I know there's a few guys on here with the Shapeoko so I figured I'd share. It's a great machine that I've gotten a lot of use out of but the Z axis has been an issue since day one, and that seems to be a common experience. I get a lot of skips or slips, and it's easily bound up because the inside traps sawdust easily and it binds up the wheels. Because the G code usually sends a single up or down coordinate, any skip or skip means the unit can either dive too far or not extract fully and cuts where it's not supposed to. It got to the point I was partially disassembling after every use and cleaning the wheels or tensioning the belt to keep from ruining a project. I was googling Z upgrades literally just as this guy got posted and it looked like exactly what I was after at a reasonable price. http://rover.ebay.com/rover/1/711-5...0001&campid=5338014327&icep_item=233480338446 I know Carbide has the HD-Z but that's too much ($400) and they've got a dumbed down version on the way but I needed this fixed ASAP and the limited supply of these seemed like it was worth a shot, especially with the return policy. Anyway, I ordered it and it came in yesterday. Installation took way longer than expected but that's mostly my fault. Directions are okay but left some things out. I spoke to the designer and he clarified a few things, so installation worked out alright in the end. Haven't gotten a chance to use it yet other than tramming but moves nicely and accurately when homing and returning to zero. The Z motor sounds noticeably less strained.