# NK3D Common Base V1 — Hardware BOM

Quantities below are per installed base. Choose either the proposed kayak fixing arrangement or the wood arrangement. Hardware is not included. No exact bolt, well nut, screw, pad or sealant has been selected or physically checked.

**Status terms:** “Verified in CAD” refers to the supplied geometry checks only. “Modeled assumption” is a nominal installation or render assumption, not a verified hardware fit. “Requires selection” means the exact part and its compatibility remain open.

## Shared printed part

| Item | Qty | Thread | Length / size | Material | Head / washer | Source | Status |
| --- | ---: | --- | --- | --- | --- | --- | --- |
| NK3D Common Base V1 | 1 | Unthreaded Ø5.5 mm bores | 58 × 35.1349 × 7.4 mm; 40 mm fixing centres | Printed polymer; filament and process to evaluate | Two 90° countersinks, Ø11.6 mm deck opening; no head washer | [Supplied STL](../PRINT/nk3d-common-base-v1.stl) and source geometry | Verified in CAD: one solid, one connected watertight mesh. Printed properties and fit untested. |

PETG is a candidate for a first prototype, not an established material specification for this base. Prusa's [PETG guide](https://help.prusa3d.com/article/petg_2059) discusses PETG for mechanical parts and its printing considerations. Follow the selected filament and printer guidance; the material choice does not establish a load or weather rating.

## Proposed kayak arrangement

| Item | Qty | Thread | Length / size | Material | Head / washer | Source / example | Status |
| --- | ---: | --- | --- | --- | --- | --- | --- |
| Countersunk bolts | 2 | M5; pitch matched to selected well nuts | Select for assembled base, support and required engagement; no fixed length | Corrosion-compatible material; stainless grade remains to select | 90° countersunk head; actual diameter, height and flush seating to check. No flat washer under the head. | [Westfield ISO 10642 guide](https://www.westfieldfasteners.co.uk/Standards/ScrewBolt-SHCsk-M.pdf), generic dimensional reference | Modeled assumption: M5 fixing strategy. Requires selection and physical seat check. |
| Well nuts | 2 | M5, matching bolt pitch | Fixing length, grip range, flange diameter/thickness and hull-hole diameter to select | Supplier-selected rubber sleeve and threaded insert; KayFast example uses brass insert | Flange below base; no generic flange recess is present in V1 | [KayFast rubber well nuts](https://www.kayfast.co.uk/view-product/Rubber-Well-Nuts), generic example | Requires selection for actual hull thickness, material and available clearance. |
| Firm matching support pad / shim | 1 arrangement | — | Measured for the deck and two selected well-nut flanges | Compatible firm support material; selection required | Accommodates flanges without rocking; supports flat base rather than forcing it into curvature | Custom measured installation part; no pad STL supplied | Requires selection/design for actual installation; not modeled in the base. |
| Compatible bedding / seals | As needed | — | Determined by actual head/shaft and hull penetration paths | Compatible with hull, print and hardware | Does not replace firm support | Selected product supplier's compatibility and installation instructions | Requires selection; no waterproof installation verified. |

### What the example sources establish

The Westfield guide lists M5 countersunk screw dimensions including a theoretical maximum head diameter of 11.20 mm and maximum head height of 3.10 mm. Those values are reference limits, not the dimensions of a chosen bolt. The base's Ø11.6 mm opening and 3.05 mm conical depth do not, by themselves, prove flush seating of a real truncated screw head. Check the actual part in the printed seat.

KayFast lists M5 well-nut examples with different fixing lengths and grip ranges: 15 mm length with 0–5 mm grip, and 25 mm length with 8–16 mm grip. Its M5 examples specify a 10 mm fixing hole and 14 mm flange diameter. These are **example product dimensions, not drilling instructions for this base or a chosen kayak**. The flange thickness and complete installation stack still need to be established for the selected part.

Do not buy or drill from thread size alone. The base bore is Ø5.5 mm; the hull hole is determined separately by the chosen well nut. No clamp force, bolt torque or installation capacity is established here.

## Wood / shed-board arrangement

| Item | Qty | Thread | Length / size | Material | Head / washer | Source | Status |
| --- | ---: | --- | --- | --- | --- | --- | --- |
| Countersunk wood screws | 2 | Wood-screw form selected for actual substrate | Shaft must clear the printed Ø5.5 mm bore; length and embedment to select for the actual board/backing | Material/coating suitable for the location | 90° countersunk head compatible with Ø11.6 mm seat; check actual head. No flat washer under the head. | Generic local fixing supplier; no exact product chosen | Modeled assumption: two wood fixings in illustrative renders. Requires selection and physical seat check. |
| Sound board / structural backing | 1 mounting location | — | Thickness, support and fixing location to select | Actual wood/substrate | Flat support beneath the base | Actual installation | Requires selection; representative plywood renders are not tested substrate evidence. |

Wood-screw pilot diameter is specified by the selected screw and wood, not by the base bore. The render's screw arrangement does not establish screw length, embedment or holding strength.

## Checks before ordering

- Check the actual countersunk head geometry and drive access against a first print.
- Check length and engagement against the whole installed stack.
- For well nuts, establish grip range, hull-hole size, flange dimensions and expansion clearance before drilling.
- Provide firm support beneath the flat base and accommodate both flanges without bending the base.
- Select sealing and corrosion compatibility for the actual materials and environment.

See the [installation guide](INSTALLATION_GUIDE.md) for the sequence and [representative exploded render](../IMAGES/05_HARDWARE_EXPLODED.png) for context. The render is illustrative and does not substitute for selected hardware dimensions.


# NK3D Common Base V1 — Installation Guide

V1 is a base geometry prototype. No physical fit, strength or installation testing has been completed, and there is no load rating. A receiver, latch and accessory are not supplied. Check the first print and select the mounting hardware before making permanent holes.

## Know the interface

| Feature | Nominal CAD / exported STL |
| --- | --- |
| Overall exported STL | 58 × 35.1349 × 7.4 mm |
| Main deck | 7.0 mm above the flat underside |
| Perimeter crest | 7.4 mm above the underside |
| Upper flank widths before rounding | 28 → 36 mm |
| Fastener centres | 40 mm apart; 9 and 49 mm from the narrow end |
| Shaft bores | Ø5.5 mm |
| Countersinks | 90°; Ø11.6 mm at the main deck; 3.05 mm cone depth |

The base holes clear the proposed M5 bolts. They do not specify a hull hole or a wood-screw pilot hole. Those holes depend on the selected fixing and substrate.

## Before mounting

1. Print the base underside down at 100% scale. See the [print guide](PRINT_GUIDE.md).
2. Inspect the print for missing material, cracks, distorted shoulders and blocked holes. Clear loose strings or debris without changing the capture surfaces.
3. Measure the hole spacing and check the selected fasteners in both seats. The shaft must pass freely. The actual 90° head must seat flush with or below the 7.0 mm main deck without forcing or damaging the print. A nominal M5 thread does not establish head fit.
4. Confirm the base has firm, continuous support appropriate to the surface. It must not rock on well-nut flanges or be pulled into a curve by tightening the fasteners.
5. Check access behind the mounting surface, drilling clearance and the future receiver's insertion and release space. Verify the receiver against the full 7.4 mm crest and the raised end rims.

Do not add a flat washer beneath a countersunk head: this model uses a conical head seat. Any additional support or sealing belongs in a separately selected installation arrangement.

## Shed board or wood installation

Use two 90° countersunk wood screws compatible with the printed Ø5.5 mm bores and Ø11.6 mm seats. Screw diameter, head dimensions, length, pilot diameter and embedment must suit the actual wood and selected screw. Thin panel material alone is not automatically a suitable anchor; use a sound board or appropriate structural backing.

1. Choose a flat, firmly supported mounting location. Position the base so the future receiver has room to slide on and off. Wide end down is the intended gravity-seating direction on a wall; it does not replace receiver retention.
2. Mark both fixing centres from the checked print. Confirm the 40 mm spacing before drilling.
3. Drill the pilot holes specified for the selected screws and wood. Do not use the base's Ø5.5 mm clearance diameter as the pilot-hole specification.
4. Fit both screws and tighten gradually, alternating between them. Stop if the base bows, cracks or loses flat support. No installation torque has been validated for this printed base.
5. Confirm both heads remain flush or below the deck, and that the base cannot rock or shift by hand. This is an installation check, not a load test.

The supplied wood-board installation images use generic reference heads and a modeled screw arrangement. They do not identify a selected screw length or demonstrate physical testing.

## Proposed kayak installation: M5 bolts and M5 well nuts

Select two M5 well nuts and compatible 90° countersunk M5 bolts for the actual hull material, thickness, mounting location and environment. Check the well-nut grip range, required hull-hole diameter, flange diameter and thickness, expansion clearance, thread engagement and bolt length using the selected supplier's instructions. The [hardware BOM](HARDWARE_BOM.md) gives examples, not a chosen fixing kit.

The underside of this STL is flat and has **no well-nut flange recess**. A curved deck adds another support requirement. Use a measured, firmly supported pad or shim that matches the deck and accommodates the selected flanges. A thin soft gasket alone does not establish structural support. Keep the base STL unchanged; any required support is a separately selected part.

1. Confirm the location and fixing method are suitable for the actual kayak before drilling. Check behind the hull for cables, mechanisms and sufficient well-nut expansion space.
2. Measure the hull thickness at the fixing locations and dry-fit the selected support arrangement. The base must sit level and firmly supported without bolt tension.
3. Mark the two centres from the checked print. Drill the hull using the selected well-nut supplier's specified diameter, not Ø5.5 mm.
4. Fit the well nuts and the support arrangement as instructed by their supplier. Select bolt length for the complete assembled stack and required engagement; do not infer it from the 7.4 mm base height alone.
5. Use compatible bedding or seals for the hull, printed polymer and selected hardware. Address hull penetrations and the head/shaft water path as the chosen installation requires. This base alone does not create a waterproof mounting.
6. Start both bolts by hand. Tighten according to the selected well-nut instructions while watching the base and support. Stop if the base rocks, bows or cracks, or a well nut spins. Do not pull the flat base into deck curvature.
7. Check for movement, head clearance and leakage using the actual installation. Reinspect after initial use and periodically for loosening, print damage or support movement.

No universal hull-hole size, bolt length, pad thickness or torque is specified because the actual well nut and kayak have not been selected.

## Before adding an accessory

The base alone supplies neither a complete receiver nor a validated withdrawal latch. A future receiver must clear the perimeter, fastener heads and badge area, and must provide positive retention and accessible release in its installed orientation. Check the complete receiver, accessory, hardware and substrate together before assigning a working load.

## Reference images

- [Print orientation](../IMAGES/07_PRINT_ORIENTATION.png)
- [Representative hardware arrangement](../IMAGES/05_HARDWARE_EXPLODED.png)
- [Representative shed-board installation](../IMAGES/08_PHOTOREALISTIC_INSTALLED.png)
- [Installed close-up render](../IMAGES/09_PHOTOREALISTIC_CLOSEUP.png)

## Sources

- Geometry: supplied V1 `parameters.json`, `verification.json` and original README, included in the source archive.
- [Westfield Fasteners — ISO 10642 countersunk screw specification](https://www.westfieldfasteners.co.uk/Standards/ScrewBolt-SHCsk-M.pdf): generic head-dimension reference; not a selected bolt.
- [KayFast — Rubber Well Nuts](https://www.kayfast.co.uk/view-product/Rubber-Well-Nuts): supplier example showing separate fixing lengths, grip ranges, hull-hole sizes and flange dimensions; not the selected installation hardware.


# NK3D Common Base V1 — Print Guide

This is the first geometry prototype of the common base. It has not been physically printed or tested. The supplied STL has passed geometry checks, but that does not establish print quality, fit, strength, wear, sealing or outdoor life. There is no load rating. The receiver, end stop, release latch and accessories are not included.

## First-print starting settings

These are suggested starting settings, not a tested printer profile. Start with the filament manufacturer's PETG guidance and your printer's working PETG profile.

| Item | Starting point |
| --- | --- |
| Material and colour | Black PETG; brand not specified |
| Nozzle | 0.4 mm |
| Layer height | 0.20 mm |
| Orientation | Flat underside on the bed, logo upward |
| Scale and units | 100%, millimetres |
| Walls/perimeters | 5 |
| Top and bottom layers | 6 each |
| Infill | 40% gyroid |
| Supports | Initially none; inspect the preview before printing |
| Support blockers | None supplied or initially required |
| Modifier meshes | None supplied or initially required |
| Bed adhesion | Start with your proven PETG adhesion method; optional 3 mm brim if needed |
| Raft | None for the first attempt |
| Seam | Place away from the two long mating flanks |
| Fuzzy skin | Off on this part |
| Colour changes, pauses or inserts | None required |
| Temperatures, cooling, speed and drying | Follow the selected filament's guidance and the printer's proven PETG profile |
| Print time and filament use | Read from your own slicer; no verified estimate is supplied |

Use a bed surface and release method compatible with PETG. PETG can adhere strongly to some surfaces. [Prusa's PETG guide](https://help.prusa3d.com/article/petg_2059) is useful background; its printer-specific settings are not a tested profile for this part.

## Check the slice

Import `nk3d-common-base-v1.stl` as one part. The exported bounds are 58 × 35.1349 × 7.4 mm. The theoretical flank widths run from 28 to 36 mm before rounding; do not scale the STL to force a 36 mm bounding width.

The underside starts at Z=0. The main deck is at Z=7.0 mm, and the perimeter crest reaches Z=7.4 mm. The 3 mm inset per long side gives a gradual side overhang of roughly 22° from vertical. This supports trying the supplied orientation without supports, but the local corners and rounded edges still need preview and print checks.

Step through the layers and check:

- Both shaft holes stay open, and the countersinks widen toward the top.
- The logo grows from the recess floor at Z=5.8 mm and finishes at Z=6.6 mm. Check for missing fine details or unsupported islands in the toolpaths.
- The shoulders and countersink seats have continuous material around them. Watch for missing walls, gaps or unexpected bridges.
- The seam and any brim stay clear of the finished sliding faces. Remove brim remnants before checking fit.

Curves, sloping faces and the shallow logo will show normal FDM layer stepping. Inspect the actual toolpaths rather than judging the print from a smooth render. The lower edge already has a small bevel; tune first-layer behaviour and elephant-foot compensation on a sample if needed, without changing the whole part's scale. If supports are needed after inspection, keep their contact away from mating flanks where practical. No support or modifier file needs to be imported.

## First-print fit checks

1. Let the print cool. Inspect the shoulders, crest, logo and countersinks for lifted corners, cracks, missing material, strings and rough edges. Remove loose strings and brim remnants without rounding the mating flanks.
2. Try the actual selected fasteners through both nominal 5.5 mm bores. They should pass without being forced. Printed hole size can differ from CAD size; record the result before changing slicer compensation or drilling a prototype hole.
3. Check the heads against the 90° countersinks, with their 11.6 mm openings. Verify the real head angle, diameter and shaft length. Seated heads must not stand above the 7.0 mm deck. The 7.4 mm crest is a separate, higher feature that a future receiver must also clear.
4. Check the underside on the intended support surface. It should sit steadily. A curved kayak surface or well-nut flange needs a firm, measured support arrangement that accommodates the flanges. The supplied underside has no generic flange recess. Do not tighten screws to force the base flat over an unsuitable surface.
5. Mount the prototype with the selected hardware, then check again for bowing, cracks and raised heads. Well nuts, bolt length, grip range, hull hole size, gasket, sealing method and tightening torque remain unselected. The 5.5 mm base bores do not specify the larger hull holes for well nuts.
6. Record the printer, filament, settings, hardware and fit observations. Keep one unchanged reference base. When a receiver is developed, test short fit coupons first, then a complete receiver on this mounted base. Check the whole 7.4 mm crest and both end rims throughout its slide path.

A successful first print is a starting point for receiver and installation development. Retention, repeated sliding, sustained loads and accessory leverage still require physical verification with the completed mount.


# NK3D Common Base V1 — Technical Notes

This download is the **base only**, a first geometry prototype. It does not include a mating receiver, latch, stop mechanism or accessory. It has no load rating. Printed fit, installation, durability and strength have not been physically tested.

## Dimensions of this version

Import the STL at **100% scale in millimetres**. STL does not encode a unit system.

| Feature | V1 dimension or position |
| --- | --- |
| Exported mesh bounding box | 58.000 × 35.134873 × 7.400 mm |
| Theoretical unrounded upper widths | 28 mm at the narrow end; 36 mm at the wide end |
| Long-side inset toward underside | 3 mm per side before edge rounding |
| Main deck height | Z = 7.0 mm; flat underside at Z = 0 |
| Broad perimeter shoulder crest | Z = 7.4 mm |
| Nominal broad upper side-ridge width | Approximately 2.6 mm |
| Through bores | Two, nominal Ø5.5 mm |
| Bore centres | On the centreline, 9 and 49 mm from the narrow end |
| Fastener centre spacing | 40 mm |
| Countersinks | Nominal Ø11.6 mm opening at the 7 mm deck; 90° included angle |
| Conical seat depth | 3.05 mm; cone transition at Z = 3.95 mm |
| Circular logo recess | Nominal Ø21 mm; floor at Z = 5.8 mm |
| Highest integral logo relief | Z = 6.6 mm, 0.4 mm below the main deck |

The 28–36 mm widths describe theoretical flank intersections before rounded corners and edge fillets. They are not the widest measured bounding-box dimensions. This released draft is **58 mm long**; earlier 50 mm concept illustrations do not define its dimensions.

The shoulders are part of one solid body. The upper long-side flanks are wider than the underside. Broad raised shoulders continue around both ends. This geometry is not a complete sliding interface: any future receiver must be developed against the actual model and allow for the **7.4 mm crest and both end rims**, rather than only the 7.0 mm deck. No receiver clearance or insertion path has been verified.

## Hardware and mounting

The bores provide nominal clearance for M5 shafts, but an M5 label does not establish head compatibility. Check the selected fastener's actual shaft diameter, countersunk-head diameter, head angle and seated height. A head must not project into a future receiver's clearance envelope.

For a kayak, the proposed arrangement is countersunk bolts into separately selected M5 well nuts. The **Ø5.5 mm base bore is not the well-nut installation hole in the hull**. Well-nut body diameter, flange size, grip range, bolt length and installation instructions depend on the actual hardware. None has been selected or validated for a specific kayak.

The underside is flat and contains no generic well-nut flange recess or sealing groove. A well-nut flange needs measured clearance or a supported pad/gasket that prevents rocking. A curved hull needs a fitted support surface. Do not tighten the base to force it against an unsuitable surface. Penetration sealing, bedding compatibility and installation torque must be established for the actual hull, fasteners and printed material.

For wood, select countersunk wood screws that fit the existing bores and seats. Screw length, penetration, pilot-hole requirements, wood condition and installation torque remain application-specific and untested.

## First-print inspection

The suggested starting orientation is flat underside down. No material, slicer profile or printer has been qualified. At 100% scale, inspect the sliced result for one connected body, open shaft bores, conical seats and the recessed logo. Check the printed part and selected hardware before installation, including cracking, distortion, head seating and support under the entire base.

## What has been checked

Digital checks found one valid CAD solid and an STL with one connected watertight shell, consistent triangle winding and **28,032 triangles**. Those checks establish properties of the supplied digital geometry. They do not establish print quality, hardware fit, receiver fit, weather resistance, installation quality or load capacity.

Physical print, assembly, fit, insertion, wear, environmental and load tests remain outstanding. Without a mating receiver model, simultaneous fit, collision, seating, insertion and release cannot be evaluated. No SnapRail R10 track, receiver or accessory geometry is included or implied by this base.