Comgrow Robo Replacement Y Axis Bearing Plate

thingiverse

This plate is designed to replace and upgrade the stock y axis bearing plate for the 'Robo' cnc mill/router by Comgrow. It is designed to accept upgraded SBR12UU bearings. SBR12UU bearings from China may not all adhere to the same dimensions, so you may want to order the bearings first to verify that they will match this plate. Some considerations: There is a pocket milled for the lead-nut housing. The depth of that pocket is designed to accomodate the size of my bearing, which i purchased from AZ. If the height from the axis of your bearing to the plate does not match the height of the SBR12UU that I used, your lead screw will bind as it bends, especially near the extremes of y-axis travel. You can use spacers/shims to fix this if your bearings are not a perfect match to mine. However, if you are unable to mill that pocket (for instance, you have a drill press but your Robo hasn't been upgraded to cut aluminum yet) you could instead make spacers of that same height and raise the bearings instead of lowering the lead-nut, and let the lead-nut housing sit on the plate directly without milling the pocket. All of the holes are sized for the appropriate tap for their screws. However, this is only actually necessary for the lead screw nut block and the limit switches. You don't have to thread the holes for the bearings, they should be threaded themselves. If you are tapping these holes by hand, be aware that the tap will be extremely difficult. You may want to move up a drill size and trade slightly looser threads for an easier tap. I intentionally did not include the holes on the ends of the bearing plate for the gantry arms in the model. You'll have to take the existing gantry legs and use them to mark your holes. If you have upgraded the spindle and z-axis, your spindle probably hangs out pretty far in the -y direction. If you put the arms on the -y end of the gantry bearing plate, you can make the spindle stick out even further, potentially past the end of the machine. This means that you can make cuts past the end of the table. This allows you to work on the ends of long parts that hang off the end of the machine vertically, which otherwise wouldn't fit in the z-axis. For example, you could drill a hole in the end of a long rod clamped vertically off the end of the table. However, this means that you can't use the table at the back of your machine, as the y-bearing plate will hit the frame before the spindle reaches the back of the table. Having the spindle so far (in the -y) from the bearings also reduces machine rigidity. Mounting the gantry arms to the back (+y) of the y-axis bearing plate reduces these problems, but you may lose the ability to work past the table edge. Have fun!