EmilieEvans

I run half a dozen Duet but one of them started to give me a lot of headaches and only this one (unique hardware + configuration so no other to compare to).

issue: tool head 3 heater is always enabled. The software detects a thermal runaway but the heater stays enabled. The only option to stop the machine from catching fire is to remove the main power.

Hardware:

• Duet 2 wifi
• Due5X

troubleshooting done (hardware):

• measuring the mosfets => good
• checking the driver for obvious issues with a multimeter => no issue found
• moving toolheads hotends around. Issue persists on #3 spot (4th toolhead) so it is unrelated to the tool head. disconnecting it entirely also causes the heater to stay on
• removing the SD-card => issue is gone.
• sometimes it works like it should. Most of the time it doesn't.
• on this particular unit there were some other minor anomalies regarding the WIFI earlier (wouldn't connect to the network) but those fixed themselves after a few rounds of resetting the wifi module, adding it to the wifi network again, waiting a few days for it fail once more.

**TL;DR Is my assumption correct that this indicated an issue with the Firmware from Duet which isn't just on this device but also on the newer Duet 3?

Did anybody has run into a similar issue and was able to resolve it?

In the wider picture: Is every duet product unsafe?** This is an older Duet 2 but it runs the same/similar firmware as the current generation Duet 3. So one of the big questions is if all of the Duet products are unsafe. Would be bad as this has been my controller of choice meaning a lot of work to replace all of them.

Btw. If you buy a duet: don't expect ANY support from the manufacturer.

Here is the main config file:

config-overwrite:

Upgraded from a NEMA24 to a NEMA34.

Before going out and milling or buying it in metal it is always a good idea to testprint it.

Probably will use the plastic part for a while as 3mm wall-thickness PETG seems might already be good enough.

How is the build chamber in your 3D-printer heated? Is there any thermal insulation and if how thick is it?

My two cents:

** thermal insulation**

That's the math for a small 300x300mm printer heated to 70°C (for 130°C tripple this number).

With a 6030 aluminium extrusion a 60mm insulation would fit within the walls and bring down the heatloss to approx. 45W. In other words: Once it is heated up the thermal losses are small enough for it to hold the temperature on its own. Reducing the overall power consumption.

heating/temperature control

For cooling and heating: oil<-> air heat exchanger/radiator might be a good solution:

• place one inside the printer
• the other on the outside
• insert a heater in the loop (only when heating is required, for cooling keep it off)
• possible to push past the 100°C liquid temperature.

Add a fan that circulates the air within the chamber to equalize the temperature.

This way the chamber can be heated and cooled without venting any air into the room.

Next week is the FormNext 2024 trade show in FFM. Are you looking forward to visiting it or watching news coverage?

Looking into it I notice that this year there is a noticeable fluctuation. To name one example: Duet3D isn't there this year.

TL;DR No.

What you should do:

• buy fresh IPA. It is approx. $5/L. As such a 2L washing bin is approx. $10 + 10L waste disposal. In the broader picture of total costs and production value, this is manageable (resin cost, machine depreciation, PPE/gloves, ...)!
• use two or three stages of washing
• fill the washing containers with as little as necessary to get it done
• periodically expose the liquid to sunlight and let the particles settle down. Separate the "clean" liquid from the sump (you might add special chemicals to speed up this process).
• if the first stage needs replacement: 1.) responsible disposal of the liquid in compliance with local regulation 2.) move the liquids around: (the third stage is the new fresh liquid, the second is the prior third stage and the second washing station is now the first "dirty" stage).
• check for alternative chemicals that can be used with your particular resin

If you use water-washable resin: IT IS A DANGEROUS LIQUID! Dispose of dirty water responsibly as chemical waste.

Long answer:

To answer that, let's first look at what isopropanol (IPA) is: Its formal name is propan-2-ol and its CAS number is 67-63-0.

As a starting point, check a database like GESTIS (German) and NOT wikipedia: https://gestis.dguv.de/data?name=011190

At the top of the page we see that it has GHS-02 and GHS-07 warning labels. Looking further, it is a colourless liquid with a flash point of 12°C and an ignition point of 425°C. The explosive range is 2-13.4% vol. The signal word is DANGER.

Scrolling down:

The substance forms explosive peroxides.

What does this mean?

There is no mechanism mentioned, but generally, if you expose these chemicals to sunlight they will react over time to form a peroxide, which is much more reactive and can explode at high concentrations (there are exceptions to this rule, but most of them go boom).

This means for distillation:

• avoid "old" IPA if possible
• check for peroxides (if necessary, treat the peroxides before distillation)
• don't distill dry (leave some liquid in the sump to avoid high concentrations of peroxides)

As I believe this shouldn't be done at home I won't tell you how it can be safely done (if this isn't enough to deter you: read scientific literature/books describing how it shall be done).

Instead, focus further on what advice is out there on the internet/YouTube:

• A water distiller is made for water and water isn't flammable and doesn't form explosive atmospheres. In other words they are unsafe for Isopropanol or Ethanol.
• Do you think a 2kg fire extinguisher is enough? Are you truly capable of thinking rationally when there is a fire or would you panic like most people?
• Don't even consider doing it indoors or in a garage.
• Don't work with large volumes. In a laboratory with proper fumehoods and equipment, there might be limits like 500mL batch sizes.
• If somebody isn't wearing eye protection or heating large amounts of liquid without stirring question his qualification to talk about this topic. Being an influencer or posting online, like this post, doesn't require any formal qualification as such even the big YouTubers/influencers post horrendous content that is dangerous or misleading.

Prusa video: https://www.youtube.com/watch?v=VO2MaQrUcqE

TL;DR For those who don't want to watch 10-minute video:

0. MK4 to MK4s uprade kit: 109€ + shipping (MK4 customer will receive a voucher (except shipping cost))

1. Larger cooling fan

2. Improved cooling duct

3. high flow nozzle

4. NFC for app

5. some parts upgraded from PETG to PC-CF

6. MK4s still ship without an accelerometer. Prusa claims this isn't needed.

7. No camera.

8. No upgrades for the Prusa XL in the near future!!!!

other stuff:

• accelerometer board

• GPIO board

Personal Opinion:

This should have been the MK4 to begin with and shows once more how blindsided Prusa was. BambuLab put so much pressure on them that they had to publish the MK4 in the state it is.

Regrading the Prusa XL the trouble continues. This launch/printer has been riddled by issues after issue and now the statement that the improved part cooling won't make it to the XL in the near future.... My guess it that they screwed up with the XL and didn't consider large toolheads at the design stage favoring a 5 toolhead design over a 4 head option and now run into the same issue I do with the E3D (it can fit those 6023 fans but not like they mount it on the MK4s). For example, with my E3D tool changer, a tool must fit within a 85mm(w) x 60mm(depth) surface area.

For the technical side?

The larger fan is great as it allows to use fans with decent pressure at the target airflow with a low noise. Those 4020 found on most printers aren't a great choice.

High flow nozzle? Yeah ... nothing groundbreaking or new.

NFC and app? A year ago was prusa connect at best a beta. Maybe a an alpha as I would need to restart the printer twice a day because it froze/crash. The value here depends on if they meanwhile fixed it or it is still a joke.

GPIO board? Depends. Might be held back by the firmware as those things require macros to be useful and Prusa firmware never was build around this idea. Still nice to see them publishing this.

Quick upgrade for easy to plug and unplug end effectors/toolheads. Activity/status LED are also moved from the back of the printer to the top and some more voltage regulation to provide additional voltage rails.

While a nice connector adds significant cost it is also a big value add for certain 3D-printer. I think more manefacturer should consider tiny details like this when designing their product.

Strain relief isn't installed on this tool for reasons ...

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).