M6 x 18mm x 1.6mm A4 Stainless Steel Washer for Fin/Foil Screws.
High Quality Stainless Steel washer with large outside diameter to suit all types of Pan Head, Cheese Head, Cap Head or Button Head screws and every board we have come across using Powerbox, Tuttle Box, Midi Tuttle, Deep Tuttle, Mini Tittle or Trim System, when using an M6 screw.
We recommend using two Stainless M6 x 18 x 1.6mm washers to minimise friction when tightening and to spread the load even more effectively into the deck of the board and the use of our Soft Polyurethane washers (which grip the screw to keep the washers in place) really helps to protect the deck as well, so these are frequently bought together.
This Soft Urethane washer works really well with with Round Screw Holes up to 8mm in dia.
If you have slotted screw holes in the deck of your board, this Soft Urethane washer will tend to tear, so its life is shorter than with a round hole - for slotted screw holes we recommend using a hard Rubber washer or just 2 x 18mm x 1.6mm Stainless washers.
Always make sure you have enough screw engagement with the Fin or Foil Insert.
With a 9mm diameter brass insert, aim for 7 to 8 full turns of the screw, with 10mm Brass or Stainless you want 8 to 9 full turns and with 12mm inserts, 9 to 10 full turns.
Some fins and foils will allow you to go deeper, but the turn count above will make sure you do not become 'thread bound' which can feel like the screw is tight as it's 'bottomed out', but is not actually pulling the fin or foil securely into the box - a few spare Stainless 18mm washers can be real asset for getting as much thread engaged as possible if you cannot easily change the screw length by a few mm.