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Mechanical Essentials Kit: Bases and Post Holders

  • Kit Contains 100 Pieces
  • Stackable, Heavy-Duty Welded Steel Cabinet Frame
  • Cabinet Frame can be Wall Mounted or Stacked
  • Equipped with Easy-to-Read Labels


Kit Components

Related Items

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  • Imperial and Metric Kits
  • Frame Dimensions (L x W x H): 17" x 11" x 11" (432 mm x 279 mm x 279 mm)
  • Drawer Dimensions (L x W x H): 10.56" x 5.19" x 3.06" (268 mm x 132 mm x 78 mm)
  • Clear Labels with Product Icons Facilitate the Process of Locating the Desired Part
  • Greater than 10% Savings Over Individual Items
Back Side of ESK Kit
Click to Enlarge

Slots on the rear of the case allow for wall mounting.

This Bases and Post Holders Essentials Kit contains all of the commonly used post holders, bases, and table clamps in easy-to-use, labeled compartments. The large variety of sizes provides the maximum amount of flexibility when breadboarding an optical system. Refer to the Contents tab above for detailed information about the components included with the imperial and metric versions of this kit. This kit is best used in conjunction with the ESK16 (ESK16/M) Post and Accessory Essentials Kit.

Application Idea: Use the RK4101 rack shelf to organize our ESK Series Essential Kits within our RK3884 standard 19" rack. Post-mounted optical elements can be stored in the 19" rack with the use of the RK4102 rack shelf as shown in the photo to the right.

All ESK Series Essentials Kits are equipped with easy-to-read labels complete with product icons, allowing quick access to all products housed within the kits. All ESK Series Cabinets have slots in the rear of the case, shown to the left, for wall mounting and feature indentations on the top and four feet on the bottom for stable stacking.

Item # in ESK01
Item # in ESK01/M
Description Image Quantity
PH1 PH30/M Post Holder with Spring-Loaded Hex Locking Thumbscrew, L= 1" (30 mm) 1" Post Holder
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PH1.5 PH40/M Post Holder with Spring-Loaded Hex Locking Thumbscrew, L= 1.5" (40 mm) 1.5" Post Holder
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PH2 PH50/M Post Holder with Spring-Loaded Hex Locking Thumbscrew, L= 2" (50 mm) 2" Post Holder
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PH3 PH75/M Post Holder with Spring-Loaded Hex Locking Thumbscrew, L= 3" (75 mm) 3" Post Holder
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PH4 PH100/M Post Holder with Spring-Loaded Hex Locking Thumbscrew, L= 4" (100 mm) 4" Post Holder
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PH6 PH150/M Post Holder with Spring-Loaded Hex Locking Thumbscrew, L= 6" (150 mm) 6" Post Holder
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CL5 L-Shape General Purpose Table Clamp L-Shape General Purpose Table Clamp
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BA1 BA1/M Mounting Base, 1" x 3" x 3/8" (25 mm x 75 mm x 10 mm) Mounting Base, 1" x 3" x 3/8" (25 mm x 75 mm x 10 mm)
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BA1S BA1S/M Mounting Base, 1" x 2.3" x 3/8" (25 mm x 58 mm x 10 mm) Mounting Base, 1" x 2.3" x 3/8" (25 mm x 58 mm x 10 mm)
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BA2 BA2/M Mounting Base, 2" x 3" x 3/8" (50 mm x 75 mm x 10 mm) Mounting Base, 2" x 3" x 3/8" (50 mm x 75 mm x 10 mm)
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S19909 9 Drawer Stackable Cabinet 9 Drawer Stackable Cabinet
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ESK01 SmartPack Packaging
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ESK01 Packaging

Smart Pack

Item #% Weight
ESK01 83.10% 322.46 kg
ESK01/M 83.10% 381.90 kg

Smart Pack

  • Reduce Weight of Packaging Materials
  • Increase Usage of Recyclable Packing Materials
  • Improve Packing Integrity
  • Decrease Shipping Costs

Thorlabs' Smart Pack Initiative is aimed at waste minimization while still maintaining adequate protection for our products. By eliminating any unnecessary packaging, implementing packaging design changes, and utilizing eco-friendly packaging materials for our customers when possible, this initiative seeks to improve the environmental impact of our product packaging. Products listed above are now shipped in re-engineered packaging that minimizes the weight and the use of non-recyclable materials.b As we move through our product line, we will indicate re-engineered packages with our Smart Pack logo.

  • Travel-based emissions reduction calculations are estimated based on the total weight reduction of packaging materials used for all of 2013’s product sales, traveling 1,000 miles on an airplane, to provide general understanding of the impact of packaging material reduction. Calculations were made using the EPA’s shipping emissions values for different modes of transport.
  • Some Smart Pack products may show a negative weight reduction percentage as the substitution of greener packaging materials, such as the Greenwrap, at times slightly increases the weight of the product packaging.

Insights into Best Lab Practices

Scroll down to read about a few things we consider when setting up lab equipment.

  • Washers: Using Them with Optomech
  • Bases: For Stability Orient the Side with the Undercut Down
  • Post Holders: Rectangular Channel in the Inner Bore

Click here for more insights into lab practices and equipment.


Washers: Using Them with Optomech

Washers should be placed between bolts and slots
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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.
Washers distribute force of bolt heads
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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


Bases: For Stability Orient the Side with the Undercut Down

An undercut is machined into the bottom surface of bases like the BA2 (Figures 3 and 4). The undercut creates feet, which are called pads. For maximum stability, the base should be oriented with its pads in contact with the table or breadboard.

The top surface of the base does not have an undercut and is the intended mounting surface for components.

Mounting the base upside down could result in the base rocking on the table or breadboard, or the base may exhibit other mechanical instability.

The Pads are Flatter than the Top Surface
The undercut is key to the flatness of the pads. The pads are machined flat after the undercut is made.

Friction heats the pads during the processing step that provides them with a maximally flat profile. By reducing the surface area of the pads, the undercut reduces the amount of heat generated during this step.

It is beneficial to minimize the heat generated during machining. Metal expands when heated, and the uneven heating that occurs during machining can distort the dimensions of the part. If the dimensions of the part are distorted during machining, the part can be left with high spots and other undesirable features after it cools. This can cause instability and misalignment when using the part.

Precision Instruments and Devices have Pads
Another example of a component with pads is the LX10 linear stage shown in Figure 5.

LX10 with Undercut Indicated, Bottom
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Figure 5: Pads machined into Thorlabs' devices improve their stability when bolted in place. The pads are highly flat and project above the undercut region, which is highlighted red. The undercut limits the contact area with the table or breadboard.
BA2 with Undercut Indicated, Bottom
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Figure 4: This view of the bottom shows the undercut highlighted in red. By removing this material, the pads can be made maximally flat.
BA2 with Undercut Indicated, Top
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Figure 3: For optimal stability, the base should be mounted with the undercut facing the optical table or breadboard.

Date of Last Edit: Dec. 9, 2019


Post Holders: Rectangular Channel in the Inner Bore

Contact Point between post holder and post
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Figure 7: Top view. The three contact locations between the post and post holder, highlighted in red, prevent the post from translating or rotating around the X or Y axes. Friction resists the post's translation and rotation around the Z axis.
Broached channel in post holder
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Figure 6: A channel with sharp edges is machined into the inner bore of Thorlabs' post holders.
Linear Broach
Figure 8: A broach, such as the one illustrated above, has a row of teeth, the next taller than the previous. With the teeth in contact with the material, a machine pulls the broach across the surface. Each tooth removes a small amount of material, and the depth of the channel created by the broach equals the overall difference in tooth height.

All of Thorlabs' post holders include a channel, with straight parallel edges, running the length of the inner bore (Figure 6). Tightening the setscrew pushes the post against the two edges of the channel (Figure 7). Since the edges of the channel are separated by a wide distance, approximately half the inner diameter of the post holder, the seating of the post against the channel's edges is stable and repeatable.

Contact with the two edges of the channel eliminates four of the post's six degrees of freedom, since the edges block the post from translating along or rotating around either the Y or Z axis. In addition, the friction between the side of the post and the edges of the channel resists the post's movement along and around the X axis, which are the post's two remaining degrees of freedom.

Without the channel in the inner bore, there would be a single line of contact between the post and post holder. The position of the post would not be stable, since the post would be free to rotate around the Z axis and shift along the Y axis.

Even if this instability resulted in submicron-scale unwanted shifts in each component's position in an optical setup, the cumulative effect could have a significant negative impact on system performance. In addition, more frequent realignment of the system could be required.

The channel's edges must be straight and free of bumps and roughness to hold the post stable. These post holders have straight, sharp edges when examined on a micron scale. If the edges are not completely linear, the post might rock in the holder, and / or it may not be possible to repeatably position the post in the holder.

The smooth, straight edges of the channel are achieved using a machining process called broaching. A broach (Figure 8) resembles a saw whose teeth increase in height along its length.

As the broach is pulled along a surface, each tooth removes a small amount of material. The total depth of the channel cut by the broach equals to the overall difference in tooth height (H2 - H1).

Compared with other approaches for creating channels, broaching is preferred due to its ability to provide straight profiles while being compatible with high-volume production.

Date of Last Edit: Dec. 11, 2019

Posted Comments:
peter.bechtold  (posted 2017-06-14 08:31:32.333)
Hey Thorlabs team! Great work, keep it up. We do not use your kits, but make up our own kits using Thorlabs equipment. But we would like to use your kind of labels used on the optomechanic kits (the small pictograms + article numbering). Are those available anywhere? Thanks and BR, Peter.
nbayconich  (posted 2017-06-26 05:22:01.0)
Thank you for contacting Thorlabs. We can provide these labels. I will reach out to you directly with more information.
Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Imperial Price Available
ESK01 Support Documentation
ESK01Bases and Post Holders Essentials Kit, Imperial and Universal Components
+1 Qty Docs Part Number - Metric Price Available
ESK01/M Support Documentation
ESK01/MBases and Post Holders Essentials Kit, Metric and Universal Components
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