Hey, Slab!

Today, I decided it was time to reduce the noise of my printer.

First I did some measurements. I created a single-layer print of pure infill, increased first layer speed, and adjusted infill angle to make the printer move X, Y, or diagonally. Sure, I could have done a custom gcode sequence to just move the axis, but I didn't feel like digging into that. The first print was quite difficult to get off, so I moved Z adjustment from -0.8 to -0.6.

For each test, I used the Sound Meter app, first right in front of the printer, then on a separate table across from the printer, taking the average after about half a print. 

Y movement: Near printer 56 dB, other table 46 dB

X movement: Near printer 54.3db, other table 37.2 dB

Diag movement: Near printer 57 dB, other table 45 dB

Y movement is far noisier than X movement. There's some suggestions in this thread: Lubricate bearings, oil axis, add motor dampers. Oiling is an easy step, let's try that. After oiling, Y axis movement is 56.7 dB near the printer, 46.7 dB on the other table. Louder. Huh. Could be a measurement error.

I don't feel like taking the printer apart today, but I did get a slab of granite, and I have plenty of foam. So let's do some tests with them.

First step: Put pieces of simple camping foam under the feet of the printer. This reduced the noise level of the Y movement to 48.3 dB near the printer, 35 dB on the other table. Already noticeable! And this foam is pretty stable, so shouldn't make the printer too wobbly.

There's also a sound coming from the power supply, probably the fan there. Slightly irregular, not that loud yet.

I took the opportunity to fasten what bolts I could get to. I tried to open the power supply, but wasn't able to without taking more apart than I felt like. I did however notice a small piece underneath it that wasn't fastened correctly, so I fixed that. After that and putting the printer on a slab with soft foam underneath, the test print measures 40.4 dB near the printer, 31.5 dB on the other table. So this shaved off in total 15 dB, impressive! Even the power supply fan seems quieter.

Of course, I should have measured between fastening bolts and putting it on a slab, but I didn't. Maybe another day.

Luckily, the filament spool just fits under the cabinet above

I might want to have the filament spool mounted separately, possible between the two edges on the sides (you can see one in the picture). I would need a setup where the holder was easy to remove, though. I suspect some of the noise from fast moves is from the filament spool.

Clearly, this merits printing a really nice McBenchy!

There's a smidgeon stringing (that I have cleaned off), and the Z level is not quite perfect, but overall it's super smooth.

The first layer of the McBenchy had an average noise level of 34.9 dB (measured in front of the printer), the second one where the usually noisy bed fan started got up to 39.5 dB - that's not just the fan, though there were also some fast zig-zag moves that were somewhat noisy. Apparently moving the printer about has at least temporarily fixed what was wrong with the fan. Later layers averaged 37.7 dB, though there were places that were somewhat louder, it seems to occasionally hit a resonant frequency. Measured on my chair arm, so at normal distance for me, it's 29 dB, at the other table 28.2 dB.

All in all, I am satisfied with this noise improvement. In fact the power supply is not responsible for a fair amount of the noise, maybe I could dampen that by adding some rubber washers to the various screws.

Obligatory Borderlands 2 reference:

Last miniature test, I promise

Having had some luck with the 0.04mm layer (yes, that's 40 microns, less than what many resin printers advertise), but also having read that thinner layers may need higher temperatures, I tried to vary that. Also, due to stringing, I tried to vary retraction. Results were mixed, shown  belowwithout any cleanup.

This one (front and back) is (accidentally) at 230°, with 1.2mm retraction.

This is also at 230°, with 2mm retraction:

And finally, at 235° and 3mm retraction, an accidental skeleton king:

Clearly, 235° is too much, though it should also be mentioned that these were done after a failed attempt at a temperature tower that broke loose from the print bed. 230° is also a bit high, I liked the 225° better, the print was smoother. And 3mm retraction is quite obviously a bad idea here. 

This temperature tower was done at 0.16mm layer height, still 0.25mm nozzle, and it's really hard to tell any difference between the temperatures. Actual temperatures are, from the bottom, 225, 215, 205, and 195. There is a bit more bridging droop at 225, and the overhang seems a bit less regular at 205 and 195. The most interesting difference is that at 195, the surface is matte rather than shiny. 

Full-size front shot, layers clearly visible:

These shots were taken in my new mini-softbox, a cut-open plastic container. It can bounce the light enough to give reasonable shadow,s while the highlights of irregularities are easy to see in the sun. Lens is a 60mm macro at 1:1, f/16 on APS-C.

Now back to a regular 0.4mm nozzle and some normal prints.

Many good prints done

Using PETG from Beta2Shape on the steel dust surface, I calibrated it to -1.09mm. Prints still fell off unless I used 3dlac. When I tried the flat surface, I was hardly able to get the print off at all. There is also a lot of very fine stringing when I use the default Prusament PETG settings. I'll try some of the tips in https://all3dp.com/2/petg-stringing-3-easy-ways-to-prevent-it/ to improve that.

For PLA, I couldn't use the steel dust surface, instead I use the flat one calibrated to -1.0mm. The PLA from DasFilament has done good by me. Curiously, after switching to the powdered surface and back, the calibration changed to -0.8mm. Clearly recalibration is a good idea after switching surface.

The printer has been quite busy. I joined makervsvirus.org and printed 50+ face shield holders:

I look super derpy in this shot, but it shows how the face mask works, just add a sheet of clear plastic.

50 of them delivered to our local hub.

I printed tools for my coworker Ilham for taking off the faucet filter (in German a "Percolatorschlüssel"):

Generic version that works on many faucets 

Version for a specific size of inner teeth - I didn't even know there were inner teeth! This was the size that Ilham needed, but difficult to get a good grip on

A version with better grip, but too large for our faucets. 

Some other things against Coronavirus:

My wife is doing a bunch of masks, but ran out of bias tape - as did all the suppliers. So I printed this nifty bias tape folding device, it works quite well.

Another thing for masks, this holds the straps instead of your eats getting pulled at. Unfortunately it slides downwards, and so does the mask.

And another couple of useful things around the house:

I got a used bike trailer of a kind I've previously used for the Monachium war chariot, but this one came with an attachment that tried to fill the same space as my disk brakes. Since physics has some stern words to say about doing that, I made an adapter for the other kind of attachment, printed in PETG (which is less brittle and more heat-resistant) and somewhat over-dimensioned. It works nicely so far.

For working from home, I found my WiFi connection utterly inadequate, so I decided to lay Ethernet into my room. These are Cat6-compatible clips that can be stuck onto the wall. I now have a pretty well routed wire, firmly attached. 

The new PrusaSlicer 2.2.0 has some nice details to it, like when an SD card is detected, it will add a button to write to the SD card and after that another button to eject. Now that's a UI that helps smooth the common path. Too many engineers in particular forget to do that, presumably thinking that it's enough that the functionality is available, there's no need to duplicate it. Kinda like the mathematician reducing a fire to "a known problem."

Perfect prints produced by Prusa printer

It printeth! Verily, it printeth! My new Prusa i3 mk3s printeth! And wow, does it do a good job of it. Here's the obligatory Benchy McBenchface, in a quality I haven't even gotten close to on my old printer:

None of the sloppiness around the brow, no extra lines around edges, the print on the bottom totally clear, and it's almost possible to read the tiny writing on the aft. Impressive!

I got this as a kit (of course!), and putting it together was pretty easy, though not trivial. There's quite a tome of a manual, with each step illustrated with photos and text. No soldering is involved, and all the necessary tools were provided. On the down side, some texts were ambiguous ("put the screw in the left hole" - but I can turn this thing any which way!) and the photos were not very good, especially since they had to show details of black on black. I could certainly take better shots (and did a couple of times, just as a sample). I worked together with my friend Christina, and we only made one mistake where I had to go back and undo some of the assembly. Inserting the nuts was sometimes tricky, in most cases we were able to pull them in using a screw from the other side, but not always.

The basic design is the same as my current one, with the bed moving in the Y axis, the extruder running along the X axis, which is in turn lifted by threaded rods on the Z axis. The details have improved a lot, though. Gone are all the endstops, since the motors are able to sense when they skip, which is enough to detect the end. The extruder has a built-in filament sensor, so it can stop printing if running out of filament. There's also a power panic system in case of power outages. The bed is with a separable bendable steel plate, held on by so many magnets that there are warnings not to use it if you have a pacemaker.

The operations are also very easy. There is a panel in front with a little dial, which allows controlling the printer in many ways. Starting a print from an SD card is three clicks away, and it auto-calibrates the bed height before each print. The self-test and larger calibration was quite effective, pointed out an issue I had missed.

For Z axis calibration, there is a live adjustment option, so while the print is happening I can adjust - micrometer by micrometer - how close the the bed the first layer should be. To get the right height, I printed the Prusa logo model that came on the SD card, adjusting the height by 0.05 mm every two centimeters or so. I stopped printing after the first layer, so I could see the quality:

Top side of print. Left part is with the nozzle closer to the bed

Bottom side of print. Left side is nozzle closer to the bed. 

It was clear when the nozzle was way too low or way too high. In between, at about -0.95 to -1.1, the printing was just about perfect. This is a way better calibration than the single-strip built-in method.

The main problem since I got printing going has been to make the prints stick during printing. At first, I just used the recommended isopropyl alcohol swap to clean the plate. That didn't help much. Increasing the bed and extrusion temperature made it possible for a large flat piece to stick. Washing thoroughly with soap made things somewhat better, but printing this little hedgie proved too much for that. Next step was my trusty hair spray, which didn't help either. The trick from this video of putting a bit of gluestick on and spreading it with alcohol made no difference whatsoever. Only when I smeared the printing area with gluestick did it actually stick, but then that also adds more thickness. After reading various discussions about this problem, I ordered a flat sheet instead. It's supposedly less durable, but being able to print without smearing the plate is important.

I also ordered some filament - this is a 1.75mm extruder where my old printer is a 2.85mm - and some different-sized nozzles. I even got one of the experimental 0.15mm nozzles, since I want to try printing miniatures for gaming. I understand even using the 0.25mm one is tricky, so I don't expect instant success. I grabbed a 0.8mm nozzle for the old printer, it can be relegated to the easier tasks.

All in all, this is a really nice printer. The printing world has moved a lot since I got my Mendel90 half-kit, and it shows. I expect (hope) to be able to spend less time repairing the printer and more time designing.

The new wonder! What shall I call it?

Purple printing process promises perfect pieces

Got the new thermistor from e3d faster than expected, so I had some time to put it in this weekend. Putting in the thermistors was a bit fiddly as the covering was fraying, hopefully using the crimps will help:

Other than that, putting it back together was easy enough.

At 220C, 50mm/s, extruded 44 mm out of 50. There was a faint sweet smell, so this is hot enough to melt the PLA properly. At 75mm/s, the same. At 210C 100mm/s, it extruded somewhat less. 100mm/s at 230 extruded 42 mm, but with 75mm/s 44mm. Doesn't look like I can get more than 45 mm out of this, so I'll adjust the firmware accordingly.

After adjusting, it gave 47mm. Odd. Resetting the multiplier and trying again, getting 34mm, 33mm, 34mm. Adjusting for that give about 48mm at 50mm/s, but once I went to 75mm/s, only 46mm. That's exactly the same weirdness I saw before switching.

The brand new nozzle and brand new Innofill filament curled up at the nozzle at once, but after a bit more extrusion it got better, nice and smooth.

First test box got overextruded because Slic3r again didn't pick up the right settings. I've reverted to not specifying a settings file.

On the next print, it picked up the change in layer height (2mm -> 2.5mm) but not the change in temperature. Huh. The cube came out nicer, but still with upturned corners and splits in the top layer. Since my bed stickiness is good, the corners hint at too high a print temperature, or lack of fan.

Added the slanted fan mount and got a decidedly nicer result. No corner lifting, nicer top cover. A bit of gap in the top, though. Changed the slic3r command to be very specific: /Users/lars/Applications/Slic3r.app/Contents/MacOS/slic3r $s --output $o --load "/Users/lars/Library/Application Support/Slic3r/print/Simple Mode.ini" --load "/Users/lars/Library/Application Support/Slic3r/printer/Simple Mode.ini" --load "/Users/lars/Library/Application Support/Slic3r/filament/Simple Mode.ini". Now it picks up changes from Simple Mode. I have only one skirt, but with this hotend/filament combination, that doesn't matter.

Trying with 0.2 layer height instead of 0.25, plus no bed heat since the previous part was really hard to get off. First layer adhesion was much worse, but it fixed itself. The top is great, 0.2mm is the way to go. It was, however, so hard to get off that I had to use the stovetop scraper and tear the tape.

Just for kicks, made a more complex cube. Also took off the tape to see how well that works, and turned off bed heat. Why test only one thing at a time? :) It did quite well until it got up to the top part, then the cube itself came loose from the glass.

Tried again with hotter plate. Came loose at pretty much the same place and in the same way. Curious.

Tried, as I have seen suggested multiple times, coating the glass with UHU stic, still with 80C bed temperature for the first layer and 60C for the rest. And it worked! This piece is pretty close to perfect! And pretty close to impossible to remove...

That cube is at a 60 degree angle, and the overhang is just fine.