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Compac Test Indicator
Single Revolution Series 240 - Inch models
Horizontal Style

This test indicator is unjustly neglected and easily overlooked. It has one fantastic advantage over any other test indicator: it is rugged. If your shop routinely destroys the otherwise excellent Bestest indicator it is time to switch to these Compac one-revolution indicators.

IMG0389

 

Swiss made Compac model 244A is shown above, with box and two stem attachments (4 mm and 8 mm). The hand moves smoothly once around the easy to read dial. These are heavier and sturdier than the Bestest indicators (made by the same manufacturer). The large and solid ball bearings are not prone to damage which is the bane of Bestest indicators among others.

Although most inch reading series 240 indicators have been discontinued, they are still available in metric.

  • Metric models can be found on page 108.
  • Contact points can be found on page 21
     

Large dial Compac model 245GA is available exclusively from Long Island Indicator Service. You can place your order online by clicking the appropriate link shown below.
 

Graduations

Total
range

Compac no.

Dial Ø

Contact point length

Purchase Order price

Discount Internet price

.0005"

.030"

244A

1.06"

.68"

162.00**

145.80

order now

.0001"

.008"

245GA

1.58"

.72"

199.00

exclusive

order now

.0005"

.030"

244GA

1.58"

.68"

discontinued

.0005"

.020"

244LA

1.06"

1.80"

discontinued

.0005"

.020"

244GLA

1.58"

1.80"

discontinued

.0001"

.008"

245A

1.06"

.72"

discontinued

(**) Model 244A has been discontinued by the manufacturer and we will sell our remaining stock, while it lasts.

 

 

A schematic drawing is available showing indicator dimensions. Two stem attachments T4 (5/32" equivalent to 4 mm) and T8 (8mm) are included. For tolerances see below. Model 20-055-0 has the same tolerances and specifications as model 245GA

Metric models can be found on page 108.

Black dial - yellow dial - white dial

 

Compac model 244BF and other black dial models have been discontinued. It had a black dial and orange hand like the more popular Bestest indicators. Long Island Indicator has replacement dials and hands for some of these models, and because all other parts are identical to the standard white dial models these indicators will remain serviceable for years to come.

Yellow dials are the standard for metric gages in the USA. While most new metric Compac indicators are shipped with white dials, yellow dials can be purchased and installed.

Important calibration information

 

Compac models are designed to permit a true reading when the angle between the stylus and the reference surface is 0° (ie., they are parallel).

Since the dial test indicator is used as a comparator, the angle can usually be set to remain at 0° for all comparisons. However, when the indicator is run through its range while attempting direct readings or for calibration, this angle will of necessity change, introducing the cosine error.

In the rare cases when measurement is required with the stylus at an angle other than 0° with respect to the reference surface the readings should be corrected. Refer to calibration instructions on gage 7 for details.

All new Compac test indicators come with a calibration certificate from the manufacturer, but they are not NIST traceable. If you need an NIST calibration cert, please specify at time of ordering.

While Compac test indicators are accurate ± 1 graduation when used as a comparator, they have total allowable deviations over their entire range as follows:

 

Model

total range

dial configuration

total deviation

hysteresis

repeatability

measuring force

244A/244GA

.030"

0-15-0

.0005"

.00015"

.0001"

0.25N

244LA/244GLA

.020"

0-10-0

.0005"

.00015"

.00015"

0.10N

245A/245GA

.008"

0-4-0

.00015"

.00015"

.00006"

0.25N

 

Source: Tesa SA, July 2005

Contact point length

 

It is imperative that the correct length of contact point be used with dial test indicators. Test indicators rely on leverage ratios to amplify the readings. Changing the length of the contact point will alter the ratio and result in incorrect readings. The common problem of incremental errors (ie, the readings gradually get worse from one revolution to the next) is most likely due to the installation of the wrong length point.

Most manufacturers specify the proper point length in their catalogs. It is not always clear, however, how the over-all length of the point is measured.

Compac contact points should be measured from the center of the carbide ball to the far end of the threads.

Some end-users purposely install extra-long contact points because their application requires it. If the contact point is exactly twice the length, then the readings on the dial will be doubled. Most .0001" Compac indicators can be fitted with a long point which will make the graduations read .0002"

Most manufacturers make indicators designed for use with long contact points. Compac test indicators have the letter designation "L" as a component of their model numbers.

Contact points can have a variety of ball diameters typically ranging from .015" to .120" and are available in carbide or ruby (special order). It is highly recommended that contact points fitted with carbide balls be used, especially for .0001" indicators. The size of the ball diameter has no effect on the indicator's accuracy.

To find the ordering number for contact points refer to the contact points list shown on page 21.

Compac indicator repair service

 

All parts are available and with 55 years of experience repairs can effectively be made on any of these indicators: Even the discontinued inch models on this page.

It's our policy to replace any damaged or worn parts necessary for the full function of the indicator. This way you'll be sure to get an instrument that's as good as new and one you can rely on. If you use a credit card for payment, turn-around is less than one week. For full details regarding repairs of Compac as well as other brands of indicators, please refer to page 30.

Plus, if you request it, we'll provide you with a short-form certificate of calibration free with every indicator repair. After all, when your instrument comes back, you need to know that it's accurate.

Q&A

 

Q: I have a Compac 244A that I discovered is not working with the dial face inverted (pointed towards the floor), when dialing in a bore on a horizontal axis. It came to me used, so I thought it was possible that someone had been inside it and made a mistake. I took the bezel off so I could watch the gear train, and it looks like one gear and shaft slides towards the dial face when upside down and disengages from the pointer gear. I was about to send it in to you for repair, but I found a page on your website saying that most indicators don't work upside down.

  • You bring up an interesting point. The upside-down rule applies mostly to DIAL indicators, not to TEST indicators which should work in any position. The Compac 244A should also work upside down. What happened is that, upon opening the gage a small spacer fell out from under the dial and was lost. This spacer kept the gears from disengaging. It is a situation commonly overlooked even by repair shops who don’t usually have a lot of experience with the Compac indicators. Please take a look at the bottom of page 78 for a clearer explanation.

Q: Currently, we are using the Bestest dial indicator model # 7023-3. These work great for our application, but they don't have a long service life. Our first inclination is to order some more, but I was wondering if there is a more robust indicator we could use that may last longer before failure or needing repair. We have tried other brands of indicators that had the same specs as the Bestest, only to find they would not register the small deviations of run-out. I do not know why this is the case, but for some reason other indicators do not pick up the run-out. Do you think that the heavier built Compact would do the job?

  • The Bestest indicator is very responsive, more so than any other indicator and I think that this is what you are looking for. The Compac will outlast the Bestest but it is not nearly as quick to respond. Trying one is probably your best bet.


     



 

 

From our reference shelf:

The Companion Reference Book on Dial and Test Indicators … page 178
BesTest and TesaTast Indicator Repair Manual … page 177
Starrett 711 Last Word Indicator Repair Manual … page 199
Interapid Indicator Repair Manual …
page 208
Compac Test Indicator Repair Manual ... page 194
 

www.longislandindicator.com

Long Island Indicator Service Inc
14 Sarah Drive — Hauppauge NY 11788 — USA


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This page's most recent revision: 23 DECEMBER 2016
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Original photographs and content copyright 2016 by René Urs Meyer

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