I got my bearings from Ebay and I use this to advance the plate or width of the wood to be cut.
Bearings - Title: 10 pcs 1621 ZZ metal shield ball bearing, 1/2x 1-3/8x 7/16 inch | eBay
To advance the sled or to determine thickness of wood
Fused with shiny surface matching with high precision. High transmission efficiency, high positioning accuracy and repeatability of positioning accuracy, long life, high stiffness, drive transmission reversibility reversibility.www.ebay.com
Biggest thing for me is I want it to be able to take apart and store easy hence all the mods I have done.