Review on Iverntech MGN12 400Mm Linear Rail Guide Upgrade For Ender 3, Corexy, Tronxy, Delta Kossel 3D Printers And CNC Machines With Stainless Steel Carriage Block by Billy Branch

ordered 2 for my 3d printer. one barely moved at all, even when vertical. the other moved and would stick in the middle then move again if you shook it. I was less than enthused.the consensus across the internet was "you get what you pay for" and "cheap Chinese rails wont ever work". still, I didn't want to just give up and return them without trying to see if I could fix them. I tried spraying them with liquid wrench spray lubrication, it helped very very little. I watched a video where someone took apart the rails, soaked them in a solution of alcohol and water, put them back together, and re-greased them. The claim here was that they were "gunked up" from the factory and needed to have better lubricant applied. I tried this and then applied "super lube". This did not work.Finally I found a video of some random kid on youtube. He replace the bearings with https://www.amazon.com/dp/B015RKOZ7G/ and also claimed this changed his barely movable rails to smoothly functioning ones. I was fresh off of watching the previous video about cleaning, and since that had failed, I was skeptical of this, but they were $8, so I figured why not. I just completed the first rail, applied some "super lube", and it now moves with the slightest tilt of one side or the other. (note: if you do this, the part I mentioned above comes with 100 bearings, each side of the carriage needs 33, and there will be a slight gap left over).so, why 3 stars? whats the bottom line? the bottom line is the consensus on the internet is largely correct. there isn't really a middle ground with rails. there's expensive ones that work really really well and come ready to go, and everything else is pretty bad. these however, are super cheap, and can be remedied for not much more of an investment. $8, some patience, a clean, and re-lubrication, and you've got a solid linear rail. if you want a cheap, good solution (albeit with some work involved), these are for you. if you want an out of box solution, be prepared to pay much more.