200k
09-25-2014, 08:43 PM
I have just replaced the Y-axis motor assembly for the second time in less than 250 hours cutting time. The first time I can take the blame because I tried to cut come Plexiglas and it threw hot balls of plastic all over the machine including the Y-axis belt, which didn't stop the motor but sure put a spot load on it. In short, it had a lot of drag in one place on the large nylon cog in the motor assembly. I replaced the Y assembly and all was hunky-dory again. For a while. Last week I notice that unwanted once-per-rotation drag on the Y-axis when I moved the truck across manually (with the power off). This time I ordered both the y-axis motor assembly AND the "offending" large nylon cog in the y-axis assembly. Unfortunately, replacing just the much cheaper cog did not solve the problem. Apparently it is the little sealed ball bearing on which the said cog rotates is the failing component. I'm not an engineer but it seems to me that the forces on this cog are entirely cantilevered on this one little ball bearing and is more than it can handle. Why don't they use an Oilite bronze bearing instead of ball bearing? I would think it would be more suited for this cantilevered (only one end of the axle supported) situation in that it would provide more surface area for support of the axle. It would be a simple replacement to exchange the ball bearing with an appropriate sized bronze sleeve. I doubt the miniscule increase in friction would be a significant factor in the motor's performance. This is all speculation, but after replacing this thing a second time, and this time I could find to causative factor, I am convinced there has to be a better way. I keep my machine meticulously clean including active dust collection, vacuuming out chips (Corian, Lexan) every half hour, and vacuuming and blowing out everything I can find between projects. I regularly clean and lubricate the rails and truck bearings. This sort of thing just shouldn't happen. Is anyone else blowing out this little bearing like me?
200k
200k