Product Description

803, 803-C Invar Kits

English unit kits for a variety of uses

The 803 and 803-C Invar Kits are designed as multipurpose kits. They are often used as scale extension tools – precisely extending the range of standard optical tooling scales for accurate measurement of larger dimensions, or to access previously unreachable points. They are also used with calibration scales such as our 6000-CE (and others) as calibration or scaling artifacts for three dimensional measurement systems.

Invar tubing is great for metrology because it has such a very low coefficient of thermal expansion, which effectively eliminates changes in length due to handling or environmental changes. This is particularly beneficial when measuring a system in its “hot” or running state.

The 803 and 803-C Kits both contain exactly the same set of components; the only difference between them is that the Invar tubing is manufactured to different length tolerances. The Invar tubing in the 803 is manufactured to its stated length within ±0.0003″, and the Invar tubing in the 803-C is manufactured to its stated length within ±0.0001″. In each kit, the Invar tubing components are hand-picked so that the total Invar tube stackup error does not exceed the stated maximum. This means that you can connect all of the tubes found in a given kit together end-to-end, and the stack will maintain the total length within the stackup error. (The table above right summarizes this information.)

Individual components may be assembled to produce lengths from 1″ to 112″, in 5″ increments. The end of each invar tube allows measuring to the tangents of shafts, and a tooling ball contact point offers the best repeatability on most machine surfaces. A special concave tip is included for use with tooling ball applications. The table below specifies all included components.

803, 803-C Invar Kit Components

Legend Part Number Description 803 Qty 803-C Qty
A 12409-20IN 20″ Invar Tube 4
12409-10IN 10″ Invar Tube 2
12409-5IN 5″ Invar Tube 2
12587-20IN 20″ Invar Tube 4
12587-10IN 10″ Invar Tube 2
12587-5IN 5″ Invar Tube 2
B 12410-G2 Concave Tip 2 2
C 12410-G1 Tooling Ball Tip 2 2
D 8665-G3 Rotating Scale Holder 1 1
E 8665-G1 Fixed Scale Holder 1 1
F 12406-G1 Stainless Steel Invar System Connectors 10 10
no photo 12421-G1 Plastic Case 1 1
no photo NIST Traceable Certification for Kit 1 1

May Be Used With

Any of our optical tooling or calibration scales


Approx. weight:
Kit and case, 17 lbs.
Shipping, 22 lbs.
Invar thermal expansion coefficient:
0.70×10−6 in./in./°F for temperature range of 0°F to 200°F
Invar tubing:
1″ diameter Invar with stainless steel end caps, having 3/8″-24 internal threads on each end
Finish: Oil and stain resistant PVC jacket, red
Case: Plastic case with foam insert