PAGE 21 — INTERAPID CONTACT POINT

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Interapid M1.7

How are they measured? From the shoulder (not including the thread) to the center of the ball. Contact point thread size is M1.7 x 0.35 Those are the measurements given below.

Why do many catalogs have different lengths from those listed below? The Interapid carbide point lengths shown in the catalogs are the length of protrusion from the front of the indicator. A useful figure in some circumstances but not particularly helpful if you have a handful of contact points and you need to sort them out. We have also listed the actual length of the point from the shoulder to the center of the ball as a reference.

Ball diameter is .080" (2 mm) on new Interapid indicators. Carbide is standard with these models.

Most significantly, for accurate readings, Interapid contact points must be at an angle of about 12-15 degrees from the work surface. This is more critical with .0001" indicators where errors can quickly add up.

Catalog length = .650"
Actual length = .687"
  • 312B-1
  • 312B-2
  • 312B-3
  • 312B-4
  • 312B-20
  • 312B-1v
  • 312B-2v
  • 312B-3v
  • 312B-20v
contact point length illustrated

Usable, exposed catalog length is the amount of protrusion (L) as shown in the sketch. The actual length is about 2 mm longer.

Ball material Ball Ø Actual length Price (US$) Manufacturer's equivalent Our Part Number
carbide .015" .687" $22.50 74.116284 MTC39-02 buy now
carbide .031" .687" $20.50 74.105998 MTC39-03 buy now
carbide .060" .687" $20.50 74.105997 MTC39-04 buy now
carbide .080" .687" $20.50 74.105996 MTC39-05 buy now
Nylon .060" .687" $29.50 none MTC39-19 buy now
Teflon .060" .687" $29.50 none MTC39-16 buy now
Teflon .080" .687" $29.50 none MTC39-17 buy now
ruby .040" .687" $29.50 none MTC39-13 buy now
ruby .080" .687" $29.50 none MTC39-14 buy now
Catalog length = 2.675"
Actual length = 2.750"
  • 312B-15
  • 312B-15v
contact point length illustrated

Usable, exposed catalog length is the amount of protrusion (L) as shown in the sketch. The actual length is about 2 mm longer.

Ball material Ball Ø Actual length Price (US$) Manufacturer's equivalent Our Part Number
carbide .015" 2.750" $22.50 none MTC40-33 buy now
carbide .031" 2.750" $21.50 74.111910 MTC40-34 buy now
carbide .080" 2.750" $21.50 74.111913 MTC40-35 buy now
carbide .100" 2.750" $21.50 74.111912 MTC40-36 buy now
carbide .080" 5.5" $55.00 74.111912 MTC39-55 order this item on page 230
Catalog length = 16.5 mm
Actual length = 18.5 mm
  • 312-1
  • 312-2
  • 312-1v
  • 312-2v
contact point length illustrated

Usable, exposed catalog length is the amount of protrusion (L) as shown in the sketch. The actual length is about 2 mm longer.

Ball material Ball Ø Actual length Price (US$) Manufacturer's equivalent Our Part Number
carbide 2.0 mm 18.5 mm $20.50 74.105993 MTC40-05 buy now
carbide 1.5 mm 18.5 mm $20.50 74.105994 MTC40-04 buy now
carbide 0.8 mm 18.5 mm $22.50 74.105995 MTC40-03 buy now
Catalog length = 15.2 mm
Actual length = 17.2 mm
  • 312-3
  • 312-4
contact point length illustrated

Usable, exposed catalog length is the amount of protrusion (L) as shown in the sketch. The actual length is about 2 mm longer.

Ball material Ball Ø Actual length Price (US$) Manufacturer's equivalent Our Part Number
carbide 2.0 mm 17.2 mm $20.50 74.110482 MTC40-15 buy now
carbide 1.5 mm 17.2 mm $20.50 74.110491 MTC40-14 buy now
carbide 0.8 mm 17.2 mm $22.50 74.110507 MTC40-13 buy now
Teflon 2.0 mm 17.2 mm $32.50 none MTC40-17 buy now
Double length

You can use these double length points on any of the models listed. The readings on the dial will be doubled as a result. The graduations on the .0005" indicator will therefore equal .001" and the graduations on the .0001" indicator will equal .0002". This only works if the contact point is exactly twice the length of the standard point.

  • 312B-1
  • 312B-2
  • 312B-3
  • 312B-4
  • 312B-20
  • 312B-1v
  • 312B-2v
  • 312B-3v
  • 312B-20v
Ball material Ball Ø Actual length Price (US$) Manufacturer's equivalent Our Part Number
carbide .030" 1.450" $22.50 74.106363 MTC39-33 buy now
carbide .060" 1.450" $22.50 none MTC39-34 buy now
carbide .080" 1.450" $22.50 74.106361 MTC39-35 buy now
carbide .120" 1.450" $22.50 none MTC39-37 buy now
Indexable bent contact point

The Indexable bent contact point is designed for use with Interapid test indicators and the photograph gives you an idea of its use.

Any notion of taking direct readings goes right out the window, however. This contortion means that you can only use your indicator for the purpose it was designed: comparison work. If you're not sure whether it'll work for you or not, buy just one piece to test it. We make no guarantees.

Ball diameters are limited and they're only available in carbide.

contact point length illustrated

Dimension A and B are approximate.

Length A Length B Carbide Ø Price (US$) Manufacturer's equivalent Our Part Number
.6875" .3" .031" $34.00 none MTC41-01 buy now
.6875" .3" .060" $34.00 none MTC41-02 buy now
1.45" .3" .031" $34.00 none MTC41-03 buy now
1.45" .3" .060" $34.00 none MTC41-04 buy now

Companion Reference Guide for Test Indicators
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