Tools for Measuring and Marking

When you need to cut off part of a piece of metal, grind it down, or weld it along a specific line – among many other possible modifications that might need to be made in your welding workshop – then you cannot simply draw on the surface with a pencil as you can when working with wood, paper, and other organic or semi-organic surfaces. The slick, hard surface of metal resists marking with graphite or the ink from ordinary pens, so special tools must be employed.

A carbide-tipped scribe is a sharp-pointed stylus that is used to literally scratch a marking into the surface of the metal. Diamond tips are also available for exceptionally hard metals, but carbide is sufficient for both aluminum and most steels. This is your most versatile tool for fine marking of the surface, although it creates a score in the metal that will be permanent unless cut or ground away, or submerged beneath a weld. You can also spray ‘bluing,’ a coloring agent, onto the outside of the piece and slice through that with the scribe, without penetrating the underlying metal, in the manner of an artist’s scratchboard -- although you should note bluing can catch fire.

A piece of soapstone can be sharpened to a point almost like a pencil, and used to draw in marks for modification on the base metal surface, persisting even through the heat of a welding arc. You can tap small dimples into the surface with a punch to mark a line of division, or you can use markers – however, markers tend to contain compounds that can weaken a weld laid over them, so scribing and soapstone are preferable.

Measuring the place where the base metal needs to be marked (and ultimately cut or otherwise modified) is also essential. Ordinary rulers and tape measures are part of the measuring equipment you should have on hand in your workshop, in whichever measuring system you prefer, Imperial or metric. It is prudent to keep at least one measuring instrument in your less-preferred system, so that if you are obliged to figure out how large something is when information is presented in only that system, you can measure accurately.

You will need a level, whether operating through the bubble principle or making use of modern laser technology to determine the perfectly horizontal plane. Squares are essential for any right-angle joins, and may offer other information as well, such as inches or degrees – these are known as combination squares. Where absolute accuracy is crucial, calipers and micrometers can indicate thicknesses very precisely, with the more high-tech versions offering even great accuracy than the standard ones (which are more than adequate for most non-machined parts, however).

Armed with these tools, you will be prepared to set up any modifications you might need to make in the base metal clearly and effectively, making the process faster and the results more accurate.