A protractor is an essential tool to measure an angle. It’s also used to draw an angle. This tool has many applications and is used in engineering drawing, metalworking, woodworking, carpentry, etc.
There are several types of protractors. The protractor used to measure an angle of 2D object (geometry drawing) is different from an angle of 3D object (tools, machined workpieces, etc). That said, the protractor for school is different for protractor for machine shop. You need to buy the right protractor for a certain purpose.
The accuracy of your protractor also matters. For greater accuracy, you can get the one with a resolution down to 5 minutes (1/12 of a degree). This model employs vernier scale to magnify the reading.
In terms of their measuring mechanism, protractor can be analog/mechanical or digital. The mechanical shows the reading pointed by the pointer directly on the scale. It doesn’t require battery power and you could use it for life. In comparison, the digital one has LED display that shows the reading instantly and gives some nice features. But, take care of the battery you use as the power drops, it may interfere with the accurate reading.
If you need a reference for the best mechanical protractor products on the market, you may need this post. We cover 5 products from the most accurate one to the one for school/geometry drawing.
Top 5 Best Mechanical Protractor Reviews in 2023
1. Mitutoyo 187-906 Universal Bevel Protractor [Most Accurate]
This protractor from the Japanese company Mitutoyo is the choice if requiring high accuracy.
Its vernier scale lets you get a fine resolution down to 5 minutes (1/12 of a degree). Don’t worry about this kind of scale, it comes with a magnifying glass over it, so it’s not too tiny to read.
This is the best protractor for machinists, metrologists, metalworkers, etc.
Check here on how to use and read this kind of protractor.
- The instrument from Mitutoyo is reliable and durable.
- Easy to use as it comes with a complete function manual.
2. General Tools 17 Squarehead Stainless Steel Angle Protractor
We got another unique model from General tools production. This protractor can only measure the angles between two edges. There is a circular rotational indicator that will show the curve based on the position of the steel bar.
The square head makes it possible to align the protractor against an object. Both the square head and the moving bar are both stainless steel. It can’t measure linear length.
- It is easy to use.
- Convenient to measure angles between edges.
- Not suitable for Engineering Drawing.
- The digits on the square head protractor are tiny compared to the whole instrument. Sometimes, it is hard to read the value.
3. Starrett 505P-7 Protractor [Best for Miter Saw]
We decide that Starrett 505P-7 Prosite protractor is the best protractor for a miter saw due to its capability to measure inside and outside angles easily and accurately.
This protractor works perfectly with a miter saw, as one of its applications. You will cut with an accurate angle. Though the readout is analog, it’s trusted, and even less error. While the digital system reading may interfere with, and you don’t realize it’s misleading you.
There are two laser-engraved scales. The arrows let you know the right number which is pointing out. Though the material is kind of plastic, that’s the advantage. It won’t scratch the surface being measured.
If you are looking for the best protractor for carpentry, plumbing, metalworking, etc to measure, transfer, and mark angles, then this is the right choice. For home, it can be used on the crown and baseboard molding with ease.
- Reliable, stable at a reasonable price.
- The mechanical mechanism works all the time—no need for the battery to display the values.
- Laser marking ensures the perfect visual at any place and any condition.
- Please check the delivered protractor before you use it. Sometimes the product may come damaged, or the gear may fail to provide accurate readings.
How to Read Starrett 505P-7 Protractor
Unlike reading a vernier caliper or micrometer, reading this protractor is straightforward. There are two arrows (inside and outside). The best explanation video of how to read this protractor can be seen in the following video.
4. Fiskars 12-95400J Plastic Swing Arm Protractor (For School)
We now are aiming for the drawing protractor. However, these drawing protractors are common in terms of their availability in the market. Wait! This one is unique because of its swing arm. It will give you the perfect alignment Engineering drawing. But you can’t use it as like as above four protractors. But yet, for general uses, you can use this protractor.
This Fiskars 12-95400J protractor is ideal for kids. The material used here is entirely plastic. It is only 1.13 ounces and requires 0.26x4x8.5 inches packaging dimension. It is not suitable for most metalworking uses.
- Perfect for kids.
- Swingarm provides a straight-edge guide.
- Not suitable for metalworking.
5. Bora 530401 MiteriX Angle Finder [Honorable Mention]
This is not a protractor. But we are sure this would help you a lot if your purpose is to find a protractor for the miter saw. If it doesn’t match your need, at least, it attracts your attention.
It duplicates the angle you are going to measure and directly paste the angle to the miter saw. Herewith, you could save time and work easier.
How to use it is no brainer. Duplicate the angle, then lock, and then transfer it to your miter saw. It divides the duplicated angle in half so that you don’t need to do any calculation anymore.
- Designed to use for miter saw (divide the angle in half)
- Easy to use
- You don’t know the exact reading of the angle you are duplicating.
Things to Consider Buying A Mechanical Protractor
These are the points you can consider when selecting a mechanical protactor.
There are different types of protractors out there. The protractor for a machinist is different for school. That said, the model that you are buying has great correlation to what the tool is intended for.
2. Resolution & Accuracy
The resolution is commonly 1° but you can find them 1/12 of a degree (the vernier model). Again, if the purpose is for school, the plastic model with 1 degree resolution is enough.
3. Electronic Model?
The electronic digital protractor models give you speed and convenience. However, it can mislead if the battery is weak. Make sure to check the power regularly. The digital models allows you to convert the reading, set the zero reading easily, and even send out the reading to you smartphone.
How to Check the Accuracy of Protractor
Wondering the accuracy of the protractor you are using is important. But how to do that. Simply, you could use precision angle blocks. At least, you have to check how accurate the reading of your protractor at 0°, 90° and 45°. Your angle blocks come even more complete. There are 1°, 2°, 3°, etc. The increment of 1° makes sure all the readings are trusted.
Those are some of the analog / mechanical protractors that we can share with you. Discovering the types of protractor may help you get the most suitable model for your need.
Finally, Mitutoyo 187-906 is the most accurate mechanical protractor that we pick. It can serve you with a resolution of 1/12 of a degree. But, it is expensive. The less expensive is General Tools 17 and it should be enough for woodworking projects.