6" X 6" Pre-assembled Kinematic Platform

This 6 inch by 6 inch (152 mm by 152 mm ) Kinematic Platform is designed as a turn key product that is ready to install and use.

It provides a quick, inexpensive solution to the problem of locating and relocating instruments and equipment to accuracies that can be measured in nanometers.

This small platform will carry an enormous 50-pound (23Kg) load.

The kinematic elements of this platform are mounted in the fashion of James Clerk Maxwell from his 1872 treatise.This platform is built kinematically correct.

The three Kinematic Couplings are spaced exactly 120 degrees apart, in an equilateral pattern. If a magnetic or mechanical preload is used, the components that provide the preload are placed exactly on the bisectors of the couplings, so that the force is axiomatic.The overall height of this Kinematic platform from the base to the top is one and one eighth inches, ( 1.125", 28.6 mm).

The kinematic elements are in effect three vees that are formed in the gaps between three pairs of high quality cylinders and three very precise spheres. These spheres are not ordinary commercial steel bearing balls that easily rust and are prone to fretting. They are made of an extremely fine-grained high chrome high carbon stainless steel that is hardened to 58 HRC minimum. The sphericity and surface quality are precision lapped to AFBMA instrument quality grade 10. This quality provides repeatability that can be orders of magnitude better than conventional products.

The six cylinders used for the Kinematic seats in the upper platform are made of the same material and processed in the same manner as the ultra precise balls. After hardening, they are precision ground and lapped, with a final surface texture that is well below one microinch (25 nm) Ra.

This contrasts with commercially ground only dowel pins used in competitive products. The carbon steel used to make dowel pins is prone to rust and is very susceptible to fretting, which is one of the major problems of Kinematics couplings.

The three pairs of cylinders are rigidly mounted in three precision-machined trenches, in the rugged upper, one half-inch (12.7mm) thick aluminum platform. The three spheres are secured in the same manner in the opposing platform. All of the Kinematic elements are permanently secured in place with an extreme strength, ceramic filled epoxy glue, to provide the ultimate in rigidity.

Upper Platform

There are two standard versions of the upper platform offered.

The first is 6 inches by 6 inches (152 by 152 mm) by one half inch (13 mm) thick. It has 24 holes drilled and tapped, in the top surface, that will accept one-quarter inch (1/4", 0.25", 6.35 mm) by twenty threads per inch, screws. This forms a very versatile way for clamping objects on the table. The top surface of this platform is ground flat. This is (our part number KP-6-6-HT), at a cost of $125.00 each.

The second version of the upper platform is 6 inches by 6 inches (152 by 152 mm) by one half inch (1/2", 0.5", 12.7 mm) thick. It has no holes in the top surface, and it is intended for custom installations where a tailored mounting method is used. It is part number KP-6-6-P, at a cost of $ 79.00 each.

If preferred, we will bid machining the mounting apparatus that you need, to your specifications. The top surface of this platform is ground flat. This second version is considerably less expensive than the pre-drilled and tapped design.

An additional feature of the 6 x 6 pre assembled kinematic platform is the availability of sub-plates. These inexpensive sub-plates are the full 6-inch by 6 inch (152.4 mm by 152.4 mm) and are three-eighths inch (9.52 mm) thick.

They are precision ground flat and parallel. There are three counter sunk, one quarter inch (1/4", 0.25", 6.3 mm) diameter holes, that exactly match the hole pattern in the drilled and tapped upper platform (our part number KP-6-6-T).Three flathead screws are supplied with each sub-plate, for attachment.

This inexpensive sub-plate (our part number SP-6-6) has a plain flat upper surface that can be custom tailored to hold your payload. They are priced at $19.00 each.

A tie-down screw kit consisting of a variety of one-quarter inch (6.3 mm), by 20 threads per inch hardware (part number 250-20-TD) is available for $17.00 per lot. This kit consists of the following:

There are two standard versions of the base for the 6" X 6" Kinematic Platform.

The conventional design consists of a rugged six inch by six inch ( 6" X 6", 152mm X 152mm ) by one half-inch ( 1/2", 13 mm ) thick aluminum plate. A shallow relief is machined on the bottom of the plate to leave three one and one half inch ( 3 1/2", 89mm ) square pads, that provide a stable location against the mating structure. A one-quarter inch diameter ( 1/4", 6.3 mm ) counter bored hole, is drilled through the center of each pad so the base can be rigidly clamped down with one-quarter inch or 6mm socket head cap screws. Three pieces of three quarter inch (3/4", 19mm) diameter, high precision spheres are glued into three symmetrical recesses in the top surface of this platform ( part number KP-6-6-CS) at a cost of $ 54.00 each.

The second standard version of the base consists of three rigid bars of aluminum that are one inch (1", 25.4mm) wide by four inches ( 4", 101mm ) long and one half inch (1/2", 12.7 mm ) thick. A high precision three quarter inch ( 3/4", 19mm) diameter ball is glued into a recess at one end and a one-quarter of an inch (1/4", 0.25", 6.4 mm) wide by three-inch (3", 76 mm) long, recessed slot is machined through the bar. This allows the three spheres attached to these bars to be adjusted and clamped down from a wide pattern of one-quarter inch ( 1/4", 0.25", 6mm ) threaded holes. These three bars can also be clamped to Tee Slots in the mating structure. In addition to the three bars we also supply a fourth bar with a five eighths of an inch (5/8", 0.625",16 mm) diameter hole, with 18 threads per inch, through one end to hold our super strength rare earth magnet (see the following paragraphs. It has the same three-inch long hold down slot as the other bars. This is part number KP-4-BAR at a cost of $ 52.00 for the complete set of four.

Magnetic Pre Load

There is a five eighths of an inch ( 5/8", 0.625", 16 mm) diameter with 18 threads per inch, tapped hole, through the center of all the platforms that will accept our standard five eighths of an inch ( 5/8", 0.625", 16 mm ) diameter 18 threads per inch adjustable super magnets (part number 625-18-MG-N or S), at a cost of $23.62 each. This design is far superior to embedded naked magnets.

The first advantage is that you can use the magnets or not, depending on your requirements.

The second advantage is the adjustability of the magnetic force. By using a north seeking magnet in one platform and a south seeking magnet in the other, huge magnetic forces of up to fourteen pounds (14 lb., 6.4 kg) can be generated. By adjusting the separation of the magnets, this force can be attenuated or tuned to give a small fraction of this value.

The third advantage is that when a much smaller force is needed, a high permeability disk ( part number 625-18-HPD), at a cost of $8.62 each, can be substituted for one of the magnets thus cutting the original attraction in half. Using this arrangement, forces of just an ounce (1 oz, 30 g) can be achieved.

The forth advantage is that our five eighths inch ( 5/8", 0.625", 16 mm ) diameter adjustable magnets are well shielded so that there is almost no stray magnetic leakage floating around.

The fifth advantage is that the magnetic pull exerted between the two platforms is axiomatic, thus pulling the two platforms together with perfect symmetry. The price of the magnetic preload kit (our part number 625-18-MG-KIT) including one north seeking magnet (our part number 625-18-MG-N) and one south seeking magnet (our part number 625-18-MG-S) and a high perm plug (our part number 625-18-HPD) is $55.80 each complete set.

Vertical Mounting

Mechanical Clamping

A mechanical clamping technique has been developed for this platform so that it can be used in off axis for fail safe, for high load situations and in high vibration environments.

This mechanical clamping kit consists of a 5/8-inch (16 mm) outside diameter plug with 18 threads per inch, (our part number 625-250-PLUG), at a cost of $12.00 each, that screws into the center hole in the lower platform. It has a 1/4-inch (6.3 mm) by 20 threads per inch, center hole that will accept a length of continuous threaded stock. A similar plug with a .280-inch (7.1 mm) diameter clearance hole, (our part number 625-280-PLUG), at a cost of $12.00, each, which screws into the upper platform. A rather long piece of continuous threaded stock passes through this hole and through a self-aligning spherical tilt (our part number 75-ST-270), at a cost of $32.00 each. This spherical tilt is used to isolate any X-Y or Z misalignment of the clamping force. The entire assembly is tied together by a clocking nut (our part number 250-20-CN), at a cost of $19.00 each. This clocking nut includes a ball thrust bearing that decouples the torque from the clamping. A wing nut and a washer are supplied to use as a jam nut, under conditions of moderate vibration. The entire kit including all of the parts required is (our part number KP-CLAMP), at a cost of $75.00 total.

Spring Load

Custom Versions

Custom versions of this platform will be quoted. The platforms can be supplied, hard anodized or nickel-plated and or with reference surfaces flat lapped.

The same basic design can be built with cemented tungsten carbide components that will give greater load carrying capacity, higher resonant frequency and more accurate repeatability.

It should also be noted that cemented tungsten carbide components will carry very heavy loads, with no signs of fretting.