The "Big One" (Part Number BO-PM-B200) is a giant 2.00 inch (50.8mm) diameter precision sphere mounted on a rugged 2.00 inch (50.8mm) diameter by 2-1/2 inch (63.5mm) high steel post.

It was developed for the evaluation of Computer Numerically Controlled Machining Centers according to ANSI/ASME B 5.54.1992. It is also used as a probe characterizing sphere on some Coordinate Measuring Machines. The large target is particularly well-suited for use on big machines and on multi-spindle machines.

Some of these tests include Machine Tool Repeatability, Temperature Variation Error, Hysteresis, Feature Accuracy, Pallet Change Repeatability, Tool Changer, Repeatability, Drift, Vibration and Compliance.

The surface area of this 2.00 inch ( 50.8mm ) diameter sphere is 12.566 square inches ( 319.19 square mm ) which is four times the 3.1416 square inch (79.797 square mm) area of the standard 1.00 inch ( 25.4 mm ) diameter sphere commonly used.

The 2.00 inch (50.8mm) diameter precision sphere is made of very fine grain high chrome, high carbon stainless steel that is hardened to 58 Rc for wear resistance and cold cycled for long-term dimensional stability. This large diameter component is lapped spherical within 5 millionths of an inch (127nm) and has a surface finish below 0.7 micro inches (17.78 nm) Ra. The exact diameter of the sphere can be certified to 10 millionths of an inch (254nm).

The flat base of the mounting post is recessed to leave an anular ring forming a stable connection for the sphere.

The post of the "Big One" is provided with an attractive black oxide finish that resists corrosion. A 1/4 inch (6.35mm) diameter clearance hole is cross-drilled through the post and a high tensile stainless steel pin is provided to tighten and to remove the device from its mount.

A M10 x 1.5 tapped hole is machined in the center of the flat base of the post to provide a strong means of attachment. This configuration is standard throughout the product line so that all components are interchangeable.

We carry a full line of Dual Threaded Adapter Screws which have a different thread on each end. These threaded adapters will match all of our Coordinate Measuring Machine evaluation and fixture building devices to the threads in the table of any C.M.M. or competitor's pallet system.

The short version of these threaded adapters (Table #1) have an overall length of 1.5 inches (38.1 mm) and each of the threads is 3/4 inch (19 mm) long, except the 1/4 inch-20 to M10 x 1.5, where the 1/4 inch diameter is only 1/2 inch (13 mm) long.

Because these Dual Threaded Adapter Screws get such heavy use, we machine a reduced-diameter on the very ends to avoid damaging the thread.

The two threads have an undercut in the center to allow either of the threads to be tightened fully without any chance of binding.

The Dual Threaded Adapter Screws will not rust because they are manufactured from a very corrosive resistant type 18-8 Stainless Steel.

The highest quality threads with increased tensile strength are produced by cold rolling the thread forms.

There is a screwdriver slot provided at the end of each thread of the short version and in the long threaded end of the long version. With the aid of a coin or screwdriver, the Dual Threaded Adapter Screw can be securely tightened into its mating part.

The long version of these Dual Threaded Adapter Screws (Table #2) have an overall length of 2.5 inches (76.2mm). The table, or short end thread, is 3/4 inch (1.9cm) long; and the M10x1.5 thread is 1.75 inches (44.5 mm) long, except the 1/4 inch-20 to M10x1.5, where the 1/4 inch diameter thread is only 1/2 inch (13mm) long.

If one of these fourteen combinations does not meet your requirements, we will be pleased to supply any other combination on special order..

Extensions for CMM Probe Characterization Spheres

Two standard lengths of this version are available. The 3.00 inch (76.2mm) long version (Part Number P-EP-3) and the 6.00 inch (152.4mm) long (Part Number P-EP-6).

The 1-1/4 inch ( 31.75 mm ) diameter extension posts have a 3/16 inch ( 4.76 mm ) clearance hole cross-drilled through the post diameter. A high tensile stainless steel pin that passes through this hole is used to tighten and to remove the device from its mating part.

Extensions for "The Big One" ( Part Number BO-PM B200 ) are 2.00 inches ( 50.8 mm ) diameter to match its post. Two standard lengths of this version are available. The 3.00 inch ( 76.2 mm ) long version ( Part Number BO-EP-3 ) and the 6.00 inch (152.4 mm ) long (Part Number BO-EP-6).

The 2.00 inch ( 50.8 mm ) diameter extension posts have a 1/4 inch ( 6.3 mm ) diameter clearance hole cross-drilled through the diameter of the post. A high tensile stainless steel pin that passes through this hole is used to tighten and to remove the device from its mating part.

Both ends of all extension posts are drilled and tapped M 10 x 1.5. This configuration is compatible with our full line of accessories.

The center portions of both of the flat ends of all extension posts are recessed to leave anular ring. This flat ring forms a stable connection with the mating parts.

All extensions are provided with an attractive black oxide finish which resists corrosion.

The 4 inch platform ( part number PLT-4 ) is a universal mounting tool. It is used to securely couple a variety of measuring devices to the machine under test. Among these devices are all of the CMM probe characterizing spheres on a post including the Mini Ball Bar (Dumbbell) ™ (see Technical Data Sheets CMM-7 and CMM-9).

The 45 degree Angle block (Part Number BLK 45) is designed for use with the four inch ( 101.6 mm ) platform . For performance evaluation of Computer Numerically Controlled machining centers, it will hold the standard 1.00 inch ( 25.4mm ), part number PM-UB-B100, diameter Ultra Precise Test Sphere on the 1-1/4 inch (31.75mm) diameter post. It will also hold "The Big One", a two inch (50.8mm) diameter Test Sphere mounted on a 2 inch (50.8mm) diameter by 2-1/2 inch (63.5mm) high post (Part Number PM-PB-B200).

All of these tools are coupled to the platform through a M10 x 1.5 diameter threaded stud. The platform has a tapped hole directly in the center and one near the outer edge of the top face. All of the accessories have corresponding tapped holes in them.

In addition to the central tapped hole, there are three 1/4 inch ( 6.35mm ) diameter holes drilled through the platform and counter bored from the bottom. These three holes form the vertices of an equilateral triangle. They are used to mount three 3/4 inch ( 19.05mm ) diameter truncated and tapped spheres to form the three Ball Kinematic Platform ( Part Number 3B-KM, Technical Data Sheet CMM-4) used in Ball Bar (Dumbbell) evaluation of Coordinate Measuring Machines.

This platform is manufactured from a free machining low alloy carbon steel. It may be easily modified to provide extra holes, threads, or other details. Prompt delivery of any modified configuration will be supplied at reasonable cost.

This robust steel platform is four inches ( 101.6mm ) diameter and 1-1/2 inch ( 38.1mm ) thick. It weighs over five pounds ( 2.27kg ).

There is a recess machined in its base that leaves an anular ring around the edge. This ring is precision lapped flat to form an excellent coupling to a CMM or machine tool table.

There is a drilled and counter bored hole through the platform that will accept a 3/8 inch or a 10mm diameter socket head cap screw. This screw will securely clamp the platform to its mating surface.

The 4" platform is supplied with an attractive black oxide finish which helps to retard corrosion. Other finishes are available on special order.

This device (Part Number BLK-45) inclines the probe characterizing sphere at 45 degrees, thus making it more accessible for calibration.

The block may be located in an out of the way place on the CMM table, while projecting the characterizing sphere out into the working zone of the machine.

This robust steel angle block is 3-1/2 inch ( 3.5", 88.9mm ) long by 1-1/2 inch (1.5", 63.5mm ) high and 1-1/2 inch ( 1.5", 38.1mm ) wide.

Two tapped holes that are M10 inch diameter are provided to secure the characterizing sphere's 1-1/4 inch ( 1.25", 31.75mm ) diameter post.

One tapped hole is provided in the center of the 1-1/2 inch ( 1.5", 38.1mm ) long 45 degree land, and one is provided in the top surface near the end opposite the 45 degree angle.

The base surface that locates this 45 degree block has areas of the surface relieved to leave three mounting pads. These pads are lapped flat and coplanar to form a stable clamping surface.

A counter bored hole is provided through the height of the block. Using this counter bored hole, the 45 degree angle block is clamped solidly in position by 3/8 inch ( 0.375" ) or a 10 mm socket head cap screw.

This 45 degree Block is designed to be used with the 4 inch ( 101.6 mm ) diameter steel platform, Part Number PLT4, see Technical Data Sheet CMM-6A.

The 45 degree Angle Block is supplied with an attractive black oxide finish which resists corrosion.

The 4.00 inch (101.6 mm) diameter magnetic platform was developed to hold the target sphere for evaluating Computer Numerically Controlled Machining Centers according to ANSI-ASME B 5.54-1992. The commonly used target sphere is a 1.00 inch (25.4 mm) diameter Ultra Precise Sphere mounted on a 1-1/4 inch (31.75 mm) diameter post, (Part Number PM-UB-B100, see Technical Data Sheet CMM-7).

Another popular target sphere that is compatible with this magnetic platform is the "Big One". It is particularly well-suited for the evaluation of large and multi-spindle machines. This device (Part Number PM-PB-B 200, see Technical Data Sheet CNC-1) incorporates a huge 2.00 inch (50.8 mm) diameter sphere mounted on a robust 2.00 inch (50.8 mm diameter by 2-1/2 inch (63.5 mm) high steel post.

The surface area of this sphere is four times as great as the area of the standard 1.00 inch sphere. The surface area of a 1.00 inch (25.4 mm) sphere is 3.1416 square inches (79.797 square mm) and the surface area of the 2.00 inch (50.8 mm) diameter sphere is 12.566 square inches (319.18 square mm).

The 4.00 inch (101.6 mm) diameter Magnetic Platform (Part Number M-PLT-4) is 1-1/2 inch (38.1 mm) thick and weighs over 5 lbs. (2.27 kg).

A rare earth magnet provides a holding force of over 100 pounds (45.358 kg).

Two pass-tipped jack screws are provided to assist in removing this powerful platform from the machine surface. As the jack screws are advanced, the soft pass tips press against the machine surface and smoothly raise the magnetic platform.

It is provided with a 3/8 inch by 16 threads per inch tapped hole in the center of the top surface and one near the outer edge. These threaded holes on the device are used to rigidly couple the various apparatus used with the platform.

The top surface of the magnetic platform is machinable, so that additional threaded holes or other details can be added for specific applications. We will provide prompt delivery of special machined details to your specifications.

The device is provided with an attractive black oxide finish that resists corrosion.

The 45 degree angle block (Part Number BLK-45, Technical Data Sheet CMM-11) and both the three inch (3.00", 76.2mm) long (part Number P-EP-3) and the six inch (6.00", 152.4 mm) long (Part Number P-EP-6), 1-1/4 inch ( 1.25", 31.75 mm) diameter extension posts are compatible with this platform. Both the 3.00 inch (76.2 mm) long (Part Number BO-EP-3), and the 6.00 inch (152.4 mm) long (Part Number BO-EP-3) 2 inch (50.8 mm) diameter extension posts are also compatible with this platform.

The contact probing system of a Coordinate Measuring Machine is characterized by evaluating a large number of measurements on the surface of a very precise sphere of known diameter. This precise sphere must be rigidly supported and held in a fixed position during the probe characterization process, otherwise misleading data will be collected (see Technical Data Sheet CMM-7 for Standard Characterization Spheres).

This rigid support unavoidably covers up part of the spherical surface, which is therefore hidden from measurement by the contact probe. This hidden area is of no consequence when working with vertical probes, but it is of prime importance when the probe is inclined, horizontal or of compound, i.e. star design.

The simple solution to this problem is to use the Ball Bar (Dumbbell) concept as developed many years ago. This device uses two very precise spheres of exactly the same known diameter which are securely mounted on opposite ends of a rigid bar.

This hidden area on the first sphere is exactly 180 degrees from the hidden area on the second, so 100% of the spherical surfaces are in effect available for probing.