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View Full Version : Chinese MGN rails. Should I use them?



andy1989
29-09-2017, 01:09 PM
Has anybody used the cheap Chinese MGN15 rails you can get on eBay?

Iv never built a CNC router before, and i was wondering if they are appropriate for a small desktop machine.
I hope to be able to cut aluminium. Machine cutting size would be approx 300x400mm.

I got a couple of 300mm long MGN15 rails last year originally intended for a 3D printer, but I decided against using them in the end. They have no free play, by they do stick a little in places. For a small belt driven 3D printer this would be a big issue, but would it be an issue for a nema 23 ball screw or rack and pinion driven CNC?

The other alternative I have been considering are SBR20 rails. Would these be a better option on a small budget (£500 ish for the mechanical componants).

Boyan Silyavski
30-09-2017, 08:40 PM
I bought for my current build MGN12 and am very happy with the quality. I am super duper picky and "always Hiwin " type of a guy :stupid: . Before a couple of years i have ordered a test 20 size rail and was Not ok to my liking.

To understand better what's happening - In China around every corner they sell linear rails at some places. Which means they make them in hundreds of places. Obviously quality differs. In worst case scenario you will need to change the balls with better ones. But my thinking was if i buy from big factory that makes them they will be good. So that was what happened. They turned good.

In short they needed cleaning the rails and the carriages and then were ok. Rails are really hardened and ground. carriages are made so that could be taken out from the rails without spilling the balls. the preload is adequate.


Here is the link to the manufacturer (https://www.aliexpress.com/store/group/MGN-linear-guide/822038_250570030.html?spm=2114.12010612.0.0.25ea31 5zWAVMu), he has good prices so my advice is not to experiment from other places. They know English and you can order custom configurations. had some problems with shipping which they corrected.

I have real MGN12 rails and carriages here, so i compared them side to side and i know what i am talking about.

But as i said if you buy from another place there is no guarantee that it will not be a lemon. The real problem is that normally only 3D printer guys and other amateurs compare them on the web and they never have touched real rails or had a serious machine, so in reality i couldn't find real information prior to purchasing, from someone that knows better. So it was a bit risky when i bought near 10 meters of them and some carriages. But i am happy without doubt and will do the job.

Hope that helps

Desertboy
05-10-2017, 05:27 PM
I have a set of clone rails and 2 sets of original hiwin's I honestly can't tell the difference so I think it's a matter of time after a year of hard work we shall have a better idea.

The clone rails were 1/3 the price of new Hiwin's.
http://www.ebay.co.uk/itm/15-1500mm-2x-Linear-Guideway-Rail-4x-Square-Type-Bearing-Block-Machinery-Unique-/182772661138?epid=894536523&hash=item2a8e197b92:g:QqUAAOSwez5ZvxoH

I paid £100 early in the year but I noticed since the brexit fiasco prices have gone up and back down a bit they peaked at £160 about a month ago so variable lol but Germany shipping so no import tax and were shipped in 3 days.

andy1989
10-10-2017, 05:29 PM
Thanks for the advice guys.

I'm certainly going to look into using clone rails for this this build now!

andy1989
13-10-2017, 08:13 AM
Just got a quote from hongyi automation for a kit with 300, 650, and 850 profile rails and 3 ball screws. For hgr20 rails it was 376usd and hgr15 rails was 355usd. They confirmed that are not hiwin rails. Has anyone used the hgr rails from this place? Would you recommend them?

Boyan Silyavski
17-10-2017, 01:25 PM
Just got a quote from hongyi automation for a kit with 300, 650, and 850 profile rails and 3 ball screws. For hgr20 rails it was 376usd and hgr15 rails was 355usd. They confirmed that are not hiwin rails. Has anyone used the hgr rails from this place? Would you recommend them?

You will have to risk it. The fact that the other rails from them were great and that as seen on pictures they have bothered to laser mark the blocks are very encouraging. I would say the chance for them to be great rails is more than 90%.