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RH_Dreambox
(@rh_dreambox)
Prominent Member
Fine tune your MK3 Z axis

This part is about the Z axis and how to fine tune it. It's part 1 of 3 planned posts.

Background
While I was waiting (still waiting) for my MK3, I've had plenty of time to read your posts, watched your videos as well as read manuals both forward and backward. It made me wonder what causes some quality problems when printing.

I also realized that in order to get a high quality of printouts, all components of the printer must be of high quality.
A small defect can cause some type of printing problem.

To check if there were any details on the printer that I could improve, I began to draw a Prusa Original MK3 in my CAD system (Inventor).
I have read the measurements in Prusas SCAD files.
With a 3D model of the printer, you can explore, twist and turn to every detail.

I then found that there are some improvements to make on the X, Y and Z axes.
It is important that all interacting components have as little tolerances as possible.

Z-axis motor consoles have a built-in fault which causes the Z motors to have a center distance that deviates slightly from the other Z components.
The engine bracket is 0.5 mm too narrow, which means that the Z motor does not fit into its intended position.
When the motor is mounted, it will end up slightly beyond the intended center line.
The screw holes in the brackets are slightly too large, which means that both the upper and lower Z brackets can be mounted in the wrong position.

The modified and attached components have been adjusted for a better function.
The two motor brackets have been widened 0.5 mm so that the Z motor can be centered correctly and the screw hole dimension has changed from ø3,6 mm (large) ø3,2 mm (fine).
This adjustment should Prusa implement as soon as there is an obvious error in the original details.

Bear MK3 with Bondtech extruder

Postato : 23/01/2018 2:08 pm
Brigandier
(@brigandier)
Reputable Member
Re: Fine tune your MK3 Z axis

Sign me up, got these parts sliced and printing now. Will report back later when I get a chance to throw them on.

My MK3 Parts: [Bowden] [New Shoes] [TPU Micro Springs]

Postato : 23/01/2018 2:25 pm
Paul Meyer
(@paul-meyer)
Honorable Member
Re: Fine tune your MK3 Z axis

Very cool, downloaded.

Did you implement them in SCAD? Can you share the source?

Postato : 23/01/2018 2:29 pm
RH_Dreambox
(@rh_dreambox)
Prominent Member
Topic starter answered:
Re: Fine tune your MK3 Z axis

Very cool, downloaded.
Did you implement them in SCAD? Can you share the source?

All parts are drawn in Inventor as IPT files.
Unfortunately, I can only convert them to STL files, not SCAD.

Bear MK3 with Bondtech extruder

Postato : 23/01/2018 2:45 pm
Brigandier
(@brigandier)
Reputable Member
Re: Fine tune your MK3 Z axis


Very cool, downloaded.
Did you implement them in SCAD? Can you share the source?

All parts are drawn in Inventor as IPT files.
Unfortunately, I can only convert them to STL files, not SCAD.

The yin/yang logo is a nice touch, had a moment of panic on that first layer thinking it had lifted off the bed. 🙂

My MK3 Parts: [Bowden] [New Shoes] [TPU Micro Springs]

Postato : 23/01/2018 2:56 pm
RH_Dreambox
(@rh_dreambox)
Prominent Member
Topic starter answered:
Re: Fine tune your MK3 Z axis

The yin/yang logo is a nice touch, had a moment of panic on that first layer thinking it had lifted off the bed.

Yes, I like surprises 😀

Bear MK3 with Bondtech extruder

Postato : 23/01/2018 5:24 pm
Paul Meyer
(@paul-meyer)
Honorable Member
Re: Fine tune your MK3 Z axis


Very cool, downloaded.
Did you implement them in SCAD? Can you share the source?

All parts are drawn in Inventor as IPT files.
Unfortunately, I can only convert them to STL files, not SCAD.

Actually, if you are comfortable sharing the IPT files, or save as STEP, that would work as well. I use Fusion 360 which can read either.

I don't have short term plans to modify either, but it would be nice to have the capability.

Postato : 23/01/2018 7:51 pm
jweaver
(@jweaver)
Honorable Member
Re: Fine tune your MK3 Z axis

I havnt even got to this point in the build yet.. Assuming i can get PETG working on my old printer, is it generally agreed that this is a worthwhile upgrade?

Postato : 23/01/2018 7:57 pm
fulcrum
(@fulcrum)
Trusted Member
Re: Fine tune your MK3 Z axis



Very cool, downloaded.
Did you implement them in SCAD? Can you share the source?

All parts are drawn in Inventor as IPT files.
Unfortunately, I can only convert them to STL files, not SCAD.

Actually, if you are comfortable sharing the IPT files, or save as STEP, that would work as well. I use Fusion 360 which can read either.

I don't have short term plans to modify either, but it would be nice to have the capability.

Actually, for those of us who use Fusion360, it would be AWESOME if you could release the entire printer assembly from Inventor.

Postato : 23/01/2018 8:09 pm
RH_Dreambox
(@rh_dreambox)
Prominent Member
Topic starter answered:
Re: Fine tune your MK3 Z axis

Paul
Actually, if you are comfortable sharing the IPT files, or save as STEP, that would work as well. I use Fusion 360 which can read either.

I don't have short term plans to modify either, but it would be nice to have the capability.

and
fulcrum
Actually, for those of us who use Fusion360, it would be AWESOME if you could release the entire printer assembly from Inventor.

Can Fusion 360 read .IPT (part) and .IDW (assembly) files ? Or would it be better with .STEP files ?

Bear MK3 with Bondtech extruder

Postato : 23/01/2018 8:38 pm
RH_Dreambox
(@rh_dreambox)
Prominent Member
Topic starter answered:
Re: Fine tune your MK3 Z axis

jweaver
I havnt even got to this point in the build yet.. Assuming i can get PETG working on my old printer, is it generally agreed that this is a worthwhile upgrade?

3D printing is about precision.
If you can eliminate a small source of error, you should do that.

Bear MK3 with Bondtech extruder

Postato : 23/01/2018 8:42 pm
jweaver
(@jweaver)
Honorable Member
Re: Fine tune your MK3 Z axis


jweaver
I havnt even got to this point in the build yet.. Assuming i can get PETG working on my old printer, is it generally agreed that this is a worthwhile upgrade?

3D printing is about precision.
If you can eliminate a small source of error, you should do that.

My fear is whether my current pirinter is accurate enough and by printing these parts myself i may add more inaccuracies the these parts fix.

Postato : 23/01/2018 8:50 pm
Brigandier
(@brigandier)
Reputable Member
Re: Fine tune your MK3 Z axis

Hi RHDreambox,

Got mine printed and installed, worked great and I can confirm the fit is better. I had looked at my Z rods/screws several times thinking they looked slightly bowed but thought it was my imagination. After installing these, I can confirm they look straight as an arrow now and action is very good. Alignment is well enough that I can grab one of the Z rods and lift it up/down without significant pressure required, so no bind whatsoever. Performed Z calibration and printing a Benchy to celebrate. 🙂

Thanks!

My MK3 Parts: [Bowden] [New Shoes] [TPU Micro Springs]

Postato : 23/01/2018 9:00 pm
Paul Meyer
(@paul-meyer)
Honorable Member
Re: Fine tune your MK3 Z axis


Can Fusion 360 read .IPT (part) and .IDW (assembly) files ? Or would it be better with .STEP files ?

Fusion360 can read ipt/iam files:

https://knowledge.autodesk.com/support/fusion-360/troubleshooting/caas/sfdcarticles/sfdcarticles/How-to-import-or-open-a-file-in-Autodesk-Fusion-360.html

Isn't IDW a drawing format? I'm not an inventor user. In general, I would expect Fusion to be able to pull in Inventor.

Step might be useful for those using other modeling programs.

Postato : 23/01/2018 9:03 pm
Paul Meyer
(@paul-meyer)
Honorable Member
Re: Fine tune your MK3 Z axis


My fear is whether my current pirinter is accurate enough and by printing these parts myself i may add more inaccuracies the these parts fix.

If you are printing this in PETG, the printer should be accurate enough. Remember, Prusa was printing the original parts for your printer on a MK2s (or maybe mk3 by now).

Sources of inaccuracy:

  • plastic shrinkage. shouldn't be a huge concern if printing with PETG. You can check with the micrometer

  • badly calibrated X/Y or Z. Unless you swapped steppers, pulleys, or firmware, this will not be an issue.

  • bad print (sloppy, filament hanging out, ragged holes): you'll be able to see this visually and reject the parts
  • I'd say go for it.

    Postato : 23/01/2018 9:07 pm
    fulcrum
    (@fulcrum)
    Trusted Member
    Re: Fine tune your MK3 Z axis


    fulcrum
    Actually, for those of us who use Fusion360, it would be AWESOME if you could release the entire printer assembly from Inventor.

    Can Fusion 360 read .IPT (part) and .IDW (assembly) files ? Or would it be better with .STEP files ?

    I haven't verified (I can do that tonight) but I am assuming that since both are Autodesk, the cloud uploader for Fusion would be able to convert .IPT to .F3D files.

    Postato : 23/01/2018 9:59 pm
    Tomaz
    (@tomaz)
    Eminent Member
    Re: Fine tune your MK3 Z axis

    well ... it is not always so straight forward with autodesk ,,, you can't even open ipt or iam in inventor, which is an older version like the one, where the files were created (due to new tools i guess). stp files are the best for sharing in my experience ...

    Postato : 23/01/2018 10:22 pm
    fulcrum
    (@fulcrum)
    Trusted Member
    Re: Fine tune your MK3 Z axis


    well ... it is not always so straight forward with autodesk ,,, you can't even open ipt or iam in inventor, which is an older version like the one, where the files were created (due to new tools i guess). stp files are the best for sharing in my experience ...

    The reason why I originally requested .IPT is that STL files are not always "decoded" correctly. For example, I downloaded the STL files that were posted in the CAD models for MK3 parts post and some parts don't show up correctly (they don't show up as bodies but more like meshes.)

    Since Fusion360 can import .IPT, I am thinking that it would show up more accurately.

    Postato : 23/01/2018 10:30 pm
    john.n13
    (@john-n13)
    Estimable Member
    Re: Fine tune your MK3 Z axis



    Can Fusion 360 read .IPT (part) and .IDW (assembly) files ? Or would it be better with .STEP files ?

    Fusion360 can read ipt/iam files:

    https://knowledge.autodesk.com/support/fusion-360/troubleshooting/caas/sfdcarticles/sfdcarticles/How-to-import-or-open-a-file-in-Autodesk-Fusion-360.html

    Isn't IDW a drawing format? I'm not an inventor user. In general, I would expect Fusion to be able to pull in Inventor.

    Step might be useful for those using other modeling programs.

    Can Fusion 360 not open STEP files? They are on its list.

    Postato : 23/01/2018 10:39 pm
    Paul Meyer
    (@paul-meyer)
    Honorable Member
    Re: Fine tune your MK3 Z axis




    Can Fusion 360 read .IPT (part) and .IDW (assembly) files ? Or would it be better with .STEP files ?

    Fusion360 can read ipt/iam files:

    https://knowledge.autodesk.com/support/fusion-360/troubleshooting/caas/sfdcarticles/sfdcarticles/How-to-import-or-open-a-file-in-Autodesk-Fusion-360.html

    Isn't IDW a drawing format? I'm not an inventor user. In general, I would expect Fusion to be able to pull in Inventor.

    Step might be useful for those using other modeling programs.

    Can Fusion 360 not open STEP files? They are on its list.

    Yes, fusion 360 can open both STEP files and inventor files. My comment on "other modeling programs" was that inventor file formats might not be openable in non-Autodesk modeling programs, so STEP might be useful there.

    Postato : 23/01/2018 10:48 pm
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