Prusa i3 Bear Half Upgrade v1.0

by pekcitron Oct 1, 2017
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I'm building my Bear Half Upgrade and i was about to comment on the 15mm bolts being too long but i noticed that you have released version 2.0 that has already fixed all problems that i had.
When i saw this upgrade i just had to do it because it looked so good and professional.
Nice work, I love it!

Thank you, I hope you will like your new frame :) . Do not hesitate if you have questions or remarks!

Cutting the 20x40 to correct length is very difficult. I have published some shims that will compensate for very small errors in cutting. The frame actually looks a little nicer with the shims and there is no metal to metal contact in the front and back.
See https://www.thingiverse.com/thing:2810293

20x40 V-Slot shims
by Jimbo70

That is a good idea! Note that I have publish the V2.0 this week and I have added a margin of 0.6mm (total) in the rod holders in case you cut the v-slot too shortly. Thanks fo sharing :)

I have also done a V-Slot Hand Cutting Jig that can help to have precise cut.

Prusa i3 Bear Upgrade v2.0
V-Slot Hand Cutting Jig

Can anyone tell me what is exact lenght of the smooth rods for every axis and exact thickness of the allu frame?!
Thanks you <3

Same as the original, no need to buy new rods. That's the idea of this build, keeping as much as possible the original parts :)

i know, but i don't know the lenght of the original rods and frame thickness, that's why i'm asking :p
i want to do it on my own :)
I have access to a CNC machine :p

Forgot the frame : 6mm

hahaha sorry! Here they are :

  • X : 370mm
  • Y : 330mm
  • Z : 320mm

Awesome! thank you!

That's so cool. I'll check it out
Amazing project btw !
Can't wait to build this one! :p
Thanks a lot <3

Thank you for my project. Do not hesitate if you have other questions ;)

Some comments are the build maybe the changes can be listed as an option.

  • very easy to assemble
  • frame holes need cobalt bits in 2-3 sizes for accurate drilling (drill press helps a lot)


  1. Rod holders don’t need zip ties, make full rod enclosure as an option. Insert caps into rods then screw down into v slots.
  2. Make hole aid mirrored so both can be installed and holes drilled at the same time. I had to reverse frame to make second set of holes. Would be easier with a L and R set of hole aids.
  3. Lcd cable holding clips work great but could use another variant that is 90deg rotated in line with v slot rail to assist with some cable locations. Will post files of my install. Just a rough pic attached now.

Both of my Prusa mk2s calibrated fantastically and maybe my gf and I got used to them, but it seems printing noise has reduced significantly after upgrade :)

Great overall and well worth the effort. Maker was excellent with instructions, this how to was like buying a Prusa kit all over again, only better.

Huge thanks for the feedback! Very useful!

  1. I do not think we will get something strong enough to avoid zip ties (they are very capable!)
  2. This question comes back too much, I will add mirrored one
  3. Good idea, I will try to create one. You can also use the rotated one with zip tie

I also observed a noise reduction, those threaded where a very bad idea (except for the price)

I meant more like I am not using zip ties since I tried to click the rods into place, but no chance. The cutout for the rods was so tight that the only way to get them to fit nicely was to insert the current caps on each end of the rod, then screw holder into place. Therefore my machines do not use any zip ties and its rock solid. Thats where the idea to have a slightly bulkier rod holder came in but even that may be overkill.

I'm using the zip tie clip with a loose fitting zip tie for the cable where the 90 Deg would come in ... if we got really fancy and could fit a freely rotating clip that would be even more flexible :)

My 2nd machine has not start printing yet, but the first one has been going for a decent 24+ hours with some large prints and it is very solid.

I see what you mean for the rod holders. The problem is that if the rod holes is not perfect in diameter (no so well calibrated printer), then the zip tie will solve it.

I have to think more about the 90° lcd cable clip, thanks for the ideas.

Very cool, that is the first micro farm of Bear upgrade printer :D

On my side, it is possible that first version of Full Upgrade will be running this week-end :)

Added note for Canadian/USA builders, the original post mentions it but web stores such as OpenBuilds (https://openbuildspartstore.com) will accommodate pre-cut V-Slot orders, simply add the dimensions need in your notes when placing your order. They accommodated my cuts even last minute by saving the shipment.

I just placed my order with them and can vouch for the service. I will be making my wish list for the V2.0 bear upgrade V slot with the same store as they accommodate the cuts, should be easy as pie :)

Thanks for the feedback, I have added a note on this ;)

Hi ! I'm planning to update my MK2 to your Bear-mod. But I'm not sure if the "Fine-Tune" mods from RHDreambox (prusa forum) are already implemented.

For Half upgrade V2.0 and V1.0, I will add it soon to the optional parts. For the V2.0 Full upgrade, it is already implemented ;-)

THX. I check the versions on github.

Half and Full upgrade Z motor mounts have been pushed ;)

Not sure on the new Mk3, is the body 20x20 or 40x40 ? Or would that interfere with the x-y table too much in the mk2? Or just overkill in structure and weight.

I noticed OpenBuilds also sells 40x40 profiles, not sure if that would make it even stronger overall as a frame. But this would require now 8 holes per side (16 in total for the Z axis frame).

Im in the process of ordering my parts to update 2 of my mk2 machines so certainly interested to hear your thoughts :)
Added a list of build materials (2 machines). Hopefully they can accommodate cutting the V-rails.

I like the mk3 but as its well known, the upgrade cost does not make sense for previous mk2 owners as so little parts are transferable.

Hi, the MK3 is 30x30 : https://github.com/prusa3d/Original-Prusa-i3/blob/MK3/Frame/Extrusions.pdf . Going to 40x40 will not make it very much stronger. The 20x40 are already adding lots of rigidity and the weak point becomes the flex of the Z aluminum frame.

Perfect, 20x40 works for me. I hope to get my parts in soon for the upgrade.
My center frame keeps sliding off on the Mk2 damaging the prints, so im very glad i found your bear upgrade alternative.

Hey pek. This is a fantastic build. I am halfway through assembling the Bear upgrade and I really like it. I have a concern though about the y-axis. The rods on the Prusa build wiki specifies them as 350mm, but your lengths from end-to-end (of slots) are just 330mm. I just want to verify with you if are aware of this. Or do you have a different length rod? Thanks again. I will share pictures when the build is done!

Really happy you like it :) . My upgrade has the same length than Prusa Y rods. They are 330mm not 350mm long, you can see this in their manual here : http://manual.prusa3d.com/Guide/2.+Y-axis+assembly/298?lang=en#s5069 (step 10). Thanks in advance for the pics, always very happy and curious to see others building it!

Hi pekcitron,

I am wondering, can this upgrade also work with the MK3 (especially version 2.0)? I am thinking of the MK3 firmware that assumes an extra 1 cm on Z 1, assuming one would get the Einsy board and the other 24V components.

The new "full" upgrade (version 2.0) will be compatible with MK2, MK2s, MK2.5 and MK3. Several parts will be shared between MK2 style and the current "half" upgrade. However, MK3 will be a bit different due to new dimensions and only very few parts will be shared.

I have a request, if you have the MK3 and few minutes to make some measurements, could you give me the dimension of the MK3's PSU (the part that is outside the PSU cover)? Thanks in advance ;)

Are you still planning a version 2.0 upgrade for the bear frame ?

Thanks again for the wicked plans.

Yes sure, check out the dev branch of my github here : https://github.com/gregsaun/prusa_i3_bear_upgrade/tree/dev .

Half upgrade is almost finished (including documentation/manual). I am waiting a mitre saw to start building the Full upgrade and currently working on documentation and very small adjustments to printed parts.

very detailed work, are you sure you dont want to take on the role of the new Josef Prusa ?? I mean the designs are just amazing. Im going to do the half mk2s upgrade V1.0 for now and order the separate parts to build the full upgrade firm once the V1.0 printer is up and running.

Quick note for V2.0 bear upgrade, with the fully updated Z frame, perhaps a simple PRUSA logo just the letters would look neat at the very top where it is normally stamped into the frame as an optional add on for users to keep the brand on their printers, followed by a bear logo.

Huge thank you for this comment! :blush: . That should be very interesting to work with him!

Happy building :)

Haha I like the idea of the Prusa logo, in the backlog! (tell me if you do it before me)

Can you predict when the half bear V2 will be finished?

By the way. amazing project. well done and documented


Hard to say but roughly 3 or 4 weeks. I am waiting for my miter saw which takes more time than expected to arrive :(

I am Crossing fingers that it arrives as soon as possible. ;-)

Different topic: Is the available Z height the same as for the original MK2? Might it be even possible to increase it?

On the Half v2.0 upgrade, the Z height is the same. However, on the Full v2.0, the Z height is the same as MK3 as well as on the MK2(s)/MK2.5 version (which corresponds to a bit higher Z). I am not sure this will work with stock MK2s firmware, will be tested once my printer is build. If you install bigger smooth rod and "threaded" rod, then you can increase the Z height.

One user from OpenBuilds will try the Half upgrade v2.0 this week-end. For the Half it is quite safe as it is only refinement from v1.0.

I will probably try V2 then and adapt it to industry standard extrusions (as these seem to be much cheaper). I will report.

In the Fusion 360 V2.0 files, I have added a parameter on each parts in order to easily adapt width and depth of extrusion ergot ;)

Oh man awesome. This is really great!!! (and professionell) Also a parameter for the angle of the chamfer? Probably 45° for the V-SLot system.

I try to satisfy my readers/supporters :-)

For now at least it is not possible to set the angle through a parameter, for two reasons :

  1. Some parts are printed vertically which means you will need to add a support, which results in fairly low accuracy
  2. When you print angles, the plastic will take a small shortcut which results in a rounded angle. All my "v-slots ergots" have a special shape to avoid this (advantages : more precise fitting, avoid stressing plastic parts on a small surface, avoid bad alignments when building). Making this shape in parameter is not that easy.

Yes V-Slot is 45° and as you could see it has some advantages!

Okay, I understand. That would be a point for spending the extra money and getting V-Slots.

Sadly I am not a lucky owner of a MK3. The upgrade cost was too much for me. I am trying to figure out if sourcing some of the components myself would be cheaper.

I have been looking over different printer upgrades prior to my Prusa Mk3 conversion kit to come in. Once I found this upgrade I knew that this will be the one that I will use to convert all of my leftover parts from my old Mk2S. Amazing work on the detail and on the machine pekcitron!!

I do have a question about the drilling guide. Since your instructions only say to print one of the drilling guides, when drilling the Prusa frame is one supposed to flip the guide to the back side of the frame a drill the same as the front? Or would one need to print a mirrored drilling guide for both sides?

Thanks for any input!!

Thanks for your comment :)

Yes it is intended to flip the guide and mount it on the back of the frame. But a second mirrored will work fine as well. I recommend to print two of this guide (mirrored or not), in case you break one.

I just finished modification on my Prusa i3 rework 1.5 from Emotion Tech (French manufacturer), I changed my bearing with Igus.
This is a very good modification. You did a great job. Thank you...

Thank you for the feedback, nice to see it works with the rework 1.5 :) . Happy printing!

Just started printing the parts out for this mod now. Just wanted to comment that I ordered all my parts from ooznest in the UK (all pre-cut and tapped) on the 27th and they arrived today (29th) in the US, for anyone wanting to build this and not have to worry about cutting and tapping the threads yourself I'd recommend checking them out. The link is in the Openbuilds store list on the Thing Details tab. Will update with a make and build photos when finished.

Yes Ooznest are very good! They also produce very good manual for their CNC.

Hope you will like my upgrade. Any feedback is very welcome, even negative one!

Hi pekcitron,

I love this thing you've built and I am agonizing on whether I should build it or go for a haribo/zaribo mod.
I do have a few questions:

  • does it help with the y-axis/vibrations noise(Oh man, the noise...)
  • what are those pads you have under the feet in the pictures?
  • also in the build manual you say one should pre-drill the frame with the center drill - what do you mean by that?

Hey, thanks for your comment!

  • It reduces the noise/vibration significantly due to the heavier and much sturdier base. Simple example is that my spooler was sometimes shaking when mounted on top of the frame and not anymore after this build.
  • I used these pads : https://tinyurl.com/y72a2v4f . Not bad but I suspect you can find something better... Or add a stone with them and they will be perfect I think
  • Checkout this video about center drill : https://www.youtube.com/watch?v=_uS_8D2K64A

If you still want to take the haribo/zaribo mod path, then it might be interesting to wait for my "full upgrade" : https://github.com/gregsaun/prusa_i3_bear_upgrade/tree/dev . It will be more expensive and I am pretty sure that noise level will be very close. However, the PSU will not be needed anymore to rigidify the frame, which means you can put the printer in an enclosure with PSU outside. Some parts will be shared between these two versions and both will be maintained.

Just my 2 cents. The best material for pads is cork. I use cork coasters under my Prusa and it significantly reduces the noise.

Thanks for the tip! I have some high density cork laying around, I will try :)

I'leave two photos of the metal ruler perpendicularity adjustment!
and other one of the little problem I've.

I hope I can be of some help.

Ah I forgot, you must reset your XYZ calibration and use this pinda height calibration tool https://www.thingiverse.com/thing:1977997.

Thank you very much again!

Prusa i3 MK2 PINDA height calibration tool

And did you get a good calibration result? The problem I see in this method is that you assume, that the x-axis is absolutely parallel to the frame. That would mean that the z-axis mounts are of the same thickness and that the x-axis parts sitting on the z-axis are of the same dimensions. Not sure if that is the case.
If you tape a needle at the extruder (just temporarily) and lower the extruder until the needle is just 1 mm above the print bed directly above one of the white lines, you can easily see the skew by moving the extruder left and right. And that is the real skew that matters. I hope you could follow my thoughts :-)

Hello Ol1ver! I get a great calibration result! Only 220mm in the live z adjust.... I've made a fine bed tune following the steps that i found here: https://www.thingiverse.com/thing:2169501/#comments

Following your thoughts, I think that the real problem of the old frame is that you can make all kind of desviations between all axis. In the past when I made the fine adjustment i 've to choose between the best worse adjustment (It sound worse that the finall results I get).

Now the frame is not perfect but is consistly imperfect. I think that the auto level and desciation correction is made for this kind of imperfection. I say this because the fine tune have been really simple, and i've not to choose between get better print in on the rear left and rear right.

I think that the old framework permit the twist of the platform between the movements. The software handle it, but in the fine tune you can see the effect that you have described.Probably because the axles of the bed were so deviated that they twisted the bed.

Now the calibration is consistly. and the firmware correction can handle it really well. I would try to print the X calibration of pekcitron and show you.

Z Height calibration for Original Prusa i3 MK2

I've finish my update yesterday and I making the calibration today! I'm really happy. It's really great.It works really fine. It's a professional update. I was searching for a mk3 prusa frame update and I find this.

I've only detect one problems during the build, int the step 8 you must put first the screw of the left down corner(fig 8.1), othwerwise you couldn't put before when the motor holder have been screwed to the frame.

I've one suggestion. I've used metal ruler to adjust the perpendicularity of the frame and bed. that's ok..... but when i started the calibration it's important that the pinda sensor it's perfect aligned with the bed circle indicating the magnet position.
Well, move the bed, lef or right it's no problem but it will be a sweet touch to be able to adjust slightly the up and down position of the bed throught the rod holders.

Thank you Pekcitron. That's and incredible job.

Thanks for the feedback, I have update the description and image of step 8.1, hope that is better now :)

I have re-designed the y_motor_mount to use M5x12mm instead of 15mm. For now it is still in beta but if you would like to try it, check out here : https://github.com/gregsaun/prusa_i3_bear_upgrade/blob/dev/printed_parts/for_mk2_mk2s/stl/y_motor_mount.stl

If I find a nice way to add a vertical adjustment on rod_holders I will do it. Metal ruler tip is a good idea, I will maybe add it in the manual.

Looks really nice the new version. I have not printed it yet since my printer is set up now and works fine, but next time when I start to modify something I will give it a try. I think the problem should be solved now.

But another thing which came into my mind regarding y_motor_mount. In the original prusa design I had that Y-motor-distance part which is designed to prevent bending of the y-motor mount around z-axis when the y-belt is tightened. Although the new y_motor_mount seems to be much stronger, bending is still possible.
During assembly I thought it would be nice to have such an motor-distance piece as well. But I do not have a problem with that actually (my belt is running exactly in the middle of the pulley). But in case that there are problems such an support might help.

I do not have this problem on my printer, but it is a good point and I will think about it, thanks :)

That's the same issue I noticed when assembling the y-stepper holder. Maybe the holder has to be modified a bit by setting down the screw towards the slot profile.

Thanks for the feedback, I have update the description and image of step 8.1, hope that is better now :)

I have re-designed the y_motor_mount to use M5x12mm instead of 15mm. For now it is still in beta but if you would like to try it, check out here : https://github.com/gregsaun/prusa_i3_bear_upgrade/blob/dev/printed_parts/for_mk2_mk2s/stl/y_motor_mount.stl

Nice project pekcitron! I was looking for an mod to upgrade my MK2S for some month and I had to choose between the bear upgrade and the Haribo mod. I decided to go with yours since I could reuse a lot of parts, and the changes effect just the Y-axis while Z and X remain the same. I bought a my parts from rigrag. It's not that easy to get these V-slot profiles here is Germany. Parts are precut, although there are differences of +1,5 mm to some parts.
Nevertheless - I finished my upgrade yesterday :-). The result is very satisfying! It is really helpful that you provided the Fusion 360 files. That made the few changes I had to make very easy.

Congratulations! Thank you for the feedback, really happy you are satisfied :). Do not hesitate to tell me if you see something that can be improved!

I would like to do something for other extrusions, more than sharing Fusion360/STEP files... I will first finish V2 (with extrusion on Z axis), then report some little improvements from V2 to V1 as well (both will be maintained) and then check if I can do something for extrusions (a least Misumi version would be a good deal).

I drilled the frame today. It went out well.
I have a question. In the bom there are only 4 pieces of black angle corners. I think we need 12?

I have just decided to remove them, it is too hard to correctly square the frame. I could not see any difference in rigidity. New rendering will come soon, I just would like to improve one piece before posting ;)

You mean the corners that attach to Z - frame? They looked very neat there. :-)

yep, the idea was good but after some tests I do not find them very useful and make the build harder (and more expensive). Maybe I am wrong, if you want you can try with them and give me your feedback :)

I had no problems getting my frame square using 12 brackets. Atleast what I can notice :)

As long as the ends on the profiles are pendicular skipping the brackets and using screws should be strong enough.

Good to read that too, I thing you are right, we need to have very clean ends of the profiles for that.

You were right. I tried it with all the corners and could not avoid some wobble.

Thanks for the feedback :)

Actually very similar to the MK3 design being released soon!

I designed a similar upgrade of this printer but with Z in openbuilds aluminum extrusion as well. I released the first images 1 or 2 weeks before they announced the MK3. This was with the same idea in mind: use as much as components from the original printer.

When I saw the MK3, I decided to put this project on hold. But after few comments, the fact that MK2s will still be sold and the 2.5 upgrade, I decided to switch to similar build than MK3 to reduce price (hardware and printed parts).

I am pretty sure that my upgrade is stiffer than the new MK3 for these 2 reasons :
* I use 20x40 extrusion in vertical and goes almost at top level of the Z motors. MK3 has small 20x20mm extrusions and they are lower
* I am not sure but the bottom of the new Z frame seems to be lower than the MK2, and so more flex

However, Prusa has to keep the price very low and they are mastering on this point! Using 20x40 instead of 20x20 is more expensive...

My project of the printer using only Openbuilds extrusions is not dead but first I will see how the z wobble will be reduced with the current upgrade. Maybe it is useless to add extrusion on Z axis... And I can not do both at the same time... :D

My plan was to build a Haribo first, but then I saw your design and I liked that it used so much of the original parts. That makes it a lot cheaper to complete. And prefer how it looks with the original z frame compared to using 20x20 profiles for the z.

Happy you like it :) . I am now working on v2.0 which will use extrusions on Z axis as well and will keep as much as possible original parts. However, v1.0 will stays and I will continue to provide updates (if necessary). V1.0 et v2.0 will share lots of printed parts (but not the extrusions, they will be longer).

I think Prusa actually used 4040 or at least 3030 extrusion (4 screw holes at the end).

Now that parts are available on their GitHub, we can see that MK3 has 30x30mm.

However, the left and right part of the aluminum frame are 5mm less wide (50 instead of 55mm). I suspect this makes the Z axis more probe to vibration than previous MK2 frame. Sounds like a weird choice but maybe the difference is not perceptible...

I am working on V2 which will be more close to Haribo mod (extrusion on Z axis) but I will be using as much as possible all the components from the original printer (including original Prusa firmware).

I have checked few videos again and I think you are totally right. I vote for 3030, let's see in few days/weeks :)

Not sure if this is you or just one our members on the Facebook group but someone looks like they’ve built your mod.

I do like their drilling guide. They actually use the motor mount screw to hold it in place which would reduce the possibility of it moving when getting the holes started


It is not me ( I do not have facebook account ) but thanks for sharing. Very interesting to see someone else building my project, very happy! Interesting to read the comments too, feedback is always very welcome.

He says :
"it is sturdier. The surface area you bolt the frame to with this mod is very much bigger than the area of the nuts on threaded rods on the stock lower frame.
The only deflection (front to back) I can see comes from the aluminum z-frame itself."

(can not read what's following this comment because I do not have a facebook account)

I like the drilling guide too, I will give a try... However, I do not think it is a good idea to drill with the guide, it should be used to mark the holes only.

He is using different extrusion than Openbuilds V-Slots, why not, if someone has trouble getting them pre-cut... He had to adapt the printed parts because the extrusion dimensions are slightly different.


The facebook link is my build. I live in Sweden, so it was cheaper for me to get the profiles from a Swedish company and they only had 5mm slot profiles. As you kindly shared the step files the changes to the parts was easy to do. My plan is to make a remix of it and share the modified parts for the non v-slot profiles, but time is always limited.

I made my drill guide flat on both sides so I could just flip it to drill the other side. I clamped down the z frame to my manual mill and then used the guide to align the drill to the holes. So, I actually didn’t use the guide to guide the drill, just getting it where it needed to be. I let the guide stay in place during the drilling, but with careful alignment the drill didn’t damage the guide.

Your frame idea made the machine a lot sturdier and I cannot advice people enough to fasten the frame to something stable and heavy. The whole machine got so sturdy when I bolted the frame to the marble base. I drilled holes in the corner brackets and used those holes to mount the frame to the marble base. This led to that I cannot run cables under the frame. I will probably drill some holes in the profiles so I can run the cables through the profiles instead of going around the whole frame.

Next on the list is to switch around so the frame is narrower in the front than in the rear. This to make it possible to add some 20x20 from the base frame to the top of the z frame. This way the z wobble from the z frame should be eliminated and it will also be a good tool to get the z frame perpendicular to the y base if there is misalignment anywhere. But this is only possible if you don’t have the electronics and PSU attached to the back of the z frame. I plan to have it outside the printer cabinet.


Best Regards

Could you please send me those parts? Iam facing the exactly same problem as you did - 5mm slot in local profiles
(profiles from item24 sourced in cezch republic)

Sure, send me a message with the email where you want me to send the files. I only have made the parts for the motor and idle mount and the rod mounts though.

Hopefully I will have time to add them to thingiverse during the Christmas holiday

First of all thank you for your post on facebook! I read it carefully and did some fix after that, was very useful! I was also impressed to see someone building my project while my openbuilds' extrusion where still not cut :-D

I know Openbuilds is not available everywhere but as you might have read on the description I choose them on purpose. I was also thinking of T-Slot version of my project but it seems they do not have the exact same dimensions everywhere... Do not hesitate to fork my project on github or remix it here. However, be careful because since your build I have added selective infill around frame holes (to make holes stronger and avoid cracks). It should be okay but better to mention (best place to see them is in the slicer). I am also providing Fusion 360 file, it is easier to manage than a step file, but you need to know how to use this software. Do not hesitate to ask if you have trouble modifying the parts ;)

I have seen your drill guide and it inspired me to make similar one but not flat (to save material). Thanks for that as well! In my case you just have to rotate the frame to fix it on the other side, not a big deal.

Your marble base with drilled hole is very interesting, thanks for sharing! Why don't you add some feet between the marble and the printer, then you could pass the cable under the printer. In case of, I have added recently some cable clips to help with cable management.

Before doing the switch, wait for the v2.0, most of the files are already in the github on the dev branch (still beta). After lots of thinking and analysis I decided to not adding extrusion to rigidify the Z alu frame, it makes the build more difficult and will not be cheaper than full extrusion frame. On the v2.0 you will be able to keep the original RAMBo cover and it will be compatible with MK3 as well. It will also add a bit of Z height like on MK3 (but I still need to test this).

Great minds think alike.

I upgraded to mk2x by davtr and also to multimaterial. I ordered the bed/pinda/extruder upgrade that should be shipped in January.

That leaves me with lot of spare parts for building another printer. My plan was to use alu axtrusions for the base and reuse the z-frame. Then i found your design. Excellent!

Thank you!

Haha nice! And I have also ordered the bed/pinda/extruder upgrade :)

Do not hesitate to challenge my build, any comment is very welcome!

I am about to place an order on ooznest and have a quick question.
I wonder if I could use the Drop in Tee Nuts
instead of flat Tee nuts
I like the drop ins better and they are the same price. Just wonder if there wont be any collision with printed parts nipples that go to V-groves.

Looking on it again. Actually I think they will collide. Ordering flat Tee Nuts after all.

Yep they will collide with most pieces. I chose them because they are stronger and less chance to loose them when you rotate/move extrusions during build. With a good manual you should not forget any of the tee-nuts (manual will be done during/after the first build). Then for all accessories fixed on V-Slots (camera, raspi, ...), drop in tee nuts will be perfect.

is it possible to get the extrusions pre-cut? This is one of the things I liked about the Haribo is the ability to buy everything cut to the exact length.

They are some resellers that propose pre-cut and pre-tap Openbuilds extrusions. In Europe you have http://ooznest.co.uk/ which is very good and ratrig.com (never tested). You can also have a look in this issue : https://github.com/gregsaun/prusa_i3_bear_upgrade/issues/4 . Do not hesitate to add one if you find another one.

I hope this project will grow enough to have someone start selling extrusion (and why not frame) dedicated to this upgrade. If anyone is interested in doing this please contact me ;)

Can you add a framed project file that has additional holes for your modification?

Good idea, I will do this and put on the github (not here to avoid confusion)

Can you add a frame file in dxf?

Done! Under the github space -> optional parts -> alu_frame

(I found an issue with PSU mounts while doing the DXF)

I'm following along with your change log. I downloaded the PSU cover from Prusa's Website and laid it on top of your new PSU Lower Mount and there is some interference with the angled stubs on the top surface you put in on this newer version. One of the stub ups is different from the other so you would have to move the holes in your part in two directions to correct it or you'd need to make the angles match and then move the holes 1mm towards center

I added an image link on the Open Builds discussion for this part

Now that I think of it: I'd recommend to get rid of the plastic pieces to screw the extrusions to the z-frame. It looks better but these connections are crucial for the rigidity and plastic is not a good choice for structural parts.

Are you speaking about the Haribo? Yes plastic is not good for that, it is one of the reason why I started something different (and printed plastic can be more expensive than metal). This is where openbuilds excel, it is not only extrusion but plates, bracket, t-nuts, low profile M5 screws... And it is open source, so if you want to print it, then no problem...

I was thinking about these pieces:

Or are they not used to fix the extrusions to the frame?

I am aware of Openbuilds. It's an amazing site. I also think your project is way superior to the Haribo. It's a simple solution to the rigidity problem that isn't nearly as overbuilt as the Haribo. If you had been a few weeks earlier you'd have saved me quite some time :D

The only printed pieces are in orange in my screenshots. Those brackets are metal : http://openbuildspartstore.com/black-angle-corner-connector/ . I am working on the BOM list to make it more clear.

I am sorry for you, I also wish I came earlier with this project :-D

Don't be!

Nice that they are metal. That'll be interesting.

Nice! I will start building the Haribo tomorrow but I was checking what to do when I install the 2.5 upgrade. This looks like it could be the home of the "old" MK2(S) hardware. Or I will build a HyperCube (Evolution?) with direct drive. Decisions decisions...

P.S. It sucks a little bit that owning a 3D printer in its own creates a lot of work. You constantly look for new stuff to do.

HyperCube Evolution look like a good choice, you can also have a look on openbuilds here : http://www.openbuilds.org/?category=h-bot-and-core-xy&id=274

I agree, we take too much time to custom our printers. But I was very surprise how the MK2(s) frame is flimsy and how it moves when it is doing very fast movements! I could not try to fix this :-D . And while building this project, I found some issues in their files like the Z top axis fix I propose on my thingiverse.

Comments deleted.

Does this use existing holes in the original Z frame, or will you need to drill new ones? Thanks for sharing. I'm very interested in how your build goes. I bought the MK2S kit right before the 3.0 release and I was immediately surprised at how flimsy it was given the outstanding reviews. This looks like a robust retrofit.

Like you I purchase the MK2s and I was also very surprise how flimsy it is!

You will need to drill new holes but I provide a 3D print to help with this.

My first try was to build a full openbuilds kit where you do not need to drill any holes. However, you need to print 8 more parts and it was a bit too expensive in openbuilds parts to really make sense...