Chinese ‘cheap’ clone linear rails MGN12 Beware and a teardown

The Cheapy ‘Hiwin’ clone rails and blocks arrived a while back and they haven’t really dissapointed. By that, I mean, I kinda got what I was expecting. Still, only a small premium paid and 3 workable carriages / rails……

To recap,

I ordered 3 sets of 500mm MGN Linear rails and MGN12H carriages based upon a recommendation from a few forums…

I ordered an additional 3 MGN12H style carriages to make Six in total

I’ve since done a lot of googling for various terms, such as “improving chinese linear rail performance” and the like

Frankly speaking, out of the box, the performance of two of the blocks was passable, the other four, terrible. Eventually, after cleaning, ONE further block works well enough, making it a 50% success rate


Hints given on google to fix sticky rails……

After all that, I figured something must not be quite right, So………..lets have it apart

I present to you in it’s glorious nakedness, a Clone MGN12H bearing block, all stripped down!

Teardown, 66 balls, four screws n’ stuff.


All looks OK superficially, but, look what I spotted inside the holes the bearings go through. The holes in the block have clearly been drilled from both sides to meet in the middle, rather than Just straight through from one side….

This’ll need a fix with a drill press and a suitable bit………….


hole clearly shows a ring half way down where the drill hasn’t met properly from each side


Whilst looking at those holes and figuring out a way to show them in a photo for the store I puchased them off, I discovered that one side of the bearing groove that is normally covered by the wire and balls is not machine finished, it’s very rough!


This one’s the good side….looks slightly rough, but it feels smooth, the line is my dragging a wire over the grease in the groove 


Look at that bottom groove, it’s not been machine finished…it’s very rough.

Author: Bleugh

Early Fourties, Wife, two kids in primary school. Both of us work full time...5 years now we’ve been Back in Blighty after a decade away...It's a new country for everyone! Still finding time to tinker!

2 thoughts on “Chinese ‘cheap’ clone linear rails MGN12 Beware and a teardown”

  1. it’d be hard to drill such a hard material with household stuff. specially with a hole that long. after you do that one side of thehole will be bigger causing play in your block!


    1. Agree! It’s why I haven’t really tried 🙂
      But now you remind me! I’ve since purchased some dremel de-burring attachments that may well fit in the cavity….all I need to do is create a ramp inside that gradually phases one profile to the other 🙂 blog post incoming when I get time 🙂


Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

%d bloggers like this: