Test indicator is recommended to use when it comes to measuring runout with a higher degree of accuracy. It also overcomes the measuring challenge when unable to measure the runout perpendicularly.
Therefore, it’s not weird that a test indicator is mostly applied in the machine shop. You can also apply it to woodworking projects.
There are a number of test indicators on the market today. Some of them are not far away from these well-established brand names such as Mitutoyo, Interapid, Starrett, etc.
Choosing the best test indicator can be an overwhelming task. It asks you to consider a number of things such as the travel range, resolution, accuracy, material, etc. While the options spread over, picking the best one may take your time.
We aim to make your selection easier through this post by sharing our top 10 test indicators. Some guides and other information about test indicators are also presented to make your selection more insightful.
Top 10 Best Test Indicator Reviews 2021
1. Mitutoyo 513-406-10E Test Indicator [Best Overall]
Mitutoyo 513-406-10E is overall the best test indicator that you have to purchase if you are really looking for the best. It gives you a complete set of advantages while maintaining the price reasonably.
These are the advantages you will get:
- Two readings (inch and mm). You don’t find this feature from other test indicators reviewed here.
- Carbide contact point. Carbide has great resistance against repetitive wear and more heat resistant; makes it long last.
- Glare-free & scratch-resistant crystal. Facing difficulties seeing the reading in a certain position? Solved with the glare-free crystal. The scratch-resistant property keeps the crystals clean and clear.
- Jeweled bearing. Jeweled bearing benefits you with smooth pointer movement and bearing durability.
- Anti-magnetic. This stuff will not stick and interfere with reading although measuring around ferrous materials.
- Three dovetail rails. There are three selectable dovetail rails (top, back, front) the dovetail clamp can stick on.
- More resistant against dust and oil. The O-ring seal design makes it repels dust and oil from entering the internal part of the dial face.
In terms of the accuracy specification, it gives you a resolution of 0.0005″/0.01mm within the range of 0.03″/0.7mm. This specification should be sufficient to cover most measurements. While the accuracy is ±0.0005″, hysteresis is 0.0002″, and repeatability is 0.0002″. [Source: Mitutoyo Bulletin No. 2232 Page. 10]
The Inch Reading
The outer scale (black) is the inch reading with white background. The lines are printed with varying thickness and length for noticeable reading. Each division counts 0.0005″. There are 10 divisions between the marking 0 and 5, and therefore it counts for 0.005″.
The mm Reading
The inner scale (red) is the mm reading with a yellow background. Similar to the inch scale, the line-markings vary in thickness and length. Each division counts 0.01mm. This one is far easier to count because the 10th division is marked with the number 10. Because there are 10 divisions, then the value between the marking 0 and 10 is 0.1 mm.
Some Drawback Issues
The rubber O-ring seal on the bezel allows the dial to repel dust and oil, and also provides smoothness to the bezel rotation. However, it’s less durable. Fortunately, you can change this seal (rubber O-ring) easily with the bought one to turn back its initial smoothness.
It comes with a plastic bezel. The plastic bezel can break. But it’s replaceable.
Though this Mitutoyo comes with several drawbacks, the company seems to provide the solutions for you. Even these things can be considered advantages. The crystals may break all the way up to the bezel. Order the crystal with the plastic bezel installed and replace the broken one. Imagine if the bezel has different construction which asks to disassemble the further parts.
With all benefits from a single Mitutoyo 513406-10E, it just costs you a reasonable price. It’s appropriate to use both for beginners and advanced users. Check the price through the following button.
- Accurate and smooth
- Fully benefits (the crystals, jeweled bearing, carbide point, O-ring seal, two readings, integrated dovetail rails)
- Great for advanced users who want to upgrade their test indicators
- Replaceable crystal
- Reasonable price
- The bezel may lose when the usage has been for so long but it’s acceptable
- When the spare parts are broken, it’s better off replaced rather than repaired.
2. Interapid 312b-1 Test Indicator [Very Sensitive]
Another remarkable model that enriches the test indicator’s market is this Swiss-made Interapid 312 Serie 312b-1 test indicator. For more serious measurement, pick this option due to its accuracy and sensitivity. Moreover, the two revolutions, ease to read, mounting versatility, and durability are things you have to really consider.
It measures with a resolution down to 0.0005″, backed up with an accuracy of ±0.0004″ and repeatability of 0.00012″ for a measuring range of 0.06″. This range is twice wider than others (typically 0.03″); provides 2 revolutions. Others are only one revolution.
More superior, the measuring force is very small which is only 0.12 N (more twice smaller than Mitutoyo 513-406-10 which is 0.3 N); makes it very sensitive to any given force and leads more accurate measurement. If you handle a wood surface irregularity, this one may be suitable for that.
Two Revolution Range
Many test indicators have only a range equal to one revolution of its pointer. This Interapid is different. Its travel range is two revolutions. For 0.0005″ resolution test indicators, the two-revolution range may not be really required, however, if you buy this model that comes with a 0.0001″ resolution, the two rev range will be so helpful. Sometimes, the runout can excess. Having a more range will help you measure accurately.
Ease of Reading; with Revolution Counter
There is a revolution counter available; helps keeps track of the reading. This feature is very important for the two revolution range indicator. When the pointer jumps all over the place, stay accurate by reading the revolution counter. The line and number markings are also clear to read.
In terms of ways to mount it, two dovetail rails (at the front and the back) and a swivel stem (at the top) are available. And there is a swivel holder designed exclusively for this model. The two dovetail rails are screwed and replaceable. Though replaceable, it’s made of hardened steel which should be hard to wear down and last longer.
Regarding the material, it’s made of hardened stainless steel which increases durability. However, since most hardened stainless steels are magnetic, we don’t know exactly whether this indicator (especially the gears inside) interferes with the magnetic area or not. In terms of the contact point, it is carbide which is more abrasion resistant and wear-resistant.
The contact point is far less magnetic due to carbide and this part should not attract anything. It is replaceable as well. In case requiring to replace it, use the black disk wrench that comes with the indicator. Make sure you use the same contact point length (0.687″) as it causes a cosine error. And the last thing about the contact point, its lever is also able to swivel up and down within 210°.
Tips to Measure
Keep in mind to apply an angle of 12° between the contact spindle and the measured surface to maintain its accuracy. If you have to apply an angle of 0°, multiply by 1.022. And you need a calculator.
How to Repair?
Interapid 312 Serie 312b-1 test indicator is repairable. This video may help you.
What makes us not put it as the best overall is the angle you have to apply when performing the measurement. A 12° angle is not as easy for everyone, especially beginners. Further, how could you exactly know that it’s a 12° angle unless using a T-bevel protractor? You are still able to apply the 0° angle with this indicator but it may slow you down.
In summary, Interapid 312 Serie 312b-1 test indicator is a perfect choice for taking a more serious measurement. It’s designed for advanced users, professionals, and the likes who require a high degree of accuracy.
- Accurate and sensitive
- The 0.0001″ resolution model is available
- The travel range is within 2 revolutions
- Revolution counter; makes reading easier
- Long-lasting mechanical life
- Hardened metal dovetail rails; replaceable
- Jeweled bearing [Check this out]
- Expensive price range
- Has to be 12° angle measurement; 0° angle measurement needs to use a calculator
3. Khcraft Test Indicator [Best for Budget]
It assists you by giving 0.03″ of measurement range and 0.0005″ of resolution.
The markings are divided into 60 divisions. Each division counts 0.0005″.
The lever is able to move up and down (bi-directional) within a span of 180°. That also means you can put the surface to be measured either on the top or bottom of the contact point.
In terms of the body, there is no plastic bezel, gears, etc which is good. All the parts are made of hardened steel with a satin chrome finish. This material allows for long last use. Around the body, you can find three dovetail rails that allow you to select freely where the dovetail is clamped on. The dovetail clamp can be mounted on top, back, and front because the dovetail clamp rails are found on top, back, and front.
If you don’t have dovetails, no worry. The plastic storage box of this test indicator contains two dovetail clamp accessories: 2 made-of-steel dovetail clamps with a diameter of respectively 3/8” and 5/32”.
All in all, for beginners and hobbyists, this indicator is the right choice. For this kind of price range, this one has been the most favorited by customers on the market so far. The drawbacks are no jeweled bearing and the level of accuracy is unknown. Considering the price, these drawbacks should be acceptable.
- Great for hobbyist, beginner, not certified works.
- Metal body construction
- Protective box
- Unknown accuracy
- No jeweled bearing
4. Mitutoyo 513-504T Pocket Test Indicator [Tubular Shape]
When you have to measure the spindle bore’ runout, you are better off using a tubular shape test indicator to get into the deeper area. Here Mitutoyo 513-504T full set presents to solve the challenge.
- Range: 0,01″ (one revolution)
- Resolution: 0.0001″
- 100-division scale with 0-5-0 dial marking
- Accuracy: ±0.0002″
- Measuring force ≤0,3 N
- Swiveling lever within 220°
- Contact point diameter: 0.079″
- Contact point lever length: 0.74″ (18.7 mm)
- Dial face diameter: 1.6″ (40mm)
- Stem diameter: 3/8″ (0.375″)
In the case of mounting, Mitutoyo 513-504T doesn’t have dovetail rails but a stem with a diameter of 3/8″. This stem diameter is similar to the tubular body diameter which is also 3/8″. You can replace the stem. There is another stem with a diameter of 0.157″ in the package.
The contact point is also replaceable. Since Mitutoyo 513-504T comes as a full set, there are other two carbide contact points with a diameter respectively of 0.039″ & 0.118″. These three contact points have the same length and you don’t need to worry concerning the deviation.
In terms of the bezel smoothness, it’s empowered by O-ring rubber. It makes the pointer movement smooth. This rubber also takes a role to prevent dust and oil from intruding the internal parts of the dial. Further, the jeweled bearing that is less friction, makes it more smooth, accurate, and durable.
In summary, Mitutoyo 513-504T is a great choice due to its tubular shape for the runout measurement of a narrow bore. Plus, its 0.0001″ resolution is also preferred than the 0.0005″ ones. For general runout tests, it’s surely able to do that. If you want to look at it when in action, see the picture here.
- High resolution
- Tubular shape
- Smooth; rubber O-ring seal, jeweled bearing.
5. Starrett 711LCSZ Last Word Test Indicator [Another Tubular Shape]
It comes with 0-15-0 dial marking, 60-division scale, 0.03″ range, 0.0005″ resolution, and ±0.0005″ accuracy.
The line-markings are nice. They differ in length and thickness which is good for the eyes. Additionally, the yellow shading enhances clarity and makes vision easy to read the readout.
Like many premium models, it serves the bearing with jeweled. It generates smoothness, accuracy, and durability due to less friction.
The contact point is replaceable. Starrett 711LCSZ provides 3 contact points with a diameter of 0.035″, 0.062″, and 0.120″ and an identical length of 5/32″ (4mm). But, as we discover, the contact point is not carbide but steel. This can be a significant downside in some cases. Still, if you want carbide, you can purchase the carbide point separately individually.
- Clear to read
- Jeweled bearing
- Replaceable contact point
- Small dial face
- May react to magnetism
6. Mitutoyo 513-403 Test Indicator [Another 0.0001″ Resolution Pick]
If your measurement requires more accuracy, Mitutoyo 513-403 can be another consideration as it comes with a 0.0001″ resolution and ±0.0001″ accuracy. What puts it as the second option is the 0.008″ travel range which means only one revolution of a pointer.
Calculating the reading even becomes so much easier because you just multiply it with 0.0001″, moreover, every 10 divisions marked with 1 increment number up to 4.
No less importantly, it possesses all advantages that you highly require to perform a measurement. The pointer rotates smoothly yet durable due to the jeweled bearing. Its contact point is durable due to the carbide. O-ring seal is designed for nice bezel movement. The crystal provides high visibility due to its glare-free and scratch-resistant property.
Mounting becomes effortlessly because of the 3 integrated rails that you can use to attach the dovetail clamp on there. Plus it comes with a nice box where you can store the test indicator safely and fittingly. Basically, this Mitutoyo 513-403 is similar to our best-recommended test indicator Mitutoyo 513-406-10E, however, the reading unit and accuracy specification make it distinct.
- Designed for some purposes that require a high degree of measurement accuracy
- Easy to take the reading
- High visibility (anti-glare crystal)
- Durable (carbide, jeweled bearing)
- Replaceable crystal
7. Mitutoyo 513-402-10E Test Indicator [Best Affordable Mitutoyo Test Indicator]
It has a 0.03″ (one revolution) range, 0.0005″ resolution, and ±0.0005″ accuracy. Moreover, it has nice a ±0,0002″ repeatability which is less than a half value of its resolution.
Like other Mitutoyo, the crystal presents glare-free property. The bezel friction smoothness is supported by the rubber O-ring seal. This replaceable seal is also designed to defend the dial from oil and dust.
The contact point is made from carbide material with a diameter of 0.079″ and a length of 16,4 mm.
In the case of mounting, there are three dovetail rails and an accessory of a 3/8″ diameter stem to mount at the top.
This is a nice option as it provides decent spec. Another series with a more full set can be found on Mitutoyo 513-402-10T. This model comes with three different diameter contact points, two stems, a swivel clamp, a clamp ring, and a holding bar.
- Quality product
- One of the cheap option of Mitutoyo test indicator
- You may not like the plastic bezel
8. Accusize P900-S108 Test Indicator [Another Budget Option]
Unless the jeweled bearing, Accusize Tools P900-S108 test indicator is similar to the Khcraft test indicator in terms of spec, dial scale (numbers and lines), dovetail rail position, two dovetail clamp accessories, and storage box.
It has a travel range of 0.03″ and a resolution of 0.0005″. The numeric markings have an interval of 5. The line-markings are printed with different lengths for easy indication. There are three dovetail rails for easy mounting. Two dovetail clamps are found on the box. A single small black disk is also included that functions for contact point removal. Lastly, the compact blue storage box is nice to protect the indicator while in storage.
Made with jeweled bearing makes the Accusize Tools P900-S108 test indicator better than Khcraft. This jeweled bearing increases the bearing life and provide smooth movement of the pointer. By paying a little higher but comes with more confidence in durability, we consider Accusize Tools P900-S108 as another nice budget option worth to offer.
- Jeweled bearing
- Great for hobbyist, beginner, not certified works.
- Protective storage
- Unknown accuracy
9. Gold Plus Lightweight Copper Alloy Test Indicator [Mid Price]
The travel range is twice as wider as other test indicators. Plus, it presents with a revolution counter which is important for the two rev range.
It comes with two carbide contact points (0.080″ & 0.120″) and a single steel point (0.040″).
There are two integrated dovetail rails and a single 3/8″ stem. You can easily mount the stem to the collet.
- Jeweled bearing
- Two revolutions per travel range with revolution counter
- Unknown accuracy
10. Fowler X-Test 52-562-001-0 Test Indicator
Similar to Gold Plus, it comes with a revolution counter, 5/32″ stem, carbide contact points, 2 dovetail rails, and jeweled bearing.
However, there is no information about the accuracy. Therefore, it’s not purposed for serious measurement.
- Jeweled bearing
- Two revolutions per travel range with revolution counter
- Unknown accuracy
What is Test Indicator?
Similar to the dial indicator, the test indicator functions to make some magnifications over a certain distance. Any small linear measurement which is hard to read by eyes then becomes able to take the reading.
Things such as runout, surface irregularity, roundness, flatness, and straightness can be expressed in numbers by means of this linear measuring tool.
However, there are some differences. It utilizes a lever as the contact point rather than a plunger. The contact point swivels up and down. It has generally smaller size, lighter weight, designed for consistency measurement, smaller travel range, higher resolution.
Buying Guide of the Test Indicator
Resolution indicates the smallest distance it can measure and display on the dial scale. When determining the best test indicator, you need to consider your preferred resolution first.
In regard to testing lathe accuracy, it needs some runout inspections of the lathe parts. That said, you need to know the runout tolerance of those parts. Let this guide on “Tuning your Lathe” from Jon Siegel to be the reference. According to it, the spindle bore total runout should be less than 0.001″. And based on the Rule of tens, your test indicator has to be 10 times accurate than the tolerated value. Therefore, it has to be a 0.0001″ resolution indicator.
However, some people prefer the 0.0005″ resolution. If you don’t follow the rule of tens, then we recommend no less than 0.0005″.
The 0.0001″ resolution has a drawback as it can jump all over the place on the dial scale. If the travel range is wide (two revolutions) and the revolution counter is available, the 0.0001″ resolution test indicator will be so powerful to use.
The test indicator’s accuracy must be at least the same as the resolution value. For example, if the resolution is 0.0005″, then the accuracy must be at least ±0.0005″. If the resolution is 0.0001″, then the accuracy must be at least ±0.0001″.
The test indicator has a very limited measuring range. Commonly, it comes with a range of one revolution. If one revolution is divided into 60 divisions and each division (resolution) has a value of 0.0005″ reading, then one revolution (60 x 0.0005″) is equal to 0.03″ reading. In other words, the measuring range is only 0.03″.
As a comparison, a plunger-type indicator is generally a 1″ range.
If you could purchase a model that has a measuring range of two revolutions, that would be highly recommended. When the range is too short, the contact point and the surface (to be measured) must be put so close to starts off the measurement.
To sum up, if the resolution is 0.0001″, the travel range should be at least 0.015″. On the other hand, if the resolution is 0.0005″, the range should be at least 0.03″.
4. Measuring Force
Another critical factor you have to be careful of when selecting the best test indicator is the measuring force. Measuring force is the force needed to move the lever swivel up and down.
Test indicators have a much lower measuring force compared to the dial indicator. Due to this low force, the test indicator is more suitable to use when measuring a thin deformable surface. Additionally, lower force means higher lever sensitivity. It can also be expressed in other words, the contact point doesn’t compress the surface.
When choosing the test indicator, try to get the smallest force.
5. Bezel Friction
Does it smooth enough to rotate the bezel and no movement caused to the contact point or overall indicator? If it’s too tough to rotate, then the indicator may slide slightly from its initial perfect position. When this case happens frequently, you may feel inconvenient. Things could be different if your stand holds the indicator strongly.
To get to know about this bezel friction, you can explore the customer reviews.
6. Contact Point (Material, Length, and Angle Positioning)
There are some points you have to put into attention to when it comes to the contact point: material, length, and angle position.
Some indicators may come with a contact point made from steel, carbide, and even ruby.
In this case, hardened steel may magnetize but it’s affordable. Carbide costs more but it’s less magnetic, wear-resistant, heat resistant, high compressive strength, and surely durable; most micrometers today use it. You will save money in the long term with carbide. While ruby, despite rarely seen, gives high corrosion resistance, less friction; not scratch, anti-magnetic, heat resistant, and compression strength. Pick carbide and you’ll get a great deal.
Some brands like Mitutoyo and Interapid give a suggestion of the best contact point length you have to use. When you have to replace the contact point, make sure you follow the company suggestion. This length is important because it can generate a cosine error. Talking about the contact point length also means torque, and furthermore, lead the discussion to the measuring force (contact point sensitivity).
The next is about the angle. Some contact point has to position at a certain angle such as 12° to generate the readout as it should be. While some others position at a general angle of 0°. Make sure you follow this direction as it can cause a cosine error. If you think it’s overwhelmed to use only this angle, other models also have a certain rule in regard to this measuring angle. Decide which one you are suitable for.
Crystals means the barrier that protects the needles (pointer) and scales from thrust, dust, oil, and even water. Why you have to consider this part? In some situations, a cheap crystal is easy to scratch and even break apart. Consider to replace it. However, there are only some models that allow you to easily replace the crystal. The crystal quality also determines how possible it is to see the reading clearly from any position. In this case, an anti-glare crystal is able to do that. Wherever the light lamp takes place, you don’t see the crystal glares. Although this is not an essential thing, you may want to figure it out.
“The Barnett effect is the magnetization of an uncharged body when spun on its axis”, cited from Wikipedia. Rotating metal may generate magnetism. A ruby contact point can totally handle this. Perhaps, this is the reason some models come with plastic gears. Make sure your indicator can overcome this issue.
FAQ (Frequently Asked Questions)
This section put together some questions along with the answers that PERHAPS you ask regarding the test indicator.
Q: What is Runout?
A: Runout is the term that expresses the inaccuracy level of a circular object’s radial or axial alignment.
Q: Can I mark my test indicator with my name?
A: Sure. You can do it with an engraving pen. But be careful because it may interfere with the dial’s internal parts.
Q: What is a cosine error?
A: Try to compare the readout of two identical test indicators positioned at a different angle that measures a single feeler gauge. For example, one test indicator is positioned at 0° and the second is at 10°. The reading result will be different. That said, cosine error is a reading deviation generated by the measurement angle which doesn’t give a reading as it should be.
Test indicator or dial test indicator is a great tool that provides a high level of accuracy. It’s common to use in a machine shop for runout inspection or machine setup. This indicator has a lever instead plunger; swivel up and down.
There are some brands on the market in terms of test indicators: Mitutoyo, Interapid, Starrett, Fowler, etc. However, as our recommendation, the best pick is Mitutoyo 513-406-10E. Another choice is Interapid 312 Serie 312b-1 as it’s most sensitive. We put Interapid as the second choice because you need to measure at a 12° angle. Lastly, if you are on a budget, the nice pick is Khcraft.