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Interapid test indicator
Premium Quality Swiss Indicators

Caution! Beware of imitation and 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.

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.

Horizontal Interapid test indicator made in Switzerland

 

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. Purchase orders can only be accepted based on credit review or for established accounts. In most cases, ordering online will save a considerable amount of money.

  • Amazon undersells everyone with its big discounts and we find we can no longer compete. Our sales have dropped 70% in the past three years as a result of Amazon. If you place the order through Amazon using our web page we still receive a small commission which is better than selling none at all.


     

Graduations

Range

Dial Ø

Point Length

Model

Order No.

Purchase Order Price

Your Internet Price

0.001"(*)

0.120"

1.5"

5.5"

312B-15X

74.111965X

435.00

435.00 order now

0.0005"

0.06"

1.5"

0.687"

312B-1

74.111370

273.00

269.00 order now

0.0005"

0.06"

1.5"

2.750"

312B-15

74.111965

380.00

379.00 order now

0.0005"

0.06"

1"

0.687"

312B-2

74.111371

271.00

269.00 order now

0.001"

0.06"

1"

0.687"

312B-20

74.111374

276.00

269.00 order now

0.0001"

0.016"

1.5"

0.687"

312B-3

74.111372

336.00

329.00 order now

0.0001"

0.016"

1"

0.687"

312B-4

74.111373

339.00

263.00 order now

0,01 mm

1,6 mm

37.5 mm

16.5 mm

312-1

74.111366

280.00

check stock & price

0,01 mm

1,6 mm

30 mm

16.5 mm

312-2

74.111367

279.00

279.00 order now

0,002 mm

0,4 mm

37.5 mm

15.2 mm

312-3

74.111368

343.00

339.00 order now

0,002 mm

0,4 mm

30 mm

15.2 mm

312-4

74.111369

339.00

339.00 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
 

106361

19.50 order now

3/8" adapter (slips over the 4 mm mounting stem). Special price available only with the purchase of an Interapid indicator.

74.108943

20.00 order now

8 mm adapter (slips over the 4 mm mounting stem). Special price available only with the purchase of an Interapid indicator.

74.108942

20.00 order now

See page 36 for other adapters, holders and attachments.


(*) Important! See information regarding this indicator with the special 5.5" long contact point.

 

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 see the chart below. There is no metric equivalent for this long point model and it is only available with .0005" graduations.

You can request this indicator with a custom 5.5" extra long point in which case the graduations on the indicator are equal to .001" You'll have to make sure that whoever uses this indicator knows about the change. Attaching a tag to the indicator isn't a bad idea. This extra long point is not sanctioned by the manufacturer, so if you use it, all guarantees of accuracy are void. Customers who have used this special item report that the indicator works fine and that accuracy is not compromised. Be aware that we can not accept returns on this item if you decide that it doesn't meet your needs.

  • Special horizontal 5.5" model 312B-15X (74111965X) ... $435.00 order now
  • Special vertical 5.5" model 312B-15VX (74111958X) ... $435.00 order now

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.

2014 List Price

Your Price

0.001"(*)

0.120"

1.5"

5.5"

312B-15VX

74.111958X

n/a

435.00 order now

0.0005"

0.060"

1.5"

2.75"

312B-15V

74.111958

389.00

389.00 order now

0.0005"

0.060"

1.5"

.687"

312B-1V

74.111377

296.00

289.00 order now

0.001"

0.060"

1"

.687"

312B-20V

74.111379

281.00

279.00 order now

0.0005"

0.060"

1"

.687"

312B-2V

74.111378

298.00

289.00 order now

0.0001"

0.016"

1.5"

.687"

312B-3V

74.111957

369.00

369.00 order now

0,01 mm

1.6 mm

37.5 mm

16.5 mm

312-1V

74.111375

306.00

check stock / price

0,01 mm

1.6 mm

30 mm

16.5 mm

312-2V

74.111376

297.00

289.00 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
 

106361

19.50

3/8" adapter (slips over the 4 mm mounting stem).

74.108943

20.00

8 mm adapter (slips over the 4 mm mounting stem).

74.108942

20.00

(*) Important! See information regarding this indicator with the special 5.5" long contact point.

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. 074108943 ... $20.00
  • For metric set-ups, use the 8 mm stem adapter. Order no. 074108942 ... $20.00

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 repairable for the normal cost quoted in the paragraph above.

Do you only need a new crystal installed? We charge $30 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 specs as published by the manufacturer:

 

Model

Graduations

Deviation per revolution

Deviation Total

Repeatability

Hysteresis

Measuring force

 

74.111372
74.111373
74.111957

.0001"

.00016"

.0005"

.00005"

.0001"

0,25 N

 

74.111370
74.111371
74.111965
74.111377
74.111378
74.111958

.0005"

.0004"

.0012"

.0002"

.0002"

0,12 N

 

74.111368
74.111369
74.10002
74.10003

0.002 mm

4 µm

10 µm

1 µm

2 µm

0,25 N

 

74.111366
74.111367
74.111375
74.111376
74.10000
74.10001

0.01 mm

10 µm

23 µm

3 µm

3 µm

0,12 N

 

Source: Tesa specifications (1899.011.9706) which are included with each indicator as of August, 2014. These are the same specifications in effect since 2005.

 

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 of .0002" (for .0005" models) and .00005" (for .0001" models). Refer to the specs 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 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. For instructions on replacing stem attachments see our Do-it-Yourself page.

 

Questions and Answers about the Interapid indicator

Q: If I purchase a new Interapid through an eBay seller, is the warranty honored by the manufacturer?

A: If the item is new when purchased, then TESA will honor the warranty. You would have to keep the purchase receipt to prove the date of purchase. It does not matter if the seller is an authorized distributor or not.

 

Q: Contrary to my nature, I thought I'd ask for advice before I screwed up something. After all, you do say "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 [Interapid] indicator."  However, on your "Do It Yourself" web page you say this about Interapid stem attachment: "You will notice that you can increase the swivel friction by tightening screw A." Can the swivel friction on the contact point be adjusted in the same way?  The contact point on mine doesn't want to swivel, and I'm worried that I shouldn't push any harder on it.  Also, should I put any oil on this friction clutch?

A: This is a good question and I'm glad you asked. The contact point friction can not be adjusted in any way. The Interapid has fairly hard friction on the point. After all, you don’t want it to move on its own. Don’t be afraid. The contact point angle can be adjusted. Just use your thumb and the point will yield. A tiny drop of oil can be put on the “clutch” if you still feel that there is too much resistance. 

 

Q: My Interapid seems a little jumpy, especially when changing direction. Is it in need of repair?

A: Jumpiness is most often the result of a dirty hairspring. When the spring gets oily, it stops functioning and needs to be cleaned. This is easier said than done and should be put in the hands of a professional.

 

Q: We use the 312B series Interapid here on a daily basis. A few of them from time to time get abused by inexperienced or negligent machine operators. My question to you is, is there a way to zero out the small dial (rev counter) on these things? Repeatability does not seem to be a problem, I just would like to keep the needles in line as they were from factory.

 

Q: The contact point moves up and down (forward and backward is a better description) but one direction is noticeably harder than the other. Shouldn't they be the same?

 

Q: I know you have been asked before, but I really don't like the peeling paint on my Interapid. Isn't there something I can do?

 

Q: I have a model 310-B1. I see that parts are no longer available. The only thing wrong with the indicator is that the face comes off easily. The plastic split-ring that holds it on needs to be replaced and I was hoping that there might be another indicator that incorporates the same ring that I could purchase. Please let me know if that is the case.

 

Q: We recently purchased a new Interapid 312B-3 indicator and noticed that the dial appears to slightly lift from the base. Is this common with these indicators ?

 

Q: I would like to know if the 2.75" #111913 indicator point can be used with the 312B-3 Interapid indicator? I believe that the divisions will now be 0.0005" instead of 0.0001" with this longer point.

 

Q: Can I get the small wrenches to change the Interapid contact point properly? The tips all have the small flat machined into the shank and a new indicator used to have one of these wrenches supplied with the kit but I haven't seen one with any of the new indicators we've purchased recently. It used to be a simple round disk with a notch that fit the flat on the tip shank. Without this a needle-nose pliers works but seems wrong putting a pliers on something so delicate.

 

Q: I purchased a spring and gear assembly for the Interapid indicator (312B-3) and I am having a difficult time getting the indicator to return to 0 accurately (within .0001). Part of the problem is adjusting the ball bearing with spanner nuts. Will you please help me with this?

 

Q: I have a model 310-B1. I see that parts are no longer available. The only thing wrong with the indicator is that the face comes off easily. The plastic split-ring that holds it on needs to be replaced and I was hoping that there might be another indicator that incorporates the same ring that I could purchase. Please let me know if that is the case.

 

Q: I have an Interapid model 312-b3 indicator. I need to use it to center a rifle barrel (center the interior bored hole) in a lathe at a point fairly deep into the hole. I believe I could use your long indicator points for this operation as long as I'm aware that the accuracy of the dial is decreased.

 

Q: I recently purchased an Interapid 312B-1V (used, no directions). In order to move the contact you state: "be sure that the point is securely fastened before attempting to move it." Would this mean to ensure point is tight in holder then run the contact against the stop? Then move to desired angle?

 

Q: I have an older Interapid test indicator, model # 311B-1 and I was wondering if by any chance you would still have parts for it? The part I'm looking for is the one that holds the bezel to the extension ring. It looks like a horse shoe, or if you know of any company that makes replicas such as this.

 

Q: I have a brand new Horizontal model 312B-15 with 2.75" long contact point. I ordered the wrong one, so I bought some shorter tips for this indicator, now it acts jerking and does not repeat with a shorter tip on it. Does this mean that I can only use the long tip?

 

Q: The paint is peeling from my Interapid indicator. Can I do anything?

 

Q: How could I sterilize an Interapid indicator used in biological experiments?

 

Q: The contact point moves up and down (forward and backward is a better description) but one direction is noticeably harder than the other. Shouldn't they be the same?

 

Q: We have an Interapid 312b-2, the hair spring is currently not wound up, when you're looking at the dial and needle as if you were using the indicator, would you spin the needle clockwise to put tension on the spring or counter clockwise to put tension on the spring? The crown gear has a bent tooth which stops the large needle from turning more then 4 revolutions in the counter clockwise direction. Can the crown gear be removed and turned so the bent tooth doesn't hinder the movement?

 

Q: I have an Interapid indicator that has a little play side to side with the end. It will repeat fine as long as you don't move side to side on the part you're indicating. I was wondering if you could give me some advice on what i can do to fix the play?

 

These and other questions about test indicators are answered in our new publication:

newThe Long Island Indicator Companion Reference Book on Dial and Test Indicators

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This page's most recent revision: 17 APRIL 2015
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