300mm Ball Screw SFU1204 RM1204 with Nut (End Processing) Precision Part for CNC Machine

I purchased these to upgrade a CNC wood router. The build quality is excellent and the accuracy is well above the simple plastic nut lead screws I am replacing. The only concern is that one needs to provide a suitable bellowed covering to prevent dust from getting into the ball screws. I plan to use thin plastic poly wrap tubing and 3d printed parts to achieve this.

I am giving my review 3 starts because the nut fit very well and didn't feel all crudded up before I cleaned the screw. I ended up returning the screws because the upper end shafts were over spec: both measure around 8.012mm at 22c. I froze the screws to -20c and the upper end shrunk to 8.002mm. Still over spec. These screws don't need an interference fit. The lower shaft on one screw was ground properly (9.991mm at room temp) so I could get a set of angular contact bearing on but the second screw was over sized at 10.007mm. I could have froze that screw and got some bearings on but there's no need for that sort of hijinks. No need to press a bearing or freeze a shaft for a ball screw. A location fit should be good enough. Sorry, long rant. 3 starts for nice screw/nut combo; however, the machined ends might not work for you as they didn't for me.

The media could not be loaded. This item was of a very poor quality. It worked fine while going up and down for several turns, and then it got stuck and couldn't move dow anymore.With a little bit of hand-force, it started moving down, but ball bearings started to pop-out through the bottom.So glad I didn't install it yet. It would be a hassle to reassembly my router lift all over again.

Best ball screw nut to screw fit I've seen in the past year over a dozen or so Chinese ball screws from 12mm to 20mm. Once it was cleaned (yes YOU clean it) and lubricated (again YOU), the motion was consistent over the 400mm with little to no binding and no grit. The fit was great.. I'm used to having to repack the but with bigger balls to get a proper fit, but this one was spot on. For you newbies, you do not want it to just spin freely. Packaging was great and shipping time was quick.Now the bad.. how is it possible to send these out with diameters that do not fit inside the bearing blocks? They're oversized and will not go! Little bit of elbow grease fixed it but I don't understand how that slips through QC.Overall, great deal for the price.. but do not expect perfection.

Good: The bearing blocks, hardware are quite ok. Less than .0005" runout between the ball screw races and ball nut.Bad: operation to turn the screw ends down was done poorly. Bad surface quality. Chuck marks catch the ball nut at either end of travel on the screw. Heres the tir i got from the ball nut to either screw end .003" runout on fixed end. Nearly .005" on the floated end.If end user wishes? You can make a ball nut ball retainer on your 3d printer, take the nut off, clean up the screw and repack the nut. Can re-grind the ends also concentric to the ball nut and take down any holding/tooling marks with a stone and flex abbrasive. My other option was a used thk that cost 10x more. Little elbow grease saves a lot of money.Be aware what you're getting into.

This ball screw if one of the worst I've experienced. Out of the packaging it has a thick goo on the screw that must me removed to even get started. Some of it had melted off and soaked the cardboard box. after careful cleaning, the motion is still jerky and not smooth like it should be. There's a lot of resistance in movement of the bearing block. Might be ok to replace a simple leadscrew in a cheap 3d printer, but it's far from precision.

While I get that with linear rails you should always clean in iso alcohol and then re lubricate, I don't feel the same for ball screws, maybe I should but when I buy more expensive screws they come properly lubed and without needing to be cleaned at all, plus I have never had any of them sound like they have sand in them. The preload on these is pretty high I think which is fine once you are aware of it and the sand sound went away after running the nut up and down the threads a few times. Still these will never just be able to be free spun to move up and down due to the preload. My other screws I can give the nut a good spin and it will keep going a good way up or down the threads. Nothing wrong with these aside from the noise but like I said run the nut back and forth a few times and it runs smoothly enough still better than lead screws any day. The price is decent enough and from first looks I don't see any appreciable run out, will check once I get everything mounted up and update if it's an issue

Excelente producto