I just took the plunge and ordered the Onefinity CNC! Excited and daunted as I am new to CNC, though I have done some laser CNC.
My main worry is the lifespan on the Ball Screw’s and how much they would cost to replace, and can they be replaced at home? I looked all over the forum and didnt see anything about this topic really.
I don’t love that there isnt an option to seal off the ballscrews with some kind of shielding, so I keep wondering how long does it take debris to get in there and mess up the ballscrews.
Will, this one the same question I asked back in April or May before I even ordered the machine. There are coverings out there (they are called bellows) but after having the machine for a solid month, i really don’t know that they are needed. I use the dust boot most of the time so not much even gets on the screws, but what does is wiped off by the seals. I honestly wouldn’t let it bother you. Ballscrews are not expensive and this machine appears to be easy to service when that time come. Get the machine and just enjoy it.
Yes, THIS. Ballscrews are industrial-grade components and should be the least of your worries. The truth is, you’d probably have to have thousands upon thousands of hours of use before they show even a hint of wear, and only then if you’re doing some very precision work. Contamination is unlikely with reasonable cleaning & care, the seals do a good job of protecting the bearings within the nut. Same for the round rails, they have the least chance of getting contaminated as compared to any other style linear rails.
Thanks for the feedback Bill, Jared, and Jake, very much appreciate your knowledge on the topic! I will stop worrying and just prepare my spot in the garage.
I was already imagining some accordion like cover i could put around the round rails that would expand and contract as the gantry moved to prevent dust and debris from landing on the rail. But that sounds like it might be overkill
Yeah, that doesn’t appear to be an item of concern, really. Nothing wrong with minimizing exposure to dust, but probably not a game-changer.
charleyntexas
(Charley Thomas (Onefinity/Triquetra Touch Probe))
7
Here are two pictures a ball nut. They are designed to prevent anything from getting inside the internal part of the nut where the ball bearings are circulating. On both ends of the ball nut you can see a White ring. They are like big thick washers that are threaded to fit the screw. This is a wiper ring and is designed to collect any debris that is on the outside of the screw and push it off. Think of it as a snow plow. The debris will built up on the wiper ring and as it accumulates, it will simply fall off. I’m not sure what the ring is made of but it feels like it delrin or teflon. They fit snug around the screw and do a great job of keeping debris out.
I considered using an accordion style rail cover also, but the mounting of it will be a bit tricky since the machine that uses stall based homing. The spindle gantry has to be able to make contact with the left and front rail ends without obstruction. I’m sure there’s a way around it but from what I’ve been reading if you keep the rails cleaned off every so often the bearing wipers and seals themselves should be sufficient. I still keep coming back to how much better this has to be than rubber belts and v-wheels!
I am thinking of cutting some plexi shields to place on the inside of the Y rails. I think that would keep most of the dust off the rails. I don’t think the X rail is much of a worry
So Charley, I haven’t even got mine yet but think I should have some spare parts. What can you tell me that maybe I should get/order for spare parts. Standard size set screws?? Plastic parts? Any ideas?
Dan
Does increasing the jerk/accel/velocity to its maximum have an impact on wear of the ballscrew/bearings? I’m weary to increase it, and can deal with excess time if it means less wear.
Aiph5u
(Aiph5u (not affiliated with Onefinity))
19
Hey Dan,
you did understand that in my previous post above, with the clickable link in the word “precisely”, I led you to the posting where the project of the external wipers is presented, did you?
Just in case anyone wants to see how the ball screws actually work. Unlike a lead screw nut (which is subject to wear from friction) the ball screw is like a ball bearing. https://www.youtube.com/watch?v=oEPrXljqeHA
My first attempt to protect the ball nuts was indeed a bellows-style setup, but it required me to install standoffs to allow the machine to stall home a couple inches prior to hitting the axis end, this was to leave enough room for the retracted bellows. I assumed most people would not want to lose 4-6" on both X and Y axis… I haven’t abandoned the idea, but I don’t have a better solution that doesn’t reduce travel.
Currently I use curtains and wipers on my machine. The curtains are not the most elegant solution, but really help contain chips and keep the Y axis rails and leadscrews nice and clean.
Defects aside, I think ball nut lifespan will greatly depend on your maintenance routine, materials you work with, lubrication of the machine, humidity levels etc… I have some old DIY machines with cheap ball nuts that are close to 10 years old and still kicking.
