Currently, Prusa is doing a terrible job with the Printables competition, to the point where they could be in legal trouble if someone were to push for it.

A few examples to prove this statement (5th is in my opinion the worst):

1. insect hotel -> canceled due to security concerns. Great work, but why not look into it before you start and provide a design guideline? https://www.printables.com/contest/436-insect-hotels

2. Bathtub toys -> Mentioned explicitly: "Safety is our top priority, so make sure your creations are child-friendly, [...]". As these are bath toys, one might assume that they mean safety standards for young children. https://www.printables.com/contest/428-bathtub-toys

Great. Safety is a top priority. So let's see how they moderate it. They haven't... If you scroll through the valid submissions, there are dozens that aren't safe for children. Prusa is EU, so I would expect them to be familiar with the basic EU regulations for children's toys when they say we want safety first. There are very strict test requirements that a toy has to meet. The simplest one is a bin/cylinder that a part cannot fit into (choking hazard). Does every design meet this very basic design rule? No. Next comes impact resistance and the like. Does the design meet these requirements? no.

You could say that it's just not feasible to review every submission, so let's take a look at the winning entries that they definitely looked at: Rubber Band Submarine. I'm not a toy designer, but I'm pretty sure that an exposed rubber band is not safe for small children, who are the target audience for bath toys.

3. fish tank tweaks: Recommending PLA for prints that are permanently submerged ("It is usually recommended to use ABS or specific food-safe PLA..."). Seriously???? These days they are PLA under these conditions is rubbish within a year. Discoloration and expansion destroy some PLA blends/filaments.

4. soldering aid: Seeing this design as a winning soldering aid raises serious questions as to whether the person involved has any practical experience in assembling electronics. Placing a PCB 2cm in the air with sharp objects around the mounting holes is the opposite of ergonomic and comfortable SMD soldering: https://www.printables.com/model/740818-parametric-stackable-pcb-standoffs-m2-m14-holes

****5. This contest had questionable practices and here's where things get wild. Now we're not just talking about knowledge gaps, we're talking about breaking your own rules, which could be a legal problem. One of the contest rules states: "A valid entry may change its slope, altitude or distance." Simple. Right? Not for Prusa: https://www.printables.com/model/837104-the-rig-r11-diy-helper-stand-for-testing-electroni

This is a winning entry that can't do any of those things, and would probably qualify as a generic holder (also not a valid entry).

Another winning entry that wouldn't be a valid entry if Prusa followed the contest rules: "Skip the organisers: We love a tidy workplace, but today we're focusing on ergonomic improvements": https://www.printables.com/model/808502-heat-insert-press

Want a third from the same competition? Here it is: https://www.printables.com/model/808502-heat-insert-press "Specific adaptability: Designs must provide flexibility in the user's interaction with the tool or aid (height, tilt, distance or orientation adjustments). Simply accommodating different sizes of objects doesn't quite fit the bill".

To recapitulate, Prusa broke the rules not once, not twice, but three times within this competition (which, being EU, has some legal requirements on how you can and can't run competitions) by awarding prizes with monetary value and talking them away from other competitions that followed the rules.

There is more wrong with how this was organized/done, but I think this is damning enough. Never assume evil, so I would kindly call it Prusa being utterly incompetent.****

6. The current XPR challenge. Design a part for a robotics kit. Sounds exciting. First bummer, it's $115 + tax, but that wouldn't be noteworthy enough to write this:

6.1 To design for it a.) either buy it (providing a $35 discount if you do so) or b.) try to work with whatever this is: https://www.printables.com/model/576581-xrp-robot-part-of-the-experiential-consortia/files the picture shows a complete model with PCB and sensors (some connectors and wiring are missing) but would be workable. What do they actually deliver? The frame with no electronics or components. Good luck working with that.

6.2 While this may or may not go in the direction of predatory, there is more: "Photo quality - Well lit, in focus and clear photos will help showcase your work and help us choose the best designs." Quick questions: How do I take good and compelling photos without the $115 robot kit? | Prusa: "This also means that you don't need to own a 3D printer to enter". Question: "How do you make photos without a 3D print to show of? the wording is very clear that they mean photos and not computer 3d-Render. Just by looking at these two aspects, this thing has a $115 + tax ticket to improve the "chance" of winning.

6.3 Moral issues: This work is unpaid to begin with. Does Prusa really expect people to spend tens of manhours working on a good design, printing it, taking pictures, writing instructions and text, when they have absolutely no use for it themselves, since this kit has probably only been sold a handful of times to end users. There is only a small chance of wining something (remember exhibit 5 where they didn't even follow their own rules)?

Last but not least: "Popularity – Share your model to increase its popularity, and prove that users appreciate such a model." This is fairly common for some events and I always dislike it as this asking for free advertisement. Prusa at least limits it to the model itself while others use a broader approach where it is for the entire project/organization. Regardless such terms always have a negative impact. Just remember all the MakerWorld spam everywhere after they launched with high rewards.

I am curious how often do you service the linear rails on the 3D-printer:

• How often do you lubricate them (MGN9 or MGN12)?
• How do you lubricate them?
• What volume of lube do you use?

Short overview of how good the nesting capabilities of various 3D slicer are.

The task is simple: placing as many of these shapes on a 200x300mm printed as possible. Manual (quick and dirty for reference): 6 pcs.

Ranking:

1. Ultimaker Cura: 7 pcs.
2. human (me): 6 pcs.
3. Orca slicer: 5 pcs.
4. PrusaSlicer & BCN3D stratos: 4 pcs. By switching (for this particular part) from the worst (Prusa) to the best (Cura) slicer the nesting performance improved by a whopping 75%!

Ultimaker Cura:

Prusa:

BCN3D Stratos (forked from an old version of Cura):

OrcaSlicer:

After half a dozen iterations, this was the first reasonably working, acceptable feeling, and good-sounding ratchet mechanism.

allows clockwise rotation blocks counterclockwise rotation

design features:

• allows for a large inner bore (e.g. rotary encoder shaft or 5.2mm screwdriver bit)
• printable with 0.4mm nozzle
• 2cm diameter
• no assembly required. Print in place.

To get a full ratchet: mirror the assembly and add a mechanism/part that pushes one of the springs out. In neutral both leavers are engaged and the ratchet is completely locked.

Btw. Good luck copying it without going through half a dozen of iterations. Going from it barely works to this isn't easy. For my part: Version 5 was working and close to the final design. It took another 10 rounds to get it usable and from there some more to fine-tune it.

Quick and dirty 5 minutes craft: Draw a rough shape, define the contact surfaces & load, click run, and get the optimized shape. The last step is converting the output to a printable shape and running one more simulation to double-check it is strong enough.

This particular holder is a filament spool holder designed to be loaded with up to 5.5kg of filament (1x2.5kg, 3x1kg).

Building a 3D printer is easy. Getting the details right to build a great 3D printer is hard, as this is where most companies fail. Why?

For example, on this printer, the bed is a three-point mount (two wheels for adjustment at the front of the printbed) and the printer's bed levelling dialogue doesn't show the height difference that needs to be adjusted (which most 3D printers do). It does show how much it needs to be turned, and the bed levelling wheels have 1/8th turn indicators, making it easy to get it perfect.

In short, instead of an arbitrary number like 0.3mm that has no meaning to the user, they tell the user to turn this knob 1/4 of a turn. An instruction the user can follow.

** Why is this so outstanding? It doesn't cost much, but it improves the user experience. Are companies blind to these improvements because the engineers are experienced, or is there a lack of testing during development?**

By the way, years ago I did such a fix/modification myself on a Tronxy XY2 pro by adding indicators on the wheel for 0.2mm height difference so I could convert the number to rotation: https://www.printables.com/model/301670-replacement-bed-leveling-wheel

With 3D printers like the Open-5x or tool changers (e.g. Prusa XL) both, 5-axis simultaneous 3D-printing as well as hybrid manufacturing (additive followed up by subtractive), is more accessible than they ever were.

For those already venturing into this endeavor: What is your toolchain/software?

Currently, I finish the additive/3D print before running a second gcode for the subtractive part (contact surfaces, threads, ...). This is far from an efficient and powerful process.

The extruder of the 3Dgence P255 3d-printer features a brush to clean the extruder gear.

Needed as soon as possible a spool holder for larger spools so printing anything that is dozens of hours was out of the question.

Solution? Looked at the heavy shelves and had an idea.

One remix later, a 1-hour print and with some round wood that was lying around this spool holder was born.

I like the position of the spool so much that it is here to stay.

With this particular model, Prusaslicer is very optimistic about bridging and support generation:

1. the right side (dark blue) has no support that could help with load-bearing
2. the entire layer will be connected to those two lines
3. more than 5cm long bridges

I don't think this gcode will successfully print.

How do fix adjust the cura setting to generate a printable output?

The model in question is: https://www.delta-fan.com/Download/3D/BUB0612HJ-00.stp

What cameras did you add to your 3D printer? What is your favorite camera angle?

For me, the nozzle cam watching the first layer is my personal favorite (OV9281 image sensor).

As you might be aware BambuLab issued a recall for the BambuLab A1 3d-printer. In particular, the issue is the mains-voltage (230V AC) heat bed cable.

As a resolution, they offer two solutions:

1. Ship the entire printer back to them and receive a replacement printer.
2. They mail a new cable and you install it.

What BambuLab doesn't mention at all is the test according to EN 50678 (Verification of the effectiveness of protective measures of electrical equipment after repair). Unless you can perform this test I would recommend choosing the printer replacement.