Kinematic Mount Technology Comparison
(Product Page)
 BiCollar (MKM)
(Product Page)
BiCollar (OTx)
(Product Page)
Sphere-in-Cone and
Contact Geometry Sphere-in-Cone only
In-plane linear
XY and Z fully decoupled
Motion GeometryTop-of-arc
Some Z cross-coupling
2 ton (SPH-M25)
∅4.1cm [~∅1.61"]
Load scales with size2
SPH-M05 - SPH-M50
Load Capacity

Available sizes
2 ton (BC0500)
∅3.7 cm [~∅1.45"]
Load scales with size2
BC0500 - BC2000
1 ton
5 optical table grid points

One size
PerpendicularBolt-through GeometryIn-lineN/A
LowStiction Lower
GoodFatigue Life Best
Minimal Part CountHigher
100% Stainless MaterialSS Kinematic components
Elastic Seal
SS Kinematic components
Al base, Elastic Seal
Best High Vacuum CompatibilityCan vent
>10 years Deployment History1 year
N/A"Flatless" Cone-Groove-FlatAvailable
N/A4-legged mountsAvailable
N/AEmbedded mountAvailable (EKM)N/A
HigherPrice Lower

Contact and Motion Geometries

The Spherolinder acheives a 1-DOF motion by sliding a cylindrical surface in a V-groove, whereas the BiCollar achieves it by combining two ball-in-cone rotations

The ball-in-cone mechanics are superior, but the resultant 1-DOF motion is not a top-of-arc, not a planar straight line. This is the basic trade-off between the two designs.

Load Capacity

Both product families, Spherolinders and BiCollars, offer roughly comparable load capacity for a given footprint - 2 tons over a ~1.5" diameter base (SPH-M25 or BC0500).

This recommended load is for horizontal and static assemblies, and is just under 50% of the calculated yield load for the Herzian contact elements.

For tip-tilt and dynamic loads, the retention pre-load must be calculated in. Care must be taken not to exceed the load limit during assembly.

OTx products are designed only for horizontal static loads. In all cases, load may be limited by the taps for the bolt-down bolts.

For both mounts, load capacity scales with the square of the spherical diameter, so the SPH-M50 and the BC1000 are good for four times as much load, or 8 tons, per mount point.

Bolt-Through Geometry

The Spherolinder uses a single central stud, fixed in place, perpendicular to the plane. The top component is clamped using a set of beleville washers, which give it compliance.

The BiColar mount uses two parallel studs that can rotate to remain along the line-of-force. The top component is clamped using a large beleville washer, but additional spherical nut allow for all motions without relying on spring compliance.

Stiction and Fatigue Life

The sphere-in-cone rotation used by the BiCollar is a better movement compared with the cylinder-in-groove sliding used by the Spherolinder, since there is no “leading edge” to the movement. Additionally, the BC0500 uses simple ground Spheres, which have very high Sphericity and very good surface smoothness.

The reduced stiction manifests itself in lower residual stresses, and therefore inproved repeatability.

An immediate result of reduced stiction is improved fatigue life.

Part Count, material

The Spherolinder is a simpler device that uses large components and is 100% stainless steel. The BiCollar mount is a bit more complex, and has a polymer retainer seal. The OTx version uses Aluminum baseplates and clamp plates.

The Spherolinder naturally has no trapped volumes, and so is better suited for high-vacuum applications. The BiCollar mount can be adapted to high vaccuum service by adding vent channels.

Flatless cone-groove-flat

The regular 3-legged mount uses the "2-2-2" kinematic configuration, which is symmetrical, and uses 3 groove elements.

The MKM and OTx mounts also feature a "3-2-1" kinematic configuration, also known as a "cone-groove-flat". In our version of the mount, we replace the "flat" mount point with a vertical 1-DOF bicollar element that functions in a pretty similar way, but is not alignment-sensitive like other flat mount points.

4-legged mount

MKM and OTx mounts also allow "2-2-1-1" kinematic configuration, which is suitable for rigid rectangular frames. Click here for general information on 4-legged mounts.

Embedded mounts

BiCollar mounts can be embedded directly into your product by integrating the baseplates into your components. Contact us for more details.

Modular Kinematic Mount Part Catalog
Spherolinder Modular Mounts (SPH)

The Spherolinder is our original product line. It is intended for industrial duty, and has the highest load capacity for a given mating surface interface radius. All mating components are fabricated from hardened and precision ground 440C stainless steel. SPH mounts always have three mating elements.

For more information, see Product page
M10 Side A (V and Spherolinders, blind)SPH-M10-BTM-BLIND$2970
Side A (V and Spherolinders, thru)SPH-M10-BTM-THRU$3120
Side B (Cone blocks, common)SPH-M10-TOP$975
M25 Side A (V and Spherolinders, blind)SPH-M25-BTM-BLIND$3255
Side A (V and Spherolinders, thru)SPH-M25-BTM-THRU$3435
Side B (Cone blocks, common)SPH-M25-TOP$1125
M50 Side A (V and Spherolinders, blind)SPH-M50-BTM-BLIND$9000
Side A (V and Spherolinders, thru)SPH-M50-BTM-THRU$9600
Side B (Cone blocks, common)SPH-M50-TOP$2700

Modular Kinematic Mounts (MKM)

MKM products are intended for industrial duty, are designed for high-cycle operation, high loads, and are available in various sizes. Both 3-legged and 4-legged configurations are available.

For more information, see Product page

BC0500 3-Groove (222) Basic SetBC0500-MKM-3G-SET$
Top side onlyBC0500-MKM-3G-TOP$
Top Extended TravelBC0500-MKM-3G-TOPx$
Bottom side onlyBC0500-MKM-3G-BTM$
Spherolinder adapterBC0500-MKM-3G-SPH$
BC0500 Cone-Groove-Flat (321) Basic SetBC0500-MKM-CGF-SET$
Top side onlyBC0500-MKM-CGF-TOP$
Bottom side onlyBC0500-MKM-CGF-BTM$
BC0500 4-Legged (2211) Basic SetBC0500-MKM-2G2D-SET$
Bottom (C) side onlyBC0500-MKM-2G2D-BTM$
Top (V) side onlyBC0500-MKM-2G2D-TOP$
BC0500 4-Legged (3111) Basic SetBC0500-MKM-C3D-SET$
Bottom (C) side onlyBC0500-MKM-C3D-BTM$
Top (V) side onlyBC0500-MKM-C3D-TOP$
BC0500 6-Legged Basic SetBC0500-MKM-6D-SET$
BC0375 Coming Soon!
BC0750 Coming Soon!

Kinematic Mounts for Optical Tables (OTx)

OTx products are intended for lab-duty use, and are designed to attach directly to optical tables and breadboards. The mount is designed for horizontal applications, room temperature, atmospheric environment. Static load limit is 500 kg per mount point, and both 3-legged and 4-legged products are available. OTM for Metric, OTS for Standard optical grids.

For more information, see the Product page

Metric Grid 3-Groove (2-2-2) SetOTM-3G-SET$
3-Groove (2-2-2) TopOTM-3G-TOP$
3-Groove (2-2-2) BottomOTM-3G-BTM$
Cone-Groove-Flat (3-2-1) SetOTM-CGF-SET$
Cone-Groove-Flat (3-2-1) TopOTM-CGF-TOP$
Cone-Groove-Flat (3-2-1) BottomOTM-CGF-BTM$
4-legged (2-2-1-1) SetOTM-2G2D-SET$
4-legged (2-2-1-1) TopOTM-2G2D-TOP$
4-legged (2-2-1-1) BottomOTM-2G2D-BTM$
4-legged (3-1-1-1) SetOTM-C3D-SET$
4-legged (3-1-1-1) TopOTM-C3D-TOP$
4-legged (3-1-1-1) BottomOTM-C3D-BTM$
Metric Grid 3-Groove (2-2-2) SetOTS-3G-SET$
3-Groove (2-2-2) TopOTS-3G-TOP$
3-Groove (2-2-2) BottomOTS-3G-BTM$
Cone-Groove-Flat (3-2-1) SetOTS-CGF-SET$
Cone-Groove-Flat (3-2-1) TopOTS-CGF-TOP$
Cone-Groove-Flat (3-2-1) BottomOTS-CGF-BTM$
4-legged (2-2-1-1) SetOTS-2G2D-SET$
4-legged (2-2-1-1) TopOTS-2G2D-TOP$
4-legged (2-2-1-1) BottomOTS-2G2D-BTM$
4-legged (3-1-1-1) SetOTS-C3D-SET$
4-legged (3-1-1-1) TopOTS-C3D-TOP$
4-legged (3-1-1-1) BottomOTS-C3D-BTM$