Lumen PNP linear rail mods

NOTE: This is for V2 of the LumenPnP. If you have a V3 or want to upgrade your V2 to a V3, go to the V3 mod.

Minimalist parts required to convert the LumenPnP from v-slot rollers to linear rails. This preserves the overall dimensions and travel of the machine, as well as maintaining the existing Z-height.

Requires:

• 2x 550mm MGN12H rails
• 1x 500mm MGN12H rails
• 2x x-gantry-block-mount
• 2x y-gantry-block-mount
• 2x y-gantry (or y-gantry-with-limit-switch)
• 1x x-gantry-back
• 2x MGN12 alignment block
• A handful of M3 drop in T-nuts (like these or these)
• A handful of M3x8mm bolts for the T-nuts.
• 12x M3x10mm bolts for the rail carriages.
• A few M5 bolts and nuts (sorry, I haven't had a chance to check the exact bolts needed yet)

Instructions:

1. Remove your existing X and Y gantries. 
2. Using the alignment blocks, M3x8mm bolts, and T-nuts, attach the 550mm rails to the top of the Y axis extrusions. Place T-nuts along the rail, every 3 holes is fine.
3. Using M3x10mm bolts, attach the y-gantry-block-mount to each rail's carriage.
4. Insert the X axis extrusion into the ends of the y gantries, don't bolt them down yet.
5. Sit the X axis assembly with the Y gantries on top of the block mounts.
6. Use a short M5 bolt to secure the Y gantries to the block mounts. The holes in the block mount are designed so the bolts self-thread. Make sure the bolt is not so long that it scrapes the top of the linear rail- use a nut as a spacer if you need to.
7. Complete the Y gantry assembly as per the normal instructions. Secure the X axis extrusion, attach the Y axis belts, and mount the X motor.
8. Using the alignment blocks, M3x8mm bolts, and t-nuts, attach the 500mm rail to the top of the X axis extrusion.
9. Attach one of the X gantry block mounts to the rail carriage using the M3x10mm bolts, with the flat side up.
10. Using relatively short M5 bolts, screw the front of the X gantry into the block mount using the two existing holes that were previously used to hold the wheels. The X gantry block mount is designed so that the M5 bolts self-thread into them.
11. Attach the second X gantry mounting block to the X gantry underneath the extrusion, using the two slotted holes that were previously used to hold the wheels.
12. Attach the X gantry back to the X gantry mounting blocks using four M5 bolts on the other side.
13. Finish the X gantry assembly as per the normal instructions.

After completing the build steps, you need to update your calibration in OpenPNP. While this mod attempts to keep the Z-height the same, it does end up a mm or so different. 

1. Jog the head over to the datum board and re-focus the top camera.
2. Re-calibrate your top camera's mm/pixel.
3. Re-calibrate the Z-height for the primary (and secondary, if applicable) fiducials.
4. Update the Z-height on all feeders, tool changer locations, and board locations. If you don't, you risk the head crashing into things.