the Prusa behind.

Print quality from the Maker Select Plus was pretty good, but I’m hoping for much better quality from the MINI. One important thing to note is that while the MINI has a smaller bed, it can probably print more reliably across the entire bed. I’ve found that cheap printer with large beds don’t always excel at using the entire bed. Part of this is probably leveling. While I’ve been a gruff old veteran who says “Argh! All ya need is a sheet of paper and some patience to level things!” the probing and leveling system of the Prusa is great. (Yes, I know I could add it to the MSP, and upgrade the firmware to support it and… at this point I really just need to print.

In 2021 I started having to print more quality items that were for sale, and sometimes it was difficult to keep up and get good quality prints. I started eyeing the Prusa MINI again. I finally decided to grab one (after selling some other equipment I didn’t need) and it arrived in less than four weeks, which sounds like a long time but I was expecting 6+ weeks. So that’s a win.

As for the actual experience, here we go. Assembling it was a bit of a pain. I’ve put together two Ender 3 printers and it was very simple. The MINI assembly (while not many steps) kind of sucks. Maybe because I expect a certain level of Prusa experience. Luckily you should only have to do it once. (To be clear, I got the assembled model, so it was just bolting the two halves together, plugging in and routing all the wires, and that was it. Still a painful experience.) Remember how I said “you should only have to do it once”? Well…

After assembly the setup and calibration was great. Excellent experience! The machine walks you through the process very smoothly. I then did a test print found on the included USB drive and it looked good. (I used some Hatchbox filament, not the included Prusament.) So yeah, cool! From opening the box to getting a first print was a little over an hour in my freezing cold basement. I called it a night.

The next night I went down with a file I sliced with PrusaSlicer (which is a really nice piece of software) and get ready to print it but… ERROR! It showed an error on the screen. You can then look up the error code online or scan the QR code with your mobile. Seems the hotend thermistor was having issues. I checked on it, including opening up the enclosure to check the wiring, thinking maybe I didn’t secure things. Again, the wiring is a pain. Ugh. Painful. But at least I was getting used to it. So here’s the deal… It was cold in my basement, and this printer is so smart (ha!) it thought the thermistor had failed because, well… if the reading is that low, something is wrong. The only thing wrong was that I have a basement in Wisconsin. I ended up pointing a space heater at the printer until the thermistor read warm enough to pass the check. (It was honestly just a few degrees, but still.)

Okay, that was the second night. Not great, but a little annoying. I get why they do it, but hey, it’s winter in Wisconsin. I know how cold my basement is. And yes, the cold may affect the print quality. I know that.

Right so time to print! I put in the included USB drive and… nothing. It doesn’t see the thumb drive. Oh hell, now what!? I go upstairs to my computer, insert the drive, and… it’s corrupted itself. Damn. My old printer used SD cards and they always worked. Is this going to be a normal occurrence? I hope not! I reformat the drive, then copy files to it again, and I print. All good. (Note: The drive had been fine since then, as is the other one I use for printing.)

A bit of a rough start, but overall I am really pleased with the machine itself, the experience of using it (apart from the few hiccups at the beginning) and that printing plate is awesome. I was at first worried about the “bubbles” that appeared on the surface, because the (cheap) plates I’ve used with the MSP wear out, but I’ve been told these will last… and they sort of “self heal” after a bit of time. Sweet.

Now of course the real test is when things go wrong. With the Prusa i3 I used at work, it was amazing, but once we had to tear down the extruder to deal with a nasty clog and that was a nightmare. So time will tell as far as how things go when things go wrong. Right now I can pull apart the extruder to remove a clog on my MSP or an Ender 3 in less than ten minutes. For the MINI, well… I don’t know yet. Maybe it won’t clog. (Ha! Just kidding! It will. It’s a 3D printer after all.)

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Ryobi Air Pump Repair

I got one of these Ryobi Air Pumps a few years ago, and it worked great for filling bike tires, and I occasionally used it to fill my car tires, though it’s really not great for that. At some point last year it started smoking a bit and I thought the motor was burning up, so I opened it to find the fan (that appears to be meant to cool the motor) slightly broken.

I found a customizable fan blade file and modeled it to fit the motor shaft. It printed well enough and I put it in place.

I did have to ream out the hole with a drill bit, but once I did it pressure fit on the shaft perfectly. I’m not really sure how the original fan broke, but at least now I’ve got a replacement, and can make more if needed. (I printed it in PLA, so it might melt… who knows?)

Oh, and does it work? Well, the pump runs, but it always runs. I did smell what seemed like burned motor winding, so I’ll need to try it out on the bike tires and see if it’s up to the task.

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3D Printed Print Baren

In the world of printmaking (of which I am far from an expert) there are many ways to print, including a printing press. I no longer have easy access to a press, so I’ve been using alternate methods of getting ink on paper. One method is to use a baren. The baren is a thing you hold in your hand to rub the paper against the printing plate, thus causing the ink to be transferred.

I bought a cheap Speedball baren years ago, and I never liked it, so I started looking at other barens. Now, printmakers tend to appreciate fine things and aesthetics, and there are a lot of different barens out there. Some are made of glass, some are bamboo, some have rope or ball bearings or pads, etc. So I finally asked the wisest of printmakers I know, and Jessica told me she just uses a wooden spoon.

Well, I decided to just make my own baren. So I quickly modeled something really ugly, and I 3D printed it. After I printed it I thought of a better way to model it, and I still haven’t made a new one. This one works, so I’ll just keep using it for now. It’s functional. It’s good enough.

I did sand the bottom of it… quite a bit! Working my way up to high grit sandpaper until the bottom was smooth. Really smooth. It’s smooth. Yeah. Smooooooth. I also sprayed it with Liquid Wrench and rubbed that in real good. It glides across the paper really nice. I’ve done a few prints with it and I’m pretty happy. 3D Printing. It’s handy!

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3D Printed Skull

I printed this skull back in 2019. The original file is this skull from Thingiverse. Now, it’s October 2020, so yeah, this took a while. I mean, I had it all printed long ago, and then I did an experiment where I covered one half of it with wood glue, and the other half with Smooth-On XTC-3D High Performance 3D Print Coating. I did this because I hate sanding prints (or wood, for that matter) and I wanted to test both methods of coating. For this application, I don’t know that it made much of a difference, but that might be due to the organic shape, and the fact that I primed and painted it afterwards…

Somewhere I’ve got photos of the coating process, but since they are nearly a year old now, I forgot to locate them. I do remember that the glue method took many more coats than the Smooth-On method, though of course glue is a much cheaper material…

You’ll notice the skull also looks a bit “weathered” and yeah, that was another test. I am not an “authentic movie prop maker” so I don’t know all those methods, and what I did was actually rub mud/moist dirt all over this thing and then let is sit for a long time. I eventually washed off a lot of the dirt because, well it was really dirty looking.

There are a few delicate parts of the print, and I’m pretty sure I broke off at least one piece and glued it back together. Again, since this is a pretty organic shape, no worries. And yes, it is pretty much life size.

I printed it in two pieces after slicing it in half, which means the surfaces touching the print bed are not visible as they are in the center of the skull, glue together. There’s a pretty bad seam that I never managed to get that sanded down quite right. I probably should have just taken a Dremel to it.

Overall I’m fairly pleased with how the skull turned out for a 3D printed object. It’s rare that I print “decorative” or “sculptural” prints since most of my prints are internal to some sort of enclosure with electronics inside.

Remember, the great thing about skulls is that we’ve all got one! (At least I hope.)

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Vinten Tripod Leg Lock

I was doing a video shoot with Ben Nelson for Brown Dog Gadgets last week and I noticed his Vinten tripod leg had an issue staying locked in place… Seems one of the leg lock pieces had broke in half. It seemed liked a perfect reason to fire up OpenSCAD and get the 3D printer spitting out a new part.

In the photo above you can see the new part in silver, and the two original parts on the other legs, in black.

It took two prints to get an acceptable fit. The first was a little too wide and wouldn’t quite fit in place. I tweaked the file just a bit and the second version worked well. I’ll walk through the process a bit below.

For an organic shape like this I usually start by putting it on a desktop scanner to get the profile. This one is curvy, and I’m not big on drawing curves in OpenSCAD, but I am big on scanning in an object and then tracing it in Inkscape. I did a few scans and even then I edited the image a bit to adjust the contrast.

I import the images into Inkscape, each layered directly on top of each other, then add another layer on top of that to do the drawing. I can then easily switch out the image below and compare things. For a symmetrical drawing like this I really just need to draw half of it, then I just dupe and flip to make the other half and combine them into one.

Once I have a vector file created I export that and then import it into an OpenSCAD file where I can extrude it changing it from a 2D shape to a 3D shape. Creating a solid object is the goal. Once I’ve got a solid object I can start knocking holes in it and adding angles by subtracting with various shapes. (The reddish parts are all subtractions or differences from the main piece.)

And yes, the above image does appear to be some sort of special forces TIE Fighter from the Star Wars universe.

Here’s our final piece, ready to be rendered, sliced, and printed. The original part had some pockets on the top and bottom, but since they were not required for functionality I left them out.

Ben installed it and briefly tested it and it seemed to work, though time will tell if it holds up under stress. (Also, this one is PLA so if he leaves the tripod in a hot car, it might soften and fail.) I’ll probably print a few more for him to keep in the tripod bag in case this one does fail in the field.

If you want to print one of these, you can grab the file from Vinten Tripod Leg Lock and have fun!