In any workshop, whether it’s a woodworking shop, metal fabrication unit, machine shop, or DIY workspace, accuracy always starts with marking. Before you cut, drill, mill, or shape anything, the first and most important step is to mark the workpiece correctly.
This is where marking tools play a critical role. Marking tools help you identify exact measurements, centre points, straight lines, and right angles, so every operation that follows comes out accurate and consistent. Without the right marks, even the best machines and cutting tools can’t deliver precise results.
What are Marking Tools?
Engineering professionals can tell how an object was developed and how it has been used just by looking at its markings. The marking process is an important step that you should never skip while making an item.
A project that is measured and marked incorrectly can lead to wasted materials and mistakes. To mark properly and correctly according to the required dimensions, you use different types of marking tools.
Generally, marking tools are used to mark a workpiece so you get the accurate size and shape. As a first step, you should apply marking media on the workpiece before using the marking tool. This will help you see clearly while you mark the workpiece.
Factors for Exact Marking
For doing any new job, it is necessary to have correct marking according to its blueprint or drawing. If the marking is not exact, the job will not be done according to the drawing measurements.
We can well imagine the difficulty of using a machine part made with wrong measurements. A lot of time is wasted in fitting the wrong part. For accurate making, keep these important points in mind:
- Read the drawing of the job carefully before you start marking.
- While you read the drawing, write down each measurement so you do not miss anything.
- Get all the tools you will need ready before you begin, based on those measurements.
- Use only tools that are accurate and in good condition for marking.
- Before you make the lines permanent with dot-punching, check the marking lines one more time.
- Mark the spot where you will drill with a center punch.
- Use different types of marking tools for different kinds of workpieces.
Types of Marking Tools
The following are used for different markings, according to drawings:
- Marking table
- Pencil
- Surface plate
- Angle plate
- Odd leg caliper
- Divider
- Scriber
- Surface gauge
- Universal surface gauge
- Try square
- Trammel
- “V” block
- Center punch
- Prick punch
- Combination set
- Parallels
- Bevel square
- Mortise gauge
#1. Marking Table.
A marking table is a special marking-out table that almost every workshop uses for marking jobs. Makers usually build it from closed-grain cast iron and give it a special heat treatment so the table stays rigid.
Marking tables come in many shapes, and rectangular and circular are the most common. The breadth runs from 4′ to 5′, and the length runs from 6′ to 10′. The top surface stays plain so you can place the work and the marking tools on it.
You use this table for simple, routine marking jobs when you work with common tools. You also use it for punching and chipping jobs.
#2. Pencil.
Pencils are writing tools with graphite leads set inside wooden shafts. People use pencils all the time for marking because you can clean them easily. You mainly use them for stenography, notes, and artistic sketching and drawing.
When you use a pencil, sharpen it very lightly so you get thin, light lines that won’t dig into the workpiece. This marking tool helps because it is easy to use and you can erase what you draw.
#3. Surface Plate.
You use a surface plate for jobs that need exact marking. The surface plate is either rectangular or circular, just like the marking table. Makers make these plates from close-grain cast iron and keep them outside for at least a year to season them.
The top surface has a fine finish and may show 10% to 20% high spots. For easy handling, the plate has two handles on opposite sides. Ribs on the inside of the plate make it stronger.
You need to take considerable care when you make a surface plate. After molding and seasoning, you cut or scratch it on the planer machine to the right size. Its surface is almost level, and scraping brings it to its true form.
Uses of Surface Plate
- To measure the smoothness of the job against the main surface of the surface plate.
- To measure the right angle of a job.
- To measure or mark the angle of a job with the help of a sine bar.
- To measure a job with a Dial Test Indicator.
#4. Angle Plate.
The main job of angle plates is to hold the workpiece parallel and at right angles to the surface. Makers build angle plates from good cast iron. They shape them at a 90° angle and cut rectangular grooves into them. Workers precisely finish both outer surfaces with a scraper.
The angle plate supports the work from behind when you measure it. For marking heavy pieces, you bolt nuts into the grooves and then machine or fasten the work to the angle plates for other machining tasks. Shops stock these plates in many sizes, usually numbered from 1 to 10.
There are two types of angle plates, big and small, which I’ll describe below.
a) Fixed Angle Plate
You use this plate to support the work at right angles. You clamp the job on it so you can carry out other machining activities.
b) Adjustable Angle Plate
You use this plate when you need to do angular marking or measurement.
#5. Odd Leg Caliper.
People also call this marking tool a Jenny Caliper or a Hermaphrodite Caliper. These tools help you scribe parallel marks on metal or plastic.
It usually has two legs, and each leg does a different job. One leg stays straight and acts as a guiding edge. The other leg holds a scribe point that bends inward about 1/8″ to 1/4″.
A rivet or a spring joins both legs. With a little pressure, you can increase or decrease the distance between these two legs. Makers build them from mild steel, and they case-harden the points. Based on how they are made, these calipers come in the following two types.
a) Fixed-point Odd Leg Caliper
This type of caliper looks like the one in the figure. The working leg of this caliper stays fixed.
b) Adjustable Point Odd Leg Caliper
This type of caliper looks like the one in the figure. One end of the working leg has a screw and a nut. Makers make this point from tool steel wire.
Because of this, the point does not wear out easily during marking. You can adjust it to fit your needs. If it ever becomes unusable, you can replace it.
Uses of Odd Leg Caliper
- You mostly use it for marking a job.
- People widely use these calipers to find the center of a round job.
- You can also use it in place of a surface gauge when marking a job.
#6. Divider.
A divider is a marking tool you use to draw circles, segments, and other geometric shapes. With a divider, you can split a line into equal parts and mark them out. These tools are usually made from mild steel.
Their pointed ends are case-hardened so they don’t wear out quickly. You can sort dividers by how wide they can open. Based on how their legs connect, they fall into two main types.
a) Firm Joint-dividers
In this type, a rivet and washer join the legs at the top. The rivet isn’t tightened all the way, so you can open and adjust the legs easily.
b) Spring Joint-divider
Here, both legs attach to a pin with a spring holding them together. An extra screw and split nut also link the legs. You open or close the legs by turning the nut, which makes adjusting quick and smooth.
Uses of Divider
- You mainly use a divider to measure the distance between two points.
- It also helps you mark circles and arcs on metal workpieces.
#7. Scriber.
You use a scriber in a workshop or fitting shop to mark a straight line on a material. A scriber is usually made of steel or carbon steel wire that is 3 mm to 5 mm thick, with one end straight and the other bent at about a 90° angle.
You use it together with an engineer square, a steel rule, and a straight gauge. When you scribe, you always tilt the scriber in the direction you move it, and you press the steel rule with just the right amount of pressure. Its length ranges from 150 mm to 300 mm.
Both ends of the scriber are sharp points. When you are not using it, you should cover the point with a cork or a cloth so it does not poke your fingers.
#8. Surface Gauge
You use a surface gauge to draw layout lines by placing it on a surface plate. People also call it a marking block or a scribing block.
For simple jobs, you can mark with a scriber and an odd-leg caliper, but when you need to draw parallel lines, you use a surface gauge. There are two main types.
a) Solid Surface Gauge
People first used this type of gauge when they needed very accurate marks. It has a solid base with a rod in the center. You fix the scriber in place by tightening a snug bolt in the gauge pillar. To use it, you adjust it by hand and then draw the line next to the steel rule.
#9. Universal Surface Gauge.
Universal surface gauges let you make precise marks quickly and easily. Their base is made of strong cast iron in a rectangular shape. It has “V” shaped slots running the full length.
On the top surface of the base, two guide pins are fixed. You use these pins to mark on a machined surface, just like an odd leg caliper, for attaching.
Because of the “V” shaped slots, the gauge does not stick to the surface plate. You can push it forward or pull it back with no trouble.
Dirt and grime on the surface plate do not mess up your marks because the dirt just moves into the slots. You can use a universal surface gauge to draw lines on vertical surfaces, not just flat ones.
#10. Try Square.
A try square is a woodworking tool you use to mark and check 90° angles on pieces of wood. People often use it to draw vertical lines on the workpiece. Among all the squares woodworkers use, the try square is one of the most important.
When you use a try square, you make sure the paths are parallel, and you draw lines at right angles to the edges. A try square has a brass front with a steel blade riveted into the wood stock.
Uses of Try Square
- You use it to check if a surface is flat.
- You use it to check a 90° angle.
- You use it to mark vertical lines on the edge of the job.
#11. Trammel.
A trammel is almost the same as a divider. You use a trammel to draw or mark a circle or parallel lines. It has a round or square rod, called a trammel bar or beam. There are two movable trams on the beam.
You can also use it as an inside or outside caliper by fixing different types of points. The beam is usually 15mm to 50mm long. In other types of trammels, the measurements are shown in millimeters. For very big jobs, you can attach extra beams.
#12. “V” Block.
For marking on a round or rectangular job, you use “V” blocks to clamp it. Makers often build V-blocks from hardened steel or cast iron, and you can find them in different sizes. With their help, you can perform drilling, punching, and other machining operations easily on such workpieces.
These marking tools come from cast iron or steel. The surface is well-machined and ground. A “V” shaped slot runs through the center with 90° angles on either side.
On the remaining two sides, rectangular grooves form where you fix the clamp. These generally come in the following three types and are available in pairs.
a) Simple “V” Block
This is a rectangular block that has a “V” shaped groove on its upper surface. You place heavy round jobs over it for marking or machining. There is no provision to clamp the job since, because of the heavy weight of the job, it stays fixed.
b) Clamping “V” Block
It is also a rectangular block. A “V” shaped groove is cut on the two surfaces facing each other, and rectangular grooves are cut on the remaining two surfaces to which you fix the clamp.
You place the job on the “V” groove, and you fix the clamp with the clamping screw. Its distinct feature is that while you carry out any operation on a round job, the job does not move or shake.
c) Magnetic “V” Block
This “V” block looks like an ordinary “V” block, in which the maker adds the provision of magnetic power. Because of the magnetic effect, the job stays stuck to the block.
A switch lets you start or turn off the magnetic effect. When you put the switch in the “ON” position, the workpiece gets trapped in the block, and the magnetic effect stops in the “OFF” position.
#13. Centre Punch.
The punch is made of high-carbon steel with hardening and tempering treatment. The point of this is ground at an angle of about 90°, and the handling part is knurled. Its length runs from 35mm to 125mm, and its width runs from 4 to 12 mm.
You usually use a Centre punch to center the drilling point so that the drill point can rest properly there.
If you do not make this center with the centre punch, the point might slip and drill at the wrong spot. Some center punches are automatic, with a striking mechanism built into the handle.
#14. Prick Punch.
A prick punch is a layout marking tool that is made of carbon steel and has a length of about 100mm to 150mm.
Both ends of the punch are hardened and tempered. The pointed tip of this punch is ground at an angle of 30° to 60°. You commonly use these types of marking tools to mark jobs on thin metal sheets or to make holes in them.
#15. Combination Set.
The combination set helps you in marking and taking measurements. The four main parts of this equipment are a steel rule, a square head, a protractor head, and a center head.
It is usually made of alloy steel, and its measuring faces are well-ground. Using the protractor head, you can achieve 1° accuracy when marking and measuring angles.
#16. Parallels.
These are square or rectangular rods made of high steel. They have a square surface and are ground in parallel.
To make the layout easier, you use these in pairs to raise the work to the right height. In addition, parallels support work commonly when it is in a vice or attached to a machine bed.
#17. Bevel Square.
It is a flexible tool that woodworkers use for laying angles and testing the accuracy of work surfaces on slopes. You use a bevel square in fitting shops to measure angles along edges or to test the angle accuracy of oblique surfaces.
These are usually made of steel, and the parallel ends are ground. Some types vary slightly in size but have a blade that you can move 360° and lock in a fixed position.
#18. Mortise Gauge.
A mortise gauge is an instrument that lets you scribe two lines parallel to an edge. These are usually made of hardwood with brass fittings.
Essentially, it is composed of two sharp spurs that you can adjust before marking the workpiece and adjust by the mortise chisel width. It is a woodworking tool that a carpenter or joiner uses.
Methods of Marking
Although no specific rules can be framed for marking yet for general marking, the following methods are adopted:
- Draw a picture of the work you plan to make and study it so you understand it.
- Before you mark, clean and prepare the two sides next to each other and the job surface after filling, scraping, and any other machining.
- Coat the marking surface with a thin paste of Persian blue, copper sulfate, or chalk, whichever you prefer, before you start marking.
- If you use a surface gauge or vernier gauge for marking, place the job correctly on the surface with the angle plate and “V” block.
- While you mark, keep the scriber or punch sharp and pointed.
- Pick marking tools that fit the job.
- If you want to make a chop or a circle on the work, first make a deep mark in the middle of the work with a center punch. Otherwise, the divider might slip.
- If you need to mark for drilling, draw a circle the same size outside the center and also draw another larger circle from the same center so you know the drill goes in the right place.
- If a line must reach a cut or slot, fill that gap with lead or similar material.
- To mark a circle, make four marks on its circumference with a point punch, one opposite each other.
- After you mark according to the drawing, check it again.
- When the marking is correct, make it permanent with a dot punch or another punch as needed. But clear away the other helper lines before you make the marking permanent.