Prusa Mini Silicone Bed Leveling Mod  

RE: Prusa Mini Silicone Bed Leveling Mod

@benji

They are 3mm ID, 6mm OD. It is all I could get without waiting a month for delivery and spending lots of money for 7-8mm OD.

@oliver

I couldn't get a single print to work before this otherwise I definitely would have printed a wrench

RE: Prusa Mini Silicone Bed Leveling Mod

@briancotton4

😳 That's terrible... guess I was lucky 🙃

RE: Prusa Mini Silicone Bed Leveling Mod

I am about to make this mod on my printer but I have a question. Does the known issue with MINDA probe affect the measurements? I mean you take the measurement with a cold MINDA because its away from the bed right? Do we need to preheat it like during prints to avoid error?

RE: Prusa Mini Silicone Bed Leveling Mod

@geoper2

A preheated MINDA returns consistent measurements. So just make sure it's nice and toasty before hand. 

RE: Prusa Mini Silicone Bed Leveling Mod

Has anyone in the US/Canada been able to source silicone tubing or low-profile nylon lock nuts? I haven't found low-profile lock nuts anywhere, including the McMaster-Carr catalog.

My bed has slowly fallen more and more out of level since I received it two months ago. The current delta is 0.5mm so I'm trying to only print things in the one corner that is pretty good.

RE: Prusa Mini Silicone Bed Leveling Mod

@jl

Please note, only 1 low-profile nylon lock nut is required (center back). If you cannot find them, you can grind a regular one down.

RE: Prusa Mini Silicone Bed Leveling Mod

I can source all the parts from McMaster-Carr but I would need to buy in larger quantities, the smallest of which would be enough for 5 additional sets.

Is anyone in North America interested in buying a kit? I'm just looking to recoup my costs and help other members by coordinating and assembling the parts. I'm guessing each kit would be ~$12 with shipping being the bulk of that.

RE: Prusa Mini Silicone Bed Leveling Mod

I'm attempting the mod now but clearly I'm missing something. The heatbed assembly page referenced in benji's step #5 ( https://manual.prusa3d.com/Guide/7.+Heatbed++&+PSU+assembly+(textile+sleeve)/589#s9738  ) is no longer valid so I cannot reference those directions. I cannot figure out how to remove the right-side center hex screw (the one nearest the x-axis assembly). The clearance between the screw head and the aluminum rail seems too small for any hex wrench to fit (I'm specifically using the wrench that came with the MINI).

I feel pretty dumb for not being able to figure this out as no one else seems to have struggled with this.

RE: Prusa Mini Silicone Bed Leveling Mod

@jl

I don't have the time right now to find where they moved that page to, but I attached a screenshot below.

As for removing the screw (note that it is TORX not HEX), have you tried moving the bed forward/backwards? 😀

RE: Prusa Mini Silicone Bed Leveling Mod

@jl

You should be able to use a torx bit on the top screw and needle nose pliers to hold the spacer.

Then once the bed is off use needle nose pliers on the nut and use a spanner / wrench on the spacer, mine were not on much more than finger tight TBH

RE: Prusa Mini Silicone Bed Leveling Mod

@benji

Thanks for the picture. I got it figured out yesterday (I was clearly having a moment) and finished my leveling last night. I took lots of pictures and I'll post them soon to help make the process even more clear.

RE: Prusa Mini Silicone Bed Leveling Mod

Posted by: @jl

Has anyone in the US/Canada been able to source silicone tubing or low-profile nylon lock nuts? I haven't found low-profile lock nuts anywhere, including the McMaster-Carr catalog.

 

My bed has slowly fallen more and more out of level since I received it two months ago. The current delta is 0.5mm so I'm trying to only print things in the one corner that is pretty good.

@jl

I’d be interested in a kit. You still putting them together?

RE: Prusa Mini Silicone Bed Leveling Mod

On Amazon: 

Axial AXA1052 Thin Nylon Locking Hex Nut (10-Piece), M3, Black

https://www.amazon.com/gp/product/B003Z6VHE4/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

Search for:    B003Z6VHE4

RE: Prusa Mini Silicone Bed Leveling Mod

On Amazon: 

Autobahn88 High Performance Silicone Vacuum Hose, ID 0.12" (3mm), OD 0.31" (8mm), 15 Feet per reel (4.5 Meter), Blue

https://www.amazon.com/gp/product/B01CTXVJY6/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

Search for:  B01CTXVJY6

This is on the expensive side.   

RE: Prusa Mini Silicone Bed Leveling Mod

I did this yesterday and it took a long time but I took pictures which might help other people considering doing this. Here are the directions again but with pictures

1. Make sure your X-Z assembly is square with the Y assembly. If you can't get it right, try shimming.
2. Power off the printer.
3. Cut 8 pieces of silicone tubing using the jig linked above. Or if you have a steady hand, cut 8 x 10mm pieces without the jig.
   
4. Remove printbed
5. Remove heatbed
   
6. Remove the 8 3mm screws and spacers along the outside of the Y carriage (leave the center screw & spacer)
   
7. Replace the heatbed while placing the cut silicone tubing between the carriage and the bed. Place the 8 Torx screws through the heatbed, silicone tube and carriage to hold it all together.
   
8. Carefully apply pressure to a corner Torx screw to compress the silicone tube and loosely attach a low-profile 3mm nut.
9. Go to the opposite corner and do the same. Now the other two corners and then the remaining screws. Be very careful here, you can break the heatbed if it bends too much.
10. Start tightening the screws back into place until approximately 6mm between the Y carriage and the heatbed. ONE TURN EACH! This takes a while but ensures you get it back on level and without unnecessarily stressing the bed.
    
    
11. Now screw in the center screw until tight.
    
12. See first post for the remainder of the steps! The end result will look like this:
     

Here is my before and after:

I really have no idea if I will ever notice any benefit from what I did, but it was a fun and interesting modification to make! Also I can always go back if for some reason I want a non-level bed again. 😂

My notes

The time consuming part was the final levelling, copying and pasting from Octoprint to the spreadsheet took a while, and then waiting for it to cool down.

Definitely print the M3 wrench Oliver recommended before you start, it takes 6 minutes and will save you so much time later: https://www.thingiverse.com/thing:2440589

Compressing the silicone enough to put on the nut was very difficult for me, and this is the very scary "I may break my heated bed" part. I didn't have the strength to do this so I used 20mm long bolts, but then some of them fouled things so I had to replace them with the recommended length bolts (you can only use longer bolts for the left side and front right).

It doesn't say it in the original instructions that I noticed, but I always did the bed levelling tests with the PEI sheet on. 🤷‍♀️

You will know when you are very close to 6mm because the centre screw is visible through the screw hole.

RE: Prusa Mini Silicone Bed Leveling Mod

does anyone know how long this solution works without re-adjusting?

RE: Prusa Mini Silicone Bed Leveling Mod

@robee

Awesome, thanks for the pics!
I have been planning on moving the guide to Github. Do you mind if I use your pictures there? I will credit you of course.

@oxygen

I have been running this mod for 5 months now, and not once have I had to readjust. That's one of the advantages of using the thick silicone tubing compared to springs.

RE: Prusa Mini Silicone Bed Leveling Mod

Posted by: @benji

@robee

Awesome, thanks for the pics!
I have been planning on moving the guide to Github. Do you mind if I use your pictures there? I will credit you of course.

You are most welcome to use them in anyway you wish, there is no need to credit me. Thank you so much for the initial guide!

And thank you to everyone who linked to parts I could buy and the wrench I could print!

RE: Prusa Mini Silicone Bed Leveling Mod

@robee

Thanks for the pictures made it so much easier to understand exactly what was required..

Took my time and did mine.. getting all the parts took me ages.. but finally got them.

End result is good enough for me.. should have taken a before and after.. but forgot.

RE: Prusa Mini Silicone Bed Leveling Mod

@robee

What process did you use to check the squareness of the X-Z to the Y? Did you have to shim?