Prusa Iteration 2 LM8UU y-bushing question

Hello everyone,

I'm getting started on my first build, and I'm attempting to build the current version of Prusa iter. 2 with lm8uu bearings from github. I've downloaded the .stls and printed them on my work's 3D printer. I'm getting ready to do the actual assembly, and I've read a bunch of the assembly instructions (on the reprap wiki, reprapbook.appspot.com, visual instructions, etc.) and one question remains.

Both the wiki page on Prusa and the github repo say to print three of the y-bushing.stl files. Why three? It seems to me that all of the other instructions I've read (and common sense) say to use 4 bushings for the y axis; two on each smooth rod. Is this a persistent typo, or is one bearing on one side, centered along the length of the print bottom plate, enough? Or am I totally incorrect about where these parts go?

Thanks a bunch, I look forward to working with this community as I build my first printer!
Chris

Hello,

It works with 3 LM8UU bearings thats why they say 3 becaus it's a litle bit cheaper.

But with 4 works perfectly! I have 2 printers running and they run on 4 bearings.

Charlie

Okay, cool. One more question; are the bearing-guide parts unnecessary if I use the skate bearings and washers as the assembly instructions recommend?

Thanks again, and maybe once I've finished building mine, I'll make some changes to the wiki or the visual instructions to try to bring it up to date.

Chris

Chris,

You have a choice; either you print your own bearings, OR, you buy LM8UU bearings.

The printed bearings I have read about are usually printed out of PLA. Having read only yesterday that PLA has a higher coefficient of friction than ABS, that doesn't make a whole lot of sense to me,

Regards,

Peter.

Hello,


Bearings off PLA is the first methode. If you want good quality you need to use LM8UU bearings.

Charlie

And yes you don't need them if u use fender washers

PandPP Wrote:
-------------------------------------------------------
>Having read only yesterday
> that PLA has a higher coefficient of friction than
> ABS, that doesn't make a whole lot of sense to
> me,

ABS is too soft and wears much faster than PLA. PLA is a nice, hard plastic that will last a reasonable length of time in a bushing application.

Thank you Charlie. Now I think I'm ready to begin assembly!