BQLZR SC8UU Linear Motion Ball Bearing CNC Slide Bushing 34.5mm Length Pack of 4

They work really nicely and the fit is perfect.

Worked for what I needed. I purchased them as replacements for the ones that came with my 3d printer (a Prusa I3 clone). I knew they would probably be similar quality, especially given the price point of the printer and the bearings. Some of the ones that came with my printer had all the ball bearings fall out of the assembly. I don't know if it was the way I inserted the linear shaft, or if they were cheaply made. I was hoping it was just one bad bearing but it happened on a few different ones, and also on one of the ones I purchased here.But the ones I have on my printer now are working fine, one I had the shaft on them, I don't have to worry. They seem to slide ok, a little rough, but again for the price, I don't really have a complaint. I know high precision bearings cost a lot more. These worked for what I needed them for.

Great for their cost. Sure they are cheap and maybe they had a couple of rough motions at first, but that worked out. I wasn't willing to pay McMaster-Carr prices for my slide and I knew that I get what I pay for. I say they are great for the price.

The media could not be loaded. Construction is excellent but the friction to movement was about 25g. For your application that might be no problem. For mine it was a deal breaker.

Screw holes are inconsistently sized. Most fit for M6, some are a little larger, threads dont 'grip' and screw just turns instead of tightens,. With one of the blocks the screw holes are tapped larger than M6 and the screws fall out.Other than being unable to fix the blocks to the Y-plate without a larger screw and affixed bolt that interferes with the printers frame, these do slide up and down linearly.Get what you pay for.

slides smoothly and at a great price. The bearings are held in with some c-clips on the units I received, making the replacement of a faulty bearing in the future easy enough to service.

thought i would be stiffer in all axis. i already planned on using two per axis should be fine for a printer

Partially tapped holes limit you to only top mounting. The wholes are not square on all blocks. Some of the bushings are missing 3-4 ball bearings making them jerky. I guess for $8 you get what you pay for.EDIT: Bought a second set because the 1st ones were useless. These came with the bearings on the outside! Loose in the bag, so... again completely useless! The seller NEVER response to emails and shipping to return them costs more than they did.