For anyone who wants a bit of inspiration re what plugs & feathers can achieve, this short video is worth a watch:

https://www.youtube.com/watch?v=cBMcMGBhUVk

He mentions seeing water running out at each end of the rock when it starts to crack. I think he must have poured some water in the holes before starting the split. In this way he was able to monitor the progression of the crack.

(Obviously to do this the holes need to be far deeper than the length of the plugs & feathers.)

Im sure Jimmy Lister put a clip on here some years ago with him splitting a big lump in a few minutes. Cant find it on youtube though.

The video is great - it's like a granite xylophone. They've been invaluable to me over the last couple of years, especially for disassembling super-tough calcite rhombs in a wall when nothing else would work. Even caps just sputtered harmlessly. The P&Fs took them apart in no time.

Go get em -- Vurley.

Jimmy Lister mentioned to me that if a plug and feather gets stuck, he might just leave it where it is and come back another time to find that the rock has relaxed and split all by itself. I guess he leaves it as a nice surprise for the next trip into Ink Sump.

I don't think Jim will mind me saying that he is risk averse when it comes to splitting rock, so prefers to use Plugs and Feathers rather than Hilti Caps.

I've used them a couple of times, but sometimes I get undesirable results. Like shearing of the face of the rock rather than splitting, I think it could be the hammer i'm using, as I had better results with Pwhole's lump hammer than my Brick hammer.

When Splitting some smaller ones we needed to save battery power, so just smashed them with a lump hammer (certainly warms you up )

What usually causes shearing off of the face (rather than properly splitting the rock where you want) is not drilling the holes deep enough. A useful rule of thumb (and this does depend on the situation) is that if you can drill holes two thirds of the way down through the rock's depth, it'll split beautifully.

The results obtained with plugs and feathers definitely improve with experience. It's worth an afternoon playing in a quarry before using them for real because, in awkward situations, you can get the plugs and feathers stuck if you don't know how to get the best out of them. I'm no expert but I can use these things a lot more effectively now than when I first started using them.

Hmm longer drill bit then...

http://shop.g-gibson.com/plugs--feathers-wedge--shims-937-p.asp is where I got mine. They don't come cheap and you need at least 3 sets. However they are incredibly tough. They need a 14 mm drill so a fair bit of battery power. At present we are lucky enough to run a cable in from a generator for the drill. I like the idea of pouring water into the holes.  I have had some sticky moments with jammed p and f's but usually it's when there has been a partial split and then it is a question of just knocking hell out of the boulder for longer thasn ideal.