User avatar
jakub.d
Forum admin
Forum admin
Posts: 1044
Joined: Oct 30, 2016 6:59 pm
Contact: Send private message

New printed parts B7/R3 and other improvements for the MK3

Nov 01, 2018 10:58 am

This Autumn is such a busy time at Prusa Research headquarters! Launching several products, attending exhibitions all around the world... and just in case you've missed some important announcements, here is a quick recap:

Multi Material upgrade 2.0 is shipping

Prusament the best filament you can inspect

Introducing Original Prusa SL1

Autum update by Josef


New printed parts B7/R3 and other improvements for the MK3

The Original Prusa i3 MK3 just celebrated its first year from being announced back in September 2017. Throughout this year, we've been collecting testing data from our farm and carefully listening to your complaints and wishes for improvements. Many of them were already applied along the way and some are still to come.

For the last several months our developers were trying to further improve the cooling of the MK3's extruder and this research resulted in the seventh iteration of our plastic parts (B7/R3). Improving the overall aerodynamics and adding extra air inlet had a significant effect on the temperature distribution along the hotend. All theory behind this upgrade is described here on our forum, including detailed comparison and final results from the FLIR thermal camera.
MK3_extruder_parts_P1.jpg
MK3_extruder_parts_P1.jpg (215.04 KiB) Viewed 8151 times

As a little bonus for our customers, the new printed parts for the extruder are included in the MMU2 upgrade kit. Of course, you can print them on your own using available STL files as well. If you don't have PETG and ABS filament, you can also order an Extruder upgrade package in black or orange versions from our e-shop (login needed). As usual, we've prepared a detailed step-by-step guide for this upgrade.

The feedback to this latest MK3 upgrade was overwhelming. Till today the thread was visited more than 73 000 times with over 550 comments. We are pleased to see our improvements are bringing great attention and discussion.

It is important to say, we aren't finished yet. Recently, we've introduced several new plastic parts with the B7/R3 badge on it and before we dive in the description of all the changes I would like to thank you for your feedback and ideas, how to improve the printer's performance even more.


Spiral wrap vs textile sleeve

Let's first address the Elephant in the Room. As of today all our MK3's leaving the factory will be equipped with the textile sleeve and this has raised many questions since we first swapped the spiral wrap for the sleeve earlier this year on a heatbed. Was this some kind of a design flaw and do you need immediately change all your plastic wraps for the braided ones?
MK3_textile_sleeve_P2.jpg
MK3_textile_sleeve_P2.jpg (192.95 KiB) Viewed 8150 times

No, stay calm and keep on printing :) Your printer is safe and the upgrade to another cable management solution is an evolution thing. Though if you print a lot you might consider this upgrade, let me explain.

Our farm printers are running 24/7 and after several hundreds of printing hours, we started to observe the wearing of the cables, which were held together by a plastic spiral wrap. The wrap itself is quite rigid and over a very long period of time starts to grind the cables.

For a regular 3D printing enthusiasts this might never happen as it would require a long period of time. However, if you are using your 3D printer daily, you might experience similar damage to the cable, which sometimes leads to a printer failure. To avoid this from happening, make sure that the plastic spiral wrap on your printer is installed according to the assembly manual. Incorrectly installed wrap or generally any sharp edges may decrease the lifespan of your printer's wiring.

To prevent this completely, we were looking for a suitable solution and we made the following decision: all cable bundles will be wrapped in a textile sleeve from now on. The sleeve is softer and therefore less abrasive. Moreover, to further expand the lifespan of the cables, we decided to remove the nylon from the heatbed. For the extruder, the nylon has to stay, because the cables would sag down and potentially hit the printed object.

To conclude this “wrap-gate”: if you use MK3 as a hobbyist you shouldn't be affected (just make sure the wrap is correctly installed). If you print larger objects on a daily basis, we recommend updating. Here are the dimensions of the textile sleeves, so you can purchase them in your local shop.

Extruder sleeve: 13x 490 mm
Heatbed sleeve: 6 x 300 mm
X-axis sleeve: 6 x 300 mm


Now, to the printed parts ;)


The new Einsy case

The Einsy case, which is effectively a cover for the MK3's motherboard, received two significant upgrades in the B7/R3 release. First, we have completely reworked cable retaining mechanism. The previous version serves its purpose well, but for an inexperienced user building the printer for the first time, this part of the assembly was complicated and it required a lot of effort to secure the entire bundle properly.

Over the time, I've seen several printers on the social networks where the owners damaged the cables or simply gave up and inserted the cables without a wrap, which isn't a long-term solution. We've sat back with the designers and thought long for another solution. Several iterations later, we have a brand new Einsy case for the MK3.
MK3_cable_manage_P3.jpg
MK3_cable_manage_P3.jpg (193.35 KiB) Viewed 8149 times

Openings for the cables are wider and instead of fixing the cables using the zip tie, we are using 3D printed clips, so much greater area is dedicated to holding the sleeve in place.

The second improvement is all about OctoPrint. As you are aware, the MK3 is compatible with the Raspberry Pi Zero W, which can then run an OctoPrint and control the entire printer. The previous iteration of the Einsy case required you to completely remove the board from the case before inserting the RPi, but this is now over.
RPi_cover_P4.jpg
RPi_cover_P4.jpg (215.24 KiB) Viewed 8149 times

All the Einsy cases, which will leave our factory are now prepared for the Raspberry Pi without a need to disassemble anything. Look at the back side of the cover, where you will see a part in the middle, which is separated from the rest by several small “bridges”. In case you want to use RPi, carefully cut this entire part out and insert the tiny Pi board inside. Our developers prepared a removable cover, so you can shield the RPi and remove it anytime necessary.
RPi_cover_P5.jpg
RPi_cover_P5.jpg (196.89 KiB) Viewed 8149 times

Improved X-carriage

Inserting nuts and the nylon in the x-carriage wasn't as easy as we would like it to be. The B7 version brings reworked traps to better accommodate the square nuts and the nylon hole was widened allowing easier insertion. Also slightly different assembling approach is used. More in the manual ;)


Reworked X-ends

Both x-ends were already upgraded several times, but there were still some parts, which needed more polishing. Previously introduced openings to check, whether the smooth rods are properly seated, where only in the bottom, now they are on both sides.
X_end_check_P6.jpg
X_end_check_P6.jpg (106.97 KiB) Viewed 8149 times

Improved were all holes for the plastic and steel nuts. Inserting the nuts should be now easier, but still tight enough to hold them in place.

Last upgrade is dedicated to the x-end-idler, where a lot of customers experienced cracks during tightening the idler. We've reinforced the problematic wall significantly, though it is still advised to use reasonable force while tightening the idler as you are tightening steel part against the plastic material.
X_end_idler_P7.jpg
X_end_idler_P7.jpg (110.68 KiB) Viewed 8149 times


Y-motor-holder and Y-rod-holder

Both parts were further reinforced to provide more strength and avoid cracking during the build. While tensioning the belt on the Y-axis keep in mind that the belt shouldn't be stretched like a string on a music instrument, as the motor won't be able to move the Y-carriage.


Z-axis-bottom

Printed parts on the Z-axis holding the motors, were reinforced as well. The entire part is now thicker providing increased bearing capacity. Also, the screws can be now aligned with the surface, thus creating a cleaner design.
---

To upgrade or not to upgrade your current MK3: that is the question. All these B7 upgrades aren't fixing any significant flaw, but mostly improving the assembling experience. If you are satisfied with your printer's performance, you can leave it as it is. Only in case you are using the RPi Zero W, you might consider changing the Einsy-case to the latest design.

As usual, all parts are available for download on our Prusa3D site. Use PETG or similar heat resistant material. In case of the extruder parts, don't forget to use black colour. https://www.prusa3d.com/prusa-i3-printable-parts/


That's it for today, see you in the next design upgrade ;)
Assembly manuals / Knowledge Base
Manuály pro složení / Centrum nápovědy

The guy behind Prusa assembly manuals...

steve.j
Posts: 39
Joined: May 18, 2016 10:07 pm
Contact: Send private message

Re: New printed parts B7 and other improvements for the MK3

Nov 02, 2018 9:44 am

Just printing these updated parts now and will install when my MMU2 comes in a few weeks.

Jakub, I note that for the Y rod holder part that there is no version number. I assume though that the STL file included in the latest printed parts download file reflects the most recent version of this part?

User avatar
CybrSage
Posts: 151
Joined: Dec 19, 2017 6:48 am
Contact: Send private message

Re: New printed parts B7 and other improvements for the MK3

Nov 02, 2018 1:44 pm

If anyone is looking for a user created EINSY case that also includes a new cable entrance for the MMU2 (so you do not need to cut the cover), take a look here. I will be printing it later today. It uses the new EINSY case but adds the needed extra entrance for the MMU2.

user-mods-octoprint-enclosures-nozzles- ... ml#p114352



This is a lot less ghetto than simply cutting the cover. :)

User avatar
jakub.d
Forum admin
Forum admin
Posts: 1044
Joined: Oct 30, 2016 6:59 pm
Contact: Send private message

Re: New printed parts B7 and other improvements for the MK3

Nov 02, 2018 2:44 pm

steve.j wrote:
Nov 02, 2018 9:44 am
...I note that for the Y rod holder part that there is no version number. I assume though that the STL file included in the latest printed parts download file reflects the most recent version of this part?
Hi Steve,
yes the Y-rod-holder is uploaded in the latest revision. You can always check the date of the upload :)
Assembly manuals / Knowledge Base
Manuály pro složení / Centrum nápovědy

The guy behind Prusa assembly manuals...

eric.n2
Posts: 3
Joined: Mar 05, 2017 2:29 pm
Contact: Send private message

Re: New printed parts B7/R3 and other improvements for the MK3

Nov 03, 2018 1:39 pm

Excellent update, I really appreciate all the detail here, it helps allot. I have 6 printers total and they work great. I have a suggestion,
Could you offer a belt tension specifically for each belt that is kg pull and mm deflected. These should be with the axis all the way to the left or back, and measured mid belt span. This would once and for all offer people an actual tension. I have read the software determined belt indicator and all other attempted descriptions of how tight is tight. Your musical instrument comment reminded me. It would be nice to put this issue to bed. I read forum posts of people with damaged pulley bearings or ghosting problems or shifted layers and although I am luck and have no such issues I would like to get it right! Thank you for your awesome work, I love my PRUSA printers...
Eric

martin.a22
Posts: 81
Joined: Feb 25, 2018 3:45 am
Contact: Send private message

Re: New printed parts B7/R3 and other improvements for the MK3

Nov 03, 2018 8:15 pm

I tried to get some numbers from the Facebook forums. I suggested hanging a can of soft drink (easily available) from the x-axis and measuring deflection as a way of checking actual tension against the claimed belt values. Nobody responded with their data,but there was a rather useless discussion on whether density differed across soft drinks.

User avatar
randolph.l
Posts: 326
Joined: Sep 14, 2018 7:15 pm
Answers: 3
Contact: Send private message

Re: New printed parts B7/R3 and other improvements for the MK3

Nov 04, 2018 3:58 am

I just tuned them to 220 cycles per sec using one of the instrument tuning apps for my smart phone that is a low tone to me and it results in the beltension report from the firm ware to be right in the middle of the desired range.

User avatar
Area51
Posts: 163
Joined: Oct 18, 2016 2:03 pm
Contact: Send private message

Re: New printed parts B7/R3 and other improvements for the MK3

Nov 04, 2018 12:22 pm

randolph.l wrote:
Nov 04, 2018 3:58 am
I just tuned them to 220 cycles per sec using one of the instrument tuning apps for my smart phone that is a low tone to me and it results in the beltension report from the firm ware to be right in the middle of the desired range.
Could you reveal the name of the instrument tuning app? :D

User avatar
randolph.l
Posts: 326
Joined: Sep 14, 2018 7:15 pm
Answers: 3
Contact: Send private message

Re: New printed parts B7/R3 and other improvements for the MK3

Nov 04, 2018 2:04 pm

sure n-Track Tuner its available for iOS and android but I can only say the iOS version is fine for this.
https://ntrack.com/ios-tuner.php
also note that quoted below from this thread, is a new instruction, the old instruction from when I built at the end of September was "to a low note" and it would be useful to have this clarified by Prusa
Both parts were further reinforced to provide more strength and avoid cracking during the build. While tensioning the belt on the Y-axis keep in mind that the belt shouldn't be stretched like a string on a music instrument, as the motor won't be able to move the Y-carriage.

User avatar
jakub.d
Forum admin
Forum admin
Posts: 1044
Joined: Oct 30, 2016 6:59 pm
Contact: Send private message

Re: New printed parts B7/R3 and other improvements for the MK3

Nov 04, 2018 5:36 pm

eric.n2 wrote:
Nov 03, 2018 1:39 pm
...Could you offer a belt tension specifically for each belt that is kg pull and mm deflected...
Hi Eric, great suggestion and I'm collecting ideas about achieving the proper tension for couple of months. However, I would like to achieve this using bundled parts/tools. Giving exact weight and deflection might be a solution for some users, but I need to verify it is applicable to all printers leaving our factory (e.g. the belt properties are the same over time).
randolph.l wrote:
Both parts were further reinforced to provide more strength and avoid cracking during the build. While tensioning the belt on the Y-axis keep in mind that the belt shouldn't be stretched like a string on a music instrument, as the motor won't be able to move the Y-carriage.
Hi Randoplh,
this issue was addressed in the MK3 assembly from the very beginning. Several steps are dedicated to the belt assembly, alignment and optimal tension. Both over and under-tension situations are explained, I specifically pointed out, that you can damage the printer, but still some users managed to crack the printed parts. I don't blame them and we are constantly working on improvements to avoid situations like these. Strengthening parts is one way to go.

I will try your app, but first I need to ask Joe for a new iPhone :D
Assembly manuals / Knowledge Base
Manuály pro složení / Centrum nápovědy

The guy behind Prusa assembly manuals...

Return to “General discussion, announcements and releases”

Who is online

Users browsing this forum: martin.g16 and 7 guests