93 replies to this topic

[knackers]

i was using lead when i first started to mill my own and thought it was ok, untill i saw what it should have burned like.. i have changed my media form lead to stainless steel ball bearings, 5/8`` diam, about 24 off them in a 6``diam * 8`` long tub and saw a huge difference in my bp, i use ..75/15/10, riced with 50/50 water and ether screened through my kitchen 25 mesh, using apricot or mountain ash charcoal and atomic sulphur,, i can lift a 3`` 7-->10 oz projectile 200--->300 mtrs

[Labs2008]

wow that sounds awesome i thought any type of steel was not safe for milling bp due to the chance of sparking. I do know stainless is not magnetic but it still can spark right. What about ceramic? what type of stainless steel do you use? If i could lift a shell 100 meters i would be happy. My pine charcoal seems good it is airfloat and my kno3 is pure atomic sulphur is that like a certain grade?

[knackers]

i wouldn`t use mild steel ( this has also been touched on in the bp thread), and yes stainless will spark but the friction needed is not produced in my mill,( being a boilermaker) i have a good idea what frictions are needed for different species of metal and feel comfortably safe using stainless, the grade of ss is 302 food grade, and my sulpher is purified, and like air float charcoal, purchased from an explosives manufacturer, my charcoal is home made, cooked in a sauce pan with 2 aluminium foil sheets for a lid, with a small hole in it and left sealed when finished for about 24 hrs,..... i can`t comment on pine charcoal, i have not used it but am under the impression soft woods are infearier to hard woods

Edited by phill 63, 11 August 2008 - 04:08 AM.

[portfire]

Hi Labs2008, and welcome to the forum

It look's to me that your under charging your mill. Under and over charging will effect the mills efficiency to, well mill, and effect milling time and burn-rate of your BP. Try 100g batches and see how it compares.

[digger]

i wouldn`t use mild steel ( this has also been touched on in the bp thread), and yes stainless will spark but the friction needed is not produced in my mill,( being a boilermaker) i have a good idea what frictions are needed for different species of metal and feel comfortably safe using stainless, the grade of ss is 302 food grade, and my sulpher is purified, and like air float charcoal, purchased from an explosives manufacturer, my charcoal is home made, cooked in a sauce pan with 2 aluminium foil sheets for a lid, with a small hole in it and left sealed when finished for about 24 hrs,..... i can`t comment on pine charcoal, i have not used it but am under the impression soft woods are infearier to hard woods

Whilst I agree that stainless steels are less prone to sparking than carbon / mild steels. I would not go as far as to say it is safe.

So being a boiler maker, what training do you get regarding friction sparking effects on Austenitic stainless steels? Have you any data on what levels of frictional forces are required to produce a spark?

Labs2008 If I were you I would avoid the use of media that CAN spark such as stainless steel and stick to something that definitely won't spark such as lead, brass or ceramic at a push (although this is controversial too). In industry the use of steels for the milling of black powders would not even be contemplated.

As to SS media being more efficient I am sure it would be good for milling hard materials such as metal powders but my optimised mill will produce outrageously fast BP in six hours with ceramic media. The fastest meal I have seen was produced by a member on here and he uses lead media with a nice willow charcoal.

Edited by digger, 11 August 2008 - 09:49 AM.

[knackers]

No  data sorry..... 27 years experience wacking the daylights out of , austenetic  s/steels, tempered, mild,exotic,alloyed, anealed,cast iron, pig iron, low carbon and high carbon steels, to name a few, 10 years experience as a certified welding supervisor/inspector....  In all of my experience i have witnessed sparking  austenetic  s/s  and the forces inside a 6`` ball mill rotating at 60 odd rpm are not enough to spark s/s  on  s/s............sorry i couldn`t be more specific with  kilogram newtons


in industry they wouldn`t be bothered with a 6`` ball mill

Edited by phill 63, 11 August 2008 - 10:11 AM.

[digger]

No  data sorry..... 27 years experience wacking the daylights out of , austenetic  s/steels, tempered, mild,exotic,alloyed, anealed,cast iron, pig iron, low carbon and high carbon steels, to name a few, 10 years experience as a certified welding supervisor/inspector....  In all of my experience i have witnessed sparking  austenetic  s/s  and the forces inside a 6`` ball mill rotating at 60 odd rpm are not enough to spark s/s  on  s/s............sorry i couldn`t be more specific with  kilogram newtons


in industry they wouldn`t be bothered with a 6`` ball mill

Home mills have been known to explode (admittedly all of the ones that have exploded that I know of have been in US). You are prepared to take the risk of using a material that is more likely to spark do you think others should?

[knackers]

Home mills have been known to explode (admittedly all of the ones that have exploded that I know of have been in US). You are prepared to take the risk of using a material that is more likely to spark do you think others should?

perhaps you should also do more research,, lead also sparks,, ( but not in a 6" ball mill ) it requires conciderable kgn > s/s, i will keep using my medium with no risk,, ...i don`t expect others to take a risk, and i appreciate your concern

[digger]

perhaps you should also do more research,, lead also sparks,, ( but not in a 6" ball mill ) it requires conciderable kgn > s/s, i will keep using my medium with no risk,, ...i don`t expect others to take a risk, and i appreciate your concern

Just to set it straight I am not trying to have a go at you.

I agree it is possible to get virtually any material to spark given enough energy.

However with harder materials the energy density of the collisions will be far higher especially with round media.

All it takes is for there to be a single spark of sufficient energy. Can you honestly unequivocally say that under the conditions in your mill this will never ever happen?. If so then I think you should publish your evidence so that we can all start using stainless steel without risk.

I find it hard to believe that you say you are using your mill with "NO RISK". I use materials that have a much higher spark energy threshold and I still only turn on the mill remotely and have it dug into a hole so in the event of a blast the energy will go up rather that out.

I would always recommend to people to use the safest possible practices.

As they say there are old pyro's, there are bold pyro's but there are very few old bold pyro's.

Edited by digger, 11 August 2008 - 11:10 AM.

[knackers]

Just to set it straight I am not trying to have a go at you.

I agree it is possible to get virtually any material to spark given enough energy.

However with harder materials the energy density of the collisions will be far higher especially with round media.

All it takes is for there to be a single spark of sufficient energy. Can you honestly unequivocally say that under the conditions in your mill this will never ever happen?. If so then I think you should publish your evidence so that we can all start using stainless steel without risk.

I find it hard to believe that you say you are using your mill with "NO RISK". I use materials that have a much higher spark energy threshold and I still only turn on the mill remotely and have it dug into a hole so in the event of a blast the energy will go up rather that out.

In pyrotechnics as I am sure that you know during the production of compositions all steps should be taken to reduce the risk where practically possible. If not possible then look for another way of doing it. Hence I would always recommend to people to use the safest possible practices.

As they say there are old pyro's, there are bold pyro's but there are very few old bold pyro's.

i respect what you say, and don`t believe you are having a go, ..i do disagree that energy density in this case is sufficient to create a spark at all nether lone one of sufficient energy to create ignition, please enlighten me as to what medium you use that has a much higher spark energy threshold.. .....btw i just performed a crude but realistic experiment and my ball has an energy of .06kg/m...+ - 10g equivelent to approx 15grams /ft... i will get back to you on its kinetic energy with concideration of the rpm of the mill... but at this stage it looks more like it cannot initiate a spark with Austenetic s/s....... maybe we can all start using s/s.....soon

Edited by phill 63, 11 August 2008 - 11:27 AM.

[digger]

i respect what you say, and don`t believe you are having a go, ..i do disagree that energy density in this case is sufficient to create a spark at all nether lone one of sufficient energy to create ignition, please enlighten me as to what medium you use that has a much higher spark energy threshold.. .....btw i just performed a crude but realistic experiment and my ball has an energy of .06kg/m...+ - 10g equivelent to approx 15grams /ft... i will get back to you on its kinetic energy with concideration of the rpm of the mill... but at this stage it looks more like it cannot initiate a spark with Austenetic s/s....... maybe we can all start using s/s.....soon

Hey I am not saying that it will produce a spark, what I am saying is prove it won't. I know I can produce a spark by belting stainless steel but no matter how hard I try I have not produced a spark with Lead or Brass.

We have many ATEX zone 1 compliant areas on my site and the only material that is allowed for tools used whilst the plant is in operation is alubronze (due to its hard non sparking nature), even reduced sparking stainless tools are not allowed.

Lead, brass and ceramic has been used by many people for a considerable length of time hence there is plenty of anecdotal evidence to say that it is relatively safe (although there have been reported explosions using ceramic).

By the way kg/m is not a measure of energy. I assume that you meant kg.m²/s² or Nm. I will be very interested to see the results of your research.

Edited by digger, 11 August 2008 - 11:49 AM.

[knackers]

[quote name='digger' post='47492' date='Aug 11 2008, 11:45 AM']Hey I am not saying that it will produce a spark, what I am saying is prove it won't. I know I can produce a spark by belting stainless steel but no matter how hard I try I have not produced a spark with Lead or Brass.

We have many ATEX zone 1 compliant areas on my site and the only material that is allowed for tools used whilst the plant is in operation is alubronze (due to its hard non sparking nature), even reduced sparking stainless tools are not allowed.

Lead, brass and ceramic has been used by many people for a considerable length of time hence there is plenty of anecdotal evidence to say that it is relatively safe (although there have been reported explosions using ceramic).


kg/m is not a measurement of force? oh well, you know what i mean.....anecdotal evidence is where i`ve been coming from....27 years worth... my 16.3g ball ( not 9.5g as stated) has a weight of approx 60g when dropped from 1 meter ( as quick as i could read anyway), my mill runs at 3600 rp/h and it takes 2123 rp/klm,,i think thats about 1.7 klm/h, the ball has a maximum fall distance of 6". therefore my ball falls 6" @1.7 klm/h with a weight of 24g.... i will have to consult somebody else to supply me with the impact energy, and perhaps a metalurgist with that effect on s/s.....i`ll get back to you.... you never said what medium you use i also think this tooing and frowing has run its coarse in this forum,

Edited by phill 63, 11 August 2008 - 12:45 PM.

[digger]

kg/m is not a measurement of force? oh well, you know what i mean.....anecdotal evidence is where i`ve been coming from....27 years worth... my 16.3g ball ( not 9.5g as stated) has a weight of approx 60g when dropped from 1 meter ( as quick as i could read anyway), my mill runs at 3600 rp/h and it takes 2123 rp/klm i will have to consult somebody else to supply me with the impact energy, and perhaps a metalurgist with that effect on s/s......... you never said what medium you also use,, i also think this tooing and frowing has run its coarse in this forum, i`ll get back to you

I agree. I am sure you have allot of experience with these materials as do I. However what I don't have is experience with using these materials within a ball mill full of BP hence the interest.

I would believe there is very little evidence / experimentation that has been done "out there" using this method. Therefore I would like to see someone prove it is safe.

I use several media in my mill. Lead (4% antimony), brass and ceramic. However I would only ever recommend lead. When I use ceramic it is done in a very big field well away from anyone if anything goes wrong.

Edited by digger, 11 August 2008 - 12:49 PM.

[Labs2008]

wow the debate roars on. I am going to stick with lead for now because that is what i have. Most is of the somewhat hardened type the muskt load balls.
the fishing sinkers i know are soft but for now they will do until I can get more hardened lead. I have a huge 3.5 lb chunk of brass that i am considering cutting down to small pieces.

[dr thrust]

hi, did you say you added your kn03 after milling?