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Prusa Bear Mini Mk3s  

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rinkel
(@rinkel)
Estimable Member
RE:

Just to report back here

I got it to acceptable levels now. It was a mixture of things

  • PTFE tube replaced
  • Re-aligned the drive gear (was 0.5 - 1 mm off)
  • Reduced the extruder motor current to E375. This also removed most of the diagonal ripples.

 

Posted : 30/09/2022 3:12 pm
pear3d.ch
(@pear3d-ch)
Trusted Member
Topic starter answered:
RE:

Hello guys can you try this profile from file as the following in the attached picture:

 

 

https://media.printables.com/media/prints/37939/stls/2544060_5dde97c7-b88c-4fe1-8154-0efbd4e6c46a/print-profile-smoki-bear-prusa-minilaretractions.3mf

 
This post was modified 2 months ago by pear3d.ch
Posted : 04/10/2022 3:06 pm
rinkel liked
rinkel
(@rinkel)
Estimable Member
RE: Prusa Bear Mini Mk3s

I just imported the profile, but not much better then your original, which i prefer and installed.

I thought about the issues many (including me) had with the Bondtech heatbreak. This looked similar. So i took apart the heatbreak and re-pasted the heatbreak again. This helped quite a bit. 

 

Posted : 04/10/2022 5:51 pm
rinkel
(@rinkel)
Estimable Member
RE: Prusa Bear Mini Mk3s

Checking back again.

The horrible case of inconsistent extrusion seem to be a case of issue 602, which was caused by the Mk3 extruder.
It could be that my print was bad, wrong dimensions. But i replaced it with an Orbiter V2, for which i had to remix the Mk3 version.
It took me ages to configure this thing, i had a lot of bad layer lines and the manual states to use an 850 current, which is way too much (i now use 400)

The inconsistent extrusion is nearly gone and vertical walls are near stock Mini. 

 

Posted : 23/10/2022 10:15 pm
singlefin
(@singlefin)
Eminent Member
RE:

I already have a Mini+ and the tinkerer in me can’t keep my hands still… so I bought a Blurolls Mini bear frame kit that also comes with a Z stepper motor, 310mm smooth rods, and linear bearings and looking to start converting soon.
I have a few questions and appreciate someone can help me clarify:

1) Are the 310mm smooth rods from the kit too short? I have seen mentioned here in a tentative BOM that Mk3S smooth rods are needed, but I believe they are 320mm long.  Would I have a problem with the shorter 310mm rods?

2) How many linear bearings do I need for the new X and Z arrangements?  I assume 2 for the X carriage.  How about for the dual Z rods, 2 also?

3) Has anyone mixed Z stepper brands with stable results?  I know it is recommended to match with OEM Prusa if I already have Mini.  But seeing that the Blurolls kit comes with a Z stepper, thinking if there’s a way to save $50-60.  

4) Do I need to print a new Y belt holder, or can I reuses the stock Mini holder?

Thanks!

This post was modified 4 weeks ago by singlefin
Posted : 01/11/2022 5:40 pm
rinkel
(@rinkel)
Estimable Member
RE:

I don't have a reply to all your questions, but will give it a shot

  1. I use the original rods and actually had to sand them down a bit, they're shorter than 310
  2. You need 3 for the Y, 3 for the X, 4 for the Z (if you use the 8mm rods), if you use the original 10mm z-rods from the prusa mini, you can re-use the z-bearings. So 10 in total when you use the 8mm z-rods.
  3. This i don't know. I use original Prusa, but i guess it's best to use the same on both sides
  4. Do you mean the holder on the Y-carriage itself? No, you can keep this. I just moved the whole bed from Mini to Bear. But you do need new belts, for both X and Y. You will need to print a new belt tensioner.

Here is a picture of the Z endcaps. I had to use a grinder to cut off a bit to make it fit.

 

Posted by: @singlefin

I already have a Mini+ and the tinkerer in me can’t keep my hands still… so I bought a Blurolls Mini bear frame kit that also comes with a Z stepper motor, 310mm smooth rods, and linear bearings and looking to start converting soon.
I have a few questions and appreciate someone can help me clarify:

1) Are the 310mm smooth rods from the kit too short? I have seen mentioned here in a tentative BOM that Mk3S smooth rods are needed, but I believe they are 320mm long.  Would I have a problem with the shorter 310mm rods?

2) How many linear bearings do I need for the new X and Z arrangements?  I assume 2 for the X carriage.  How about for the dual Z rods, 2 also?

3) Has anyone mixed Z stepper brands with stable results?  I know it is recommended to match with OEM Prusa if I already have Mini.  But seeing that the Blurolls kit comes with a Z stepper, thinking if there’s a way to save $50-60.  

4) Do I need to print a new Y belt holder, or can I reuses the stock Mini holder?

Thanks!

 

Posted : 01/11/2022 7:42 pm
rinkel
(@rinkel)
Estimable Member
RE:

To add (cannot edit my post anymore):
This has been a fun project, i loved every minute of the build, but it has taken me more time than i anticipated.
The Mini has now become a much much more stable and reliable printer than before and will never return back to the original Mini. Although prints are much nicer and more accurate than on the original Mini, the vertical walls are still king on the original Mini, due to the bowden setup.

Posted : 01/11/2022 7:50 pm
singlefin
(@singlefin)
Eminent Member
RE:

Thank you for sharing your experience and thoughts.  I'm sure it will be a fun project for me too! 

By the way, do you know which Y-rod holders to print?  I have seen 2 versions shared for downloads: "rod_holder_main" and "rod_holder_main_SPECIAL".  There appears to be some minor differences in one of the mounting holes in the "SPECIAL" version.  But I am not sure which one or both are needed and how many of each version is required for successful conversion.  I only have one working printer and once I tear it apart for the conversion it's gonna be painful trying to put it back together to print a part that I missed...

Thanks!

Posted by: @rinkel

To add (cannot edit my post anymore):
This has been a fun project, i loved every minute of the build, but it has taken me more time than i anticipated.
The Mini has now become a much much more stable and reliable printer than before and will never return back to the original Mini. Although prints are much nicer and more accurate than on the original Mini, the vertical walls are still king on the original Mini, due to the bowden setup.

 

This post was modified 4 weeks ago 5 times by singlefin
Posted : 02/11/2022 9:29 pm
rinkel
(@rinkel)
Estimable Member
RE:

There is one y-rod holder that is different. This one goes next to the y-stepper-motor. There is just not enough room for the normal rod holders.

You need 3 normal ones and 1 for next to the stepper.
I'm not 100% sure this one is called "Special"

In my case the rod-holders were not high enough and the back middle bed-screw was touching (scraping) the stepper motor mount.
Print one and see if this your case, although it seems i'm the only one.

I know the feeling about "i have one printer", i was in the exact same situation. Luckily i printed everything. Except then i discovered that my y-rod holders were not high enough. I managed to grind off a bit off the stepper mount... luckily.
I also had to combine two models to make it work (i used the original 10mm z-rods)
Also decide which extruder you'll use. I started out with the original one. I actually mirrored all the parts from the latest version, you can find it on printables.

Just check and double check to see if you have everything.

Posted : 02/11/2022 10:08 pm
singlefin
(@singlefin)
Eminent Member
RE: Prusa Bear Mini Mk3s

Thank you for the clarification on the Y Rod holders, super helpful!  

As for extruder, I plan to go with the mirrored MK3s route.  I had bought a Revo Micro few months ago for the Mini and plan to keep using it for the Bear, so I bought a Revo Six heatsink to fit into the mirrored MK3S extruder housing.  Will reuse the stock Mini E stepper and gears from my Bondtech IFS Extruder for the Mini.  I've confirmed with Bondtech that the gears are the same as the ones they supply for the MK3S+ bondtech gear upgrade.  I'm studying how the Mini filament sensor will work at the moment and have saved your Mirrored Extruder in to my Printables collection already! 

 

Posted : 02/11/2022 10:19 pm
rinkel liked
rinkel
(@rinkel)
Estimable Member
RE: Prusa Bear Mini Mk3s

The filament sensor is a bit weird. I believe you need to switch 2 wires. Change the filament sensor in the hidden menu (not sure) and use the "reversed" fs lever.

But you'll figure it out when you're (almost) done. This sensor is very nice to have, but doesn't stop you from printing.

Posted by: @singlefin

Thank you for the clarification on the Y Rod holders, super helpful!  

As for extruder, I plan to go with the mirrored MK3s route.  I had bought a Revo Micro few months ago for the Mini and plan to keep using it for the Bear, so I bought a Revo Six heatsink to fit into the mirrored MK3S extruder housing.  Will reuse the stock Mini E stepper and gears from my Bondtech IFS Extruder for the Mini.  I've confirmed with Bondtech that the gears are the same as the ones they supply for the MK3S+ bondtech gear upgrade.  I'm studying how the Mini filament sensor will work at the moment and have saved your Mirrored Extruder in to my Printables collection already! 

 

 

Posted : 02/11/2022 10:25 pm
singlefin
(@singlefin)
Eminent Member
RE:

I'm looking at various options for the Mini Bear build before finalizing and starting the project and came across Bear Exxa parts.  I'm wondering if anyone has tried, or know, if mirrored Bear Exxa extruder and x-ends will work with either pear3d or Tomson's Bear builds?  Do I need to change anything in the firmware or settings to compensate for dimensional differences of the Exxa parts?

Thanks!

This post was modified 3 weeks ago by singlefin
Posted : 07/11/2022 1:46 am
Adrian Dobre
(@adrian-dobre)
Eminent Member
RE: Prusa Bear Mini Mk3s

Hi!

I used Bear Exxa as a base for my setup, although heavily modified; I only used the base... My setup: Sherpa Mini + Revo Voron (rigid mount and looks cool :)) in a Bear Exxa body. It fit fine. 

Posted : 07/11/2022 5:11 am
escnic
(@escnic)
New Member
RE: Prusa Bear Mini Mk3s

Hey guys,

Awesome mod. I am looking at doing something similar to my mini. I have the revo micro setup on mine. So I thought I might keep the bowden setup for now.

But my question to the more experienced crowd. Would this kit work with these files, and would it be a plug and play sorta mod if I keep the bowden setup "as is"?

 

Aliexpress: Blurolls Prusa Mini 3d printer Bear upgrade kit with Z axis motor LM8UU bearings extrusions MINI Bear

https://a.aliexpress.com/_mqr6t7w

Posted : 11/11/2022 8:58 pm
rinkel
(@rinkel)
Estimable Member
RE:

No, the x-rods are not the same distance, they're the same as the Mk3. This makes it possible to use the Mk3 extruder, only mirrored.
This is in no way a plug and play mod. It took me days of tinkering and changing. But i loved every minute of it.

The Bluerolls set works fine though.

This post was modified 2 days ago by rinkel
Posted : 25/11/2022 6:16 pm
rinkel
(@rinkel)
Estimable Member
RE: Prusa Bear Mini Mk3s

Talking about tinkering, just decided to start to tinker again.

The first issue i had was that the Pinda has an offset of 11mm to the nozzle. This means the mesh bed leveling caused the pinda to measue off the bed at the back of the bed. Then the Z level so way off. It started printing by digging the nozzle into the bed with brute force.

I solved this by adding to the start gcode (and in octoprint on connect)
M851 Y12

Whish i could store it with an M500

 

Posted : 25/11/2022 6:24 pm
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