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MK3S nozzle not aligned with thumbtack in purge mechanism  

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Michael Santos
(@michael-santos)
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01/08/2020 10:21 pm  

Just got my parts in the mail (USPS is slow these days!) and assembled everything. Is there a way to adjust the RPM in the Y-axis direction. The nozzle on my stock Prusa MK3S seems to be several mm forward of the thumbtack, so when I attempt the purge blob test, the filament just pours through the mechanism to the build plate.


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Michael Santos
(@michael-santos)
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Joined: 4 months ago
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01/08/2020 10:30 pm  

I don't see the attach file button below, but here's a link to a photo showing the nozzle in relation to the purge hole:

Side view

This post was modified 3 months ago by Michael Santos

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BigBrain3D
(@bigbrain3d)
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01/08/2020 10:57 pm  

Hi @michael-santos,

Attached is a modified version of the right mount. Please print and check if it moved it into the correct position.

 


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Michael Santos
(@michael-santos)
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02/08/2020 12:27 am  

Thanks! That seems to be in a much better place now. Unfortunately, the blob got stuck on the washer, and removing it also pulled out the washer, so looks like I've got a bit of disassembly ahead of me.


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Michael Santos
(@michael-santos)
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03/08/2020 2:06 am  

Actually, maybe not. I had to reprint the catcher and cage because I couldn't get the cage back off to reinsert the washer. Tried again, and the same thing happened. The filament poured onto the edge of the washer, I think, and then down to the thumbtack, but then when the mechanism attempted to eject it, it dislodged the washer again. Is it possible to get a right mount that's somewhere in between. Or if you have the model file, I might be able to experiment with various sizes.

Is there a trick to getting the washer seated again without having to remove the cage? Or a trick to taking the cage off without breaking it? (Thank you for including extra kapton and foil tape in the parts, BTW!)


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Michael Santos
(@michael-santos)
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03/08/2020 2:13 am  

Here's a photo of the new location.


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BigBrain3D
(@bigbrain3d)
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04/08/2020 12:11 am  

@michael-santos

I think 4mm was too much. Here is one that is only 2mm forward.

 


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Michael Santos
(@michael-santos)
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04/08/2020 3:47 am  

@bigbrain3d Thank you! I'll give it a try.

 


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Michael Santos
(@michael-santos)
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07/08/2020 5:10 am  

Thanks again @bigbrain3d. The 2mm seems to get the nozzle into position. The blob gets formed on the thumbtack. But when the mechanism ejects, it still has a tendency to grab onto the washer, dislodge it, and then jam the ejection mechanism. Do you have any suggestions? I'm thinking about just supergluing the washer into position.


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BigBrain3D
(@bigbrain3d)
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11/08/2020 4:37 pm  

@michael-santos

The Blob should form under the washer. It should not stick to the washer at all.
Could you attach a video looking from the front-underneath so I can see what is happening?

 


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David Brown
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26/08/2020 9:09 pm  
Posted by: @bigbrain3d

@michael-santos

The Blob should form under the washer. It should not stick to the washer at all.
Could you attach a video looking from the front-underneath so I can see what is happening?

 

I'm running into the exact same issue, but its not right away.  I can create/purge 20-30 blobs, then it starts to stick to the washer and gets jammed.  If I take the washer out it doesn't jam, but it tends to drop the blobs on the bed.

How can I adjust it so that the washer doesn't get stuck to the blob?

I've also tried to adjust the amount of springs, to start, 4 was too much, 3 seems to work the best, 2 doesnt have enough juice to pop back.

 


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BigBrain3D
(@bigbrain3d)
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28/08/2020 10:36 pm  

@david-brown

Does the forming blob look like in this video? https://youtu.be/5uCCGqLctP4

If you measure the thickness of the blob (top to bottom) is it 3mm tall?

If the blobs are forming properly then you should get infinite blobs with no sticking. If there is a failure at after any number of them then the relationship between the nozzle and the tack is incorrect. All components are necessary.

 


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David Brown
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28/08/2020 10:53 pm  

I just ran the blob purge test, you can see the results Here.  Each one measures 4mm top to bottom.


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David Brown
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28/08/2020 11:20 pm  

To clarify, I am measuring the blob from the bottom to the very tip of the blob.


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BigBrain3D
(@bigbrain3d)
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28/08/2020 11:56 pm  

@david-brown

Those blobs look great. 4mm is pretty close to perfect. They are nice and smooth on the sides too.

Something must still be off because you are only getting 20-30 before failure. If you could send a video that showed the failure that would be worth 1Million guesses....

Out of curiosity, when did you buy/receive your i3 mk3s?

 


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