making a notched level

[simon1138]

Hello,

I am trying to make a notched level for my guitar building. I started with a metal rule that I have had sitting around for years doing nothing. I measured out the notches and proceeded to hack at it with a grinder. The finish is a little rough but the notches are the correct distance apart to fit over the frets. Problem there is that the ruler is not completely level. I checked it after notching it, against a straight edge that I have. Another thing would be, "how do I know that that straight edge has a straight edge". Well it came off of a mechanical cutting machine and I assume that it is straight. I have tried other things against it and it seems to be straight. I then bought a notched straight edge off ebay and found that it is also not straight. In the center there is about 1mm of light to been seen on both sides.

What is the best way to get this completely straight? I was thinking about laying it flat on something and rubbing it down with sand paper but then, is the flat surface straight?

Any helps or hints would be greatly appreciated.

Thanks

 

[ScottR]

An easy way to tell if your straight edge is really straight is to to draw a line with the edge in question, and then flip the straight edge over and draw a line with same edge right on, or right next to the first line and see if there is any separation.

SR

[MiKro]

10 hours ago, simon1138 said:

Hello,

I am trying to make a notched level for my guitar building. I started with a metal rule that I have had sitting around for years doing nothing. I measured out the notches and proceeded to hack at it with a grinder. The finish is a little rough but the notches are the correct distance apart to fit over the frets. Problem there is that the ruler is not completely level. I checked it after notching it, against a straight edge that I have. Another thing would be, "how do I know that that straight edge has a straight edge". Well it came off of a mechanical cutting machine and I assume that it is straight. I have tried other things against it and it seems to be straight. I then bought a notched straight edge off ebay and found that it is also not straight. In the center there is about 1mm of light to been seen on both sides.

What is the best way to get this completely straight? I was thinking about laying it flat on something and rubbing it down with sand paper but then, is the flat surface straight?

Any helps or hints would be greatly appreciated.

Thanks

 

best bet is to get a good machinist with an accurate machine to true the edge. Or use a granite surface plate that is for a machinist that is known to be flat and surface it to that with sand paper. .