To achieve precise and accurate job finish, marking plays an important role and for that, you are going need Marking Tools. Marking is a preliminary step before starting any project.
Marking Tools are ideal and a must-tool for any craftsman. By marking any job, it gives fifty percent shape to your work and guides the craftsman when cutting, filing, and sawing the job.
Here I have described the following Marking Tools used for marking:
When it comes to testing the flatness of the work, you are most likely going to need a surface plate. Surface plates are generally used for small jobs, as they are not suitable for larger jobs. For larger jobs, you will need a marking-out table.
Surface plates are robust and are made out of grey cast iron. Grey cast iron makes it unreflective. Surface plates are held at 800mm high from the floor and rest horizontally on a firm support.
The dimension of the plates varies by 1.5x5m, 1.5x3m, 2x2m, and 2x4m.
The surface plates come in two grades in respect to their accuracy.
- Grade A Plate: Scraped to within 0.005mm of flatness.
- Grade B Plate: 0.02mm of flatness.
In order to achieve true flatness, the surface plate is kept clean and smeared with oil or grease after use. By doing so, it protects the plate from rust and dust.
As the name suggests, it is a Marking Tool meant for scribing lines on metal jobs. It is made of hardened steel having pointed ends and held like a pencil. The length varies from 150 to 300mm and 3 to 5mm in diameter.
Another vital tool that falls in the Marking Tools is the Punch. They are used for locating centres and marking out work. Punches are of two types:
- Prick Punch: They are sharply pointed at the end, having an angle of 40 degrees. They are usually used for marking layout lines by creating indent on the job, making a series of definite lines. Those lines act as a guide to the fitter during work.
- Centre Punch: They are tapered point punch having an angle of 60 degrees. They are usually used for marking centres before drilling.
V-Block is another Marking Tool used for holding cylindrical metal rods. It is a rigid block of steel having a V groove where the metal job is placed for marking and drilling. V-Block comes in many sizes, and the most commonly used lengths are from 50 to 250mm in width and height from 50 to 100m.
Angle Plate is another marking and holding tool with two right-angled surface planes. One of the planes is used in conjunction with the surface plate for holding and supporting the metal job in a perpendicular position. It is also made of grey cast iron.
Another vital tool that falls in the Marking Tools is the Try-Square. A Try-square is a metal structure having one blade and a beam at right angles to each other. It is used to test and mark the surface or edges of the job, whether it is exactly at a right angle or not.
These are the most common Marking Tools used in bench work for marking.
Important points of Marking Out
- All markings should be done in reference to any surface or by using right angles or referring to certain datum lines.
- The surface of the job to be marked out is first treated with chalk or with copper sulphate solution.
- For marking Cylindrical jobs, it should be held in a V-block
- Horizontal and vertical lines are scribed over a vertical surface by a scribing block.