Product Description

803-M, 803-MC Metric Invar Kits

Metric unit kits for a variety of uses

The 803-M and 803-MC 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-CM (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-M and 803-MC 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-M is manufactured to its stated length within ±0.008 mm, and the Invar tubing in the 803-MC is manufactured to its stated length within ±0.003 mm. Our metric Invar tubing covered with a tough polyvinyl layer designed to protect your tubing and to allow for easy cleaning. Our metric tubing is yellow in color (English tubing is red).

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 25 mm to 2800 mm, in 125 mm 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. The table below specifies all included components. Be sure to have a look at our other Invar System components.

803-M, 803-MC Invar Kit Components

Legend Part Number Description 803 Qty 803-C Qty
A 12409-500MM 500 mm Invar Tube 4
12409-250MM 250 mm Invar Tube 2
12409-125MM 125 mm Invar Tube 2
12587-500MM 500 mm Invar Tube 4
12587-250MM 250 mm Invar Tube 2
12587-125MM 125 mm Invar Tube 2
B 12410-G1 Tooling Ball Tip 2 2
C 8665-G3 Rotating Scale Holder 1 1
D 8665-G1 Fixed Scale Holder 1 1
E 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 except for the 6040 or 6100


Approx. weight:
Kit and case, 7.7 kg (17 lbs.)
Shipping, 10 kg (22 lbs.)
Thermal expansion coefficient:
1.26×10−6 m/m/°C for temperature range of -18°C to 93°C (0.68 x 10−6 in./in.°F for temperature range of 0-200°F)
Invar tubing:
25.4 mm diameter Invar with stainless steel end caps, having 3/8″-24 internal threads on each end
Finish: Oil and stain resistant PVC jacket, yellow
Case: Plastic case with foam insert