Womelsdorf Lab Probe Drives

Overview

This project covers the design of the probe drives used by the Womelsdorf lab. As of 2022, these are mostly derivatives of the "Triad drive" 3-probe drive commissioned in FIXME - year from Kevin Barker of Neuronitek.

The original "Triad" drive has three BNM07-1207 Namiki motors, each with a 105x reduction gear (SPG07-105). These drive #0-80 threaded rods, which move probe-holding "arms" along paths defined by the outer shell of the drive (the "body") and an internal "girder" with precisely-machined channels.

Derivative variants of the "Triad" drive replace the arms, the outer shell of the drive, and the foot of the drive, but keep the basic architecture the same and do not modify the motor section.

Alternate drive designs that are not direct derivatives of the "Triad" drive are noted where present.

Folders

Top-level folders:

• aux-XXX -- CAD files and notes specific to a given auxiliary tool.
• drive-XXX -- CAD files and notes specific to a given drive variant.
• notes -- Assorted notes that apply to several different devices.
• obsolete -- Devices and specifications that are no longer in service.
• procedures -- Assorted SOPs that apply to several different devices.
• reference -- Assorted reference material that isn't vendor documentation.
• vendor-docs -- Vendor-provided documentation and datasheets. Under vendor copyright.

Sub-folders in drive-XXX and aux-XXX:

• bom -- List of vendor-supplied parts needed.
• cad -- Mechanical design CAD files. These are in FreeCAD format.
• cad-ext -- Mechanical design CAD or IGES files imported from a different folder or provided by external sources (usually Isaac).
• datasheets -- Vendor-supplied mechanical drawings and component information.
• drawings -- Mechanical drawings of various components.
• iges -- Exported mechanical designs in IGES format.
• meshes -- Exported solid models in STL format.
• notes -- Assorted notes that are specific to this device.
• photos -- Photographs of the device or of associated equipment.
• procedures -- SOPs that are specific to this device.
• renders -- Screenshots of CAD views of various mechanical assemblies.

Specific Designs

Active Triad drive variants are as follows:

• drive-kevin -- This is the initial Triad drive designed by Kevin for the Womelsdorf lab. There were two variants: the "old" variant had a 45mm long channel for the arms and the "new" variant had a 55mm long channel.

• drive-close-short -- This is a short-reach design with closely-spaced probe sites. This drive is in service (with Kevin-style clips; the M0.5 screw-mount arms are obsolete). This can hold tungsten probes, NeuroNexus probes, and Diagnostic BioChip probes (but not Atlas probes).

• drive-close-long -- This is a long-reach drive with the same closely-spaced sites as the short-reach drive. This drive is in service. Probes are held using Kevin-style clips. Guide tubes are held by a "foot" that extends into the chamber. This drive is mainly used with Diagnostic BioChip probes, which have a mechanical conflict between the probes and guide tubes that limits range with the short-reach drives.

• drive-close-atlas -- This is a long-reach drive that is intended to hold Atlas probes using the same "rectangular rod" scheme as the obsolete "v2b" drive. This drive provides close-spaced probe sites with somewhat wider spacing than the other close-spaced drives.

• drive-kia-dev -- Modified long-reach drives intended to work with Diagnostic Bio-Chip probes, developed by one of our postdocs. This folder contains his development tree (Autodesk CAD files, STL meshes, and gcode for the printer he used).

Relevant auxiliary components are as follows:

• aux-cabling -- This folder contains documentation and models for cables and connectors that the Triad drives and probes interface with.

• aux-clips -- This folder contains CAD models of clips used to hold probes and guide tubes. Some are compatible with Kevin-style clip mounts, while others are intended for different mounting methods.

• aux-jig-atlas-long -- This folder contains design files for tools for loading Atlas probes into long-reach drives (drives that use the "rectangular rod" system for holding probes).

• aux-jig-nnex -- This folder contains design files for the jig used to pre-load NeuroNexus probes into guide tubes. The same jig works with Diagnostic BioChip probes if the block holding the probe is shimmed with tape to raise it.

• aux-mounts-dbc -- This folder contains cable mounts that replace the mounting clip of the Triad drive. These hold the ZIF-clip connector boards used with the 2022 Diagnostic BioChip probes.

• aux-mounts-hflex -- This folder contains cable mounts that replace the mounting clip of the Triad drive. These hold the "heavy flex" analog signal cables used with Atlas and NeuroNexus probes.

• aux-probes -- This folder contains CAD models of probes and CAD models of printable components for making mechanical mock-ups of probes.

• aux-proxies -- This folder contains printable simplified proxy models of drives and associated hardware. These are stencils intended to be used on the mounting frame to check drive setups without needing to fully configure drives.

• aux-washers -- This folder contains spacer "washers" used to raise the Triad drives above their default mounting locations.

Drives not directly tied to the Triad Drive design:

• drive-compact -- This is a single-probe miniature manual drive intended to be arrayed inside the chamber. This is a more manufacturable variant of the 2018 "semi-chronic" drive concept.

• drive-unidrive -- This is a proof-of-concept single-probe drive based on the same principles as the Triad drive but designed to be easier to manufacture.

Remarks

• I've been repeatedly reassured that the Womelsdorf Lab owns all of the IP for the original drives that we commissioned, so there should be no IP issues with derived variants.

• Kevin is a superb engineer. Every aspect of his original design is there for a reason, and the reasons are not always obvious. Kevin also gets precision about twice as good as standard "shop" precision (better than 0.1mm, vs typical shop precision of 0.15 mm or worse). The downside to this is that understanding the original design was nontrivial and third-party parts typically have wobble due to worse tolerances.

• I have a love/hate relationship with the FreeCAD program. It works just well enough that it isn't worth my time to learn a new program, but it has strange ideas about how many operations should be done and it lacks several features that would be helpful for building and testing models. If you need to modify existing mechanical models, I suggest importing .iges models into your preferred CAD program.

• IGES models should be saved as solids (type 186), rather than as surfaces (type 144). Surfaces are the default, but solids can have additional operations performed on them after import (especially boolean operations).

This is the end of the file.