DIY Laser levelling using webcam and laser level

[Kitwn]

For me one of the great attractions of this forum is the mixture of common sense, common sense being not at all common in general usage, and cutting edge science that is available on an almost daily basis. I want to read Dean's and Boyan's blunt comments on what is sensible for someone wishing to build a first machine for cutting out wooden parts for their hobby projects, and I want to see what Joe and John can offer in the way of extreme accuracy for a home hobbyist on a DIY budget for those that are interested in achieving it. Our main problem is ensuring the novice reader is not confused regarding what is practical and achievable within their target spend of both money and time.

[devmonkey]

For me one of the great attractions of this forum is the mixture of common sense, common sense being not at all common in general usage, and cutting edge science that is available on an almost daily basis. I want to read Dean's and Boyan's blunt comments on what is sensible for someone wishing to build a first machine for cutting out wooden parts for their hobby projects, and I want to see what Joe and John can offer in the way of extreme accuracy for a home hobbyist on a DIY budget for those that are interested in achieving it. Our main problem is ensuring the novice reader is not confused regarding what is practical and achievable within their target spend of both money and time.

I agree which is why I have confined the discussion of the optical stuff to this thread, and my current machine build to the build log thread. I will however have to use some parts of building that machine to demonstrate how one might use the optical system, no one need copy it, but there does seem to be interest which is why I keep posting.

The two tasks which I'm attempting with this system are
1. Making the X beams planar to carry the rails,
2. Straightening the master X rail (this is trivial, just attach sensor to a carriage and align to laser).

(1) as an alternative to epoxy, or scraping against a 876 grade 1 surface plate which I don't have and would be very expensive even for a moderate machine, or using a precision level.
(2) as an alternative to using a precision straight edge.

If a cheap penta prism can be scrounged from somewhere then this can be used for tramming the Z and squaring the gantry, but I'm not so bothered about that as there are other methods.