Bulkhead Documentation

General Notes on Cable Penetration

Previous Waterproofing Method (2025)

• Method did not hold under stress.
• Tugging or bending the cable near the bulkhead caused water leaks, especially at depth.

Diagram of Water Leak

CAD Diagram of Previous Bulkheads

• Component cost: very low, only cents per piece.

CAD Diagram of Improved Bulkheads

• Cost: ~$10 per bulkhead.
• Pins require purchasing corresponding wires in predetermined quantities.
• You would think "Wait don't you get the same issue as the previous" But this time, we can fill the cavity of the detachable component with epoxy, and the part will still be detachable. This feature needs to be tested as of 2/28/26.

SP13 6-Pin Waterproof Male Plug / Female Socket (Panel Mount)

Price: $7–10
Product Link: https://a.co/d/0dtU4ycA

Notes

• We will be using SP1310/S6I and SP1310/P6I connectors. Type I connectors have outer diameter range 4-6.5 mm, and our cable has diameter 4.5mm.
• This link to aliexpress has the type I connectors for cheaper.
• The outer cable diameter has a range instead of a specific diameter since they want to keep it open for users.

Usage

Images

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Bulkhead Specifications

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Waterproof USB-C Panel Mount Coupler (Dual Port USB 3.1 Type-C)

Price: $7–10
Product Link: https://a.co/d/039xJJgL

Notes

Usage

Images

Drilling Holes

Drill Press Setup

• Use a vice with thin pieces of wood between the vice and the box.
• Clamp the vice to the drill press platform.
• Recommended drill press speed ~700 RPM (verify ideal speed experimentally).
• Drill press shown: DIB wood shop model.

Wooden pieces used in the process

Note that using the 1/2 drill bit size resulted in a slightly too small hole for the SP13 Bulkhead penetrator. Needed to sand it in order for the right fit.

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Step Bit Usage

• Step bits can start or expand holes.
• Some DIB step bits are dull; avoid forcing holes to prevent melting plastic.

Step bit used to start holes. Found in the top drawer next to drill press in DIB metal shop. Important sizes: 1/2", 9/16", 13/16".

Step bit for expanding holes ≥1/2". Longer steps produce smoother results.

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Step Bit vs Forstner Bit

Left: Step bit, Right: Forstner bit

Step drill hole — smoother outside finish

Forstner bit hole — jagged edges, uneven diameter

Step bit, nice finish.

Permanent Installation

Mixing Epoxy

Mixed batch of two-part epoxy resin in a small plastic cup

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Applying Epoxy to Bulkheads

Excess resin visible squeezed out between the bulkhead and the box

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Waterproofing results to be updated.

Waterproof testing

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Research further:

https://www.aliexpress.us/item/2251832570925901.html?spm=a2g0o.productlist.main.23.43aa3iTh3iTh5A&algo_pvid=7b2f07fb-133e-4e33-b85a-fb02a668bb16&algo_exp_id=7b2f07fb-133e-4e33-b85a-fb02a668bb16-20&pdp_ext_f=%7B%22order%22%3A%226001%22%2C%22eval%22%3A%221%22%2C%22fromPage%22%3A%22search%22%7D&pdp_npi=6%40dis%21USD%211.78%211.25%21%21%211.78%211.25%21%40210328d417775749530992993e3f65%2112000046695116135%21sea%21US%216452185011%21X%211%210%21n_tag%3A-29919%3Bd%3A36ec700b%3Bm03_new_user%3A-29895&curPageLogUid=NQFn7qIVgRS4&utparam-url=scene%3Asearch%7Cquery_from%3A%7Cx_object_id%3A32757240653%7C_p_origin_prod%3A

https://www.aliexpress.us/item/2255799893315943.html?spm=a2g0o.productlist.main.24.43aa3iTh3iTh5A&algo_pvid=7b2f07fb-133e-4e33-b85a-fb02a668bb16&algo_exp_id=7b2f07fb-133e-4e33-b85a-fb02a668bb16-21&pdp_ext_f=%7B%22order%22%3A%22125%22%2C%22eval%22%3A%221%22%2C%22fromPage%22%3A%22search%22%7D&pdp_npi=6%40dis%21USD%212.26%212.03%21%21%212.26%212.03%21%40210328d417775749530992993e3f65%2110000000211802128%21sea%21US%216452185011%21X%211%210%21n_tag%3A-29919%3Bd%3A36ec700b%3Bm03_new_user%3A-29895&curPageLogUid=9boodlCeezha&utparam-url=scene%3Asearch%7Cquery_from%3A%7Cx_object_id%3A4000079630695%7C_p_origin_prod%3A

This one is good? https://www.aliexpress.us/item/3256809856081754.html?spm=a2g0o.productlist.main.28.43aa3iTh3iTh5A&algo_pvid=7b2f07fb-133e-4e33-b85a-fb02a668bb16&algo_exp_id=7b2f07fb-133e-4e33-b85a-fb02a668bb16-25&pdp_ext_f=%7B%22order%22%3A%22270%22%2C%22eval%22%3A%221%22%2C%22fromPage%22%3A%22search%22%7D&pdp_npi=6%40dis%21USD%216.15%211.99%21%21%2141.84%2113.54%21%40210328d417775749530992993e3f65%2112000050926467996%21sea%21US%216452185011%21X%211%210%21n_tag%3A-29919%3Bd%3A36ec700b%3Bm03_new_user%3A-29895%3BpisId%3A5000000203799455&curPageLogUid=cE0LKSAIo59b&utparam-url=scene%3Asearch%7Cquery_from%3A%7Cx_object_id%3A1005010042396506%7C_p_origin_prod%3A

General Search: https://www.aliexpress.us/w/wholesale-sp13-waterproof-connector-6p.html?spm=a2g0o.productlist.search.0

Amazon link for the one we already have is at the top of this page.