How to properly attach fittings to mast?

[RaymondR]

Originally Posted by Clivevon

If you use rivets, make sure they are made of Monel metal.

I have mast steps which were fixed using monel rivets dipped in chromate paste about 27 years ago, no corrosion yet.

The problem with drilling/tapping and screwing is that you invariably get corrosion which locks the thread in place. Then when you drill out the stub you almost invariably get off-centred. One or the other of these will then require you to redrill and re-tap for a larger screw size.

It is far better to use monel rivets as the hole through the centre will guide the drill and if you use for example a 3/16" drill for a 3/16" rivet you will get it out in one pass and be able to use the hole again for another 3/16" rivet.

When drilling SS or monel you use a sharp drill and a slow speed setting with a cutting paste, if you try to drill with a blunt drill on a fast setting you will heat up the SS or monel and it will then quench harden when it rapidly cools making it more difficult to drill.

If you need more strength drill the holes out for a bigger sized rivet or drill and rivet more holes.

In thin alloy you often get a stronger fastening using a rivet than that provided by only a few threads in relatively soft alloy.