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1. Rolled ball screws crunch. Its the nature of the beast.
2. puny motors stall.
3. I like the G540. the 24v will work. Upgrade to 48v when you can.
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I completed my X2 (Micro-Mark) conversion last night with CNC Fusion kit #4. Just a small amount of grinding required at the back of the y-axis screw to maximize travel. Otherwise, seemingly went well. BUT:
1. The ballscrews sound "crunchy", especially the Z, but the X and Y to some extent. I did my best to keep the ballscrews clean during install, but it is possible very minor amounts of contamination snuck in. How sensitive are the ballscrews to contamination? As a note, I did order the upgraded preloaded ballnuts for all three axes along with the zero backlash couplings. Is it possible the preloaded ballnuts are supposed to sound extra crunchy? I searched and saw some people that suggest this is normal, but others that say to flush out the ballnuts. I'm worried about binding and/or tight gibs. I still haven't gotten the hang of adjusting them -- I feel like I tend to go too tight to minimize any unwanted movement. Do I have to lube the ballscrews? They came covered in a light oil and I thought that was sufficient for now.
2. I ordered (3) 382 oz/in stepper motors from Kelling. I had a bunch of Probotix ProboStep drivers and breakout boards from a previous project and was planning to use them... but failed to recognize that the ProboStep drivers are unipolar only (6 or 8 wire motors). The Kelling steppers are 4 wire. So, I installed these little 160 oz/in bipolar motors I had on the axes... and they seem to stall. Maybe I shouldn't be surprised, but this is with NO loading (not machining anything, just running the tables) and I thought they'd be sufficient to move the axes about for testing. Is this normal? Certainly, they are better at low velocity/acceleration, but still stall at points throughout the range. I'm wondering if the fact that I can't move the tables consistently with the 160 oz/in motors has something to do with the "crunchiness" of the ballscrews. I guess I need to order a bipolar driver?
3. If I order a new driver for the motors, is it pretty universal that people recommend the Gecko 540? Also, I have a 24V power supply... is that sufficient for light projects with the 382 oz/in bipolar motors or should I order a better power supply, too?
Thanks so much for helping point a newbie in the right direction.
Jeff
1. Rolled ball screws crunch. Its the nature of the beast.
2. puny motors stall.
3. I like the G540. the 24v will work. Upgrade to 48v when you can.
Thanks for the quick reply.
Even when just moving the tables +/-?Originally Posted by MrWild
Good to know. I'll order a G540.
I gotta disagree here.... I have what are usually referred to as CHEAP ballscrews. They are rolled and when my machine is moving there is NO crunching.... If I were you I would try removing the motors and lubricate the screws liberally then try to move the table by turning the screws with your fingers. You should be able to move them with a little effort but there should be NO tight spots. IF there are tight spots you need to take things apart and look for any misalignment or physical obstructions. Never used steppers let alone ones that small but I would think that even the smallest steppers should be able to move the table back and forth without any load on it. Are your tuning settings right? What are your accelleration and rapids set at? If you do not have proper way lube you can temporarily use some heavy gear oil or similar, as long as it is clean and has adequate viscosity you should be fine. The machines movements should all be smooth and free of tight spots verified manually before you try to power things up. This should be relatively easy on an X2.... Good luck... peace
pete
Pete, I have oversized balls in my preloaded ball nut. I wonder if that is the difference. I've been searching and reading since I posted and it seems this may be the cause since any little imperfections in any of the components could cause grinding/crunching and as they wear in the noises will disappear.
I will take your suggestion, though, and disassemble to inspect. My intuition is that something isn't right.
I have never used oversized balls in a ballnut yet and my machine has a double nut configuration with spring preload for (hopefully) zero backlash. Again, when I first assembled my machine before I ran it with the motors, I turned the screws by hand all the way back and forth. Made sure they rolled nice and smooth, then applied the motors. I actually used my cordless drill to run things back and forth a bunch of times lubricating things before that as well. If it is not smooth manually or with the cordless, it sure as heck is not gonna be smooth any other time. There was a video on here from someone else that had an issue with their X2 sounding crunchy as well somewhere but I cannot seem to find it. It may have even been the same kit?? Good luck with it man... peace
Pete
I've used a lot of ballscrews, both cheap and not so much. The cheaper black plated ones do tend to "crunch" when new. The noise comes mostly from the balls pushing each other around the races. The black plating on the screws is not very smooth until it's worn in, so causes the balls to stick then release, making the noise. Keep them well oiled with heavy oil (anything will work), and they should wear in and quiet down over time. But, if there are really tight spots, that would suggest perhaps you went too far with the oversize balls, and/or you have an alignment problem. Certainly, just spinning the nut on the screw, out of the machine, they should be smooth and quiet. In fact, most, when dry, will spin down under their own weight, or very close to it, when the screw is simply held vertical.
More expensive rolled screws, like the Nook XPRs, are dead smooth and silent right out of the box, as are ground screws. If you're using double nuts, there's no reason at all to load oversize balls. The pre-load mechanism will perform the same job.
I used to oil the screws on my X2 with a mixture of ATF and moly grease, painted onto the screws with an acid brush. It was slippery as heck, but stuck really well to the screws. I only coated them maybe once a year, if that, and they're still fine to this day (+7-8 years).
Regards,
Ray L.
Easy fix for the ballscrews. Just slightly loosen the mount retaining screws to the point that they can just barely move. Grab the chosen axis and either use your hands or a drill and move the table back and forth a few times. This should self align the ball screw to the ball nut, I know it sounds crazy but eliminated all my crunching.
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