BM JAR

[oldguy]

8 Inch diameter, recessed ends, solvent welded in place

 

 

 

 

11.5 inch total length

(with lift rings on both ends)

Milling area is 8X8 inch

Edited April 11, 2012 by oldguy

[Givat]

looks great, but with the lead media isn't it too heavy? (I think more than 12 kilo is too much, you can just make 2 smaller jars)

[oldguy]

looks great, but with the lead media isn't it too heavy? (I think more than 12 kilo is too much, you can just make 2 smaller jars)

 

 

I don't use lead media. I use Zirconium M ceramic media pictured below.

 

Mills faster than lead, doesn't wear as fast as lead & doesn't contaminate the composition or it's color.

 

But, it's VERY expensive grinding media.

 

 

 

 

My mill will handle about 170 lbs in weight & three 12 ID inch jars at once.

 

 

 

Edited April 11, 2012 by oldguy

[AdmiralDonSnider]

I really envy your design, but what about motor overheating in continuous operation? My motor always became really hot after only 1/2h of milling, and I only had 10lbs of lead.

[Givat]

Admiral - I have the same problem. I use timed clock to give my motor some brakes. (So it run for 45 minutes and rest for 30, run for 45 minutes and rest again for 30....I'm not in a harry)

http://3.bp.blogspot.com/_JBHVnO_yk5A/SWh4Ew4x_pI/AAAAAAAAAGQ/F9ctiHQMchA/s320/DSC_0279.JPG

[oldguy]

I really envy your design, but what about motor overheating in continuous operation? My motor always became really hot after only 1/2h of milling, and I only had 10lbs of lead.

 

Admiral Don, thanks for the kind words

 

I run a TEFC thermally protected industrial motor rated for continuous service.

If it heats up beyond a certain point it will kick itself off & restart when it cools off.

Outside in the winter months over heating is not an issue.

In hot summer months, I point high volume squirrel cage furnace type fan close to & directly at the motor to help keep it running cooler.

 

A TEFC enclosure on a motor means "Totally Enclosed, Fan Cooled". This motor is probably the most commonly used motor in ordinary industrial environments. It costs only a few dollars more than the open motor, yet offers good protection against common hazards. The motor is constructed with a small fan on the rear shaft of the motor, usually covered by a housing. This fan draws air over the motor fins, removing excess heat and cooling the motor. The enclosure is "Totally Enclosed". This ordinarily means that the motor is dust tight, and has a moderate water seal as well.

 

Still tinkering with the jars. Roller bands solvent welded.

 

　

 

Edited April 13, 2012 by oldguy

[AdmiralDonSnider]

Really interesting info, thanks oldguy. I will have a look - my motor has recently given up.

 

The other common problem is matching the motor speed/RPM with the jar size. I plan to use larger jars in the future, but one inevitably has to change the whole setup to keep things in the optimum range, or close to it. Is there a way to electronically adjust the effictive motor rotations?

[oldguy]

The primary reason to utilize a TEFC motor on a ball mill that will run pyrotechnic compositions in the jars is that the motor is factory sealed dust tight. That gives you a very high degree of protection if a jar (for whatever reason) leaks any flammable or explosive dust or powder while the mill is in operation. If a jar happens to leak dust or powder while spinning. The spinning effect can broadcast a cloud of dust or powder that can easily come in direct contact live electrical contacts or windings in an open face type electric motor (like a washing machine motor). All it takes is a tiny electrical "spark" in a cloud of highly flammable dust to cause one hell of a big explosion.

 

I cringe thinking about novices running grinding media that could possibly cause a "spark" inside a ball mill jar containing pyro comps. Which will cause an explosion when a "spark" occurs. So, a great deal of attention is paid towards using the right type & sort of non-sparking grinding media. At the same time almost everyone seems to ignore they are running an open faced electric motor in close proximity to a ball mill jar containing highly flammable and/or explosive powders.

 

I am a believer in "Murphy's Law". Meaning something can always go wrong at the worst possible moment. Should a ball mill jar (for any reason) ever leak dust or powder while the mill is continuously spinning and the mill is equipped with an open faced electric motor. There is a very high probability of a fire or explosion occurring. I value my life, family, home, shop & belongings to much not to spend a few dollars more by investing in a TEFC ball mill motor, to dramatically lower the probability that a fire or explosion will ever occur having to do with my little hobby.

 

As far as being able to adjust RPM speed. I designed my mill so I can change either pulley in a few minutes to increase or decrease RPM speeds There are various types of electric motor speed controllers, but I have no expertise in them. Other than don't attempt to use a "dimmer" type rheostat switch.

Edited April 14, 2012 by oldguy

[FlaMtnBkr]

Any instructions on how you are making the jars? What are you using as end caps and what type of solvent to weld everything up? Do you build up a fillet of solvent or some other type of stop to keep the end caps secure with all the weight pushing out from the inside? I would like to see your process if you don't mind sharing. Thanks!

[MondoMage]

I scrounged some larger-diameter PVC pipe from a job site I was on, a length of 10" pipe and a length of 12". I'd like to adapt the construction techniques of the jars shown in this thread to the pipe I have, to make some of my own. I seem to recall (but may be misremembering) a tutorial that included pictures (gotta have pictures!) but now I can't seem to find it. Did it actually exist, or am I mistaken? And can you give any tips or pointers for this sort of thing?

 

Thanks!

[Col]

It does exist and its not too far away oldguy`s other thread

I`d like something a bit quieter than my hdpe jars so i`m giving this a go

[graumann]

Are they drag tyres? I would be very interested to see how this works out for you, sealing them up might be a pain, but I do imagine they will be near silent if done right.

[Col]

Its a tubeless kart slick, i have 2 fronts and 2 rears.

The one in the pic is a rear with a volume of 6L, its a tad big for my bp needs but it also makes a half decent (mill driven) star roller. The front tyres are smaller with a volume of 3.6L., the rubber on the tread is 7.5mm thick and the walls are internally ribbed so they are fairly rigid.

When its sealed up airtight (quite easy to do) the air trapped inside adds to the strength and keeps it nice and round. (win win)

The next job is to see how it copes at 60rpm with 25lb of lead in it

Edited August 2, 2012 by Col

[Col]

Just a quick update.

A kart tyre seems to be a viable option if you need a dirt cheap, quiet jar with no shortage of traction and a useful capacity.

 

http://www.youtube.com/watch?v=SAm5N_dveiQ

You can just about hear the dull rumble of media underneath the noise of the motor

The tyre in the vid is 252mm od, 238mm id, running at 51rpm on my stock gearing. A bit of tape/tubing on the driveshafts will increase it to the 57-58rpm needed for optimum performance. The bungs create a very solid seal which is air,dust and liquid tight, i filled the tyre with water to figure out the exact volume, you can inflate the tyre via the bungs and it stays up I can pick the fully loaded tyre/jar up by one seal without any drama, there`s no chance of a seal popping off during the mill run. The only downside is its not quite as easy to get the media and bp out of the tyre when its done.

Specs: 4.37L volume, 13.5kg lead media (50% charge), 730g (willow) bp 25% post milling.

Edited September 30, 2012 by Col

[FrankRizzo]

Super cool, Col!! When I had orginally seen this idea used for large-scale rock tumbling, the guys were using wooden discs to seal the tire. What are you using for a removable bung?

 

http://www.amateurpyro.com/forums/topic/6479-ball-mill-using-tires-as-jars/page__hl__tire#entry84072

[Col]

They are 5" pipe bungs, they have a thick but supple rubber gasket that expands outwards as you tighten the wingnut. Positioning the bungs so they`re level all the way around is a bit tedious, if the gasket had a 1/4" wide shallow slot routed around the middle it would be a doddle. The bead is 8mm thick,

There are steel wires set into the tyre bead (not visible) which restrain the bung as it expands. The gasket expands both sides of the bead which further locks the bung in place and helps shield the bead from the media.

The tyre is made from rubber coated nylon cords so there`s no steel belting to worry about. The total cost of the jar (excl media) was a thrifty £11.25 ($18.15)

If you need a bigger 6.6L jar, use the same bungs on a rear tyre

Edited October 2, 2012 by Col

[Col]

Here`s the noise test with the mill sitting on solid ground. The vibration from the media is transmitted to the paving slab..you can feel it in your feet

http://www.youtube.com/watch?v=1CHsHdFNteo

[ollie1016]

Has anyone ever used a paint can as a ball mill container? I'm thinking of using 14mm lead balls in a 5litre pair can to mill black powder. Any thoughts?

[Mumbles]

The thought of using a metal ball mill container would make me cringe a bit. It's certainly not something I would advise.

[ollie1016]

Do you rekon I should use a hdpe bottle?

[dynomike1]

Can someone help me get the pulley size i need for my mill?

 

Jar 7"

 

.5" hose = .75" on roller

 

roller .5"

 

motor 1725rpm

 

I tried the calculator and i came up with like 22" pulley on the roller, and 1" om the motor.

[Bobosan]

Check this thread for calculations;

 

http://www.amateurpy...all-mill-speed/

 

If my quick calcs are correct, you should get approx 61 rpm for a 7" outside diameter jar using the .75" roller diameter with a 2" drive sheave and a 6" driven sheave @ 1725 RPM motor.

 

edit - that's a no load calculation. With a 2.5" drive sheave the final output should be ~76 rpm unloaded. Once loaded, the final jar rpm will drop.

Edited April 21, 2013 by Bobosan

[dynomike1]

61.61

[dynomike1]

I forgot when i ordered, i ordered a 7", which i already had a 3" so i don't think it will hurt to be a little faster. I think i will have 74 RPM's if not i will get a 2". Edited April 29, 2013 by dynomike1

[Bobosan]

Yeah, actually around 79 rpm using a 3" drive and 7" driven sheave. If using a 2" drive and 7" driven, your final mill rpm would be approx 53 rpm. Factor in mechanical speed loss, your 3" and 7" should work ok.