Re-Press

My Press has worn to the point of uselessness, so time to create the re-Press.

Starting with the Z-axis, which has developed a few mm of tippiness.
Tearing it down, the play seemed to be from worn down bearing surfaces, since Solidoodle neglected to use any sort of bearing material. Lacking the mechanical skills of MacGuyverX, I decided to repair, rather than replace.

I armed myself with a couple $5 hand reamers from ebay, and a $5 pack of IGUS flange bearings, GFI-0506-04. This type of bearing has a very narrow profile and relies on a precisely sized mounting hole to compress the bearing around the rod.

I'm sure a machinist would have done better and much quicker, but I drilled an 8mm guide hole in a board, used one of the rods to line it up on the worn hole, and hot melt glued the wood in place. Chucking the rod into a drill press and gluing in place got everything lined up. After the glue cooled and set, I used a tap guide in the drill press to line up the reamers on the guide hole, and widened the hole for the bearing. After stipping off the wood and glue, and with a small amount of shimming, the bearings press fit in tightly and the rod moves smoothly with no play. Time will tell if this wears well. If enough people are interested, I can post photos. Or maybe you should wait until I get some print time on it. 

In retrospect, the bearing hole isn't quite big enough to wipe out all traces of the fingers old the SD molded bearing surfaces. A real machinist would probably have drilled and plugged a slightly bigger hole to get a more stable surface, and then drilled and reamed a new hole. (OK, a real machinist would heaved the whole bed in the dumpster and built a new one from scratch. Then looked at the warped rods, misaligned mountings, lame hot end, etc, and heaved the rest of it there too.)

Next up is the Y carriage. This is going to be tougher, because the y rods are a full mm further apart at one end than the other. Looks like SD designed for that, as one end of the carriage has a slot. Unfortunately, it's worn unevenly. The other end is also worn unevenly and has staggered bearing surfaces. All this would make it hard to refit with clip bearings, as I originally hoped to do. Might be easier to design a new carriage, but inconveniently, I have nothing to print it on.