Full Bear Y-Axis Linear Rails MGN12C

by JuanPuchol Apr 20, 2019
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Awesome work. Ordering my hiwins now! =D

Hello, should we change the firmware as on the Zaribo?

No, it works with the standard Prusa firmware in case of MK3. If you use a Bondtech BMG and IR sensor (MK3S, my case) you have to reduce the height by 5mm, so you have to change the total height from 210 to 205 to prevent z calibration fails. Using the original Prusa MK3S extruder doesn't require changes

c'est dommage, je viens de commander les rails!!

bonjour. vos pièces ne sont pas compatibles avec mon châssis. en existe t-il pour MK3 d'origine? merci

No, I'm sorry

quick question.... or two
You mention you are using MGN15 rails but link to MGN12 rails..
You say the rails must be 328-329mm and the rails you link to are 350mm.. did you cut the extra length off with a hack saw? I suspect so, I suspect it would be impossible to get the rails at the exact length you need.

with suspended rails, so you get any flex in the bed if you push on it... like you do with the 8mm rods?

Did you consider backing up the rails with a piece of extrusion?

thanks for all the hard work on this by the way.. this is most likely the way I will proceed with my Bear.

Yes, they are MGN12. I'm sorry, I confuse the size with my Zaribo rails that are 15x15. And yes I have cutted the rails with a radial saw, there are some tolerance with the length. I have to study the flex. By the other hand, on facebook Grégorie Saunier says it is better not to use extrusions.

Oh.... I need MGN15 supports, but I don't know how to edit that parts to fit with my rails (They are HGR15RH with HGH15CA blocks)

Do you think is it possible to adapt your design? Can you help me?

I am trying to adapt this design, with original Prusa Bear style:

Linear Grizzly Bear I3 upgrade
by jimmy_d

The problem with HGH15CA blocks is they are very big, I'm using them on my Zaribo printer, first thing you can use only one block on each rails, and you have to mount them over the aluminium extrusions (you will loose a lot of height, probably 2-3cm) because the y-axis will not complaint its length. See my Zaribo design and later we can talk about it (https://www.thingiverse.com/thing:3511667)

Zaribo Y-Axis Linear Rails 15x15


I bought HGW15CC blocks, that they are bigger than HGH15CA
But in Linnear Griizly they recommend them...

Thanks Juan Puchol for your repply and your work, you have a comment in the HGH15CA design

Linear Grizzly Bear I3 upgrade
by jimmy_d

Yes, but they propose to build a bigger printer. For a MK3 I think is better smaller blocks

WTF. I have mantained the original Prusa Bear dimensions.

Maybe I will try to drill the holes in the bed base

This looks so awesome! How much is the noise? Can you upload a little video on YouTube where the bed is moving, please?

Yes, I will upload a short video but in some days, the printer is at job and I have 10 days of vacation

Hi Juan

I am upgrading my mk3s to bear and really like your solution. I am second to greenDots question about the noise and the overall improvement.
Thanks a lot!!