Interapid
Premium Quality Swiss Test Indicators

 

It would be hard to give a reason why you shouldn't buy the genuine Swiss made Interapid indicator. It has quickly become the standard against which all other indicators are compared.

Contents of this page and related topics:

New Interapid test indicators, Interapid repair service and Interapid spare parts are available from Long Island Indicator Service.

Caution! Beware of look-alike Interapid indicators made in China which can be bought cheaply even through reputable catalog houses like Fowler and SPI. The low price will give them away. If the dial reads "Interapid" then you can be sure that you are buying the genuine Swiss article.

Horizontal Interapid test indicator made in Switzerland

 

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Popular Interapid model 312B-1 shown above

This genuine, Swiss-made Interapid indicator is undisputedly the best test indicator of its kind. The large hand makes two complete revolutions in either direction and the small hand helps you keep track which revolution you're on. The right hand side of the dial has a thin black half-circle in case you want to use these in a set-up involving mirrors.

The 4 mm diameter mounting stem swivels and can be replaced if damaged. The two dove tails (back and top) are mounted with screws and these can also be replaced or removed if they get in the way. These dovetails, by the way, are hardened metal and won't get squashed with wear like the brass dovetails on other indicators. If you don't want 4 mm, then you can easily slip on a 3/8" adapter.

Many different contact points, including ruby, Teflon and nylon are optionally available, and easy to install. The contact point operates on a friction clutch, so you'll have to apply a bit of force to get the point to swivel, which it does, from the front of the indicator to the back. New indicators come with a special "wrench" for removing the contact points. It's okay to use a pair of jeweler's pliers for this purpose.

Unless you know what you're doing, you should under no circumstances attempt to disassemble or adjust any of the screws or bearings on the indicator.

These indicators are designed to function when the contact angle is about 12° to the work surface (see details below).

Interapid 312B-3

Interapid 312B-3 test indicator made in Switzerland

These indicators come in a sturdy box, with a .080" diameter carbide point installed, a wrench for removing the contact point and a manufacturer's statement of conformance along with allowable errors (see bottom of this page). Calibration certificates are not available. If you require such, you will have to send the indicator to an accredited calibration lab in your area.

You can order online by clicking any of the links shown below. A separate price is shown in case you need to send us a purchase order (P.O. Price). Purchase orders can only be accepted based on credit review or for established accounts. In most cases, ordering online (Your Internet Price) will save a considerable amount of money.


 

Graduations

Range

Dial Ø

Point Length

Model

Order No.

P.O. Price

Internet Price

0.0005"

0.06"

1.5"

0.687"

312B-1

74.111370

278.00

check discount

0.0005"

0.06"

1.5"

2.750"

312B-15

74.111965

389.00

check discount

0.0005"

0.06"

1"

0.687"

312B-2

74.111371

276.00

247.00
order now

0.001"

0.06"

1"

0.687"

312B-20

74.111374

281.00

check discount

0.0001"

0.016"

1.5"

0.687"

312B-3

74.111372

342.00

check discount

0.0001"

0.016"

1"

0.687"

312B-4

74.111373

347.00

check discount

0,01 mm

1,6 mm

37.5 mm

16.5 mm

312-1

74.111366

286.00

check discount

0,01 mm

1,6 mm

30 mm

16.5 mm

312-2

74.111367

284.00

check discount

0,002 mm

0,4 mm

37.5 mm

15.2 mm

312-3

74.111368

351.00

check discount

0,002 mm

0,4 mm

30 mm

15.2 mm

312-4

74.111369

347.00

check discount

Special 1.45" long contact point to be used in place of any .687" point. When you install this point, the readings on your dial will be doubled. That is, the .0005" graduations will become .001", the .001" will become .002", and the .0001" graduations will become .0002"

See page 21 for more contact points in ruby, carbide or Teflon.
 

MTC39-35

19.50
order now

See page 36 for other adapters, holders and attachments.

 

Do you need these indicators certified NIST traceable? The only way to do this is to send us a purchase order and specifically request the full data NIST traceable certificate. It is provided free of charge. But, only with a purchase order at the purchase order prices shown above.

Extra long contact point

 

Horizontal model 312B-15 with 2.75" long contact point. See ordering chart above or, for the vertical version 312B-15V see the chart below. There is no metric equivalent for this long point model and it is only available with .0005" graduations. Points longer than 2.75" are no longer available from us.

If you want to buy the extra long contact point only, please see page 21.

 

Vertical Interapid test indicator



Vertical, jig-bore type test indicator with one dovetail and an integral 4 mm holding stem which swivels in one direction. You can buy adapters so that the diameter of this stem becomes 3/8" or 8 mm. (See below)

The contact point (Ø.080" supplied) also swivels through a wide arc. These are available from a short .687" to a very long 5.5" length. Other diameter balls and other lengths as well as contact points made of Nylon, Teflon or ruby are optionally available. (See page 21)

A friction clutch holds them in a steady position so it might take a bit of effort to move the point. Do not use any tools other than your fingers for this operation and be sure that the point is securely fastened before attempting to move it.

Never attempt to make adjustments to the ball bearings located on the side of the body, or you'll have a repair bill on your hands.

This superior vertical style indicator is well worth the invest-ment. We offer a full repair service as well as warranty repairs if there is ever a problem. Spare parts are available for anyone skilled in the repair of these admittedly difficult gages to repair. Simple "do-it-yourself" projects include replacement of the mounting stem, the dovetail and the bezel with crystal. (For parts see page 88).

 

Graduations

Range

Dial Ø

Point Length

Model

Catalog no.

P.O. Price

Internet Discount

0.0005"

0.060"

1.5"

2.75"

312B-15V

74.111958

389.00

check discount

0.0005"

0.060"

1.5"

.687"

312B-1V

74.111377

296.00

check discount

0.001"

0.060"

1"

.687"

312B-20V

74.111379

281.00

230.75
order now

0.0005"

0.060"

1"

.687"

312B-2V

74.111378

298.00

243.50
order now

0.0001"

0.016"

1.5"

.687"

312B-3V

74.111957

369.00

296.75
order now

0,01 mm

1.6 mm

37.5 mm

16.5 mm

312-1V

74.111375

314.00

check discount

0,01 mm

1.6 mm

30 mm

16.5 mm

312-2V

74.111376

304.00

248.00
order now

Special 1.45" long contact point to be used in place of any .687" point. When you install this point, the readings on your dial will be doubled. That is, the .0005" graduations will become .001", the .001" will become .002", and the .0001" graduations will become .0002"

See page 21 for more contact points in ruby, carbide or Teflon
 

MTC39-35

19.50
order now

For other contact point options, such as ruby point see contact points. You may order online by selecting any linked model number.
 

Interapid indicator features

 

These indicators have a very light measuring force: just 0,12 N for .0005" models and 0,25 N for .0001" models.

The indicator is designed to measure with the contact point held at an angle of 12° to the measuring surface. (Some sources list this angle as 13 degrees. The difference is not significant.) This allows you to take measurements down a hole or in a bore.

The .080" diameter carbide contact point is easily replaceable with other diameters (from .015" to .120") and other substances (ruby, teflon or nylon). Under some circumstances, you can even install a longer point. See contact points.

The dial hand makes two revolutions in each direction. The small counter hand keeps track of the revolutions.

The dial has balanced numbering: 0-4-0 (.0001" indicators) and 0-15-0 (.0005" indicators). The right half of the dial features a thin black band which will help identify the plus or minus side when using a mirror.

The novel tapered shape tilts the dial towards the observer. Both Mitutoyo and Starrett have recently copied this design. This makes for easier reading with less likelihood of parallax errors as well as a reduction in glare from overhead lights.

If you need to slip the indicator into an opening then you may be interested to know that the width of the body at the stylus (contact point) is 10,3 mm which is broader than Bestest, Tesatast or Compac.

The holding stem is 4 mm (5/32") in diameter. The stem swivels and is attached to the body, although it can be removed and replaced. Simple instructions for this procedure are available on our Do-It-Yourself page. If you need a holding stem with a different diameter, use one of the following adapters:

  • An elegant 3/8" adapter fits over the 4 mm stem. Order no. 74.108943 ... $28.00
  • For metric set-ups, use the 8 mm stem adapter. Order no. 74.108942 ... $29.50

The dovetails are hardened metal, screwed onto the body. These can also be removed and replaced. See our parts list for replacement parts.

See a schematic drawing of the horizontal and vertical models.

 

Interapid repair

 

Long Island Indicator is an authorized repair service for Interapid test indicators.

Top-of-the-line Interapid test indicators are probably the most challenging of all to repair. Absolute cleanliness and the replacement of critical parts is essential to a quality repair. We've been trained by masters in the craft, and having an ample supply of fresh parts directly from the manufacturer are able to return any Interapid test indicator to A-1 condition.

Our fixed repair costs are outlined on page 30. 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. And, if you request it, you'll get a short-form certificate of calibration, NIST traceable, for free; after all, when you get your indicator back you need to know that it's accurate. If you pay with a credit card, turn-around is less than a week. See page 30 for detailed information.

Is the indicator damaged beyond repair? If the body is damaged in any way (the front end is squashed, for instance) then we'd have to replace the body and you'd have to pay about $190 for the repair. Not usually worthwhile. If the whole face has come off because it was ripped off - that sounds serious, yet happens regularly - it's probably repairable for the normal cost quoted in the paragraph above.

Do you only need a new crystal installed? We charge $35 and that includes return shipping. Just enclose a check and we'll do a 2-day turn around. To make it easy, print out a packing list.

Sorry, we can't repair old models such as the 310B and 311B series. Parts for these indicators are no longer available. If have one of these, then you've gotten your money's worth since they were discontinued about 40 years ago. If you just bought one on e-bay, then you've been had.

 

Is Interapid any good?

 

We rate them among the very best. If you'd like to compare the good points and the not-so-good points of the Interapid indicator with other manufacturers then take a look at our indicator comparisons on page 37.

 

Important calibration information

 

Unlike other test indicators, Interapid indicators do not have serial numbers on them. Perhaps someday the manufacturer will remedy this situation but for now you'll have to assign your own unique serial number to each indicator if you intend to keep track of their calibration. It's easy to scratch a number into the painted body using a sharp tool. A permanent marker with a super fine point will also work. Do not use an electro-engraver because it creates sparks which have been known to damage the pinions on the gears.



Interapid series 312 test indicators are designed to permit a true reading when the angle between the stylus and the reference surface is 12° as shown in A and B (to the left).

In the rare cases when axial measurement is required with the stylus at 0° with respect to the reference surface as in C and D in the illustration, (for instance: small diameter bores) the readings must be multiplied by a factor of 1.022 (See further information on cosine error.)

It also follows that incremental calibration discrepancies can be corrected by adjusting the contact point angle.

Here are the most recent specs as published by the manufacturer (specifications for older models may be slightly different):

 

Model

Graduations

Deviation per revolution

Deviation Total

Repeatability

Hysteresis

Measuring force

 

74.111366
74.111367
74.111375
74.111376

0.01 mm

10 µm

23 µm

3 µm

3 µm

0,12 N

 

74.111368
74.111369

0.002 mm

4 µm

10 µm

1 µm

2 µm

0,25 N

 

74.111370
74.111371
74.111377
74.111378

.0005"

.0004"

.00092"

.00012"

.00012"

0,12 N

 

74.111372
74.111373
74.111957

.0001"

.00016"

.0004"

.00004"

.00008"

0,25 N

 

74.111374
74.111379

.001"

.0004"

.00092"

.00012"

.00012"

0,12 N

 

74.111958
74.111965

.0005"

.0006"

.0016"

.00004"

.0008"

0,12 N

 

Source: Tesa specifications (1899.024.1605) which are included with each indicator as of April, 2017.
 

Using the correct contact point

 

While various diameter balls do not affect readings, the correct contact point length is critical. (Refer to model information on this page.) Use only points designed for Interapid indicators. Any deviation will result in reading errors.

When ordering new points, take note of the indicator's model number and decide on the ball diameter you'll need. Contact points in carbide, ruby or Teflon can be found on page 21.

 

Problems with repeatability

 

According to the manufacturer, the Interapid test indicator is allowed a repeatability error as shown in the reference chart above.

Repeatability must be checked against the measuring surface. When the contact point is resting against the measuring surface, turn the bezel so that zero is directly in line with the pointer (hand). The indicator's "at rest" zero reading must not be used to verify repeatability.

Swiveling the contact point may cause the zero setting to change slightly. If this happens, reset zero by turning the bezel.

Zero readings may also be off when comparing contact point up and contact point down motions. Reset the zero by turning the bezel as needed.

Furthermore, repeatability can only be assured if the indicator is securely fastened to a good test stand or other fixture. Fastening by the dovetail as close as possible to the front of the indicator is the preferred method.

 

Interapid older models

 

Current test indicator models begin with the number 312. Previous models dating to the 1960s were number 311 and these are often still repairable, depending on the damage. The oldest models were number 310 and you can assume these are beyond repair simply because spare parts are obsolete. If the horse-shoe shaped clip which holds the bezel in place is missing, then you may have to improvise with a piece of spring-wire bent into the correct shape. You might be tempted to say "It only needs a cleaning," but that's almost never the case. None-the-less, if you want us to have a look, it costs you nothing but shipping.

For a brief period of time Brown & Sharpe had put its name on the Interapid indicators. For example, B&S model 7025-4 was actually Interapid model 312B-1. These can still be repaired because they were not imitations but genuine Interapid indicators made in Switzerland.

 

Interapid dove tails and stem attachments

 

It would appear that one of the advantages Interapid indicators have over other brands is the replaceable dovetails. Each of the 1 or more dovetails (depending on models) is fastened to the body with several screws. Dovetails are made of hardened steel and they won't break or wear down like those which are integral with the bodies of Bestest, Mitutoyo, Compac and others. Because they're hardened, they probably will never have to be replaced. Unless... the entire dovetail has been ripped from the body through some misadventure. In this case, the screw holes are usually damaged beyond repair anyway.

The feature of replaceability is not particularly important. However, the hardened steel is. These dovetails will outlast any others.

If you'd like to buy replacement dovetails and screws check the Interapid parts list on page 88.
 

Questions and Answers about the Interapid indicator

pointinghandvintageimagegraphicsfairy2 see page 191


The above items constitute advertisements on behalf of Amazon.com and are not to be construed as endorsements by Long Island Indicator Service. We strongly believe in buying quality tools and gages, and urge customers to check carefully before making a purchase. If the prices appear unusually low, we suggest proceeding with caution.
 

 

LONG ISLAND INDICATOR REPAIR MANUALS

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
Mitutoyo Test Indicator Repair Manual … page 102

New! Companion Reference Guide for Test Indicators … page 178
 

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


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This page's most recent revision: 8 November 2018
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Original photographs and content copyright 2018 by JWGrum

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