Blasting and Rock Breaking

[BlasterJ]

On our Sierra Blaster 6 head system, even horizontal shots will blow the heads out of the drill hole, so we block them in with 2" or bigger branches cut to size. We were blasting about 40' in our tunnel last week after getting some great readings with a friends Goldmonster, but after taking the 5000 in last week and setting up for the blasts, my partner had forgotten our air pump... and down in that canyon, the air gets thin before you even go in... so we only got a few rounds in where I was set for a bunch. We're not getting any younger these days

You might try hanging a sandbag off the head. Have you done anything like that - just adding mass? I like sandbagging anything with small explosive charges.

 

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[Reed Lukens]

Thanks thats a great idea! I have a bunch of caribeaners that will make it easy to attach some sand bags. Our drift is roughly 8 feet wide max on the top and 4' to 5' wide on the floor.

 

[BlasterJ]

If anyone else would like to read my article on micro-blasting, they just put it online for free:

https://www.icmj.com/resources/sample/

 

[Reed Lukens]

A great article John It's really nice to have a current, up to date and knowledgeable mining article writer for the ICMJ on here.
You didn't mention the "Cheetah SDS BITS" in your article and they really are a cut above the "Sierra Tuff Bits" that they sell as far as high speed drill bits for the Sierra Blaster. We bought a few cases of extra bits and when I have a choice, I always reach for the Cheetah Bits because they really are at least twice as fast in most types of rock compared to any other brands that I have used.

https://store.sierrablaster.com/Cheetah-10mmX210mm-6x8-SDS-Masonry-Drill-Bit_p_36.html

 

[BlasterJ]

A great article John It's really nice to have a current, up to date and knowledgeable mining article writer for the ICMJ on here.
You didn't mention the "Cheetah SDS BITS" in your article and they really are a cut above the "Sierra Tuff Bits" that they sell as far as high speed drill bits for the Sierra Blaster. We bought a few cases of extra bits and when I have a choice, I always reach for the Cheetah Bits because they really are at least twice as fast in most types of rock compared to any other brands that I have used.

https://store.sierrablaster.com/Cheetah-10mmX210mm-6x8-SDS-Masonry-Drill-Bit_p_36.html

Interesting. Do you find they are better pretty much all the time, or only when the rock isn't extremely hard?

 

[Reed Lukens]

When the rock is hard, they are still faster but Daina and Aaron along with my partners and myself did the initial video that they used to get their exemption back in 2013. I'll grab it for host rock every time, then switch to the Sierra Tuff or another slower brand for drilling thru quartz. The speed change is so noticeable when drilling through different layers that, it's really an eye opener along with quickly being able to determine the change in the rock layers by the different speeds.
We do a drill bit and drill test at the beginning of this video. At 3:00 you can see that the Cheetah bit comes in at being more than twice as fast as the Sierra Tuff. This is the same mine that we were blasting in last week, with my same partners, but this Sierra Blaster video was one that I filmed over 7 years ago in around June of 2013. It wasn't published for the public until after Sierra Blaster got their exemption over a year later.

 

[Mad Machinist]

On our Sierra Blaster 6 head system, even horizontal shots will blow the heads out of the drill hole, so we block them in with 2" or bigger branches cut to size. We were blasting about 40' in our tunnel last week after getting some great readings with a friends Goldmonster, but after taking the 5000 in last week and setting up for the blasts, my partner had forgotten our air pump... and down in that canyon, the air gets thin before you even go in... so we only got a few rounds in where I was set for a bunch. We're not getting any younger these days

As I said before, the Sierra Blaster cartridges will fire off of an electronic ignition box. Horizontal and overhead work is where the Sierra Blaste iis really weak.

Cat.litter is mostly bentonite clay. So a simple ball mill to break it into powder will work. Mix in enough water to make it pliable and you have the perfect stemming material for horizontal and overhead shots. I do see the Sierra Blaster working for a lot of people though with a few small modifications such as this.

 

[BlasterJ]

As I said before, the Sierra Blaster cartridges will fire off of an electronic ignition box. Horizontal and overhead work is where the Sierra Blaste iis really weak.

Cat.litter is mostly bentonite clay. So a simple ball mill to break it into powder will work. Mix in enough water to make it pliable and you have the perfect stemming material for horizontal and overhead shots. I do see the Sierra Blaster working for a lot of people though with a few small modifications such as this.

I bought some of those unfilled caulking tubes and will try milling some Bentonite next week. It seems like a great idea. The only issue is that Sierra Blaster/etc. probably can't advertise a different way to use the explosive part, as the product was probably approved "as a system."

 

[Mad Machinist]

I bought some of those unfilled caulking tubes and will try milling some Bentonite next week. It seems like a great idea. The only issue is that Sierra Blaster/etc. probably can't advertise a different way to use the explosive part, as the product was probably approved "as a system."

I think it had more.to do with the charge weight and composition than a system. It doesn't really matter ifnitnis fired on a blast box or the system as both are electronic ignitions. One benefit of the bentonite stemming is that more gases will be kept in the hole leading to less need for booster cartridges in some situations.

 

[BlasterJ]

FYI, next month's article on "Advanced Micro Blasting" is going to cover your tip on the Cheetah bits. I tried them side by side, and I agree they are way faster. My least-capable drill can get more holes per battery with them in the moderate hardness rock I drill.

I also mention a few general tips on cleaning holes, managing misfires and getting rock moved in an unbroken face.

 

[Reed Lukens]

FYI, next month's article on "Advanced Micro Blasting" is going to cover your tip on the Cheetah bits. I tried them side by side, and I agree they are way faster. My least-capable drill can get more holes per battery with them in the moderate hardness rock I drill.

I also mention a few general tips on cleaning holes, managing misfires and getting rock moved in an unbroken face.

We just came out and back into service today. We took some pictures for Aaron of Sierra Blaster of how we blocked the heads in with truck cargo bars backed by 2"x8" pressure treated boards this time. That was our friend Tom's idea, he's actually in the pictures below. Jacking the truck bars up against the heads worked great. Then we have shims to fill any gaps if needed, though we used ore this time as it was the first... We have an 8 head system and that blows them in series. With just 4, they go off all at once and with the 8, you can hear the 8 separate blasts in rapid succession

 

[BlasterJ]

We just came out and back into service today. We took some pictures for Aaron of Sierra Blaster of how we blocked the heads in with truck cargo bars backed by 2"x8" pressure treated boards this time. That was our friend Tom's idea, he's actually in the pictures below. Jacking the truck bars up against the heads worked great. Then we have shims to fill any gaps if needed, though we used ore this time as it was the first... We have an 8 head system and that blows them in series. With just 4, they go off all at once and with the 8, you can hear the 8 separate blasts in rapid succession
View attachment 1861900 View attachment 1861901 View attachment 1861902

Cool! Did you make your own sequential blast box, or use a standard 4-10J blasting model? I'm thinking about build a ~30J box based on a Ryobi drill battery for firing this and other e-match stuff.

 

[Reed Lukens]

Nope, I just stacked the wires, 4 on top of each other on each side the standard Sierra Blaster Double sided Receptical and let Tom hit the switch out at the tunnel entrance, it was his first time on the switch. I'm thinking that because we were 150' in with the 2 blaster cords (1- 100' & 1- 50') and then another 100' of 10/3 electrical cord running from the opening away from us, over the creek to the Honda 2000i, that the 250' of wire created it's own sequential blast. Last week, we picked up 2 more of the Stainless Steel Heads, another switch and the head connector wires, so that was our first 8 head blast and the rest sounded the same from then on with 8 definite individual blasts in sequence.
We were able to bring down a 6' wide x 3' tall section with the 8 heads. They worked perfectly.

 

[Mad Machinist]

Cool! Did you make your own sequential blast box, or use a standard 4-10J blasting model? I'm thinking about build a ~30J box based on a Ryobi drill battery for firing this and other e-match stuff.

I'd be interested in that 30J setup. What about one of those 56 volt deals of that EGO blower thingie?

 

[Mad Machinist]

How about this one??

https://egopowerplus.com/battery-7-5amp/

I know Milwaukee has a 12 amp hour battery out now too.

 

[Mad Machinist]

Ok I'm a little rusty on this but here goes.

Each of the Sierra Blaster heads needs 200 watts at 110 volts, so ten heads would be 2000 watts at 110 volts. It doesn't say AC or DC so it may fire on both.

Two of the EGO 56 volt batteries wired in series would give 112 volts amd should have enough power to firen10 cartridges.

Now here is where itnis gonna get interesting and a little dangerous. For every 1000 watts discharged, you need 1 farad of capacitance. Capacitors wired in parallel can be added together for total capacitance, so of you wire 4 500 microfarad capacitors in parallel, it will equal 2 farads of total capacitance. Now safety switches would have to be installed to prevent accidents. Could be done but might end up bigger than expected by the time it is done.

 

[BlasterJ]

Yes and no. You need ~1KW, but you probably only need it for 10ms for a typical e-match or cap. The actual amount of watt seconds/watt hours used is going to be pretty low. I bought some DC-DC converter boards that will take 9-24V and take it up to 400V. They are used for DIY photography strobes and lasers.

With an SCR trigger that can handle a 100A peak or better, I can put out an honest 2-3KW for a few milliseconds.

Ok I'm a little rusty on this but here goes.

Each of the Sierra Blaster heads needs 200 watts at 110 volts, so ten heads would be 2000 watts at 110 volts. It doesn't say AC or DC so it may fire on both.

Two of the EGO 56 volt batteries wired in series would give 112 volts amd should have enough power to firen10 cartridges.

Now here is where itnis gonna get interesting and a little dangerous. For every 1000 watts discharged, you need 1 farad of capacitance. Capacitors wired in parallel can be added together for total capacitance, so of you wire 4 500 microfarad capacitors in parallel, it will equal 2 farads of total capacitance. Now safety switches would have to be installed to prevent accidents. Could be done but might end up bigger than expected by the time it is done.

 

[Mad Machinist]

Yes and no. You need ~1KW, but you probably only need it for 10ms for a typical e-match or cap. The actual amount of watt seconds/watt hours used is going to be pretty low. I bought some DC-DC converter boards that will take 9-24V and take it up to 400V. They are used for DIY photography strobes and lasers.

With an SCR trigger that can handle a 100A peak or better, I can put out an honest 2-3KW for a few milliseconds.

Cool. Electronics really isn't my strong point.

 

[BlasterJ]

Cool. Electronics really isn't my strong point.

I know, the whole "short duration" thing isn't very intuitive. We're used to thinking in terms of continuous power for a motor, pump, etc. A capacitor can deliver a lot of amps/watts for a very short period of time and can use a pretty unimpressive power source.

1 watt hour = 3,600 Joules. A 2AH, 18V battery for a drill is 32 Watt hours. So at 30J, a drill battery can do a LOT of shots.

 

[Reed Lukens]

That's definitely something that I would be interested in also. I still need to run a generator for the 2 SDS's, lights and the ventilator, but the ~30J sounds like a great set up. I still miss the old crank handle style twist detonator that we used when I was a kid...
The good ol' days, no batteries... no simple push button... different times these days