Capping Accurately?

alastairgott

Well-known member
I'm looking for some advice. Recently I have had need to break up a boulder the size of a desktop PC (increasing in size to the bottom where width= 2x desktop PC's).
To clarify, the only angle of attack was from the front of the "Desktop", I had originally thought I would just take off the top leaving the Base of the Rock (but had no idea how deep it went).


In the End I resorted to plugs and feathers, as they are tried and tested approach for me and come out with very little inaccuracies. (the rock ended up coming out entirely! took some good crowbarring!)


Method used:
1 small drillbit length of a pint glass.
drilled hole handspan from the top of the rock (angle of approach front of Desktop PC)
Placed one black Cap in.
light tap, light tap, light tap..... no movement, heavy tap- twist... repeat... boom.


findings:
no breakage in rock, in fact nothing! hit rock with lump hammer after, several times, nothing.


2 more holes had been drilled prior to first cap, one (2nd hole) was a handspan diagonal to the (left and down) the other (3rd hole) was directly vertical from first hole but equidistant from the 2nd hole.


the 2nd hole went slightly better and took the side off, and the third was reasonably successful.


I think I used one more cap (4 total? maybe?), but by this time I was getting bored of the tedium of putting goggles and ear defenders on for little use.




In short, where was I going wrong?
Should my holes have been longer, ie should I buy a longer drill bit?
should I have been trying to "bite off" more rock and therefore put some more caps in?




Needless to say I've been back and disposed of the rock, but with my trusty 16mm Plugs and feathers which give you a satisfying crunch and crackle when the rock is splitting. back to mattocking mud again!
 

Badlad

Administrator
Staff member
More oomph I'd say.  In a boulder the size of a desk top I'd use three or four blacks or browns.  Obviously you need good protection.  Drill depth of 150mm is about minimum but the end result is often influenced by the structure of the rock.

PM me if you want more advice.
 

langcliffe

Well-known member
I agree with Badlad. The depth is sometimes limited by the length of your firing pin (I use a slide hammer), but in general, drilling to a depth as close to the  centre of opposite surfaces as you can get is best. In a round boulder, the absolute centre is ideal. It isn't a good idea to drill several holes as they interfere with the shock wave propagation.
 

Tommy

Active member
From memory Alastair those yellows will be about half the wellie of a black cap.

Good to hear you shifted the block, I'm liking the new unit of measurement too.
 

AR

Well-known member
If you need some conveyor belt for a capping mat, give me a shout.
 

Leclused

Active member
If you stick to capping then more caps will do the trick. However capping is imo dangerous and requires good protection.

Why not switching to straws?

Benefits :
- saver
- remote

Drawback
- more gas
- more preparation at home


 

2xw

Active member
Leclused said:
If you stick to capping then more caps will do the trick. However capping is imo dangerous and requires good protection.

Why not switching to straws?

Benefits :
- saver
- remote

Drawback
- more gas
- more preparation at home

Is there anywhere I can read more about this?
 

cavemanmike

Active member
i tend to use snappers on large stuff like that. works a treat
and more importantly not classed as explosives
 

Leclused

Active member
2xw said:
Leclused said:
If you stick to capping then more caps will do the trick. However capping is imo dangerous and requires good protection.

Why not switching to straws?

Benefits :
- saver
- remote

Drawback
- more gas
- more preparation at home

Is there anywhere I can read more about this?

First part on the following page describes the method. 

http://mdemierre.speleologie.ch/?p=3966

For the ignitor part are several solutions possible. (But not suitable to publish on a public forum)

Some result pics of the straw method to give you an idea.

https://1.bp.blogspot.com/-H_bkvwuiV_M/V5Ys4SuUoKI/AAAAAAAABnA/ySe7cKOLD1sTcotb1api5iHwaSuEBeGVQCLcB/s1600/IMG_1781.JPG
https://1.bp.blogspot.com/-Dl6Uh74XxJc/V5Ys4Yi_9JI/AAAAAAAABnE/87MhlaYB60MEhJ033i1ZFyNexBURU0vHQCEw/s1600/IMG_1786.JPG



 

mch

Member
2xw said:
Topimo said:
2xw said:
Is there anywhere I can read more about this?

http://eug.bcra.org.uk/

That's not useful at all.


Thanks Leclused I'll have a read

The system that Leclused refers to as straws looks to be very similar to the setup that the late Mel Milner taught me a few years ago. Much safer than capping but more work involved in putting together what's needed (although there are commercial versions available - at a cost!).
 

Goydenman

Well-known member
Recommend using devices like straws that create little smoke so that soon after demolishing the boulder you can go back during the same session and carry on work
 

Leclused

Active member
Goydenman said:
Recommend using devices like straws that create little smoke so that soon after demolishing the boulder you can go back during the same session and carry on work

You can go back depending on the strenght and direction of the airflow and the amount of powder used. It can be in the matter of minutes up to hours.

We always use a toxipro gas meter to check the air before to go back. We don't enter when above 50ppm co.
 

The Old Ruminator

Well-known member
Our " technician " has improved the efficiency of snappers by scoring them along the side and plugging the hole when in place with a bolt on the end of a wire . If your recourse to material is entirely legal a couple of inches of cord under the snapper seems to work well without the fumes.( not really evaluated that ). Of course it depends what we mean by snapper as there are various sorts I would not wish to explain the construction thereof. A slider is safer as a capping hammer though I have seen a nasty accident whereby the cap ended up embedded in a finger bone. We still cant work out how it fired out past the slider. Certainly some rock seems more " brittle " than others and it pays to take note of any cleavage planes or weakness. We prefer capping to HE as the latter reduces stuff to gravel and can be very destabilizing.
 

alastairgott

Well-known member
OK thanks for the responses, afraid I'm going to ignore all of the comments regarding straws, thanks for the advice anyway, I might look into it in the future. But will not be using in this instance, too close to the surface! and as I need to break rock infrequently, a lot more hassle to acquire and store.

So I think I should have gone with a larger drill bit and more caps. I'll go again next time I come across some, but the sediment seems to be continuing undeterred so hopefully will not be required.
 

nickwilliams

Well-known member
I'm intrigued by the section in that video between 4:04 and 5:30 where they are using some sort of burner to oxidise CO in the petrol powered drill exhaust. My French is limited - can someone tell me if they give any more information on the burner they are using (and if so, what is it)?
 

Leclused

Active member
nickwilliams said:
I'm intrigued by the section in that video between 4:04 and 5:30 where they are using some sort of burner to oxidise CO in the petrol powered drill exhaust. My French is limited - can someone tell me if they give any more information on the burner they are using (and if so, what is it)?

They speak about a 'Brouileur de Gaz" so imo it's a simple gas burner (stove). They also speak about a specific angle on wich the exhaust fumes of the Ryobi (= powerdrill on petrol) are introduced in the gas burner to be sure that the toxic fumes are burned.

They also mention that this method can only by used in ventilated large caves. The final exhaust of the burner is checked with a dr?ger pump.

I would use a gas meter like a Toxipro instead of the dr?ger pump.

That's all I can make of it. There are no more details mentioned.
 

wormster

Active member
*drags through hazy memory*

Capping is a way of "nibbling" larger rocks to make them smaller, rather than instantly "reducing to pebbles". Sometimes it takes a few 'oles and a slack handful of "blacks" to get that pesky rock outa teh way! I do agree that using a slide hammer is better than gingerly holding the bar with molegrips/pliers and twatting away with Mr 4pound!

One thing that is worth doing is getting hold of a length of non ferrous tube about 6-8mm diameter, (I used a bit of kite spar that's about a foot long, with a bit of hydration bladder soft hose mated to one end) to blow out any remaining debris/dust in your 'ole, before using the "soft" rod to set your cap(s), help place the anti-shrapnel mat before twatting fusk out of them with your 'ammer!

Oh yeah don't forget to use saftey speks and ear cans to protect your wibbly bits!
 
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