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Kinematic Platform Positioners
1/4"-20 (M6) Slot
A KL03L plunger provides the opposing force to a KL02 positioner. Using the KL02 adjuster, a BA2 base can move forward or backward, as indicated by the arrows.
Ball Tip Provides
3/16"-120 Fine Actuator and 1/4"-20 (M6) Taps
These kinematic positioners can be used individually or in functional groups for a variety of quick breadboard positioning and adjustment applications. The simple design and low cost make these mounts perfect alternatives for optomechanical positioning requirements when a precision translation stage is not necessary.
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Washers: Using Them with Optomech
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Figure 2: Install washers before inserting bolts into slots to protect the slot from damage. The rounded, smooth side of the washer should be placed against the slot, and the rough, flat side should be in contact with the bolt head. The smooth surface is designed to translate easily across the anodized surface, without harming it. The BA2 base is illustrated.
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Figure 1: The diameter of the washer is 35% larger than that of the bolt head. This results in over a six fold increase in overlap area with the slot of a BA2 base. By distributing the force of the bolt over a larger area, the washer help prevent gouging of the slot.
The head of a standard cap screw is not much larger than the major diameter of the thread (Figure 1). For example, a 1/4"-20 screw has a head diameter between 0.365" and 0.375" and the clearance hole diameter for the threads is 0.264".
When the screw is tightened directly through the clearance hole to secure the device, the force is applied to the edge of the through hole, often cutting into the material (Figure 1).
Once the material is permanently deformed, the screw head will want to fall back into the gouged groove, thereby moving the device back to that location when attempting to make fine adjustments.
A device with a circular through hole is not meant to translate around the screw thread so the deformation is not expected to be a problem.
However, a slot should provide the ability to secure the device anywhere along the length for the lifetime of the part. Using a washer distributes the force away from the slot edge to decrease the chance of deforming the slot and extending the lifetime of the part. Figure 1 illustrates the difference a washer can make. The contact area between the slot of a BA2 base and a 0.27" diameter cap screw is 0.010 in2. When a 0.5" diameter washer is used the contact area is 0.064 in2, which is over six times larger.
When using a Thorlabs washer, there are two distinct sides (Figure 2). One side is flat and rough and the other is curved and polished. The curved and polished side should be placed against the device, which has an anodized surface.
As the screw tightens, the screw head can force the washer to spin against the anodized coating.
If the flat side is pressed down against the anodization, the friction created by the rough flat side can scratch the anodized aluminum. However, if the curved side is facing down, the smooth surface has less friction leading to less scratches and extending the visual appearance of the device.
Date of Last Edit: Dec. 4, 2019
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Our Fixed Kinematic Stops can be used alone, in pairs to define a reference edge, or as a group of three to define a reference edge and stop. Each stop has a hardened steel ball for a true one-point contact on one end and a base that is machined with a wide, bottom-located relief cut for stable positioning when mounting to an optical table. The KL01 is convenient to use in space constrained applications because it has a smaller slot and more compact design. The KL01L has a longer slot, capable of spanning two tapped holes at a 45 degree angle on an optical table. This allows the KL01L to be secured to a table using two cap screws, providing more stability and resistance against rotation in a system.
As shown in the photo to the right, the fixed kinematic stops are useful in repeatable positioning when swapping a base plate or breadboard in and out of an optomechanical setup. Our kinematic stops maintain the position of an MB8 Breadboard with DF1 Low-Friction Feet. To match the height of the breadboard and low-friction feet, each stop is mounted on a BA2S6 Spacer. A KL01 and KL01L are used to define a line on one edge of the breadboard, while one KL01 acts as a stop for the perpendicular edge of the breadboard. Thus, the breadboard can be removed from its position and returned with good repeatability.
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Our Spring-Loaded Plungers can be used to hold an object firmly against Kinematic Stops or an Adjustable Positioner. The high-strength plastic plunger on both the KL03 and KL03L applies spring pressure over a travel range of 0.25" (6 mm). The plunger tension can be adjusted using a 5/32" (4.0 mm) hex key. The KL03 is convenient to use in space constrained applications because it has a smaller slot and more compact design. The KL03L has a longer slot, capable of spanning two tapped holes at a 45 degree angle on an optical table. This allows the KL03L to be secured to a table using two cap screws, providing more stability and resistance against rotation in a system.
In the photo to the right, one KL03 plunger is used with two KL01 kinematic stops while one KL03L plunger is used with a KL02 adjustable positioner to translate a BA2 base back and forth along a line. On one side of the base, two KL01 stops define a reference edge. On the opposite side, the KL03 presses the base against the two stops and prevents it from moving in the direction perpendicular to the reference edge. Along the other edges, the KL03L plunger presses against a KL02 adjustable positioner. Without the KL03L, the KL02 could only push the base forward. However, in this setup, as the KL02 is retracted, the KL03L provides an opposing force that pushes the base back.
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Our Adjustable Kinematic Positioners provide the same spherical contact as the Fixed Kinematic Stops presented above but adds fine adjustment capability with a 1/4"-80 actuator used as a "nudger." This feature allows for precise positioning not achievable by hand. These kinematic positioners are ideally used with two KL01 or KL01L stops to define a reference edge for a translation path. The KL02 is convenient to use in space constrained applications because it has a smaller slot and more compact design. The KL02L has a longer slot, capable of spanning two tapped holes at a 45 degree angle on an optical table. This allows the KL02L to be secured to a table using two cap screws, providing more stability and resistance against rotation in a system.
In the photo to the right, a KL02L kinematic positioner is used to nudge a BA2 base forward along a line. The line is defined by two KL01 stops which are positioned on one side of the base. A plunger on the opposite side of the base ensures that the base stays against both fixed kinematic stops while sliding forward.
Click to Enlarge UBP2 Base Along a Straight Line
The APM05(/M) Adjustable Kinematic Positioner allows for the precise positioning of breadboards or optomechanics. It contains a high-precision 3/16"-120 hex adjuster (Item # F19MS150) that has a maximum axial load capacity of 5 lbs (2.3 kg). It can be actuated using a 5/64" (2 mm) hex key, providing fine positioning. If longer or shorter translation ranges are required, the adjuster can be replaced with any other 3/16"-120 hex adjuster.
A side-located 1/4" (M6) counterbore allows the adjuster to be attached to a breadboard, base, or to the 1/4"-20 (M6) end of a Ø1/2" post using a 1/4"-20 (M6) cap screw. In addition, it can be mounted to a Ø1/2" post using a bottom-located flexure clamp, which is tightened using a side-located cap screw and a 9/64" (3 mm) hex key. When mounted via the flexure clamp, the adjuster will be centered on top of the post. In contrast, when mounted using the side-located counterbore, the adjuster will be offset to the side by 0.40" (10.2 mm).
This adjuster can be used with any 1/4"-20 (M6) tapped optomechanics or tables, as shown in the photo to the right. The photo shows the APM05 used in combination with two KL01 Stops and one KL03 Spring-Loaded Plunger to adjust the position of a UBP2 Universal Base Plate along a straight line.
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APM07 on a Rail Carrier to Finely Position Rail-Mounted Optomechanics
The APM07(/M) Adjustable Kinematic Positioner allows for the precise positioning of breadboards or optomechanics. It contains a high-precision 3/16"-120 hex adjuster (Item # F19MS150) that has a maximum axial load capacity of 5 lbs (2.3 kg). It can be actuated using a 5/64" (2 mm) hex key, providing fine positioning. If longer or shorter translation ranges are required, the adjuster can be replaced with any other 3/16"-120 hex adjuster. The positioner features two 1/4"-20 (M6) taps for mounting.
Alternatively, this adjuster can be mounted on a Ø1/2" post using a 1/4"-20 (M6) cap screw or setscrew as shown in the photo above. The photo shows the APM07 used with the APM06 Spring-Loaded Plunger to adjust the position of a lens mounted on the KMCP Centering Plate. The adjuster will be offset from the center of the post by 1/2" (12.7 mm) making it ideal for setups on Double Density Breadboards.