blasting smallish tunnels in hard rock

I want to give thanks to you and the group for all your guidance and contributions. On 17 Dec 2023 all was ahead of me. On 20 Dec 2023 when you gave the

I couldn't understand or follow what it was saying. With own reading-around - books and online - and help here, it makes sense now.

So on this first day of 2024 - my best wishes to all of you. Rich Smith

I want to give thanks to you and the group for all your guidance and contributions. On 17 Dec 2023 all was ahead of me. On 20 Dec 2023 when you gave the

I couldn't understand or follow what it was saying. With own reading-around - books and online - and help here, it makes sense now.

So on this first day of 2024 - my best wishes to all of you. Rich Smith

-------------------------------- It seemed to have been written for miners who already knew how to drill a hole but not why or where.

This has diagrams of the sequential blast pattern opening up the central uncharged borehole.

Did you read Hudson Maxim's dynamite book? It's quite funny as long as mental images of flying body parts don't bother you.

I had a quick look, copied the links to my files and bookmarked them in the browser. I have insomnia - could wrap up warm and read them.

I've worked in heavy industry and construction, so of nature do dark humour with the reality of always looking out for yourself and others.

I've worked in heavy industry and construction, so of nature do dark humour with the reality of always looking out for yourself and others.

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Maxim was willing to admit that he blew his hand off from inattention caused by lack of sleep. I put off chainsawing and similar dangerous tasks until wide awake; this morning I'm posting instead of finishing a job on the roof for that reason. I regretfully quit night school because enough evening coffee for 2 demanding classes and the late commute home kept me from getting enough sleep.

I've got 2/3rds of the way through the first one.

There is a message you want me to get ? ! Something you want me to know, which you cannot say yourself but you know this is exactly the right voice saying it?

There's a few general themes emerging from all those hundreds of seemingly disparate stories.

I've got 2/3rds of the way through the first one.

There is a message you want me to get ? ! Something you want me to know, which you cannot say yourself but you know this is exactly the right voice saying it?

There's a few general themes emerging from all those hundreds of seemingly disparate stories.

------------------------------------- No, nothing personal. Really they were the only tales of working and playing with nitroglycerine that I'd read online, when they appeared on Gutenberg's recently added page. They are too old to describe current practice, but like steam engines the evolving tech of those days interests me.

Hudson's brother Hiram took off in a winged and powered airplane before the Wrights, but they were the first to be able to fly the same plane again.

Missing fingers was fairly common among young chemistry students -- I still have all of mine.

The message I get is similar to the one about oxy-acetylene equipment

- welding and cutting. You do not mess around with it. You do not improvise. You take it out of the box and you use it "by numbers" according to instructions. If it doesn't work as-is you stop. Oxy-acetylene equipment is a good way to investigate reincarnation.

All other welding equipment - you rig, frig, improvise, adapt, oil where you have to - all sorts of things.

The situation is vastly more complex for these blasting substances. But there are some recurrent themes where things went wrong. Hopefully they will lodge in my mind and activate if I meet like situation.

There's potassium chlorate preparations in the book I already have - reprint of Guttman, "Blasting", 1906. He is dismissive of them, saying don't be distracted off NG-based media - jelly and dyna. Hudson Maxim - his treatment of the topic! Apparently relevant? No. Calibration of judgment - definitely.

Hudson Maxim's eloquent way of saying a lot with a few words:

"Now it happens that there is so much erraticism about high explosive mixtures with chlorate of potash as a base that the pathway of invention of such compounds has been strewn with the wreckage of the hopes and anatomy of their inventors."

Hudson Maxim's eloquent way of saying a lot with a few words:

"Now it happens that there is so much erraticism about high explosive mixtures with chlorate of potash as a base that the pathway of invention of such compounds has been strewn with the wreckage of the hopes and anatomy of their inventors."

------------------------------------ His style reminds me of Ambrose Bierce.

"The poets would have us believe that all of the great inventors and discoverers, scientists and philosophers, have been far inferior to the poets. The poets would have us believe that all the triumphs of chemistry and mechanics have been small compared with the triumphs of poetry. The poets would have us believe that the invention of the phonograph, of the telephone, of wireless telegraphy, the discovery of radium and the X-ray, the discovery of gravitation, are not equal to such triumphs of the poets as “Aurora Leigh,” “Curfew Must Not Ring Tonight,” and “The May Queen.”

-HM

His style reminds me of Ambrose Bierce.

I read that bit... :-)

You are a cultured person. I have a simple technical-algorithm mind which obsesses on bashing, banging and other low-tech treatments, all serving fixations too narrow for anyone else to have even seen the question could be identified - until I come up with something "new and revolutionary" by reason of no-one ever having been there to pursue such an archane question... :-)

erm, probably not quite.

They may well have used Nonel for the leadline from the exploder to the trunklines along the bridge, and possibly for the downlines from the trunklines to the charges, but the trunklines along the bridge were detcord, not nonel.

tl-dr:

at 04s18f the trunkline on the nearest section detonates. It is clearly not a nonel detonation, far too visible and extensive for anything but a detcord detonation. (nonel detonations are hard to see in daylight, especially at a distance).

Note also that the detonation is both begun and over within the frame, there is no visible travel along the trunkline to be seen.

At 30 fps one frame takes 33ms; the main span is 50m, so at 6km/s the detonation takes 8ms; the detonation is over well within one frame, though its effects may take longer to manifest.

at 04s19f the trunkline on the center section detonates.

at 04s21f the trunkline on the far section detonates.

The delays between the sections are deliberate. One reason for using delays is to minimise acoustic and overpressure loads.

at 05s00f the first two main charges blow

at 05s01f the next two charges blow

at 05s02f the last two charges blow

To step single frames in youtube pause the video and use the < and > keys

Detcord/Primacord (usually plasticised PETN, loadings for transfer cord go from about 1.5 gram per meter to about 10 g/m, effects cords go to about 50 g/m) is usually about 6 km/s or a little higher.

Nonel (which is a tube dusted on the inside with PETN powder held in place by electrostatic attraction) is about 2,100 m/s

You can hold detonating nonel in your bare hand, though I'd recommend gloves. Try that with detcord and you will lose fingers at best.

Nonel speed:

Peter Fairbrother

You are a cultured person. I have a simple technical-algorithm mind which obsesses on bashing, banging and other low-tech treatments, all serving fixations too narrow for anyone else to have even seen the question could be identified - until I come up with something "new and revolutionary" by reason of no-one ever having been there to pursue such an archane question... :-)

--------------------------- At a Mensa party several of us who had made careers of innovation and problem solving considered the question of how to design a computer algorithm to assist us. We concluded that we don't know where our new ideas come from, subconscious memory associations can't account for all of them. As Taylor Swift wrote in the Pattie Boyd interview: "But there are mystical, magical moments, inexplicable moments when an idea that is fully formed just pops into your head."

Since industrial innovation is usually too competitive to reveal in print I've looked at artistic innovation, such as the analysis of song meanings, as much for why they chose their words as what they meant to say. I'm convinced that Bob Dylan's lyrics were chosen to rhyme and prompt the audience to apply their own interpretations to them. Last night on TV a program on painter Edward Hopper held that the critics had seen more in his paintings than it was eventually revealed that he intended.

enigmatic couple are the painter and his wife, who was also a talented artist and capable chronicler of his work. She wouldn't let him use any other woman as a model.

You are a cultured person. I have a simple technical-algorithm mind which obsesses on bashing, banging and other low-tech treatments, all serving fixations too narrow for anyone else to have even seen the question could be identified - until I come up with something "new and revolutionary" by reason of no-one ever having been there to pursue such an archane question... :-)

---------------------------

You may be a product of your environment. By Alistair Cooke:

"None of my friends in England had ever heard of biology until and unless they were going into a science which in those days put them outside the pale of cultivated company."

"I'm sure this has all changed since nearly a half a century ago when the late CP Snow raised a cultural storm, especially in the ancient universities, by saying that in England then there were two cultures that lived side by side in mutual incomprehension and even hostility."

"There was the culture of literary arts people who think of themselves as the cultivated and there were the physical scientists who may know little literature but are amazed at the narrowness, the constraint, the literary intellectuals' ignorance of so much of the life and the world about them."

"The man - his name was [Harold] Macmillan - wrote in his diary, after he'd spent some days and evenings with the general [Eisenhower], he wrote: "He is a man of charm and candour and determination but I fear woefully ill-educated."

"But whereas Mr Macmillan found Eisenhower deficient I imagine in quotations from Virgil and Wordsworth, he was woefully ill-educated in mathematics, engineering, strategy and tactics, especially the economics of industrial warfare about which Eisenhower's prescience had made General Marshall insist he become supreme commander."

Macmillan's reaction to Americans: "We, my dear Crossman, are the Greeks in the American empire. You will find the Americans much as the Greeks found the Romans—great big, vulgar bustling people, more vigorous than we are and also more idle, with more unspoiled virtues, but also more corrupt. We must run AFHQ (Allied Forces Headquarters) as the Greek slaves ran the operations of the Emperor Claudius".

Americans weren't totally ignorant of the classics, Patton used Caesar's operations as a guide to where the low ground was firm enough for vehicles, and raced him to bridge the Rhine.

Funnily enough, I know of this artist. HIs work is sufficiently distinctive to have stuck in my mind.

Done my Winter / xmas / lurghi season "asperg"!!!

Last year it was "Froude number" (basic hydrodynamics) related to an unusually rapid boat I worked on.

This years is done! Moving to West Cornwall it had to be I was in a pub in Camborne with a lot of ex (and some current) tin miners. Who were explaining thing like "You just stick a stick of dynamite to it with a lump of clay and it does a job" and "No, we couldn't use gelignite in South Crofty - too hot - the rock was at about 80degrees - it would have gone off by itself before we finished loading it" (that would be an "ooops") - and the sort of things kindly Cornish ex-miners will explain over a few pints of beer.

So I am really happy with what I did through the journey through the shortest days of the year :-)

I was in a pub in Camborne with a lot of ex (and some current) tin miners. ...

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I first read that as Cambronne, a French name from British military history.

Victor Hugo dramatically fictionalized the event and added the "Word of Cambronne" in Les Miserables.

Jim - I lost your message - but I want to say to all of you how happy I am. The shortest days are over and the days are visibly lengthening, the cold (virus) season is running its course, the new year has started and thoughts turn to its opportunities. It doesn't matter that any one study - eg. any one book or article - is read to completion, because the collage of pieces so far got me where I need to be. The topic "full-on mission" is a couple of days behind me now.

I went back to the mine and all was good, then in the eve. went to the group at the working persons' club where posed with the guy and his

6ft rock-drill-bit - nd there was the lady sat at the bar with a couple of rocks in front of her on the bar (maybe that's a "pulling" technique used by ladies here?!)

So simply wanted to say to all - thanks.

I forgot to comment the obvious - when I set out I didn't know what the goal looked like - then I realised I was there and it had come into view.

"millisecond-timed detonators" set me going - idea that it is possible to blast when there are buildings up above at the surface (at the surface the maximum effect is the power of one charge is timed milliseconds apart - yet at the blast location the effect for the tunneling is the sum of all blasts).

However, the "learning payload" took me to realising this is boath very expensive and far too complicated for learning "per-blast"

Then realising the answer is right there - in rock where "nothing is going on" - drill a pattern of holes and blast one at a time - thereby needing on a "cheap" single "no timing" detonator - and looking at what each blast does - what you intended and what you see and why. Lots of learning.

As I said, I had no idea what the destination looked like then you realise you are looking at it "clear as daylight".

The comments and inputs prompted the path to finding I was at "the goal" (for now).