VEVOR Linear Rail Slide SBR20-1200mm 2 PCS and 4 PCS SBR20UU Slide Blocks Linear Guide Rail and Bearings Kit for Automated Machines DIY Project CNC Router Machines

Very easily mountable and very durable.

Robustly made, sturdy, holding up well so far in my shop where there’s significantly metal dust.

Smooth bearings. Nice finish. Works great. would buy again.

For the price of these, (which is something that needs to be fairly precise, straight, and remain that way) I was shocked at the quality. Way heavier than I expected, dead straight, witg buttery smooth operation on the bearing blocks. I'm building a flattening table for big live edge slabs so I got 3 pairs to make a roughly 4x9 table. Got them in and wanted to test it out so I put a couple together and couldn't be happier. Btw the bearing blocks thread is m6-1.0. which also happens to be a common size of backside tv screws that comes with wall mounts. And if your anything like me you'll have a bunch on hand since I can't throw away all the extra hardware that comes with stuff.

The item itself deserves a 5* rating. It's exactly as described, the brackets slide easily along the rail, it's a really nice product. I gave it 3 stars because mounting anything to it is an absolute nightmare. You have take several measurements to get your drill points and if you're off by 1/16 of an inch, your holes won't line up. For the price, they could include some plastic template or something. Also, the holes for the cross rails (separate item) don't line up with this, so you can't just attach them directly. Small tweaks to the design and this would be a perfect item.

A straight edge laid across the bar shows a deviation of about 1/8 of an inch end to end. I was going to use these for a planer sled as others have done but with the bow in the rail you would get a board thicker in the middle than on the sides. 1/8 " would be a lot of sanding to make the board flat. My old mdf sled which cost next to nothing is a lot flatter. Also the aluminum ends are very roughly cut and protrude out from the round bars, so would have to be filed off if you wanted to put two of these end to end for the table part of a router flattening jig. One of the bearings had some play on the bar but the set screws on the block adjusted the tightness. Update: Contacted Vevor support - extremely helpful and very responsive. Found out that because the difference in the thermal coefficient of expansion between aluminum and steel the bars will distort as the temperature changes ( AL is 2x or more than steel you can visually check this by using a long straight edge and warming the bar/aluminum combo with a hair dryer). They had me loosen the bars from the aluminum and check them again - the distorted one was still distorted even if I removed the aluminum entirely. I sent a picture and Vevor sent me a new bar and it is straight as it should be. Five stars for support, 1 star deduction for sending a bad bar to begin with. For those that are building a cross flattening sled - I was trying to decide whether to use just the bars or the bars with the aluminum extrusion, not knowing how much sag the bars would have with the router and it's carriage. With the aluminum there is no detectable sag, so if you are in a temperature controlled environment then if you loosen and then tighten the bars on the extrusion it will not sag with a router. If, however, you have limited room like I do and setup your flattening system outside then the temperature extremes as far as I can tell could make the bar flex by .5 to 1 mm (depends on what the temperature is and what the temperature was when the bars were tightened). Testing with just the 2 bars ( no aluminum) at full span with a 12lb weight in the middle then the weight appears to make it sag by about .3 mm. Temperature will not affect it. This is with 2 1200mm long, 20mm dia. bars. If the distance is shorter the sag will be less and if the bar diameter is smaller the sag will be more. Obviously if the router/carriage weight is less it will sag less. I am planning on making my sled with just the bars (which would have been cheaper had I known this ahead of time).

Perfectly straight

Great rails. They are strong and straight. I used them to build a router sled and I couldn't be happier. They slide very easily and provide great support for my router. I get a nice smooth surface every time. As long as you don't push down too hard, you don't have to worry about the bar bending. Highly recommend. The only downside is it doesn't tell you the tapped hole size so you need to bring the slide pieces with you to the hardware store when you figure out how you're using them so you can get the correct size.