Correct layout

[Rich_Carlstedt]

Ron
Here is a trick for you.
But first, using a flat sided scriber works because the sharp edge next to the flat compensates for scriber error..HOWEVER !

What if you have a carbide scriber, or have a normal scriber like those found in your square ?
First for accuracy , you need to develop a technique of holding the scriber at the same inclined angle ..Each Time !
Assuming you can hold the angle no matter which direction your markings go, you need to know about the "Block" ( my term) method
of laying out manual lines for maximum accuracy (As others have said, good eyesight is a must )
Lets take your Combination Square (adjustable ) and set it with a dimension of 1.3889" for example.
Now to do that, use a Depth Gauge or Vernier Caliper to set the blade to the Stock ( AKA Sliding Head)
Place the Square on the work piece edge and mark it...using the controlled angle of the scribe------ and now without moving the square,
Place a precision steel block (like an adjustable parallel ) against the end of the blade, and hold it down tightly and remove the square.
Now scribe the line using your controlled angle.
The result is two narrow parallel lines only a few thousandths apart that split your exact dimension WITHOUT Scriber error


Old Timer methods before DRO's

Rich