Calculate Error from uneven rail and reference

[John McNamara]

Hi all

One quite simple way to set rails straight is with a stretched wire. Together with a cheap digital microscope (Get one with electronic cross-hairs) off the net. Alternately an optical microscope can be used with a cross-hair reticle. Mount the microscope on a rail slider on the already positioned rail beside the stretched wire you have mounted in your machine frame already positioned in line with where the rail will be placed, best you offset it say 20mm to allow access to the rail screws.

The procedure is simple. just work your way along the rail centering the microscope cross-hairs on the wire as you go.

You will need to make up some sort of mounting for the wire to position it accurately. One end will be fixed one end will have a large weight attached to it.
The weight is normally calculated to b about .75% of the breaking strain of the wire. http://www.roeslau-draht.de/fileadmin/user_upload/Downloads/music3B_Zb_2.pdf

Thinner is better mine is .17 Round not hex.

This is not a new technique Wire alignment goes way back in time. It is still used to this day.

https://www.google.com/search?rlz=1C...iz.tTYd1bOv-T0

Accuracy of 0.001" is obtainable over long lengths.
Gravity will affect the vertical plane, to check the flatness of your rail mounting surface the Catenary sag of the wire will need to be calculated for various positions along the wire. Think of sagging power lines. https://www.google.com/search?q=cate...hrome&ie=UTF-8

Over less than a metre the sag is very small.

Cost
https://www.google.com/search?q=usb+...w=1008&bih=537

You do not need or want high power about 40 is fine.
A handy tool to have anyway
100 feet of wire
https://www.fortepiano.com/index.php...usic-menu-item

Regards
John