Welding Nuts

As you will know, the swinging arm Ariels make use of Spire fasteners and matching screws in various places, which look a lot like blunt self tappers. These appear in the rear mudguard and the seat base. Additionally, the bikes use captive nuts in sheet metal cages (I made one here) in the headlight and in the chainguard.

Of course, the captive nut in the chainguard was missing. I thought about making one, and having fiddled around for a while making a 5/16" one for the headlamp, I wasn't about to make a smaller (1/4") one for the chainguard that no-one would ever see, so I decided to weld a nut in.

Now the tab on the chainguard is not so large, and I wanted something larger than a conventional nut to weld to, and secondly I wanted to make sure the thread was in the centre of the square hole in the chainguard, so I came up with a special nut, designed to be welded in:

It's turned up from a piece of 3/4" round bar on the lathe:

It's got a 0.35" diameter journal to fit into the hole, and a lead in chamfer to a 1/4" BSCy thread:

The back is also chamfered, to allow me to make a fillet weld easily:

I'll make some 5/16" ones for the mudguard and seat.

Charlie's Shed - Captive Nuts

As part of the Huntmaster fork rebuild, I discovered that one of the captive nuts in the headlamp was damaged and no longer being retained by it's little steel cage; a bit more investigation revealed that it was not the correct nut. You can't buy these, since they are an integral part of the MCH60 headlamp supplied to Ariel by Lucas and as such don't have an Ariel part number; they are not available as spare Lucas parts either (and nor is the shallow-bowl MCH60 headlamp, for that matter).

Its quite easy to make your own, however. Start with some thin cold rolled sheet, about 0.6 mm or 24 SWG; I have to confess I have cut up an old baking tray in the shop which I use for stuff like this! You'll start by making a square nut from some 1/4" or 3/16" plate, and drill and tap a 5/16" CEI hole in the centre. Cut out a 'cross' shape with snips from a small piece of sheet a couple of millimeters wider than the nut, and about 2" longer; the width of the long arms of the cross needs to fit in the square hole in the headlamp shell. You'll need a clearance hole for 5/16 in the centre of the cross.

You should end up with something like this, with the short arms folded part way up the sides of the nut. The short arms are only about 2 mm long.

You can fold up the two long arms of the cross in the vice. Take care to fold them tight around the nut, and fold them at 45 degrees over the top of the nut. You will then fold them back such that they come up through the square hole in the headlamp shell; trim them to about 4 mm and nip off the corners:

Slip the captive nut into the hole in the headlamp shell. Using a large hammer, held in the vice as a dolly, you can fold the short ends of the captive nut outwards into the hole, tightening them down with a hammer. This is how it looks from the inside, with one of the bolts in place:

And this is how it looks from the outside - the fold is less neat than I would have liked it, but it is 100% better than it was before.