Prusa Mini is a flawed design – urgent action from Prusa required.  

RE: Prusa Mini is a flawed design – urgent action from Prusa required.

@graham-l2

I don’t have the space either.  I am planning either a shipping container work space or building a small shed that is wired to hold a print farm.  I have 23 acres on my farm to do this.  

RE: Prusa Mini is a flawed design – urgent action from Prusa required.

@graham-l2

Thanks Graham! Sounds like the hotend did the trick. Though I am sure the extruder might be nice on flex etc.

I am tempted to go the hotend route,  I'm hearing mixed things on the bondtech heatbreak. It would be nice to just not have to worry about ptfe tubes to be honest.

I saw something on thingiverse for help cutting the right (120 )angle and I have some capricorn tubing laying around so I might try that. I might make one a little longer in case it shrinks as well.

RE: Prusa Mini is a flawed design – urgent action from Prusa required.

@charles-h13

23 Acres ! I think a couple of Mk3s would squeeze in there! 🙂

Another thing to think about is heating the space you intend to build the Mk3 will run from 10C (just fine)the Mini has a higher threshold before it allows you to go.   Can't recall what it is but its above at 18C I think.  No doubt this is to discourage use where the non-temperature compensated MINDA probe would cause real pain.    This is very annoying when like me I work in an outbuilding that takes time to heat up.

G

RE: Prusa Mini is a flawed design – urgent action from Prusa required.

@graham-l2

Do you use an enclosure?  A space heater would help.  

RE: Prusa Mini is a flawed design – urgent action from Prusa required.

Until the Mini I haven't had felt the need but I've got some bits to do that on order.

From the photo below (click on it for a better view) you can see my two printers nicely sitting in a purpose-built alcove which extends out the back of a summer house.

Im going to fit a thermostatic wall mounted fan heater...

https://www.amazon.co.uk/gp/product/B01BTXKAC4/ref=ppx_od_dt_b_asin_title_s00?ie=UTF8&psc=1

high on the right-hand side blowing down and fit a blind to the front.

Its hardly a 'print farm' more an allotment...

RE: Prusa Mini is a flawed design – urgent action from Prusa required.

👍

RE: Prusa Mini is a flawed design – urgent action from Prusa required.

Posted by: @graham-l2

@jason-e-joyner

Hi Jason

before you buy any new bits read this - my conclusions at the end I think you might find interesting...

....  Prusa Mini Issues

Best

Graham

 

That's a very nice write-up and pretty much matches my experience. Though I came to the conclusion that in order to combat Z bouncing up and down, I let the printer cool down instead of pre-heating it, and have Z height adjusted to cold printer. May not work for everyone obviously, especially if you need to churn out prints faster than waiting for it to cool down.

As for PTFE ... well, I have somehow accepted it's a consumable. It's just weird that I had printed PETG for weeks and weeks until it gave in and clogged, but other people posted here they suffered the same issue within mere hours. Is it only the heatbreak, or could it be insufficient heatsink cooling? Would better fan and moving cables out of the way help?

I will be changing heatbreak to Bondtech, but if that does not help, I'll try Capricorn, or possibly replacing with V6. 

RE: Prusa Mini is a flawed design – urgent action from Prusa required.

Posted by: @charles-h13

Can someone explain what proof we have that Prusa cut corners to save money?  

As I see it, a small minority of users are having issues.  Another group has replace parts or used cold pulls and cleaner filament to get a use able product and quality prints.  What am I missing?    

Charles, we have no response from Prusa on the issue, this is the main concern. 

and as @zoltan stated: "So I would not say Prusa is not listening to the community. Some users just do not search for solution here, there is easier to post the question for which there is a standard answer on many threads."

RE: Prusa Mini is a flawed design – urgent action from Prusa required.

@graham-l2

The nozzle clogging issue is stemmed from another manufacturing flaw, this one however is probably just an assembly issue. During assembly the set-screws holding the heat brake in are not tightened enough to resist slipping when the nozzle clogs.

To solve, unload the filament, unscrew the bowden tube nut and adapter (the brass bit that screws into the heatsink) on the top of the extruder. 

Make sure the printer is off and the hotend is cooled down for this next part. 

Unscrew the three set-screws holding the heat brake tube in place by a turn or two (so they are still attached to the heatsink), once the heat brake is free, press it up into the heatsink assembly while keeping the orientation (twist / rotation) the same as it was previously. When the heat brake tube is all the way at the top, tighten the set-screws again.

Re-install the bowden tube hardware.

NOTE: This will not work if you don't remove the brass adapter first.

NOTE: This will change your Z offset

I hope this helps, it's solved my problems time and time again. Also, get a replacement heatsink and heat brake, they're cheap and come in handy when the set screws strip out.

RE: Prusa Mini is a flawed design – urgent action from Prusa required.

@drkmstr

Thanks for taking the time for that but its not working for everyone and some examples are on this thread and elsewhere.

It also does not explain the fussiness on filament makes, in my case the ptfe tube was nice and tight but still had a hard time with filament other that Prusas. 

There are a lot of experienced users out there having these issues - there is something marginal going on and perhaps most users are on the good side of that margin.

Graham

RE: Prusa Mini is a flawed design – urgent action from Prusa required.

@drkmstr

Thanks for taking the time for that but its not working for everyone and some examples are on this thread and elsewhere.

It also does not explain the fussiness on filament makes, in my case the ptfe tube was nice and tight but still had a hard time with filament other that Prusas. 

There are a lot of experienced users out there having these issues - there is something marginal going on and perhaps most users are on the good side of that margin.

Graham

RE: Prusa Mini is a flawed design – urgent action from Prusa required.

@graham-l2

Graham,

There's also another issue that I found, when filament is more oval in shape and/or it is more prone to plastic deformation (thanks to the extruder that does not have spring tension), it can get stuck in the bowden tube. I had that issue and had to change the minimum distance between retracts.

RE: Prusa Mini is a flawed design – urgent action from Prusa required.

I am having the same issues and its frustrating seeing the Prusa sycophants belittling the customer instead of allowing there could be an issue with the design of the printer. 

I see it being blamed that only unhappy people post here, have you seen the free great press Prusa gets literally everywhere? How about we take the complaints of people a little more genuinely? 

RE: Prusa Mini is a flawed design – urgent action from Prusa required.

@sometimesforever

Prusa aren't perfect, but there are a lot of happy users, many of whom have bought multiple Minis.

I got my Mini in July and was disappointed to find I needed to adjust the height of the hotend. By that time it was a 'known issue' and should have been sorted in the factory. Since then, the only problems I've had with my Mini are user error and can't be blamed on the printer so I am a genuinely happy user. That being said there is undeniably an issue ( or issues) that do effect some printers. The problem is that nobody, so far, has been able to identify the variable (or combination of variables) that makes the difference. 

Prusa have acknowledged that the "variable z height" issue is, in part, a hardware problem ( https://github.com/prusa3d/Prusa-Firmware-Buddy/issues/309#issuecomment-703460297 ) and I am confident we will see a fix released in due course, which will also be made available to current users. Prusa have had most of their engineers working from home since ~March due to the Covid situation there, which has impacted their ability to collaborate and test changes and probably contributed to the delay in resolving the issue.

Prusa do need to find a way of communicating with their customers around issues like this and shipping delays, but it's not uncommon to see this in businesses that expand rapidly.

If you start a new thread with the issues you are experiencing, then someone will help you, or you can use Prusa support, the web chat (on the e-shop page) is generally considered to be quicker than starting an email discussion.

I hope you can resolve the issues you are experiencing with the printer and move on to happily printing as you expect to be able to.

RE: Prusa Mini is a flawed design – urgent action from Prusa required.

Posted by: @gordon-w

@sometimesforever

Prusa does need to find a way of communicating with their customers around issues like this and shipping delays, but it's not uncommon to see this in businesses that expand rapidly.

This is one statement that is 100% true!  

RE: Prusa Mini is a flawed design – urgent action from Prusa required.

It's insane that Prusa is still shipping printers with the known MINDA probe issue unsolved.

I suspect a lot of Mini buyers are buying 3D printers for the first time.  They really don't know any better when the Z offset shifts, if they notice it at all. 

The printer still generally prints fine during a cold start print, and people will only notice something amiss if the first layer finish mattered to the part.  Most of the time it's the bottom of the part and people don't pay attention to it.

How do I post a review on the web store anyway?  Potential buyers need to know about this issue.

RE: Prusa Mini is a flawed design – urgent action from Prusa required.

Can someone direct me to a post to try to repeat or reproduce these concerns?  I want to try to understand what you are complaining about.  I tried before and could not.  I looked for the instructions and cannot find them.  

RE: Prusa Mini is a flawed design – urgent action from Prusa required.

@charles-h13

Here's the easiest way to do it.

Step 1. (cold printer) raise the Z axis 5+ inches above the bed. 

Step 2. Start Calibration Print

Step 3. Write down the Z offset

Step 4. "Auto-Home" printer, preheat and let sit for 5 minutes.

Step 5. Start Calibration Print

Step 6. Write Down Z offset

Step 7. Subtract and find difference in Z offset drift

RE: Prusa Mini is a flawed design – urgent action from Prusa required.

Posted by: @sometimesforever

I am having the same issues and its frustrating seeing the Prusa sycophants belittling the customer instead of allowing there could be an issue with the design of the printer. 

There are issues with any design of any product. There is no perfect 3D printer just as there's no perfect car. There are always areas that can be improved, and the MINDA issue definitely is one of those. However, there are a variety of work-arounds and techniques that are working for many users with the problem. Prusa seems to be aware of the problem and working on it. It's unfortunate those haven't worked for you, but I don't understand why you seem determined to take this personally. People suggest things. Maybe they work, maybe they don't. At least they tried to help.

It's equally frustrating to see users complaining about a problem and not be willing to try some rudimentary measures to compensate and (more importantly) provide input into the troubleshooting process. The Mk3 had its share of teething pains, but we individually helped each other out and Prusa eventually resolved all of the issues. This is very different than my experience with similar issues with other printers that cost more than the Mini.

I see it being blamed that only unhappy people post here, have you seen the free great press Prusa gets literally everywhere? How about we take the complaints of people a little more genuinely? 

It's not "blamed". It's not surprising that people posting in a user support forum are -- surprise -- needing support. That doesn't mean that there aren't far larger numbers of users having no issues. Yes, it's an issue. It's an issue that can't be resolved or worked around for a smaller subset. You are getting pushback because you continue to imply that this is an issue that affects all users when clearly it's not. That's all.

Prusa gets great press because their products are generally far above most of the competition in terms of overall user satisfaction and reliability. That doesn't mean they are problem-free for all users. I'm really not sure what you're asking short of shutting Prusa down and a big sign declaring that you're right stretched across their building. That's not going to happen, sorry.

RE: Prusa Mini is a flawed design – urgent action from Prusa required.

@charles-h13

I have already read a lot about "MINDA problems" although I have not been affected by it myself.

https://github.com/prusa3d/Prusa-Firmware-Buddy/issues/895

I don't know what type of sensor Prusa has installed, but the temperature has an influence on normal inductive sensors (23degrees ref.). In general I would also deactivate the bed heating during mesh bed leveling to reduce electromagnetic influences. It is also important to do a reference (home) run before the meshbedleveling.

To avoid collisions of the nozzle with the printing bed, I have mounted a mechanical stop on the Z-axis for safety reasons. This can happen if the sensor should fail.