Experience with chinese linear rail and ballscrews?

[Wildmine]

Looking to make a DIY cnc machine and was wondering if anyone has experience with some chinese sellers on ebay. Preferably someone that has kits with both the rails and threaded rods(like the link below).

Have been looking for hours and hours, and found this seller called kumakuma9 with this kit: 3set SBR20 linear slide rail+ballscrew RM2005-350/650/1050mm+BK/BF15 bearing CNC | eBay . Anyone got experience with them?

Thanks for any help

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[Ljungberg]

Hi
I did order a kit from banggood.
It was the rod Type of linear rail.
The Chinese do not understand how to package precision parts my was just wrapped in thin plastic just like a plastic bag. They was bent so much I could see it with the naked eye.
Another thing to consider is quality control.
China is not known to bee good at it. My rails was supposed to be hardened. One of em was not.
Several was really soft hardened in one end but was hard as tungsten in the other end.
It as 600mm rod (24in).
Get my frustration when I did find 10 times the quality for like half or quarter of the price home in Sweden.
From now on I gladly pay more (if it even is more expensive) to get it right and skip the hassle the first time. So I only buy from Sweden and Germany. Oh did I mention that they did send me a pirate copy of an jkm Nema 17 that has half the torque.

[grantnlee]

In December I bought my 1605 ballscrews on ebay from mhestore2009 as well as my motors, ballscrew nuts, and bearings from Zyltech (shipping from TX). I bought my SBR20 Linear Rails on Amazon from VXB. I'm not a machinist, but am confident that what I have is going to serve me well for the machine I am building. The Linear Rails in particular are quite heavy and the packaging was not strong enough. But everything arrived quickly and intact. Overall I would do it again, and I would actually seek out these vendors if I did so..

[grantnlee]

One more thing I will mention - if you have not yet done at least the math on the design you intend to build, I would caution you that the packages containing both ballscrews and Linear Rails are not always well matched up well in length. You need to consider that the effective use of the Linear Rail is reduced by the spacing between the linear bearings. So for example, 900mm Linear Rails on the Y-Axis, have spacing between the bearings of about 8", which comes off the total effective length. The effective length of the ballscrews is obviously reduced by about 70mm where the end is machined. If you have not designed your machine in detail, you should at least carefully consider those aspects on paper. Of course this only matters if you are trying to maximize your working envelope....

[Wildmine]

Hey Ljungberg, do you have some companies/links you could give me for the ones in Sweden/Germany? Might be able to get from them as i live in Norway. cheers

[Wildmine]

Yeah grantnlee, i have thought of that. I am making sketches in sketchup so i can see the movement i will get. With my current plans i should get about 1000x600mm cutting radius:


I found this: Square rail kit from linearmotionbearings2008 (seen the seller recommended a few times before on the forum) and i would guess that would be a better option?

I am planning to make it out of 4040, 4080 and 40120 alu profiles and the plates are 15x150mm alu and can only buy full length (6m long). Think this would be strong enough for cutting alu?

Cheers for reply

[MajorTendonitis]

Grea thread guys . I was actually looking at those parts today that you posted . Sure not liking China's packaging policies

Nice getting an idea of how much linear guide to take into account for the displacement of the blocks . I want to build a 4' by 5' , so I'll have to take that into account.

I was looking st getting a couple pairs of 1800mm , hoping it would provide a 4/5' cutting area .
Not to particularly about going with extra linear guide, just hate to fall short