UKH

I've been wondering if an acceptable belay build could consist of a figure of 8 to an anchor point then an alpine butterfly to your second point, so you can adjust the alpine butterfly loop to bring everything down to where you want your anchor point. 

Is there any reason why this build might be discouraged? If not surely it would reduce the amount of knots you'd have on your harness making everything look a bit cleaner.

The system itself comes from rope access when they build a y hang, the whole system just seems a lot simpler in ways as you can adjust the whole system from one knot.

It depends what you're doing. I like this for a system which I'm not going to be part of (eg an abseil setup), as it means that you can get away with fewer crabs. If I've understood what you've described correctly, and you're using this as a single- or multi- pitch anchor, you're going to be essentially outside the system and belaying direct from the alpine butterfly. I think direct belaying got discussed a bit on https://www.ukhillwalking.com/forums/rock_talk/trad_belay_anchor_using_a_guide... - the main concern is that your anchors need to be "unquestionably bombproof".

My experience with using this setup for abseils is that it's quite fiddly getting the butterfly to equalise properly, but that's probably just because I don't use it that often so I'm not that used to fiddling with the knot. A similar way to achieve the same thing would be to build something a bit like the anchor in this picture:

https://www.climbing.com/.image/c_limit%2Ccs_srgb%2Cq_auto:good%2Cw_1400/MT...

Again, only to be used if all pieces are beyond question, but I find this easier to adjust than using a butterfly. It seems to be functionally equivalent to what you've described though.

Sorry I should have specified, but my thought was it could be used as an alternative to a traditional anchor setup on single or multi pitch climbs where the anchors are assumed to be unquestionably sound but anchor doesn't equalise itself if one of the bits of gear were to fail.

You could still use it as a direct or indirect belay if you wanted to, the belay could be attached to a second alpine butterfly on the live end of the rope or, you could attach yourself to the rope and have your belay on your belay loop.

I'm just thinking that it's an easier knot to equalise rather than adjusting two clove hitches you just have the one, plus it would be the same set up if the anchors were out of reach.

I can't see any real problem with the system, and so just wondered if there was a major fault in doing something like this.

I'm trying to attatch pictures to show what I mean but I'm struggling 🙄

Unless things have radically changed in the last few years, a fig8 and alpine butterfly is THE accepted method used by cavers for equalised anchors in SRT. At pitch heads it's critical to get the rope to hang clear of the walls and still to load the bolts equally. For setting up abs it's great and I'd do the same above ground when abbing into a seacliff say. On the lead, for building an anchor I'd rarely use it if at all?

Have you tried doing this at the top of a pitch? It sounds like what you're suggesting is untying from the rope and then tying it to the anchor. 

It's used in rope access because you're just rigging an abseil, essentially. It's no use if you're actually tied into the rope. Also not much use for an anchor made up of more than 2 pieces. 

its fine and  a good way to equalise 2 pieces if a long way from the belay position - eg top of sea clif,  then tying a clove or another A.B where you want to belay from. Can also use an overhand-on-bight instead of AB (easier to teach, a tad harder to adjust )

No its still the same, i believe its were most of the rope access techniques come from anyways

Not at all, the fig 8 that starts the anchor would be on the bight leading to your harness, the same as if you were build an indirect belay.

If you had more than two bits of gear you could either join two close pieces together with an equalised sling to bring it to one point or, add another alpine butterfly into the system. If you were setting it up on an unquestionably sound anchor point you would need anymore than two anchor points though surely?

If the piece of gear with the fig 8 tied to it failed, the belayer may fall further than if the belay was equalized 'normally'. I guess it may use slightly more rope too. Not saying it is wrong or right, just things to think about.

Yeah fair enough, thanks for the conformation i wasn't sure if there may have been a reason as to why it couldn't be used in a anchor setup

Agreed, but I’ve not caved for a good few years. 
To the OP: if I’ve understood you correctly, it would be easier to do the alpine butterfly first and then the fig eight then readjust and equalise. Too much faff. And then you’ve got the double bowline to really complicate things!

So if you're going from your tie-in fo8 at your harness to a fo8 on the bight on the first piece of gear, how would you adjust this? That's why a clove hitch is normally used. 

I suspect you just need to try this in a real situation, ie repeatedly at the end of a pitch, you'll quickly realise why people don't use it in that situation. 

I've used it a fair bit in other situations, I work in rope access, it's good for rigging abseils and rarely anything else.