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

[Kitwn]

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.

John,
My main concern with the round rails was that a single carriage will rotate around the rail so some form of 'gantry' going accross both will be required to mount the microscope. Probably not a real problem in fact, especially if the slave rail is quite losely mounted. Nearly all the error seen will be from the nearest rail and a few iterations should sort things out as you say.

I'm not sure you can fully adjust round rails in practice. The steel rail must be far more rigid than the aluminium support and whilst shims may well sort out vertical errors, I suspect any attempt to nudge the thing sideways will more likely distort the support than the rail. I don't speak from experience however.

One day I might decide to do a serious upgrade and build a mostly-new machine in which case I will be using all the wisdom gathered from you and Joe to chase down every micron I can. Alternatively somebody with better coding skills than I will come up with a method that can detect all the errors on my machine and writes a dedicated post-processor to take them out in software. Oh No! Not another rabbit hole to head down!!!

Very amused by your last comments, my version reads "After wearing out 2 Makita routers due to the owner being being stupid it now has a Chinese 2.2kw high speed spindle"

Kit

[John McNamara]

When we built the router in 2012 it was for a community men's shed. we were on a parts budget, My mate and I put our time in for nothing so there was no cost there. A Makita router was available, from memory it was donated.
The Chinese spindle. Is much quieter than the Routers with their brush type motors. I guess I should of put this in a separate thread, it is a bit off topic. This thread is about Alignment and software.