Looking at adding to my ice screw collection - currently have two steelies for climbing and two BD ultralights that I bought for ski touring but climb on as well. The ultralights place really nicely and the weight saving is considerable, but I do worry that if I bottom them out badly at some point they're going to be a real pain to get sharp again - the steel tip looks to extend a long way down, but on the inside of the screw the aluminum comes all the way up to the teeth.
So my question is, how much do you expect the lifetime of an aluminum screw to be reduced compared to a steel one on the grounds of sharpening alone? I've only ever really had to touch up my screws, which doesn't really remove that much material, but it would be annoying to buy a load of aluminum ones (they're not much more expensive than steelies) only to have to bin them in 5 years if they can't be sharpened any more...
You can sharpen aluminium screws by the way, at least I've done so in the past with some Camp Alu ones I had. I know that's not your question, but I guess if you sharpen downwards in the alu on the new lightweight style ones it might not be the end of the world.
Not that I get to place ice screws much these days, but if I still climbed on most weekends like I used to, I don't think I'd get the new lightweight ones for exactly this reason.
I would worry more about the lower hardness of the Al and the lack of wear resistance compared with steel. The steel tips can be sharpened. Dinged threads impeding placement and scratched cores impeding clearance is how these will fail.
Lightweight screws are great for their designed purpose, lightweight alpine stuff, occasional use but as a regular workhorse they won't last long.
However, they look cool on your harness. the inbuilt obsolescence keeps the manufactures and gear shops happy.
When looking to save weight on gear, look to your midriff first.
Not used the BD aluminium screws much (mainly Petzl), but aluminum is too soft a metal to sharpen adequately if you've worn through the tips. It'll never bite adequately into vaguely hard water or glacier ice. If you've worn through the metal tip then it's probably time to replace the screw. Steel tips should stay sharp for years though if cared for, with some mild sharpening along the way. Probably not the screws to be regularly grinding the tips into rock though, as that is going to need a lot more steel removal of put right.
The UIAA has announced plans to establish a Mountain Worker Initiative with the aim of supporting people working in the expedition and trekking industry, prompted by the issues of low pay and poor working conditions raised in the documentary film The...