CNCCANEN Linear Rail SBR12-800mm Fully Support Slider 2 Set + 4 SBR12UU Bearing Block Shaft Rod Guideway kit for for 12mm Slotted Bearings

First off, for all the people thinking are buying super high end precision cnc parts, you are kidding yourself. There is a reason these are a quarter the cost of parts from avid cnc or other reputable brands. These are inexpensive for a reason and should be treated as such. So if you want super high end quality controlled engineered parts, go buy them. Otherwise stop complaining. These rails are good to go for my needs and the bearings are pretty crappy, but for my needs I'll make them work. I also knew what to expect based on the price. If I wanted perfect I would have spent a heck of a lot more than $40-ish.

It works for my needs but honestly i was expecting more precision. The mounting holes on the ends are off by a few mm i dont recall the exact measurements off the top of my head but for example: left side holes where 10mm from the end will the right side is 12mm from the end. Its a pretty negligible difference but it might be important for some one. Also it appears that the blocks that come with each rail are supposed to stay with that rail so dont mix them all up in a pile like i did, i spent an hour trying to find which one goes to each rail. Also some other reviews metioned it but ill say it here to, youll need M5 screws/bolts as for length that just depends on the thickness of material your using. I used m5x25mm for the wood portions on mine and m5x20mm when mounting the rails and blocks.

If bearings have play tighten the top and side set screws accordingly and it will tighten bearing on rail.

I needed slightly different lengths. But they were back ordered so I got shorter ones and butted them together, passes over smoothly.

Good quality rails, great customer service! I am going to make a slab flattening router jig with them. they were missing the block sliders due to shipping damage the box was blown out on the end, customer service got me a new pack of 4 slides at no charge.

The media could not be loaded.  used the for upgrading my Y-axis of my CNC plasma,1 of the sliders is very loose (has play) other 3 are tight, i hope it will not give any problems later

Should be zero starsOne rail was bowed by 2 mm.The other was straight.All the bearing blocks grind on the rail. No amount of lubrication or adjustment will Fox.Absolutely trash.

one of the 4 bearing blocks was missing a whole roll of ball bearing.