Dual HUD and NERD Mounting Extension for Dovetail Rebreather Mouthpieces

If you desire to have both a Shearwater NERD and a HUD mounted to the dovetail on your rebreather mouthpiece this extension allows it.

Works with wired or standalone NERD/NERD2 using a mount sold by Divesoft (Part 7131). That mount comes with arms made of stainless which flip to allow 4 orientations and can be bent to get the desired permanent fixed viewing angle. Then you can use your Liberty HUD or one of the other mounts for Shearwater and Narked@90 HUD.

Conceivably, you could mount a second NERD as well, one from each side, though one will sit about 5mm higher than the other.

This should work with any of the DSV and BOV with a dovetail connection from Divesoft or Dive Rite. Check the compatibility of your mouthpiece for other brands.

Be aware, there are some material shrinkage characteristics to consider. The dovetail is a tight tolerance component. You may need to do some finish sanding/filing or even adjust scaling for the perfect fit depending on material. In PETG this model works smooth for me on multiple BOV/DSV but in ABS it’s a little tight. DON’T FORCE ANYTHING. You are responsible if you break the dovetail on your mouthpiece by shoving something together when the fit is too tight.

I utilized the settings below to generate this component. Final results will vary based on your individual 3D printer, material, and settings. These are only a guide.

Material: PETG, ABS/ASA, or engineering materials

First Layer Height: 0.24mm

Layer Height: 0.16

Walls: 3

Infill Percentage: 30%

Infill Pattern: Gyroid

Top Surface Pattern: Concentric

Bottom Surface Pattern: Concentric

Supports: Yes

Support Type: Standard or Trees

Brim/Ears: No

Base Plate: PEI Textured

Print Orientation: Bottom on the build plate

Estimated Print Time using Bambu Slicer: 46min

Estimated Print Time using Prusa Slicer:

Total Estimated Material Used (g): 10g

Maximum Exterior Dimensions (LxWxH): 64x16x21

Additional Required Parts:

-Divesoft NERD Mount #7131 to scavenge for parts and optionally a second one if you intend to mount 2 NERD together.

-Divesoft Shearwater HUD Mount #8180 (only if you have a SW HUD)

-Divesoft Narked@90 HUD Mount #8181 (Only if you have a Narked@90 HUD)

-Divesoft HUD Offset Adapter 7170 (Works with #8180)

-Divesoft rEvo HUD Holders #8303 and/or #8304 (Only if you have rEvo Dream HUD)

-Divesoft HUD Rail #1321 (included in kit #7131) *Do Not attempt to print this part.

-Divesoft HUD Mount Spring #1326 (Included in kit #7131)

-Divesoft HUD Mount Thumb/Dog/Pawl #1624 (included in kit #7131)

-Assembly screws from kit #7131

Multiple Pieces, Requiring Adhesive Assembly: N/A

Heat Press Threaded Inserts: Optional 4x M2 and 4x M3