So here's the question. I want to TIG up the spoke holes in a pair of hubs but what filler, tungsten and power should I be using. I have no idea what grade of alloy they cast from but they're from a TY 175.
There's a good chance they're made from an alloy chosen for it's hardness (strength) and machinability, many of these are classed as 'not weldable' because either welding will totally destroy the mechanical properties and/or they're VERY prone to solidification cracking i.e. will crack as the welds solidify
From the layout marks on the hub i'm guessing you want to redrill for a different spoke count? Ignoring the above still going to have issues as welding will anneal the hub i.e. spokes more likely to sink into the (now) softer hub as they're tensioned
I was worried that might be the case. I have you a few sets of these hubs spare so I wouldn't be mortified if it went pete tong. Any idea what settings I should be floating around.
I'd be more worried about it working (for a while) and then having the wheel collapse later on if/when the hub lets go than having it go wrong while welding...
I missed the bit about them being cast last time (my mind jumped straight to bicycle hubs which are typically forged or machined from a 2xxx or 7xxx series alloy), if they are a casting the alloy is almost certainly a high silicon flavour which usually makes 4043 the best choice. Having witnessed the aftermath of a hub flange letting go around the spoke holes i wouldn't recommend doing this with so many unknowns but if you must i'd be looking to keep the hub from getting too hot (good excuse for tea breaks). Amperage wise you're on your own- i don't know how thick the flange is but it's effectively a bunch of tack/rossette welds i.e. form a weldpool, add filler and slope out. Use a foot pedal and the numbers won't matter
If it's going back on a TY125 then a broken hub isn't going to be the end of the world (like it would be on a Ducati) since trials riders usually fall off anyway Using it on the road might require more knowledge than I can impart. What's the project bike going to be?