DIY Laser levelling using webcam and laser level

[John McNamara]

Hi Joe
I agree medium preload is a good choice, and when the carriage is installed there will be 4 bearing blocks distributing the load, as they are spaced apart any axial twist will be much reduced. I suspect that if you ran the test with the microscope mounted in the carriage running on your already precision aligned rails You may get even better numbers due to some of the residual errors in the rail alignments averaging out.

Hi Kitwin
You mentioned that you were working with round rails, Maybe if you first fit both rails with the mounting screws just tight enough to allow them to move sideways then after sliding on the bearing pairs onto each rail you fit the carriage plate on the bearings in the same manner just tight enough to move you will be able to align one as a master rail using wire alignment and the microscope before setting up the other.
It may take a couple of cycles of this procedure but it will iron out any errors.

This worked for me when building a small All laser cut CNC router with a mate for a Men's shed in Bright Victoria in 2012 It is still in use daily apart from the Covid shut down.

It uses round rails, and yes timing belt drives apart from the Z axis which is a ball screw. Remarkably the accuracy is a lot better than you would think. After wearing out 2 Makita routers due to the high usage It now has a Chinese 2.2kw high speed spindle.

https://www.google.com/search?q=Brig...%3Apinterest.*

Regards
John