Futures Fin Box Installation — Quick Manual

Using the Greenlight Futures Router Install Kit

Full Install Video Here

What You're Working With

Before you start, get familiar with the kit:

• Greenlight or Makita variable speed router

• Sliding aluminum base plate

• Jig plate with positioning target

• Center slot router guide insert

• Three depth collars, color coded:

• 3/4" collar — rail fins

• 1/2" collar — center fin and rear fin base

• Flange collar — sets the flange pocket depth

• Router bit + bit depth gauge

• Practice foam sheet

Optional Items:

• Cant angle jig (5° and 9° sides)

• Dummy fins

• 3/8" masking tape

Step 1: Set Up for the Rail Fins

Start with the 3/4" collar on the router — this is always your starting depth for rail fins.

Place the jig plate on the board and drop the target piece into it. Line up the target's holes with your shaper's dots, then press down through the backup holes to mark micro dots on the board. These backup dots are your safety net if you ever need to reposition the jig or accidentally bump it out of place.

Step 2: Route the Rail Fin Slot

Pull the target out and insert the center jig guide.

This is plunge routing: position the bit inside the aluminum collar, turn the router on, and let it drop down slowly until it hits the collar — rocking gently back and forth as it plunges. One pass at this depth is all you need.

Step 3: Cut the Flange

Swap to the flange collar. This sets the max depth the bit will reach for the flange cut.

Start in the middle of the slot and rout clockwise — that direction is what gives you the correct width.

Step 4: Test Fit

Before moving the jig, drop a dummy fin into the box and test fit it. If it seats cleanly, you're good to move to the next slot.

Repeat Steps 1–4 for each rail fin position.

Step 5: Rear Quad Fins

Rear fins use the 1/2" collar on top of the 3/4" collar, then the flange collar on top of that — same plunge, same clockwise flange cut, same test fit at the end.

Step 6: Center Fin

Switch to the 1/2" collar for the center fin box. On this one, hold the router so you can use your fingers to drop it in small incremental passes — about four passes down rather than one continuous plunge.

Step 7: Level the Tail

Before glassing, level the tail of the board so resin stays in the routed pockets. If you skip this, tail rocker will let resin run out the back during cure. A sanding pad and level together will get you a true flat.

Step 8: Mix and Apply Resin

Mix a half ounce of resin per fin box (2.5 oz total for a 5-box setup). Use Greenlight's epoxy dispensing caps for accurate small-batch ratios, and weigh it out on a digital scale — that combo is hard to mess up.

Fill each pocket about halfway with resin. It's not an exact science — just make sure everything's covered.

Use a mixing stick or brush to push resin up onto the flange area and fully saturate the flange and the walls of the pocket.

Step 9: Set the Fin Boxes

Insert the dummy fin into the fin box, then press the box down into the cavity. Resin will shoot up through the box holes — that's exactly what you want. Squeegee the excess around, covering the foam and the box completely and pushing resin into the flange holes to minimize air bubbles once you laminate.

Step 10: Tape and Set Cant Angle

Run 3/8" tape onto the dummy fin, making sure the center fin sits perpendicular (straight up and down). Taping holds the box down while resin cures so it doesn't float.

Check cant angle with the cant jig:

• Rear quads: 5°

• Front fins: 9°

Make small adjustments before taping down, then double-check the angle again after taping to confirm nothing shifted.

Step 11: Let It Cure

Let the resin cure fully before moving on.

Step 12: Seal the Slots

Once cured, tape over the fin slots with 3/8" tape so no resin gets in during glassing. Use a razor blade for a clean cut, make sure all screws are seated, and press the tape down tight — especially at the top where the fin inserts. A resin drip into the slot means chipping it back out later, so take the extra minute here.