Hyundai Veloster N Subwoofer speaker adapters

I found a post on facebook where someone made custom printable adapters for the KICKER 48CWRT672 CompRT 6.75" Subwoofer, DVC, 2-ohm and a Dayton Audio Epique E150HE-PR 5-1/2" Carbon Fiber Cone Passive Radiator.

The Metra 72-6514 wiring adapters should work inside the sub so you do not have to cut the factory wiring in case you want to switch back to the stock one.
The wiring from the stock amp is 

I would also use foam rings between the adapter and the OEM enclosure to seal it. as well as a foam ring on top of the speaker to provide protection from the body panel inside the trunk.


The models I used for assisting me to create this suggested using 2 weights on the passive radiator and NO polyfill, same as the OEM speaker.


For this particular automotive application, ASA is my first choice, if you're really worried about heat warping. PETG is easier to print.

MaterialPETG

Nozzle0.4 mm

Layer height0.20 mm

Walls/perimeters8

Top layers6

Bottom layers6

Infill60% gyroid or cubic

OrientationSquare base flat on bed

SupportsNone

Brim5–10 mm

Outer wall speed30–35 mm/s

Inner wall speed45–55 mm/s

Infill speed60–70 mm/s

First-layer speed15–20 mm/s

Cooling~25–35%

Bed75–85 °C

Nozzle240–250 °C

I'd do one thing differently for these adapters

Because your adapters have relatively small mounting bosses and the corners where the OEM screws go will take the clamping load, I'd use a modifier region around the four OEM mounting holes and increase that area to roughly 80–100% infill.

Keep the rest of the part at 60%.

That gives you a very solid mounting area without having to print the entire adapter at 100% infill.

Dry the PETG first

This is particularly worthwhile for these parts.

Moist PETG tends to produce stringing and, more importantly for this application, inconsistent layer bonding and surface quality.

A reasonable starting point is:

60–65 °C for 4–6 hours

Then print directly from a dry box if you have one.

Follow your filament manufacturer's drying temperature if it's different.

Don't run PETG too cool

For a strong functional part, I'd rather have slightly more heat than slightly less.

I'd start at 245 °C and adjust from there based on your particular PETG.

You want very good layer bonding on the 4 mm base and around the cylindrical wall.

Enclosure

Unlike ASA, you don't need a heated enclosure for PETG.

A normal enclosed printer is fine, but I would avoid a large temperature gradient or strong drafts. You don't want the part cooling dramatically while printing.

One PETG-specific consideration

PETG is relatively tough but not as dimensionally stable under sustained heat and load as ASA.

For these adapters, I don't see that as a reason not to use PETG, especially given the 8-wall/60%-infill approach. I'd simply avoid leaving the car sitting in extreme heat with the speaker heavily clamped down if the adapter is under significant mechanical preload.

The 4 mm base + eight walls + 60% infill is a much more substantial part than a typical lightweight PETG print.

For your 3.75 mm Dayton screw holes

I'd leave the modeled 3.75 mm holes exactly as designed.

PETG can make small holes come out slightly undersized depending on your printer's extrusion calibration. That's actually helpful here because you want the screw to bite into the plastic.

Print one test hole with the exact screw you're using before printing the complete radiator adapter. A properly sized self-tapping screw should form a good thread without splitting the boss.

For the best possible result

I would use:

PETG + 0.20 mm layers + 8 walls + 60% gyroid + 100% infill around the four OEM mounting holes + 245 °C nozzle + 80 °C bed + ~30% fan + 30–35 mm/s outer walls.

And print the adapter flat with the 4 mm square base against the build plate.

One additional trick that's worth doing on these parts is enabling horizontal hole expansion compensation in the slicer, but only very slightly, around -0.05 to -0.15 mm, so the printed screw holes don't close up from PETG's tendency to produce slightly undersized small holes.

A good alternative is plain nylon (PA) if you are comfortable drying and printing nylon. PA-CF is extremely stiff, but it can make thin sections more brittle and requires much more demanding printing, so I would not automatically choose it here.

Print orientation

Print the adapter flat on the square base, exactly as it will sit in the car.

The 4 mm square plate should be directly on the build plate, with the cylindrical sleeve pointing upward.

Do not use supports. The geometry should print cleanly this way.

This orientation also puts the layer structure in a favorable direction for the mounting load.

Layer and nozzle

For a 0.4 mm nozzle:

Layer height: 0.20 mm

First layer: 0.20–0.24 mm

Line width: 0.42–0.48 mm

Perimeters/walls: 7–8

Top layers: 6

Bottom layers: 6

With the 4 mm base, the 7–8 walls will make the square mounting area very close to solid.

For these particular parts, I'd prioritize walls over extremely high infill.

Infill

Use approximately:

50–60% gyroid, cubic, or similar 3D infill

I would not bother with 100% infill. With the number of walls we're using, going from 60% to 100% adds a lot of material without providing a proportional increase in useful rigidity.

For the Dayton adapter, I'd use 60% because of the additional screw-boss area.

Print speed

For ASA, I'd stay relatively conservative:

Outer wall: 30–40 mm/s

Inner wall: 50–60 mm/s

Infill: 60–80 mm/s

First layer: 15–20 mm/s

The goal is good layer bonding, not speed.

Important ASA settings

Use an enclosure if possible.

I'd start around:

Nozzle: 250–260 °C

Bed: 100–110 °C

Part cooling: low, roughly 10–20% after the first several layers

Chamber: warm if your printer supports it

The exact temperature should follow the filament manufacturer's recommendations, because ASA formulations vary substantially.

A brim of around 5–10 mm is worthwhile because the square bases are fairly large and flat.

For maximum strength

I would use:

8 walls

60% gyroid/cubic

0.20 mm layers

ASA

Enclosed printer

Moderate print speed

That will produce a pretty beefy part despite the relatively thin 4 mm base.

Making the adapter seal well

This is almost as important as the plastic itself for your speaker installation.

I would put closed-cell automotive speaker gasket tape between the adapter and the OEM enclosure.

Something around 1–2 mm thick compressed foam gasket works well. Don't rely on the plastic-to-plastic contact alone.

Do the same between the adapter and the KICKER/Dayton mounting flange where appropriate.

For the bottom of the square adapter, I'd actually prefer a smooth build surface so the mating face comes out as flat as possible. A smooth PEI sheet is ideal.

Screw holes

For the Dayton's 3.75 mm sleeve holes, I would not modify those holes in the slicer. Let them print at the modeled size and test one screw first.

Because the screw is intended to bite into the plastic, the smaller 3.75 mm hole is useful. I would avoid making that hole larger just for easier assembly.

For the 4.5 mm OEM holes in the square base, printed holes are mostly being used as guides in your design anyway, so you can easily drill them to final size after printing.

One thing I'd change in the slicer

Turn on elephant-foot compensation or use a small first-layer horizontal expansion correction.

Because the adapter has a large flat base, a little first-layer squish can make the outer dimensions and the mounting holes slightly undersized. You want that first layer controlled, especially around the 4.5 mm holes.

MaterialASA

Nozzle0.4 mm

Layer height0.20 mm

Walls8

Top layers6

Bottom layers6

Infill60% gyroid/cubic

Print orientationSquare base flat on bed

SupportsNone

Brim5–10 mm

CoolingLow

EnclosureYes

Outer wall speed30–40 mm/s

Nozzle~250–260 °C

Bed~100–110 °C

One additional recommendation: don't print these hollow/lightweight. They're small enough that spending extra filament for eight walls and ~60% infill is well worth it for this application.

For the Dayton adapter specifically, I'd also make sure the four screw bosses have good layer bonding and don't try to make the print overly lightweight around those areas. Those are the areas I'd expect to see the most localized stress.