This doesn't fit the original Prusa MK3  

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rbish
(@rbish)
Active Member Customer
Joined: 1 month ago
Posts: 6
27/11/2019 5:38 pm  

Two problems:

1.  Z-height calibration won't work- the purge mechanism interferes with the proper Z-height calibration as the mechanism strikes the front of the upper z-brackets before topped out and bends them upwards.

2.  The purge mechanism itself is at least 10mm higher than the nozzle.

Any ongoing work to make this work with an original MK3?


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BigBrain3D
(@bigbrain3d)
Member Admin
Joined: 5 months ago
Posts: 76
28/11/2019 2:15 pm  

1. We just reran the calibration on our machine and the issue you mentioned doesn't show up here as the z calibration completes successfully. Can you please record a video of the calibration problem you are seeing? 

2. As soon as prusa sent out the free upgrade kits we installed them so we cannot test this here. Would you mind help us with this since we don't have an MK3? You would just need to 3D print the brackets and try them. We downloaded a 3D model of the i3 MK3 from grabcad. It shows that the difference is 5.75mm in height. Attached is an updated stl for the bracket that is longer by 5.75mm. If you can try this out and take a photo/measurement then we can adjust as needed.

Thanks 🙂


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rbish
(@rbish)
Active Member Customer
Joined: 1 month ago
Posts: 6
29/11/2019 8:10 pm  

I agree that the calibrate does complete, but I don't like how it bends the upper z bracket as it does so.  I can't seem to attach or upload a video that I made of this interference.

I had already modified the bracket in Fusion 360- Mine is 5.875mm longer, and that seemed to do the trick.  I also found that the bracket needed to be spaced an additional 2.54mm forward (towards you as you are looking at the printer).  I modified the Purge Mount Right bracket to do this.  Both modified parts are printed and mounted and purges are successful now.

Let me know how I can upload the short video showing the calibration concern I have.

Thanks!

 


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allen.r.marion
(@allen-r-marion)
Active Member Customer
Joined: 1 month ago
Posts: 7
01/12/2019 2:34 am  

I have the z axis brackets from JLTX on thingiverse on my machine and had the same interference. What I did was modify his bracket to not use the filler plate on the bottom side (extended the recess flush) and created a 3mm recess on the top for clearance to the purge mechanism.  With this I had to use shorter screws  in the front two holes of the motor mount.  Hope this helps.


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BigBrain3D
(@bigbrain3d)
Member Admin
Joined: 5 months ago
Posts: 76
01/12/2019 2:55 pm  

@rbish

I've attached the files with the changes you mentioned and posted them to the google drive too.

Also, putting the files into a zip will probably help with uploads to the forum posts.

This post was modified 1 week ago by BigBrain3D

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BigBrain3D
(@bigbrain3d)
Member Admin
Joined: 5 months ago
Posts: 76
01/12/2019 2:56 pm  

@allen-r-marion

Could you please attach a photo of the installed unit? Thanks!


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allen.r.marion
(@allen-r-marion)
Active Member Customer
Joined: 1 month ago
Posts: 7
01/12/2019 3:02 pm  

@bigbrain3d

Don't have a picture right now, but it is just a motor mount.  I put the .stl on thingiverse for everyone.

https://www.thingiverse.com/thing:4013705


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BigBrain3D
(@bigbrain3d)
Member Admin
Joined: 5 months ago
Posts: 76
01/12/2019 3:40 pm  

@allen-r-marion

Thank you  🙂


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