Fabricating mudguard stays? What from?

stinkwheel · Bovine Proctologist Joined: 12 Jul 2004 Karma :

I'm going to be making my own stays to fit alloy mudguards to my latest enfield project. mainly because they would cost around £70 to buy (each end) and to hell with that for a bit of bent steel tube.

Pretty much just a piece of steel tube bent into a U-shape with the ends flattened out and bolted to some captive lugs on the forks. It's not going to be particularly load bearing although the rear ones should be able to cope with a small luggage rack being bolted to the mudguard/stays with a tent/drybag on it. The front ones act as a slight fork brace in place of a heavily braced steel mudguard (hence the U-shape rather than some bits of flatbar).

I can borrow/hire a pipe bender for the day to make the shapes and I can amateurishly splatter-weld the lugs on to attach the mudguards themselves.

Two main questions really:

1) I'm not au-fait with the various grades of steel/iron tubeavailable. I can collect pretty much any length, size and grade from my local steel stockholders but they do like you to know exactly what you're ordering. Probably wants to be around 15mm OD but what grade and wall thickness should I ask for?

2) The ends. Is there a "proper" way of dong this? Should I just be flattening them in a vice and drilling holes. Or hammering them flat? Or is it more refined than that? I pictured crushing it using a bit of steel rod along one side in the vice so it has a flat back and a slightly 'B' shaped profile on the front?

Or should I make some lugs from flatbar and weld them into the ends of the tube?
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MCN · Super Spammer Joined: 22 Jul 2015 Karma :

Those stays may be hot pressed. So the flatted bits will forge and be a bit more secure structurally.

Have you tried Draganfly spares or are they wanting 70 quids a pop?

They may have an idea for fabrication as they own the patterns for BSA Triumph and fabricate a lot of stuff for auld bikes from factory drawings.

I have talked to them on the phone a few times. Helpful.
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Disclaimer: The comments above may be predicted text and not necessarily the opinion of MCN.

Ariel Badger · Super Spammer Joined: 02 Dec 2006 Karma :

I have made loads over the years, rather than a pipe bender I knock up a former in MDF with a stop to hold the tube and pull it hot adjusting with a mallet as it goes round. Plenty of flames and smoke what is not to love?
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Wheezybiker · Nitrous Nuisance Joined: 19 Jun 2017 Karma :

Copper tube is easily workable and should be strong enough
15/22mm would be usual sizes
Easy to solder or braze

lingeringstin... · Trackday Trickster Joined: 01 May 2014 Karma :

Strimmer line obviously.

Ariel Badger · Super Spammer Joined: 02 Dec 2006 Karma :

MCN · Super Spammer Joined: 22 Jul 2015 Karma :

I would take a wild guess at a Mild Steel Tube with a 1.0mm or 1.5mm wall thickness.

It may be a trade-off between robustness and weight. If 1.5mm is too heavy it may rip the bolt holes out the mudguard in service.

Where are all the bloody Mechanical Engineers with their Slide-Rules when they are needed?
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Disclaimer: The comments above may be predicted text and not necessarily the opinion of MCN.