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:

Trying out FreeCAD

While fiddling around with making a cherry picker to catch the bounty of the cherries outside out windows, I found OpenSCAD to not be the right tool for the job. Time to try out FreeCAD, which people say are the other great free tool. These are my experiences.

Downloading was easy enough, but the DMG file is not properly signed, so I got alarming warnings. I know how to get around those, but still. Sign your stuff.

Opening showed a nice intro screen as well as a whole lot of icons. Some but not all of these icons are so big they are cut off - or they're designed that way? It seems somewhat random, the magnifying glass is normal size, but next to it is a too-big one with a cursor on it.

Issue #1: Icons are randomly oversized

I loaded the STL object I wanted to adjust and tried adjusting. There's the object, all right, and I can rotate and zoom etc. But I can't seem to do anything to it. I can't select it in any way, and any attempt at using the many function icons bring up a dialog saying 'Need to select a <something>' or similar. 

Issue #2: Some of the function icons are greyed out when not available, others bring up dialogs instead. This makes me waste time trying to do functions I can't actually do.

I tried right-clicking to get a context menu. All it showed was 'Navigation styles', as if that's something I want to change so often that I need it in a context menu.

Issue #3: Navigation styles do not belong in a context menu, but in settings. It's something you try out some of, then get used to the one you prefer until it's second nature.

While trying to get the object to do something, anything, I would occasionally select a function that sent me back to the start page. Wut?

Issue #4: Randomly switching between pages when double-clicking model tree entries.

I eventually had to search the internet for how to edit an STL file. Turns out, it's a mesh, not an object, and needs to be converted first. Maybe instead of all the various "You need to select a such-and-such" messages, this could have been prompted somewhere? Unless you know what a small icon means, there's no indication what type of object this is, not even a hovertext on the model tree entry.

Issue #5: No help figuring out what kind of thing I'm poking at. Not even the 'What's this' function will tell me what it is.

Even with a transformed object, things were confusing. I would click the transformed object (I thought) only to have the mesh selected again. Eventually I realised I had hit Space, and the transformed object got hidden while the mesh object stayed there. 

Issue #6: The model tree entries have toggles in the context menu but no indication what state they're in, not even in the context menu where there's plenty of space.

Ok, now I have deleted the mesh object, made the transformed object visible and selectable, and selected a few facets. On to filleting! Clicking the Fillet icon switches the left bar to Tasks, with a long list of edges and the options of "All" or "None". Mistakingly thinking this would apply fillet to all selected edges, I clicked all, only to have FreeCAD hang for minutes. This is not a hugely complex object (it's roughly this picker with the threads from this adapter). My machine is just stuck. Now I don't have a super beefy Mac Pro tower machine, just a MacBook Pro, but I've been able to do fairly complex things in OpenSCAD while also using IntelliJ, and having way too many tabs open. Is it trying to do a preview? Is it just broken? Left it for a while in this state while doing other things.

Issue #7: Too easy to accidentally do something that hangs the program.

Force quit it after two hours of spinning beachball of death and 100% CPU usage. Not a good start. Back to the documentation... it's really in a strange order. Why explain the many different mouse models and the settings page before getting to any actual modelling?

All in all, FreeCAD - like so many other open source programs - suffer greatly from the Curse of Knowledge. Most people working to improve it know exactly how it works, can figure out how to work around strange problems, and only spend the time necessary to scratch their personal itches. That adds many interesting features but an overall confusing UI full of missing stairs and just blatantly bad inconsistencies. Fortunately, there are many many alternatives, and I shall take a look at some of them.

LibreCAD: https://librecad.org/ - free 2D-only cad. Might be a good replacement for Inkscape on Mac.

QCAD: https://www.qcad.org/en/ - another free 2D-only CAD program, the Qt version. Not a big fan of Qt.

BricsCAD: https://www.bricsys.com/en-intl/ - professional and expensive

Rhinoceros: https://www.rhino3d.com/ - also professional and expensive

NanoCAD: https://www.nanocad.com/ - commercial, less expensive ($180+), maybe has free version?

Onshape: https://www.onshape.com/- commercial, quite expensive

BRL-CAD: https://brlcad.org/ - open-source, seems more graphics-oriented, but could be tried.

IronCAD: https://www.ironcad.com/ - doesn't even list a price

Catia: https://www.3ds.com/products-services/catia - "Contact sales" level of expensive

Shapr3d: https://www.shapr3d.com/ - iPad-only app

Creo Parametric: https://www.ptc.com/en/products/creo/parametric - commercial

KeyCreator: https://www.kubotek3d.com/ - commercial

Not listed on that site:

Sketchup: https://www.sketchup.com/ - tried it early on, really meant for house design, when used for 3D prints it has horrible crack problems (pun intended)

Fusion 360: https://www.autodesk.com/products/fusion-360/overview - subscription based

DraftSight: https://www.draftsight.com/ - focused on 2D, subscription based

Solid Edge: https://solidedge.siemens.com/en/ - Windows-only, subscription based

SolidWorks: https://www.solidworks.com/ - 

TinkerCAD: https://www.tinkercad.com/ - online-only, basic version is free

Out of all these, only TinkerCAD and BRL-CAD seem worth investigating at the moment, being free and 3D-oriented.

TinkerCAD is very cute, but as far as I can tell mostly allows putting things next to each other. It has a large amount of shapes available, from the most basic ones to continents and gaming pieces. The UI is super nice and intuitive, and it does have subtraction (set a shape to be "Hole"), but not fancy features like fillet. Surprisingly, it has programming of sorts in the Codeblocks feature, a drag-and-drop system. It's essentially a gateway drug for Fusion 360, even using the same Workplane concept.

BRL-CAD is 4 years out of date for Mac, even though it's still being developed. I unfortunately can't run it on my work machine for security reasons.

There's clearly a lot of money in this area, and I can see why. I may have to *gasp* actually read the manual for FreeCAD.

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.

Magic Numbers

A small calibration test for tolerances that dmarting@ showed me. I wanted to get this done before switching back from 0.25mm to 0.4mm nozzle. This fiddler-like thing has decreasing distance between the cylinders and the frame. The cylinders are supposed to be able to rotate, the smaller distance that can rotate, the better your tolerance. This MakersMuse video explains it nicely, and of course there are now multiple versions floating around. I'm using this particular one because it's fairly small - takes less that 4 hours to print with 0.25mm nozzle/0.1mm layer height. Thinner layer height is not going to make much of a difference, since it's the sideways tolerance that matters. 

With a 0.4mm nozzle, it takes almost exactly an hour to print. Surprisingly, the smallest cylinder show roughly the same lack of actual printing for this and the small nozzle. I'm not sure which parameter to tweak to fix that.

Another interesting tweak: Reducing noise by putting the printer on a slab of concrete (!) standing on foam. Even in stealth mode, my printer is still loud enough to be noticeable on video calls. Curiously, there's a lot of fan noise right at the start, then it quiets down. I should see what's up with the fan.

Watching a bit of Tomb of 3D Printed Horrors (which is more about printing miniatures than about badly failed prints), I bought a few of their models, dialed in a 0.08mm layer height together with the 0.95 extrusion multiplier, and printed the top of the mace skeleton from the Fat Dragon Games Skeleton Set 1. For testing purposes, I cut it at 22mm height and added a raft. The print was beautiful:

At 0.04mm, it's got amazing detail. Remember, these shots are taking with my 1:1 macro lens at full macro, the part itself is 14mm high.  Even at 0.08mm, the layers in the ribs are not visible to the naked eye. Here, the teeth show up individually, the knuckles in the hand are visible, the ribs are smooth. On the downside, there's a *lot* of stringing to clean up.

There's an undead coming out of my print plate! A teeny tiny cobwebby one!

Rear view is also nice. There's some blobbiness to it, though it's hard to tell if that's due to the silver specks in the filament or actual extrusion blobs

Wanting to improve the stringiness, I printed a temperature tower, this time a bigger one. To get it done in a reasonable amount of time, I cut it down to four layers, using temperatures from 200 to 230. If I can see any difference, I can then do another tower with finer intervals. I set it to use 1.6mm layers rather than 1.5.

The results are impressive, if inconclusive. The cooler layers don't have the tops fused as nicely. The 230 layer has the spike being a bit more wobbly than the rest. There's hardly any stringing.