Established in 1952

Page: 1820

12" x 16" pre assembled Kinematic Platform

The 12 inch by 16 inch (304mm by 406mm) Kinematic Platform is a well-established design, with years of successful use.

This seasoned design is rugged, but at the same time it is lightweight.

A high stiffness is achieved through an integral ribbed structure. The cast aluminum design provides good damping and high stiffness.

The upper platform is one and one half inches (38 mm) thick but weighs only 16 pounds, (7.2 KG). The overall height from the bottom of the lower platform to the top of the upper platform is three and one quarter inches ( 3 1/4", 82.6 mm ).

The Kinematic couplings used on this platform are of a high load carrying design. It uses three spheres of three quarter inch ( 3/4", 19mm ) diameter on the base and three cylindrical vee's on the upper plate. The three spheres are not ordinary steel bearing balls; but are ultra fine grain, high chrome, high carbon stainless steel that is hardened to 58 HRC minimum and precision lapped to AFBMA instrument quality grade 10. Standard steel bearing balls used in competitive products are prone to rust and are very susceptible to fretting, which is one of the major problems of Kinematic couplings.

The Kinematic couplings in the upper platform consist of three pair of one-half inch ( 1/2", 12.7 mm) diameter cylinders that form three vees. These cylinders are securely glued into three precision-machined trenches, with a ceramic filled epoxy, that has a 3000-pound per square inch (535 kg per square cm) shear strength. These cylinders are made of exactly the same material and processed in the same manner as the precision balls. After hardening, these cylinders are ground and precision lapped to a surface texture that is below one microinch (25 nm) Ra. This contrasts with competitive products that use commercially ground only dowel pins, made of carbon steel that is prone to rust and very susceptible to fretting.

There are two standard versions of the 12"-16" upper platforms.

It is available with a plain flat top surface, so that our customer can provide any custom mounting facilities they desire; or we will bid machining the mounting features to your blue print or rough sketch. The top surface of this platform is ground flat. This plain configuration is the least expensive. It is part number KP-12-16-P, and costs only $148.00.

The upper platform is also available in our standard breadboard configuration with four precision machined tee slots that use standard three eighths of an inch ( 3/8" ) or M10 Tee-nut hardware. This arrangement allows an infinite variety of mounting configurations. The top surface of this platform is ground flat. This is part number KP-12-16-S, and costs $166.00 each.

There are also two standard versions of the lower platform. The first version of the lower platform is built in a rugged triangular configuration. There are three slots that run the length of each leg of the triangle, that will accept either three eighths of an inch or M10 socket head cap screws, for holding this platform to its mounting surface. There is also a recessed ridge around the inside and outside rim of the triangle that will facilitate the use of hold down clamping. This lower platform is part number KP-12-16-CS, and costs $124.00 each.

The second standard version of the lower platform consists of three separate, one and one half inch ( 1 1/2", 38 mm) wide, by one inch ( 1", 25.4 mm) thick, by five-inches ( 5", 127 mm) long bars. Each bar has an instrument quality, grade 10, sphere rigidly mounted on one end and a four inch long recessed slot, that will accept a three eighths of an inch or M10 socket head cap screw to hold it down. This set of 3 pieces is part number KP-3-HEAVY-BAR, and costs $ 89.00 for a complete set of three pieces.

With a symmetrical light load, the 12-16 platform can repeat in all six degrees of freedom within 4 microinches (0.1 micrometers).

This platform will carry up to 100 pounds ( 45 kg ) of load safely.

Mechanical Hold-Down

The substantial weight of the upper platform, at 16 pounds ( 7.2 kg ), usually precludes the need for additional preload; there are, however, circumstances that do require it.

Vertical Mounting

With it's very rugged construction this platform lends itself to vertical or even upside down mounting.

The facility for mechanical pre loading is built right into the design of the 12-16 Kinematic platform.

A special version of the three quarter inch ( 3/4", 19 mm ) diameter spheres used in both versions of the lower platforms can have a one-quarter inch ( 1/4", 6.4 mm) diameter clearance hole drilled through them. The three quarter inch ( 3/4", 19 mm) diameter Kinematic sphere with clearance hole drilled through it is (our part number 75-270-CH), at a cost of $21.00 each. Three of these parts are required.

Then a one-quarter inch ( 1/4", 6.3 mm ) by 20-threaded hole is drilled and tapped below these spheres. There is a one quarter inch ( 1/4", 6.3 mm) diameter clearance hole drilled through the upper Kinematic platform that allows a piece of continuous threaded stock to screw into the lower platform and pass up through the upper platform.

When mechanical clamping is used, it is important to isolate all of the potential X-Y and Z axial errors to prevent any cocking tendencies when the clamping force is applied. This is done by incorporating a spherical tilt between the clamping force and the top of the platform. This spherical tilt is (our part number 75-ST-270), at a cost of $32.00 each. The full mechanical clamp requires three of these parts.

The clamping force to hold the two platforms together is provided by three, one-inch ( 1", 25.4 mm) diameter knurled clocking nuts, ( part number 250-20-CN), at a cost of $19.00 each. These clocking nuts include a ball thrust bearing that decouples the torque generated by tightening these nuts. A wing nut and washer are supplied to be used as a jam nut, under conditions of moderate vibration. Three of these parts are required.

The clocking nut is a one-inch ( 1", 25.4 mm ) diameter knurled, stainless steel device, with a clocking line engraved on the top face, so that the clamping force generated by tightening it can be repeated time after time. This clamping force will have a major effect on the "Z" axis position as well as the pitch and roll of the upper platform.

Note: If mechanical clamping is going to be required it must be ordered at the time the platform is purchased.

Spring Loading

Spring-loaded clamping may be desirable in some applications. When this option is used it is only necessary to add springs of the proper rate and washers between the clocking nuts and the spherical tilts or between spherical tilt and the platform.

A 12-16 Kinematic platform that is provided with mechanical clamping can be converted back to a simple platform by just unscrewing the three pieces of 1/4-20 continuous threaded stock.

The complete mechanical clamping kit, with all three sets of components, installed on the platform is (our part number 12-16-FS-KIT-750), at an additional cost of $223.00.

Additional information on mechanical clamping of Kinematic couplings may be found in the addendum to our Kinematic Catalog 105A.

Custom Versions

Other features, such as hard anodize, nickel plated surfaces, or precision flat lapped reference surfaces can be supplied on special order.

This Kinematic platform can be supplied with cemented tungsten carbide component parts that will give higher load carrying capacity, a higher resonate frequency and much better repeatability.

The upper platform can also be supplied with a pattern of drilled and tapped holes of either English or metric diameter to suite the customer's requirements.