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Gluing Fin Rails - V1 - Two Part Plastic-to-Carbon Adhesive

Proven

Goal

To attach rubber fin rails securely to carbon fiber blades using a strong composite adhesive. The rails protect the blade edges, improve water flow, and extend the blade’s lifespan.

Time needed

Type Hours
Implementation 0.5 h
Waiting 12 h

Bill of Materials

Material Quantity Unit Cost Line Cost
Rubber Fin Rails
Consumable One pair of soft rubber rails sized for bifin blades		 2 m (enough for four rails) £6.00 per metre £12.00
Plastic To Carbon Adhesive
Consumable 25 ml of 3M DP420 mixed with nozzle		 1 25 ml syringe £8.25 per 25 ml syringe £8.25
Fold-back clips set
Consumable 20 mm binder clips for clamping rails during cure		 1 set Inexpensive
Total £20.25

Tools Required

Tool Purpose
Gloves Protect your hands from resin, adhesives, and carbon fibers
Sandpaper Prepare and smooth surfaces for better adhesion and finish
Window cleaner Degrease surfaces before bonding or sealing

Instructions (step-by-step)

  1. Safety

    • Wear gloves to avoid skin contact with adhesive.
    • Work in a ventilated space.

  2. Surface Preparation

    • Sand the edge of the carbon blade lightly with 400-grit sandpaper.
    • Sand the inside surface of the rubber fin rail to improve adhesion.
    • Clean both the blade edge and the inside of the rail with window cleaner.

  3. Apply Adhesive

    • Mix the two-part adhesive according to the manufacturer’s instructions.
    • Apply the adhesive generously inside the fin rail.
    • Press the rail firmly onto the blade edge, ensuring full contact along the surface.
    • Check carefully for gaps — even small gaps can expand over time and risk detachment.

  4. Remove Excess Adhesive

    • Wipe off any excess adhesive that squeezes out during pressing.

  5. Clamp the Rails

    • Secure the rails in place using fold-back paper clips spaced evenly along the edge.

  6. Curing

    • Allow the adhesive to cure fully according to the manufacturer’s specifications (usually around 12 hours).

Limitations

  • Poor surface preparation (e.g., not sanding both blade edge and rail interior) may result in weak bonding.
  • Adhesive application must be uniform; gaps reduce durability and may lead to rail detachment over time.

Inspiration

This forum thread about rails: https://spearfishing.world/thread/2440-fin-blade-rails-water-channeling-and-tendon-rails-explanation/