Optical Posts and Post Holders

We all love our friends at ThorLabs, but sometimes you just need a quick part and you don't have the cash or time to wait for one to arrive with your order of Lab Snacks. The solution, 3D printable optomechanics! A detailed Printables article on the system and designing your own components to interface with it is will arrive Soon (TM).

Here are the core components of the 3D printable optomechanics system! Fully parametric and customizable posts and post holders! Customize to your needed length, fastener type, alignment angles, and mounting patterns. All designed to print easily and reliably on any FDM 3D printer.

The system maintains compatibility with most (if not all) of your existing optomechanics and continues to grow with more 3D printable components including cage system mounts, breadboards, and lens holders.

This Printables listing includes a subset of quick print options using M6 nuts as these are the kind I use the most in my own lab. For other fastener types (1/4-20, M4,  or 8-32) as well as infinite combinations of length and mounting patterns, see the OnShape Configurator.

If you download your parts from OnShape, please download a version from here or drop a like here on Printables so that more people can find the system.

If you find the system useful, please share it with your colleagues. If it makes your lab easier or cheaper to setup, perhaps Buy Me a Coffee so I can continue to develop the system and keep it free and openly available under the Open Community License (OCL) with the General Attribution (GAtt) Plugin. 

If you have any issues, please drop a comment or send me a message. Bug fixes and suggestions are greatly appreciated. You are also welcome to develop and upload your own components for the system! Just be sure to share them under OCL or any non-commercial, share-alike license of your choice.

Recommended Print Settings

The system is designed to be as simple to print as possible. No supports, no special materials, no slicer tricks. I started developing the system on a Prusa Mk3s and am now using a Snapmaker U1 and Prusa XL. General printing guidelines are as follows:

• Print in PLA for maximum rigidity and ease of printing. 

• Use PETG, PCTG, or Carbon Fiber reinforced filaments if you need higher temperature stability (staring at your combustion researchers).

• If you are having problems with warping on longer posts, I recommend a fiber reinforced filament like PETG-CF or PET-GF.

• Use three perimeters with five top and bottom layers for best results.

• Designed for a 0.2 mm layer height, but there is not reason you couldn't got thicker or thinner. No particular reason to go smaller as details are designed for 0.2 sizing on a 0.4 mm nozzle.

• Infill is not critical here. I usually use 10% Adaptive Cubic. If you find yourself having warping problems, a non-linear infill type like Gyroid may be helpful.

• Print orientation should have all nut pockets facing upwards. An example of good part orientation is shown in the slicer image below.

Part Numbering Convention

• Post-L<length in mm>-<A or U>-<nut type>

  • E.g. Post-L200-A-M6 is a 200mm long post with an alignment tab (A) and an M6 nut pocket.

  • E.g. Post-L123-U-8 is a 123mm long post with no alignment tab (U) and a 8-32 nut pocket.

• Holder-W<base spacing in mm>-H<height in mm>-<L, R, and/or C<slot length in mm>>-<nut type>

  • E.g. Holder-W50-H100-LR-1-4 is a 50 mm base hole spacing, 100 mm tall post holder with left (L) and (R) tabs and a 1/4-20 locking nut pocket.

  • E.g. Holder-W50-H100-C20-M4 is a 80 mm base hole spacing, 40 mm tall holder with just a 20 mm long center tab (C) and an M4 locking nut pocket.

    • Note that the W base width parameter is somewhat vestigial for a C only case but it is kept for completeness to the CAD configuration.

Assembly and Use Instructions

1. Insert nuts into the appropriate nut pockets. If the tolerance is tight, thread the nut into a screw to provide more leverage when inserting them. Any standard sized flat nut should fit. I sized based on parts ordered from Amazon.co.jp and McMaster.com dimensions.

2. For compatibility with non-alignment tabbed, legacy components, use 16~20 mm long set screws.

3. Slot the post into its holder.

4. Tighten the locking screw into the nut from the front. You'll hear a cracking-like sound when the post locks into the holder. This is the post layer lines snapping into the layer line of the holder dovetail. This is where you should stop tightening the locking screw. Tightening further will simply dent the post.

   1. As a bonus, print these knurled screw caps for the screws.

5. For proper, well squared locking of the post into the holder, do not extend it higher than the bottom of the two braces on the back of the holder. If you need more height, print a longer post or taller holder at this point.

6. Remember, plastic is cheap, your time isn't. Don't kludge things together when you can just configure and print the exact size and type you need.

Configuration Parameters

• Post Length (mm): The height or length of the post

  • Minimum post length if 25 mm.

• Holder Height (mm): The height of the post holder.

  • I.e. the length of the slot into which a post can be inserted.

  • Minimum holder height of 40 mm.

• Base Hole Spacing (mm): The spacing between mounting holes on either side of the holder base.

  • Minimum spacing is 50 mm

  • E.g. For a 25 mm spaced optical table, set it to 50 mm.

  • E.g. For a 1 inch spaced optical table, set it to 50.8 mm.

  • E.g. For a double width 4040 extrusion rail, set it to 80 mm.

• Slot Tolerance (mm): This is the tolerance between the post outer dimensions and the slot inner dimensions. The post size is fixed and adjusting this value will make the slot slightly larger.

  • 0.3 mm is a good default for most modern printers with PLA.

  • You can tweak this value based on how easily you want the post to move within the holder or your own printers tolerances. 

• Locking Screw Type: Choose from M6, M4, 1/4-20, or 8-32 screw sizes for mounting components to the ends of the post and for the locking nut in the post holder. A standard flat nut for this size is inserted into the post and holder locking nut pockets.

  • The system is most tested with M6 and M4 sizes. Please report if you have sizing issues with the 1/4-20 or 8-32 screws. The slots are designed for a press or line-fit such that nuts are retained within their pockets.

• Post Alignment Tab: A unique feature of this system is a 9x3 mm tab at one end of the posts. This interfaces with slots on the component accessories such that thread location and tightness does not control the directionality of the mounted component. See the image below for the post with (left) and without (right) the alignment tab.

  • When using the system with non-printed or legacy components, un-check this box or simply use the opposite end of the post as only end has the alignment tab.

• Post Core Cylinder: The post has a hollow cylinder at its core. This serves to improve the rigidity of the part. However, on longer parts it can make the part more likely to warp.

  • Disable if your have warping issues but keep it if your don't as it will improve the function of your posts.

• Center Slot Tab: Check to include a M6 or 1/4-20 sized slotted tab off the center of the holder.

  • Center Tab Length (mm): The length of the center slot tab.

    • This option will only appear if the Center Slot Tab option is checked. 

• Right Base Tab: Check to include a M6 and 1/4-20 sized mounting tab on the right.

• Left Base Tab: Check to include a M6 or 1/4-20 sized mounting tab on the left.

• Mouse Ears: Check to add single layer brims at the tips of the post and post holder to improve first layer adhesion and prevent part warping. 

  • This becomes more necessary if printing in PETG, on a diry build plate, or for longer parts. It is recommended to try your print without mouse ears first and add them only if your particular setup requires them to keep your posts straight and your holders square.

Note that your may generate any combination of tabs desired including no tabs at all. All holders include a M6 or 1/4-20 sized and counter-bored hole at the bottom of the post cavity which can be used to mount the holders directly to breadboards, custom mounts, or existing post holder plates.