Sciencemadness Discussion Board - Safely Testing Energetic Materials

Safely Testing Energetic Materials

quicksilver - 18-9-2006 at 08:49

I was wondering about ideas of safely testing energetic materials. I live in a very rural area so I have little problems but there are those who do not and have come up with techniques that work well.
Testing energetic materials can be a problem if noise will distrub others and if th possibility of flying material or soil will inhibit examination or retrieval of the material. The solution is a testing container of some sort. The conditions met must be safety and consistency. The reduction of noise is always a benefit.
The concept is defusment of expanding air or gases which result in noise.
The concept of a "Test Box" or blast box is an old one. I once actually found a very large one at the site of an old fcatory. Thus this concept is not original in any way. but it does work. For the testing of energetic materials in both safety and relative quite one constructs a sort of "silencer" for the blast. The use of baffles is a good idea as it keeps any materials from spraying around, however the most important thing is that the gasses or air generated from whatever explodes inside is defused. This concept DOES work. It can reduce the overall sound to a very unique degree. The average #8 cap simply makes a thump when a heavy steel box is baffled with wet rags. A VERY simple subsitute is to obtain a heavy container (like a schedual 40 6" pipe) and jam the ends with wet rags at the ends. In one side place a small length of paper tubing to hold the rags up and allow the insertion of the material to be tested. The blast will blow the rags out of the container with vertually very little noise and the material will be safe and not subject to flame or impact. The container will stay put. Heavy walls are amust but high strength pipe can be excellent (no seam).

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hinz - 18-9-2006 at 13:14

I've tested some blating caps in my garden in the middle of the village.
I burried them in a large bucket of damp sand, it was not too loud, the only sound was like if you throw a sandbag on the ground, something like a "blop". It's imprtant that the sand is damp, it will prevent the formation of a cloud of dust in case the charge isn't burried deep enough.
I think the noise emitted from it isn't bad as long as noone associates it with some kind of detonation.

ethan_c - 18-9-2006 at 14:31

Quote:

Originally posted by hinz
I've tested some blating caps in my garden in the middle of the village.
I burried them in a large bucket of damp sand, it was not too loud, the only sound was like if you throw a sandbag on the ground, something like a "blop". It's imprtant that the sand is damp, it will prevent the formation of a cloud of dust in case the charge isn't burried deep enough.
I think the noise emitted from it isn't bad as long as noone associates it with some kind of detonation.

Beware of this idea.
I did almost the same thing my very first explosive of this type, except it was buried five inches or so in pile of damp sand and about a quarter mile away from any houses in the 'open space,' albeit on the face of a hill. It was a small detonator with a 150g secondary. Instead of a muffled thump and sand spray, which is what I was expecting, there was a deep *BOOOOM* that felt like it rattled my brain- I didn't so much hear it as feel it, sort of stunned me -and echoed off nearby hills for around 11 seconds. Immediately, about 8 dogs started barking, and I ran back from behind the small hill I was hiding behind to look at what happened. There was no pile of sand anymore, just a little bit strewn around a superficial crater, and I ran the hell out of there. It was in the newspaper the next day, and I have always been a liiiiittle more careful as to the location of my 'tests'.
Long story short, damp sand does not ensure muffled blast.

[Edited on 18-9-2006 by ethan_c]

12AX7 - 18-9-2006 at 14:59

Geez, I wouldn't light off 150g of confined black powder willy-nilly, let alone a true explosive!

Tim

Boomer - 19-9-2006 at 03:42

For testing small cap numbers, a simple pipe bomp made from 1.5" steel pipe with threaded end caps works well. To increase the pipe's life, a shorter piece of 1" pipe is put inside, without end caps. Into this comes a piece of 1/2" pipe with the blasting cap in it, the pipe working as a witness 'plate'. The cap and the inner pipes are wrapped in paper towels to keep them centered.

The whole construction is wrapped in old towels, since sooth and hot gasses escape the hole for the cable. The bundle is placed in my bed.

Some dozen tests, some after midnight, have never disturbed a neighbour. You hardly hear a plop. At around 250mg MHN the small pipe gets deformed, at 500mg it gets torn open. This is where I stop doing it inside, and start digging holes.....

BTW a 2g-cap once blew a bucket of sand all over the room, so better use a sturdy box with a lid.

nitro-genes - 19-9-2006 at 04:53

Hehe, another method that I use occasionally is using the sink in the kitchen filled with water. You need a good deep sink for this, at least 15+ cm. The water requires electrical firing though, but this is easy work for most here. But be carefull, depending on the explosive used, half a gram, suspended in the middle is somewhat the limit...(Without wetting the ceiling that is

)

[Edited on 19-9-2006 by nitro-genes]

The_Davster - 19-9-2006 at 05:18

At one point I used a box of sand in the basement, at another I would wrap the witness plate in a towel, put it under a beanbag chair, and cover the chair in couch cushions. Rather small caps though. Havent done any of this in a few years now.

quicksilver - 19-9-2006 at 06:32

There are some damn good ideas here! It always seems a pity to have to drive some distance to make a little test, so I thought this thread may generate some thought but I had no idea that that others had met the same challenges so effectivly.

The bouncing of sound in an area of a valley can be a very difficult thing to control.
The acoustic signiture (sp?) of such a thing is often amplified by the echo. If the air (or gases) is forced streight up there is less chance of inappropriate noise. However in studying this whole issue I have determined that the sound (gases) need to be channeled generally. And that the use of burying the material must be deep enough for defusment. One idea that worked quite well with sand was to obtain a paper tube of the type used for paper towels (approx 12") and burying that pointing upward. The soft sand is carried with the blast and the sound muffled to an extent.
What appears to be consistently viable is the use of the blast to preform work such as to blow out wet rags (or sand, etc). This slows the air surrounding the intiial blast and deadens the overall noise. If baffels can be constructed, even temporary ones, they lower the noise signiture to a great extent. A suppressor on a firearm works when it defuses the blast behind the projectile. The better the design of defusment, the lower the noise signiture.
....Worked with this idea to the point that a significant difference is noticed when a gas generting energetic material is used than when a true detonation is used. If a deflagrating material is contained and exploded (a perchlorate / chlorate based salute or BP) the gases are vastly greater and much more noise is needed to be contained than when MHN, ETN, or primaries are used. Frankly, even though the work preformed is lessened, the noise generated by deflagrating materials is much greater, IMO.

[Edited on 19-9-2006 by quicksilver]

quicksilver - 20-9-2006 at 07:06

Taking this concept a bit further, I found an old well pipe on the land that is a 2" pipe with several short elbows making a series of "7"'s until it streightened out to a 5' length. It was placed into the earth and a small deflagarant (firecracker) was tested. The elbows acted as baffles and the resultant sound was quite muted, even though a lot of gases were released. If the elbows are short the object falls right down to the bottom. This is also a simple example of the above. The only problem being that retrieval is difficult and the whole point is to examine the resultant material.
The two witness plates, if they are heary enough could be an indoor answer; placed benieth a mattress, there whould be no damage to the mattress when wrapped in rags or old towels.

[Edited on 20-9-2006 by quicksilver]

Chris The Great - 21-9-2006 at 01:16

I've fired some hugeass charges in the open before (the last one my brother heard very clearly 4km away). I've never made the papers yet... hmmm (Got to try harder)

Usually I just stick the shovel into my lawn, pry a bit to open a hole, drop in my charge and the stomp the ground back together and fire it. 3-4g methyl nitrate is about the most, even than there is a significant *thump* that travels through the earth. Not a ton of noise though.

froot - 21-9-2006 at 07:41

I suppose muffling a detonation basically involves impeding the shockwave as much as possible without harming the baffling. We're dealing with a rapid gas sepansion and a shockwave.
Looking at Quicksilver's diagram, any container with some sort of adequately sized vent will be sufficient for an appropriate size detonation, as long as it releases the pressure slower than what the gas expansion is, it will have a muffling effect.
So, if I may thumbsuck, if the test substance is expected to produce 1 cubic meter of gas, the chamber needs to release it at about 10 times slower than it was produced and you will have sufficient muffling, and it will have to sustain the interim pressure generated for that instant.
Problem is, if you overconstrain the pressure release of your vessel, you'll damage it unless you overdesign it with superthick steel. Same effect if you test too much explosive in one go.
The chamber in which the test substance will detonate will need to be alot (I'm not sure how much) larger than the volume of gas that particular test substance will produce otherwise the chamber may distort/burst and the test results may be tainted. I would also place the test chamber insode another bigger chamber on soft rubber supports to help muffle it and place the whole bangshoot on a shock absorbing suspension system to prevent shockwaves from being transmitted through the ground.
Now you can play 'fire in the hole' while your mom watches Desperate Housewives in the very next room and it will sound like you're bouncing a soccor ball.

quicksilver - 21-9-2006 at 17:05

I actually saw a box made for this type of testing from the Austin Powder Company. It was not only huge but VERY heavly walled; about 3/4" thick). I do not know how or what was being tested in it. It was at the site of the old powder works and was in a rusted condition but the top had a wondeful logo like an old safe (which is what I thought it was at first glance). I wanted to cart it home but the thing weighed much more than I would attempt to manipulate. It was about the size of a phone booth. The design was very similar to the above.

You mentioned one of the keys here, the slower release of gases! I had just stumbled on something in experimenting with this concept. Imagine a container strong enough to withstand an explostion with a hinged door on the top that only opens outward. If that "door" has weight added to it to conform to th amount of air / gases moving against it - it will slow the release of these gases. Gravity keeps the "door" in place until the explostion proforms the work of attempting to push it outward.I have actually proven this to my satisfaction and the resultant sound was so muted as to be indistinctive as an explostion. I do not know if it's 10x exactly but the concept you mention is correct in terms of effectivness.

[Edited on 23-9-2006 by quicksilver]

h0lx - 15-10-2006 at 00:04

Actually damp sand works really well, you just have to "feel" what the right amount is. I detonated 300 grams of secondary under about 50cm of sand, the noise was just like something heavy was dropped on the ground, but the sand flew like hell. A few tests should get you the feeling of the correct depth. if you go too deep you just hear a faint pop and the sand hopping up about 2 cm(dig this up, the sand near the epicenter is so pleasurably hot) while too shallow will make quite a noise. Brisance plays a great role in noise too.

quicksilver - 15-10-2006 at 08:10

The actual techniques here are very valuable. If one is to use damp sand for instance is it more effective to cover the witness-plate directly or to create a chamber of sorts from some non-ridged material like paper? Does the sand touch the explos material directly and if so will this have an effect on the results of a test? I can clearly see how using techniques like damp sand are both safe and effective from a noise reduction stand-point. Illustrating the technique indepth gives those people who are considering a test more options.
However 300 grams is a pretty big charge....what was it?

h0lx - 15-10-2006 at 10:49

It was 210 grams of CO2 and H2O balanced Flour/ammonium nitrate mix with 90 grams of EGDN IMO, it was quite a long ago so I might be wrong. I bet burying a beer keg or something with loose top cover should simulate atmospheric conditions pretty well if you could somehow suspend the charge in the middle.

I never had the material touch the sand, in a plastic bag or a cardboard tube usually.

About the effect of moisture, Ive no experience as the sand is always the same, dry layer on top and the rest damp.

Oh and a fascinating effect can be achieved, when burying a bit deeper than required and placing some big round rocks on top. No sand movement, but the rocks hop and roll apart.

edit: My technique of burying is to hand dig the desired approximate depth, place the charge, inserting cap carefully, then while holding everything in place slowly pouring some 10 cm of the damp sand on top, patting more compact with hand, then pushing the damp/dry mix on top and sometimes piling an extra 20-30cm on it. from the noise reducion side the depth is rather insensitive. The approximate depth is made up on previous experienc, IE approximately how did some size of charge at some depth perform. I rather aproximate on size than brisance.

[Edited on 15-10-2006 by h0lx]

LABORATORY DETONATION CHAMBER

franklyn - 25-1-2008 at 21:57

I could use one of these in my apartment

http://www.ozm.cz/detonation-chambers/pdf/DC-Laboratory.pdf

By the way, if you have not seen Wikipedia on explosives lately,
it has a very concise primer overview of energetic science.
http://en.wikipedia.org/wiki/Explosive

.

franklyn - 13-4-2010 at 07:22

UPDATE
to the post immediately preceding

http://www.ozm.cz/en/detonation-chambers

http://www.ozm.cz/en/laboratory-detonation-chambers

.

The WiZard is In - 13-4-2010 at 16:57

Quote: Originally posted by franklyn

I could use one of these in my apartment

I have an original of this, sorry to say it does not appear to be available on line.

Accession Number: ADP004856

Full Text (pdf) Availability:
Size: 0 KB
Handle / proxy Url: No Full Text PDF Available
Citation Status: A - Active
Title: Interim Total Containment Test Fire Facility, Pantex Plant, Amarillo, Texas,
Corporate Author: MASON AND HANGER-SILAS MASON CO INC AMARILLO TEX PANTEX PLANT
Personal Author(s): Papp, A G Nunley, J L West, G T
Report Date: Aug 1984
Media Count: 44 Pages(s)
Organization Type: 4 - INDUSTRIAL/COMMERCIAL
Identifiers: Containment chambers, Component Reports

Abstract: This report documents the results of a test program which consisted of a series of explosive tests within a confinement chamber called the Interim Total Containment Test Fire Facility. The chamber was designed for maximum explosive charge of 29 lb of TNT. The purpose and objective of the testing were to determine the effectiveness of the chamber to contain the blast loads and hazardous fragments generated by the largest HE charge expected to be fired within the chamber.

Distribution Limitation(s): 01 - APPROVED FOR PUBLIC RELEASE
Source Code: 387099
Document Location: 1 - DTIC AND NTIS
Supplementary Notes: This article is from 'Minutes of the Explosives Safety Seminar (21st) Held at Houston, Texas on 28-30 August 1984. Volume 1,' AD-A152 062, p721-764.

-------
Oh no doubt you will be A. Astounded and B. Amazed to
know there was a small expls. test chamber for sale on
eBay some years back.[

Then there do be THE ULTIMATE EXPLOSIVE CONTINENT VESSEL

JUMBO
http://www.fullbooks.com/Trinity-Atomic-Test-Site.html

Lying next to the entrance of the chain link fence that still
surrounds Trinity Site are the rusty remains of Jumbo. Jumbo was the
code name for the 214-ton Thermos shaped steel and concrete container
designed to hold the precious plutonium core of the Trinity device in
case of a nuclear mis-fire. Built by the Babcock and Wilcox Company
of Barberton, Ohio, Jumbo was 28 feet long, 12 feet, 8 inches in
diameter, and with steel walls up to 16 inches thick.

The idea of using some kind of container for the Trinity device was
based on the fact that plutonium was extremely expensive and very
difficult to produce. So, much thought went into a way of containing
the 15 lb. plutonium core of the bomb, in case the 5,300 lbs. of
conventional high explosives surrounding the core exploded without
setting off a nuclear blast, and in the process scattering the costly
plutonium (about 250 million dollars worth) across the dessert. After
extensive research and testing of other potential containment ideas,
the concept of Jumbo was decided on in the late summer of 1944.

However, by the spring of 1945, after Jumbo had already been built and
transported (with great difficulty) to the Trinity Site by the
Eichleay Corporation of Pittsburgh, it was decided not to explode the
Trinity device inside of Jumbo after all. There were several reasons
for this new decision: first, plutonium had become more readily
(relatively) available; second, the Project scientists decided that
the Trinity device would probably work as planned; and last, the
scientists realized that if Jumbo were used it would adversely affect
the test results, and add 214 tons of highly radioactive material to
the atmosphere.

Not knowing what else to do with the massive 12 million dollar Jumbo,
it was decided to suspend it from a steel tower 800 yards from Ground
Zero to see how it would withstand the Trinity test. Jumbo survived
the approximately 20 kiloton Trinity blast undamaged, but its
supporting 70-foot tall steel tower was flattened.

Two years later, in an attempt to destroy the unused Jumbo before it
and its 12 million dollar cost came to the attention of a
congressional investigating committee, Manhattan Project Director
General Groves ordered two junior officers from the Special Weapons
Division at Sandia Army Base in Albuquerque to test Jumbo. The Army
officers placed eight 500-pound conventional bombs in the bottom of
Jumbo. Since the bombs were on the bottom of Jumbo, and not the
center (the correct position), the resultant explosion blew both ends
off Jumbo. Unable to totally destroy Jumbo, the Army then buried it
in the desert near Trinity Site. It was not until the early 1970s
that the impressive remains of Jumbo, still weighing over 180 tons,
were moved to their present location.

The WiZard is In - 13-4-2010 at 17:09

KISS (Keep It Simple Stupid)

A test which combines impact and friction consists in hitting the
substance a glancing blow with a mallet or the end of a broom-stick.

Arthur Marshall
A short account of explosives
1917
[Google.com/books]

djh
-------
Tramp explosives or detonators are like
poisonous snakes — usually strike when least
expected. More often than not, they badly maim
or destroy the eyesight or other parts of the
body of their victims.

US Bureau of Mines
IC7038

update 2019

twelti - 22-4-2019 at 18:16

Just wondering if there are any updates to this discussion. I have been wanting to make a test "box" of some sort, or at least find a way to minimize noise. I saw vids of LL testing det caps in what looks like a low walled compost box full of sawdust. I suspect if I tried that, I'd get a house full of sawdust!

MineMan - 22-4-2019 at 20:49

Quote: Originally posted by ethan_c

Quote:

You did 150g under 5 inches of sand... should have used 2 feet.

I am sorry. But this is not a warning to be heeded.

MineMan - 22-4-2019 at 20:52

5 gallon bucket filled with damp sand.

Laboratory of Liptakov - 22-4-2019 at 21:42

Big building bucket with wet sand is enough for testing up to 1g. ( I have house full of sawdust)........ :cool:

....LL

twelti - 23-4-2019 at 11:31

Quote: Originally posted by Laboratory of Liptakov

Big building bucket with wet sand is enough for testing up to 1g. ( I have house full of sawdust)........ :cool:

....LL

So, your house is already full of sawdust! That IS funny!

Does that include only metal det caps taped to a plate? Or just any charge?

Laboratory of Liptakov - 23-4-2019 at 11:46

Only metal det caps up to 2g. Any bigger charge around 10g destroy plast container. My research is det caps. Not something bigger.... :cool:

...LL

Pyro_cat - 23-7-2019 at 20:46

You get the idea.

The highest altitude by a single kite is 4,879.54 m (16,009 ft) and was achieved by Robert Moore (Australia) in Cobar, New South Wales, Australia on 23 September 2014.

twelti - 23-7-2019 at 23:11

Quote: Originally posted by Pyro_cat

You get the idea.

The highest altitude by a single kite is 4,879.54 m (16,009 ft) and was achieved by Robert Moore (Australia) in Cobar, New South Wales, Australia on 23 September 2014.

???

Tyneman - 24-7-2019 at 12:03

I use a little adapted version of LL's sawdust thingy.
I have a medium sized dustbin, about 50cm high, 35cm dia. Put in a layer of cocoa-shells. Put test subject on there. Then fill to the brim with cocoa-shells.
This gives way less mess then sawdust and is much easier to clean up.
I never used wet sand because I always had the idea the sheer weight would effect performance.
This weighs nearly nothing. I can use it inside or in the garden, just pick up the bin and place elsewhere. Sounds like a dull thump. My neighbors don't even look up when I test 3 meters away from them.
Point to make is I only test detonators this way. So thats always less then 3g of energetic material. Anything bigger gets buried in the woods.

twelti - 24-7-2019 at 12:11

Quote: Originally posted by Tyneman

I use a little adapted version of LL's sawdust thingy.
I have a medium sized dustbin, about 50cm high, 35cm dia. Put in a layer of cocoa-shells. Put test subject on there. Then fill to the brim with cocoa-shells.
This gives way less mess then sawdust and is much easier to clean up.
I never used wet sand because I always had the idea the sheer weight would effect performance.
This weighs nearly nothing. I can use it inside or in the garden, just pick up the bin and place elsewhere. Sounds like a dull thump. My neighbors don't even look up when I test 3 meters away from them.
Point to make is I only test detonators this way. So thats always less then 3g of energetic material. Anything bigger gets buried in the woods.

I also have a bucket with mixed sand and sawdust, and an outer bucket, with a bunch of holes drilled in the inner bucket, and t-shirts stuffed between the two buckets. Works great! I'm interested to do a larger one and see how far I can push this concept. Would a larger bin with a couple of cubic meters of filler handle 15 or 20 grams HE? We'll see!

Pyro_cat - 24-7-2019 at 15:04

Quote: Originally posted by twelti

Quote: Originally posted by Pyro_cat

You get the idea.

The highest altitude by a single kite is 4,879.54 m (16,009 ft) and was achieved by Robert Moore (Australia) in Cobar, New South Wales, Australia on 23 September 2014.

???

Fly a kite to haul your test a mile up. Over water would be best. Silly idea but someone might like it. Just thinking be careful though, kites have a way of generating static electricity even with a blue sky.

--

More realistically if I were testing EMs I would get some 1/4 in. x 54 in. drill bit extensions and use them drill a narrow hole deep into the ground. I would think 6 feet plus down in soft earth not much noise would make it to the surface even with the hole uncovered.

Any wood bit should work just fine but if one needs a larger hole they have earth auger bits that fit in standard drills and larger diameter extensions.

[Edited on 25-7-2019 by Pyro_cat]

twelti - 25-7-2019 at 19:20

Quote: Originally posted by Pyro_cat

Quote: Originally posted by twelti

Quote: Originally posted by Pyro_cat

You get the idea.

The highest altitude by a single kite is 4,879.54 m (16,009 ft) and was achieved by Robert Moore (Australia) in Cobar, New South Wales, Australia on 23 September 2014.

???

Right. Benjamin Franklin with a twist of ETN! I'm sure a bolt of lightning would be a nice primary.

Pyro_cat - 26-7-2019 at 20:16

Quote: Originally posted by twelti

Right. Benjamin Franklin with a twist of ETN! I'm sure a bolt of lightning would be a nice primary.

Its been on my list for years to either fly a kite or use a weather balloon to lift some fishing wire during a thunderstorm and get a video of a lightning bolt hitting it. That would have to be worth millions of views on YouTube too. Get the kite started with regular monofilament , non conductive, then just set the drag on the fishing reel to slowly let out the fishing wire get away and watch. Remember to tie off the end and ground the reel to something good.

Edit: They sell copper fishing wire and I would imagine the lightning bolt would get a green tint to it if it vaporized. Copper wire 1000 feet up, how could the lightning not like that path to ground best ?

[Edited on 27-7-2019 by Pyro_cat]

twelti - 26-7-2019 at 21:54

Quote: Originally posted by Pyro_cat

Quote: Originally posted by twelti

Right. Benjamin Franklin with a twist of ETN! I'm sure a bolt of lightning would be a nice primary.

That would make a nice exploding wire!

johny5 - 21-8-2019 at 21:57

Damp sand really works well but you just need to know the right amount.

Pyro_cat - 22-8-2019 at 15:18

Quote: Originally posted by johny5

Damp sand really works well but you just need to know the right amount.

I agree. Back in the day of real M-80s I thought I was going to be funny digging a hole in the sand at the beach dropping one in covering it up real fast then having sand rain down on everyone stuff. Nope, just a tiny thump under the ground. Dug a narrow hole little past my elbow reaching down.

That winter there was a snow pile left by the plows and I poked a hole with the snow shovel handle and dropped one in somewhat expecting to send snow skyward. Nope, just a flash of light at the center of the pile.

Sulaiman - 22-8-2019 at 18:06

Maybe testing only during thunderstorms would mask the light and sound of detonations ?

Fantasma4500 - 4-9-2019 at 23:04

i saw dr lipton used sand to test blasting caps, i also talked to one guy some years back who used thunderstorms for lighting off bigger things. it still made it into the newspapers with just a few hundred grammes of material
he also dug things down in the ground under some dirt to test against metal targets in his backyard, i would argue that wouldnt be natural for a witness plate test, tamping. however you will still get a very deep thump.

you may also light it off underwater, while respecting underwater detonation physics, the shockwave will impact the nearest object. i suppose strapping it to a bamboo stick and placing it in the middle of a bucket would cause it to target the bamboo stick? but it will transmit a lot of sound still, just 100mg KMnO4 flashpowder under 10L water was quite surely felt by most people in appartment complex

maybe if water was used, and this was then suspended in the air or some rubber/foam like material to absorb the shock, as in a platform for the bucket to be placed on
honestly i would probably call it 50L to be advised for just 1g primary.

Microtek - 5-9-2019 at 08:33

I find that Liptakov's idea with coarse sawdust (which can be bought in pet stores) in a plastic container or bucket works very well, at least up to one full gram of PETN. I have placed a 20 L plastic bucket in a hole I dug in the ground inside a small shed. Then I filled the bucket with sawdust and made a double walled lid with mineral wool between the layers. A gram of PETN sounds like someone is closing a door somewhat firmly, but there is no high frequency noise, birds don't stop their singing, and neighbours don't notice anything.

Pyro_cat - 6-9-2019 at 22:07

bulb-planting-auger-garden-3-planter-plant-bulbs-faster-no-digging-earth-for-electric-drill-uk-bit-lowes.jpg - 9kB

I still say dig deep ! Use lots of extensions and make the the Kola borehole jealous.

Laboratory of Liptakov - 18-9-2019 at 01:11

....."Birds don't stop their singing".....Basical and reliable measurement of intensity of sound...

Seriously: Bucket with sawdust is lightweight and easy to move... :cool: