HOW TO PROPERLY USE AND CARE FOR YOUR DIAL TEST INDICATOR
The dial test indicator is a high quality precision measuring instrument designed to provide a long life if given proper care and use. These lever type dial test indicators are especially intended for use on the shop floor or in the quality inspection room. They are ideally suited for comparative measurements on a surface plate or any other flat precision surface. They are capable of determining form, shape, positional deviations as well as axial and runout errors. Most brands of dial test indicators are supplied with a swivel clamp, contact point wrench and a certificate of accuracy and traceability. Most contact points are carbide tipped, therefore providing a long life of measurability. Most have a full metal construction that is insensitive to magnetic fields while providing exceptional durability. There are certain steps that must be taken to ensure proper use and care of these precision measuring instruments. This article is intended to give you a basic set of guidelines to follow in order to get the longest life and most accurate readings out of your dial test indicator. This information does not pertain solely to any one brand, as proper use and care are generally the same for all brands and are the sole responsibility of the owner.
CHANGING THE CONTACT POINT
When changing the contact point of your indicator, it is of the utmost importance to follow the proper guidelines outlined in this article to ensure that no damage is done to the contact point or to the indicator itself. Use only the wrench provided by the manufacturer as the use of anything else other than what is recommended could very easily overtighten or damage the contact point or body of the indicator. Carefully loosen and remove the contact point with the provided wrench and screw in a new one of the same length. It is absolutely critical that you replace the contact point with one of the same length as long stem contact points do not fit in standard length style indicators. Long stem contact points require a long stem style indicator as the threads are different sizes. Always refer to the information provided in the indicator case if you are not sure which style to replace it with. Tighten the new contact point carefully with the wrench. It is now ready for use.
HOW TO PROPERLY HOLD YOUR INDICATOR
The majority of dial test indicators will have a dovetail style clamping system. Depending on your particular brand, this may not always be the case. For those that do not use a dovetail style, other holding devices or fixtures may have to be purchased in order to securely clamp your indicator. Always refer to the information provided in the indicator case to determine what your specific brand requires. For those that do use the dovetail style, the following is a brief explanation of how to use it. There are typically three different positions on a dovetail style dial test indicator where it can be held. Always keep these areas clean of debris as well as the clamp that slides onto them. Loosen the screw on the clamp enough so that you can easily insert the dovetail into the corresponding groove on the clamp. Never force the dovetail in. If it does not easily slide in, check to ensure that both the dovetail and clamp are clean and free of debris and then simply loosen the clamp until easily slides in. Once you have it positioned where you want it, simpy tighten the clamp until the indicator is secure. Take care not to overtighten the clamp. It is generally recommended that the indicator be clamped as close to the measuring point as possible.
HOW TO GET THE MOST ACCURATE MEASUREMENTS FROM YOUR INDICATOR
For the best possible accuracy and repeatability, make sure that the centerline of the contact point is as parallel to the surface of the workpiece as possible while taking measurements. The position of the indicator body is not important. Keeping the contact point as close as possible to 90 degrees to the direction of measurement is going to ensure the best possible accuracy.
When this recommendation cannot be achieved however, the angle (A) can be determined and the indicator reading must be multiplied by the correction factor given in the chart below.
Indicator Reading…………………………. .0085″
Angle (A)………………………………….. 30 DEG
Correction Factor…….. Cos 30 DEG = 0.87
.0085″ x .87 = .0074″
Remember as earlier stated, the position of the indicator body is not of any importance. The position of the contact point to the workpiece being measured is what determines the angle (A).
PROPER MAINTENANCE FOR YOUR DIAL TEST INDICATOR
If you use and care for your dial test indicator properly, it should require practically no maintenance. It is generally recommended that the ball bearings and the transmission should not be lubricated in any way. Refer to the information included in the indicator case for your particular brand as some brands may differ on their recommendations for maintenance. Should you detect any signs of wear and tear or possible defects, contact the respective distributor for service. This guide is intended to give you general information on how to care for and use your dial test indicator properly. It does not pertain to any one brand in particular, nor is Machining-Tutorials.com in any way affiliated with any manufacturer of dial test indicators.