DIY Laser levelling using webcam and laser level

[devmonkey]

I was just wondering (mentally wandering !) if you could get three mirrors on right-angle blocks, you could set up your rails to be co-planar by directing the laser back to the sensor at the same place.

I was thinking you'd put the laser on some fixed external support, e.g. a stack of bricks, and mounting the sensor on a hiwin block and plotting heights relative to the laser reference plane by sliding the block up and down the rail, then off the rail and onto the other rail. Best fit a plane to these 3D points and show the height error to each point, then shim and repeat. This is the same process you would use with a machinist level but possible more accurate.