Y Rod Bearing
This post describes a modification to improve the stability of the Y rod by adding a pillow block and bearing to keep it from being able to flex:
There were a few problems:
Getting the Y rod out was difficult because the grub screws had dug into the rod and made burrs the pulleys didn't want to slide over. I used brute force for this, hammering a smaller rod through the bushings to force the pulleys along the rod till I got enough rod outside the box that I could grab it and jerk on it to force the pulleys along. Once I finally got it out, a little filing and sandpapering reduced the burrs and made the rod smooth again.
Next, the new bearing wouldn't fit over the 6mm rod. I spent random bits of spare time over a few days with little rolled up tubes of sandpaper running them back and forth through the center of the bearing till I finally got it to fit.
It took a few tries to get everything pushed on the rod in the right order and to remember to put the belt for the Y motor over the rod :-). The printed pillow block won't slide behind the Z rods, so you have to position it between them and run the Y rod through it with it already in about the right place.
Finally, getting the holes drilled was a pain. I think I should have bought a nice new sharp drill bit and I might have had fewer problems :-). I had to stop and recharge the dremel battery after the 1st hole. I used the flexible shaft on my dremel to do the drilling. I don't think anything else could have gotten inside the case where I was able to use the pillow block itself as a guide for where to drill. Once I got one hole in, I added the first M3 screw to hold it securely while drilling the other hole.
I also didn't really want iron filings getting everywhere, so I used a strip of magnetic tape and stuck a sheet of wax paper under where I was drilling, and that seemed to collect all the filings nicely.
After using this for a few days, I noticed a tendency for the bearing to drift out of the pillow block. I thought about trying super glue, but I hated to do anything so permanent, so I built a couple of custom "C-clamps" (on thingiverse as Clamp for pillow block) I could use to force the bearing to stay in the pillow block:
Each clamp uses a small 5mm M3 screw to force the bearing into the pillow block:
Now the bearing isn't going anywhere :-). In fact, the Y rod isn't going anywhere either. I can't force it to move horizontally even if I try, which is probably a good thing. It makes it hard to tell if I've really gotten all lateral forces out of the pulley alignments, but it also means it doesn't really matter if I've gotten all lateral forces out since they can't affect the motion any longer.
Of course this is all exceedingly kludgy, but what else is a 3D printer for, if not kludgery?
[In fact, it was so kludgy, I decided it was making thing worse by binding the rod rather than supporting it, so I designed a completely completely new version]
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