Y-Axis motor assembly replacement...again

[200k]

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

[ktjwilliams]

Dan I believe designed n made a hole new style housing for this .. He did post the MPC's for it on the forum ... I don't have the time to search it out for ya rite now,, but will check around maybe tomorrow... Or search round for it up here ...

[bergerud]

You are absolutely right about the design weakness of the y gearbox bearings. Every 250 hours or so, they go. I made myself a better gearbox which uses a larger bearing.

See the mpc in this post (as well as the thread it is part of) : http://forum.carvewright.com/showthread.php?24819-Y-Gear-Box-Modification&p=220765#post220765

[Digitalwoodshop]

If I know LHR they will address the Gearbox at some point making it heavier with roller bearings but that is just a guess... You can search and find some other innovative ideas posted about the Y Gearbox. Your right, it is the weak point but if you follow the recommendations of replacing the inner Gearbox Bearings at 250 cut hours WITH the Cut Motor Brushes you will be fine. As you pointed out... You sort of took your SUV (CW) OFF ROAD into the woods by asking it to cut plexiglass a material really TOO HARD for the Bit FEED RATE. IF LHR would offer us a FEED RATE Slider Control on the machine that would let this HOBBY machine PLAY like the BIG BOYS for a fraction of the cost... Same Paths and everything just the ability to SLOW DOWN THE FEED RATE as Desired..... :)