Prusa Mini Silicone Bed Leveling Mod  

RE: Rear/back center nut clearance

@andrew-pawelski  Here is a somewhat out of focus picture showing the gap with a 3mm nut. See my previous post for more details.

RE: Thank you so much for this post

I just want to say, I got a bad unit.  It would not auto level to save my life.  The customer service department claims that the probe can only offset by so much and mine was apparently over these margins.  Instead of returning it, I did this mod step by step and now I am within +/- .02mm flat.  Thank you, thank you, thank you!  Words cannot describe how much aggravation this has resolved for me.

Question

hello! i bought everything but i have really problems to tighten the m3x16 screws... did i made something wong? maybe the tube is too hard? if i tighten one corner and then the other the bed would be really bended...

Re: Question

I have the same issue.

I have decided to design and print a few C clamps, so i can tighten all screws evenly.

I will let you know how it goes 🙂

Got it!

i got now all screws tighten. but if i use locknuts with nylon shouldn be the screw in the nylon part to lock it? none of my screws is long enough to get the nylon part... 😀 maybe 18mm or 20mm screws better?

Response

Posted by: @ladrogue

hello! i bought everything but i have really problems to tighten the m3x16 screws... did i made something wong? maybe the tube is too hard? if i tighten one corner and then the other the bed would be really bended...

You almost have to squeeze the table and bracket together to get the nut started on a thread 

18mm can work except for the center-rear

Yes your screws should reach the nylon. I only used the low profile RC car lock nut at the center rear and "regular" low profile nuts elsewhere. With the other nuts I used 18mm bolts, they stick out a bit when tightened but do not tough anything.

Also, when installing initially put one of the removed spacers in between the bed bottom and support arm, right next to your silicon tube. Tighten you bolt down until the spacer is just being touched and then move to the next bolt, you can't tighten it down too far like this. Also remember to tighten them in the order suggested, like a car tires lug-nuts.

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i will order 18mm and 20mm just to be safe. the center screw gets the original short screw right? or did i miss something?

RE: Correct

Posted by: @ladrogue

i will order 18mm and 20mm just to be safe. the center screw gets the original short screw right? or did i miss something?

Yes the middle one is a standard screw.

the 16mm do work it’s just harder to get them started. Hence the suggestion to compress the plates together to get the nut on the thread. 

if I hadn’t I would also order the 18’s instead to save the hassle. 

I did 8 mini’s and a mk3s so I got the process down quite well.

RE: re:

@BrettG how do you compress the plates together? any pictures of clamped plates?

I have printed a small clamp for each screw location, however, this looks like an overkill to me, and might be quite complicated.

Btw, is this Bror in the picture?

Posted by: @brettg

 

Posted by: @ladrogue

i will order 18mm and 20mm just to be safe. the center screw gets the original short screw right? or did i miss something?

Yes the middle one is a standard screw.

the 16mm do work it’s just harder to get them started. Hence the suggestion to compress the plates together to get the nut on the thread. 

if I hadn’t I would also order the 18’s instead to save the hassle. 

I did 8 mini’s and a mk3s so I got the process down quite well.

 2B5CCE6C-357B-4E08-8FC0-E0DA8ED602AB.jpeg

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where you get thos nuts from? i am from germany cant find 3mm high nuts...

compressed with my hands

I just braced it with my hand holding the nut and pressed down with my screwdriver having the proper tip.  Once I had all the bolts installed to the starting height (based upon the removed standoff) I then switched to an Allen wrench for tightening them down as the calibration indicates.

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okay but i got the problem that i bought low profile nuts but the arent low enough... they got 3,7mm geight but my bed is stuck on the plastic with this nut

made it!

okay, so i managed to install it.

the only problematic screw is the middle one on the right hand side.

i created and impromptu machinist jack ( ) with a hex screw and long nut, to offer support next to the screw, when i bear on it.

I also have access to 4mm (3,8 actually) high nuts, but they worked okay for me.

i had to file it a bit, like 0,3mm, it took around 3 minutes a nut.

German Store

I bought my screws and nuts from Germany and had them shipped to Sweden. Just FYI
https://www.rc-kleinkram.de/

Posted by: @ladrogue

where you get thos nuts from? i am from germany cant find 3mm high nuts...

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do you have a mini with printed parts or with the new plastic parts? do you mean those nuts? https://www.rc-kleinkram.de/products/01-960030

Printed Parts

I used these.. Low Profile M3 Nuts
https://www.rc-kleinkram.de/products/13-sge-03utb
I dont have the Mini+ I have the original one.

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okay but these are no locknuts right? i got the normal mini too but i replaced the printed parts in front and back. with printed parts the normal nuts work fine i think. but the new plastic parts need extra low profile nuts ^^

Lock Nuts

No the link I sent they are low profile locknuts and work perfect

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thanks i will try them! 🙂