how to apply MK4 upgrade on Bear 2.1

[bgiot]

Hi, it's more a question: I have a bear 2.1 mk3s with bondtech extruder. Will the MK4 upgrade work outofthebox ? Or do I have to comeback to the original frame design and wait for bear 3.0 design ?

[DesC21]

The biggest issue I've been running into is the width of the X axis has changed and Prusa is using a new frame, however they have yet to publish the STEP/STL of the frame so I can't validate my changes. So far I've had to add 2mm of width between the Z-motor mounts and z-tops, which makes sense, given the additional 1mm of radius per rod. (I think this will be the right number, the next set of z-motor mounts are printing now). I confirmed my bear v2.1 kit extrusions are all the right lengths and the frame is square (within an unperceivable error). The X axis fits perfectly on my MK4, so it's not the X-axis itself, therefore leaves just the Z-motor mounts as the culprit.

I just couldn't wait and had to check and you are completely right. My bear parts are missing 2mm width compared to the stock MK4. Not sure how I missed this because I did this check with the stls... sorry guys :-(. I'll fix this really soon, z-motor-mounts and z-tops are affected.

with Prusa Frame with Bear Frame and my parts

The hot weather is getting to my head I guess :-) ...;ahha use ur fridg !! hehe my concern now is about FMW , i read Greg said there was a secret menu that allowed to use for the bear frame ? or can we use the 3.10bear fmw then back to stock prusa fmw? i should receive my kit next month too..

FW should be no problem, it should work without any changes. But there is a "secret" menu where you can set the z-axis height because MK3.5 z-height being less than MK4. But right now it looks like we should be able to get full z-height with the Bear frame and MK4 parts.

[n4bft]

Just to make sure, are you HeXXy from printables? Sounds like it from the rod problem?

Maybe, maybe not. I thought it would be better to post the details here to keep the Printables comment section cleaner. The specific dimension I changed was the distance between the v-slot and the center of the motor (added 1mm). That looks like the dimension that the entire motor assembly + 10mm rods was anchored to.

Here's all the parts I've modified. I'll delete this remix once we get a finished version working to keep from confusing people - https://www.printables.com/model/525733-fixed-parts-for-bear-upgrade-for-prusa-i3-mk4-mk35/files Nuked.

The biggest issue I've been running into is the width of the X axis has changed and Prusa is using a new frame, however they have yet to publish the STEP/STL of the frame so I can't validate my changes. So far I've had to add 2mm of width between the Z-motor mounts and z-tops, which makes sense, given the additional 1mm of radius per rod. (I think this will be the right number, the next set of z-motor mounts are printing now). I confirmed my bear v2.1 kit extrusions are all the right lengths and the frame is square (within an unperceivable error). The X axis fits perfectly on my MK4, so it's not the X-axis itself, therefore leaves just the Z-motor mounts as the culprit.

I just couldn't wait and had to check and you are completely right. My bear parts are missing 2mm width compared to the stock MK4. Not sure how I missed this because I did this check with the stls... sorry guys :-(. I'll fix this really soon, z-motor-mounts and z-tops are affected.

with Prusa Frame with Bear Frame and my parts

The hot weather is getting to my head I guess :-) ...;ahha use ur fridg !! hehe my concern now is about FMW , i read Greg said there was a secret menu that allowed to use for the bear frame ? or can we use the 3.10bear fmw then back to stock prusa fmw? i should receive my kit next month too..

FW should be no problem, it should work without any changes. But there is a "secret" menu where you can set the z-axis height because MK3.5 z-height being less than MK4. But right now it looks like we should be able to get full z-height with the Bear frame and MK4 parts.

WOOHOO IM NOT CRAZY! Hahahaha no worries, this is a labor of love.

---

On another note, if you have the source files for the LCD cable clips, those need a bit of a rework to include the ability to clip in the 3mm diameter earth grounding wire that goes to the xLCD on the MK4.

[gregsaun]

Super work guys, thank you!

Looking how this is going we may have the source available before Prusa 🤣

[n4bft]

New, not so small problem. The X right motor cable length is not long enough to go around the chassis like on the mk3. If I let it cut some corners it can make it, but we need to drop the buddy box lower to the frame for a more comfortable fit. I can't read. - Not supposed to include the z-right cable in the bundle.

~~I would suggest pushing it further toward the back so it can go lower, like the power supply. It should drop it the same distance it goes out, so the tightness of the lcd cable shouldn’t increase. That’s another one I’m going to have to let it cut corners on. ~~

[n4bft]

WOOHOO!

ITS ALIVE!!!

All self-tests pass!

[Bob6y]

Thank you All for your work ! I am waiting for my mk4 kit, it will arrive at the end of august. In the meantime, my prusa bear chassis is ready for the final assembly

[n4bft]

The punchlist as it stands from my build:

• [ ] Move xbuddy box down and to the rear to ease strain on the z-right motor cable. The only other suggestion would be to find a way to safely cut the cable across, we're sacrificing length going backward then forward in a U shape If we go straight across like in the Prusa frame, it should solve the problem. (I can't read. - Not supposed to include the z-right cable in the bundle.). I would still prefer to move the xbuddy box down and to the rear to allow more vertical mounting space so I can put a pi4 enclosure above the xbuddy box without hitting the extruder cable
• [ ] update the extruder cable assembly cover - the prusa R3 version has a larger diameter cutout to allow the cables to get clamped. R1/R2 did not have enough space for the whole cable bundle.

[n4bft]

[gregsaun]

@n4bft this is beautiful to see, congrats 💫 🎉

[gregsaun]

@n4bft May I share those two pics on Twitter/Discord/Mastodon? I will tell it is not ready yet but it is coming and link to this issue.

[n4bft]

@n4bft May I share those two pics on Twitter/Discord/Mastodon? I will tell it is not ready yet but it is coming and link to this issue.

Absolutely!

[DesC21]

@n4bft thanks so much for testing and pointing out the issues!!! I already fixed z_tops and z_motor_mounts (but not uploaded yet) before seeing your remix. I am gonna fix the cable cover and lcd_cable clips this evening and update the printables post.

Do you have Prusa E3 parts and did the lcd_supports work fine?

PS.: I will also mention you on the printables page for helping with testing and fixing stuff if that's okay with you?

cough how is inputshaper working? cough

EDIT: I will also see what I can do for the xbuddy case. Since I now have the case here it will be a lot easier and no guessing anymore :-)

[gregsaun]

I did boost your work guys, hope you like it!

https://twitter.com/GregoireSaunier/status/1679168847838953490 https://fosstodon.org/@bear_lab/110702147548602122 https://discord.com/channels/448951856660480030/459053621070528513/1128723004042510378

[n4bft]

Do you have Prusa E3 parts and did the lcd_supports work fine?

Yes and yes.

PS.: I will also mention you on the printables page for helping with testing and fixing stuff if that's okay with you?

Absolutely!

cough how is inputshaper working? cough

I tried it once. I think a quote from The Italian Job (2003) fits best "... I had a bad experience."

EDIT: I will also see what I can do for the xbuddy case. Since I now have the case here it will be a lot easier and no guessing anymore :-)

Your guesses have been spot on though... super kudos there. _{Except the whole X axis width thing, but we're not gonna talk about that.}

[DesC21]

@n4bft nice, no changes to the lcd-supports! I added the mention :-). What x-axis thing? I don't know what you mean, haha

I just updated most of the parts, Version 0.4 is on printables!

1. z-axis 2mm width error fixed
2. xBuddy_case_mounts can be used with the standard M3x6mm screws now
3. cable holder cover updated to R2 spec
4. remixed cable_clips_lcd to accept the additional PE cable @n4bft I hope 3mm is correct, I count on you ;).

Hope this fixes everything and all the parts work now. I will run a full test with these parts soon. If everything goes well I will start with improving the xbuddy mounts and z-tops but no eta.

[n4bft]

As promised, I nuked my remixed parts now that you've updated. As soon as the spool holder is done printing for the new printer, I'm going to fire off these new parts.

For the xBuddy box, if we move it further out, should probably do something like the power supply and put a support behind it, as it stood when i was re-mounting the xBuddy board and all of the power terminal connections, I had to support the box with my hand to avoid bending the wall of it.

[gregsaun]

@DesC21 This is awesome! Do you think it would be possible to root the ground cable inside the slot of the extrusion? Maybe it would be risky as we could pinch the cable with the cable_clip_lcds...

[jerem2st]

WOOHOO!

ITS ALIVE!!!

All self-tests pass!

did you use the original FMW without modification ?

[techtitan3d]

Had to stop by and thank everyone for their work on this project. I ordered my full mk4 upgrade kit back on day one and had my fingers crossed that the community would make it work for our bear frames. I love my laser etched frame and would hate to go back to stock to enjoy the mk4 upgrade. I should see an email any day now for shipping. If needed I might be able to test .

[n4bft]

did you use the original FMW without modification ?

@jerem2st yes - this is 100% stock firmware

[techtitan3d]

How is it printing so far? Looks fantastic. What if any changes to you expect to see with printed parts for the full upgrade base on your current experience with the build?

[n4bft]

How is it printing so far? Looks fantastic. What if any changes to you expect to see with printed parts for the full upgrade base on your current experience with the build?

Prints great! No noticable change in print quality. I'm still working out a few unreleated print quality items like some vertical artifacts on the Y axis.

The only changes I would like to still see is moving the xbuddy box moved back and down like how the power supply is done - this frees up more space for things to go on the upright extrusions (like a pi).

[n4bft]

@DesC21 - Another change that i would like to be tested, combining the Z-tops and Z-endcaps.

The reason is due to the Z-top extended past the top edge of the rail, the previous alignment point (top of the extrusion) is no longer available. I've found up to 0.2mm of difference between sides for the length between the top of the Z-motor-mount and the bottom of the Z-tops (even when properly seated). This is enough difference to cause the X axis carriage to "float" on one side.

When I say "float", I mean the trapezodal nut on one side is not fully engaged like the other. I've had instances where I can push up on one side of the x carriage and there's play and I have to push down on the other side to find the play.

I think this is due to the 'tramming' routine that's used for aligning the Z-axis motors. Now that the motors are 0.9 degree, there's less room for error. During the tramming routine, the X carriage is held up against the z-tops and the steppers skip multiple times. However, steppers only skip in full steps. This means that if one side of the X carriage is slightly higher than the other, a 0.9 degree stepper may end up one step higher or lower than the other side. Which, shouldn't be a problem, unless the X carriage is so rigid (which it seems to be) that the trapezodal nuts aren't engaged evenly.

If we combine the z-tops and z-endcaps this makes the end of the extrusion the alignment point ensuring a perfect square of the X carriage relative to the frame.

The only issue is possible dimensionsal accuracy on the section of the part interfacing with the top of the extrusion. However, there are ways to mitigate that such as only creating an interface to the top of the rail comprised only of perimiters and ensuring the seam is on another section of the part for those layers.

I can test this myself, I just need to know how many mm the z-tops should extend past the extrusion.

[DesC21]

@n4bft Yes, this is something I also want to look at because as it stands right now, the smooth rods go into the new rubber pads on the z-motors right? (still haven't had time to build mine). But as far as I understand the bear frame doesn't rely on extrusion length, so there is no alignment point on the extrusion (the extrusion will also probably have 0,5mm tolerance). Tt only relies on the smooth rods (which now might have some "play/difference" due to the rubber pads). Even the motors will have play due to the rubber pads (In the prusa manual they even tell you how to align the leadscrews due to this "floating" mount) and how you tighten them which is were your problems maybe come from? Can you try to remove the rubber pads and see if this is still an issue? Or temporarily remove the endcaps if the z-tops need to be higher due to these new tolerances? Maybe @gregsaun can share some thoughts on this?

EDIT: right now, in the model without rubber pads, top of the z-top to top of the extrusion is 4,6mm

@DesC21 This is awesome! Do you think it would be possible to root the ground cable inside the slot of the extrusion? Maybe it would be risky as we could pinch the cable with the cable_clip_lcds...

I will check this, when I finally build my bear. But to be honest, I think it shouldn't be a big deal. I don't think we can damage the cable with the clips (good thing is it is PE so no direct safety concern with touching a damaged cable). But I will check, Prusa just needs to change the cable to a slightly different diameter and then they don't work anymore which is something I don't like ;).

Quick update on my todo list:

1. xbuddy case mount, similar to PSU
2. z-axis and prusa rubber pads
3. cable clips
4. Bear x-axis for Nextruder

[gregsaun]

I don't think it is a good idea to combine Z tops and the caps because of extrusions tolerances which, due to the way they are manufacturing, are not the most precise piece of aluminum you can find. Smooth rods are more reliable for that but as you said now we have rubber pads. Note that stock frame has similar issues as when you tighten the parts you might shift them a little as well.

Having the Z tops fixed from the sides would help I think, would be easier to have them square and increase stiffness. Personally I would also remove the rubber pads as they don't seem to improve noise of the Z axis. Maybe we could also move the steppers as close as possible to the bottom horizontal extrusion (check tolerance thickness of LDO motor specs), this would help to move the Z tops lower and so increase their stiffness.

@n4bft Are the Z motors 0.9°, I thought they were 1.8°?

[DesC21]

I don't think it is a good idea to combine Z tops and the caps because of extrusions tolerances which, due to the way they are manufacturing, are not the most precise piece of aluminum you can find. Smooth rods are more reliable for that but as you said now we have rubber pads. Note that stock frame has similar issues as when you tighten the parts you might shift them a little as well.

Having the Z tops fixed from the sides would help I think, would be easier to have them square and increase stiffness. Personally I would also remove the rubber pads as they don't seem to improve noise of the Z axis. Maybe we could also move the steppers as close as possible to the bottom horizontal extrusion (check tolerance thickness of LDO motor specs), this would help to move the Z tops lower and so increase their stiffness.

@n4bft Are the Z motors 0.9°, I thought they were 1.8°?

totally agree. It's exactly the same for the stock frame so I didn't really think much of it. I don't know if the rubber pads for the motor or the bearings help but there is zero rattling on my stock MK4, I was positively surprised to be honest. Z-tops from the side is also my preferred way to go.

Only X and Y are 0,9° according to Prusa website "The MK4 comes with redesigned, more robust plastic parts and new precise 0.9° stepper motors (0.9° / step; low inductance) on the X and Y axes that help eliminate Vertical Fine Artifacts on prints." from https://www.prusa3d.com/product/original-prusa-mk4-kit-2/

[gregsaun]

@n4bft not sure to understand what is your issue with 0.9° stepper and homing. Do you mean that if the top isn't 100% flat, when you tram the X axis then you can't home?

[gregsaun]

@DesC21 Sorry forgot to answer about the rubber pad. Apparently many Prusa MK4 users are experimenting similar noise on the Z axis than with the MK3. Someone did some testing on Discord as well and the rubber pad didn't made a significant difference for the noise (at least to me). Now if the leadscrew has a different pitch it might be different and so good to give a try if you feel so. Another interesting thing that would be good to do is look at the input shaping graph to see if there is a difference.

[PatB42]

https://discord.com/channels/448951856660480030/459053621070528513/1128723004042510378

Greg is the discord working ? the link not !! Still waiting my kit 3.9 ...so boring ..no news no reply no schedule..almost 3 months.. will start to print files ... ah 1question to be sure apparently the mk4 stock FMW work well on the bear frame ....? thx

[DesC21]

https://discord.com/channels/448951856660480030/459053621070528513/1128723004042510378

Greg is the discord working ? the link not !! Still waiting my kit 3.9 ...so boring ..no news no reply no schedule..almost 3 months.. will start to print files ... ah 1question to be sure apparently the mk4 stock FMW work well on the bear frame ....? thx

Hey Pat, fingers crossed you get your upgrade soon. I finally did the upgrade for my MK4, everything works really nicely, stock MK4 x-axis and firmware. I see slightly improved print quality with faster printing speeds (-> IS) compared to the stock frame, But only my personal impression, no scientific approach :-).

Additional feedback I posted on the discord from my build:

I didn't have any problems with the motor mounts, rods went in better than on the stock parts but I did have some trouble with the z-tops though. As people have pointed out, buddy box mounts are not good. The box is to high up, which makes the motor cables to short. Sadly the frame brackets are in the way it can't go as low as I'd like... But I am gonna improe it. Also the new cable holders are not big enough, the ribbon cables don't have enough space.

PS.: The discord link is working for me

[PatB42]

Hi DesC21 , well all fingers you can cross then with Jo you never know.... happy that all works for you asap i have my kit i'll test and then modify the part that gave problem or will try to improve too .. what is the problem in fact with the silver or black PSU and wiring heat bed cable !! as i have 1 with black and one with silver !! about the discord link still dead for me , !! maybe i need invitation as i understood !! thx

[DesC21]

I am finally back at improving some parts. Since Prusa still hasn't released any source files, I built the xbuddy box from scratch and with the correct dimensions now :-). I'll move it further down like some of you suggested and adapted the PSU mounts. This should also fix some issues with the cable length. There is still some fine tuning to be done, next up are improvements to the cable clips.

[PatB42]

ahaha great job i laugh because i was also working on it since i finally receive my kit mk4 so i took the whole dimension as you did and start to fix it on the bear frame ;-) now no need to go further it's nice..BTW i don't like this metal box as it not fitting at all on the frame..i am re design the whole xbuddy w all electronics part if some ppl want use later and see if i can fit on my box design.. i presume you post all on printables

[DesC21]

I just updated the printables post with the new parts.

Since the Bear MK4 is proven to be working, I guess we should close this issue now. You can follow all the progress on either the Wasteland/Bear discord channel or the printables page.

[PatB42]

dead for me..trying different option but so far can't go further

[PatB42]

using stock fmw 5.0

[DesC21]

@PatB42 did it work on the stock MK4?

Please check the cover on the right side of the nextrudr. For example on mine, the cover doesn't fit due to glue on the cables. I always have to remove this cover otherwise I can't pass self test (doesn't matter if bear or stock MK4) .

[PatB42]

thx for ur help and quick reply Dec , i just re installed the fmw 5.0 as in fact by chance i checked and it wasn't so i re install and then pass the test oufff but now the heatbed not !! but the bed heat very good as it was on my bear so never problem with,i am checking now with the live chat !!

[Bob6y]

On my side I have this

And even if I have this status, the printer is able to print. I don't know why the test has failed but my print are All correct, no quality issues.

I always have the self test when I start the printer, I always ignore it and I don't know if it possible to disable it.

[PatB42]

ah oui j'ai pareil, mais j'ai compris en fait tu dois passer les tests complet sinon tu auras tjs le même affichage. et moi c passé nickel ouff mais uniquement av le fmw5 qui ne s'était pas installé correctement la 1ere fois et aprés tvb .. j'ai passé ts les tests axes sauf le lit qui chauffe bien mais bon ...donc aprés j'ai sauté le test du nextrudeur qui était déjà passé et impeccalble tu peux retourner ds les réglages contrôle pour faire un test de lit et normalement tu n'auras plus le selftest au début et pourras voir dans les infos que tout est ok ..

[PatB42]

Hi DSC21

so , so far all is fine now , very happy about 1st test and 1st layer, waou have to say nice when all is working ...i don't know how u manage the yellow cable the one which do the mass from lcd to xbuddy to psu.. it's short for me so i design and print a little part that hide a little this cable i'll make pics if some want it i can add here or printables.. ! otherwise, i'll spend time to modify the X -end-idler- i really don't like their system about belt tension, unscrew x motor, turn tension, check, screw x motor again pfff, i like the Greg design on our bear so i'll see if i can re design the whole part as we still not having the cad files !!

Also as i was using the RPIOw2 on the rambo with a sd card , i see now that the transfer from slicer to prusa link is slower really slow...that come from the usb key i think ..why let the usb key plug to the lcd !!! really when u can easy add a sd card inside that nobody can touch or could easy break !!

thx for ur design again, i'll also see how to modify the xbuddy case..it's not convenient bye J'espère Greg que ça va mieux ...tu vois le Bear project est toujours en vie..;-)

[DesC21]

On my side I have this

And even if I have this status, the printer is able to print. I don't know why the test has failed but my print are All correct, no quality issues.

I always have the self test when I start the printer, I always ignore it and I don't know if it possible to disable it.

This is not an error. It should just continue with the other axes. Does it stop and not continue?

@PatB42 thanks for letting me know. Oh well I forgot about the PE cable, I actually made my own, because I have the PSU outside of an enclosure. I thought it should be the same length but maybe mine is a bit longer, thanks for letting me know. I will check with the original cable.

PS.: I am working on the BearExxa for the Nextrudr but it will take some time :-)

[Bob6y]

@DesC21 hello the test stop for the xyz test.

Here a video of this test.

https://drive.proton.me/urls/VNRW5JPKNC#-Tblh_3Rdspy

And I have the latest firmware ir the info category.

If you have any idea of this axis issue take me informed. Thank a lot.

[DesC21]

@DesC21 hello the test stop for the xyz test.

Here a video of this test.

https://drive.proton.me/urls/VNRW5JPKNC#-Tblh_3Rdspy

And I have the latest firmware ir the info category.

If you have any idea of this axis issue take me informed. Thank a lot.

ah so it is failing on the y-axis. I see you are using rails and not the standard rods. Did you use this on a MK3 Bear too and was it passing?

I think the MK4 is a lot more sensitive when it comes to homing, axis lengths, etc.. I had this when the heatbed cable was hitting the wall of my enclosure just slightly (it was still hitting the mechanical ends) but it failed nonetheless. I guess you are not getting the expected y-axis length or the "forces" are different compared to what is expected and that's why it is failing. Can you somehow measure home much the y-axis travels in total?

[PatB42]

look at the y support rail !! if they are different length from the rod support then the bearing should touch the support at the end with rail the hiwin is different !! look at this point i think !!!!!

[Bob6y]

Thank you for your comments, I will do the measure at the end of this week. Before, I had an original MK2. So no experience on Mk3 and rails.

[jerem2st]

https://discord.com/channels/448951856660480030/459053621070528513/1128723004042510378

Greg is the discord working ? the link not !! Still waiting my kit 3.9 ...so boring ..no news no reply no schedule..almost 3 months.. will start to print files ... ah 1question to be sure apparently the mk4 stock FMW work well on the bear frame ....? thx

Hey Pat, fingers crossed you get your upgrade soon. I finally did the upgrade for my MK4, everything works really nicely, stock MK4 x-axis and firmware. I see slightly improved print quality with faster printing speeds (-> IS) compared to the stock frame, But only my personal impression, no scientific approach :-).

Additional feedback I posted on the discord from my build:

I didn't have any problems with the motor mounts, rods went in better than on the stock parts but I did have some trouble with the z-tops though. As people have pointed out, buddy box mounts are not good. The box is to high up, which makes the motor cables to short. Sadly the frame brackets are in the way it can't go as low as I'd like... But I am gonna improe it. Also the new cable holders are not big enough, the ribbon cables don't have enough space.

PS.: The discord link is working for me

Do you use the rubber pads on Z motors during assembly ??

[DesC21]

@jerem2st Yes, I used the rubber pads. So far no issues works fine, but I am also not sure if they improve anything :-)

Do you use the rubber pads on Z motors during assembly ??

[PatB42]

yes me too , add it but !! i'll set up my mk4 next week will see if with the new motor is better !

[jerem2st]

@jerem2stOui, j'ai utilisé les coussinets en caoutchouc. Jusqu'à présent, aucun problème ne fonctionne correctement, mais je ne suis pas sûr non plus s'ils améliorent quoi que ce soit :-)

Utilisez-vous les patins en caoutchouc sur les moteurs Z lors du montage ??

ok great, I can't wait to receive my kit! :)