Dead ball mill

[Swede]

I had an experience today that could have been disastrous. I had a small lortone-style jar on my crappy ball mill, and was away for several hours. When I returned, the jar was open, the media everywhere, and the powder in a huge pile all through the mill.

 

One of the media had jammed the roller bar, and the motor had smoked itself with high current.

 

The composition - chunky CMC gum. If it had been BP, I strongly suspect it would have gone up.

 

Lesson: The rubbery lortone-style jars are not foolproof. Maybe a strip of electrical tape around the lid, or better yet, use a PVC style jar, or one that cannot open under any circumstances. No harm done in this case except the motor, but WOW it could have been bad.

 

Be careful.

[scarbelly]

I have had that issue as well. For now, my solution is to stick a nut on the inner lid and then put the second lid on. Then tape the outer lid to the container. That way the tape pulls the outer lid tight against the inner one to give it a tight close. But anyways, probably better to not use them at all.

[Swede]

Interesting - the motor was NOT cooked. When I touched it yesterday, it was scorching hot, and apparently dead. After it cooled off, it reset, and now works fine. The motor obviously had a thermal cutout system, which I now believe to be an important safety device for a ball mill. Most better motors ARE thermally protected. I was a bit surprised that this crappy motor is also.

 

scarbelly, that was the first time I had a lortone jar let go while milling. Some means of securing the lid is important. I do like that style of jar, especially since it is nice and quiet, but this opened my eyes a bit.

[Xtreme Pyro]

I had an experience today that could have been disastrous. I had a small lortone-style jar on my crappy ball mill, and was away for several hours. When I returned, the jar was open, the media everywhere, and the powder in a huge pile all through the mill.

 

One of the media had jammed the roller bar, and the motor had smoked itself with high current.

 

The composition - chunky CMC gum. If it had been BP, I strongly suspect it would have gone up.

 

Lesson: The rubbery lortone-style jars are not foolproof. Maybe a strip of electrical tape around the lid, or better yet, use a PVC style jar, or one that cannot open under any circumstances. No harm done in this case except the motor, but WOW it could have been bad.

 

Be careful.

 

WOW thats scary, I have one of those chicago dual drum rotary tumblers from harbor freight with those rubbery style-jars. Im definitely going to use your advice, and put a piece of electrical tape around the lid of my jar. Your right, good thing it wasn't BP or it could have turned out disastrous.

Edited July 19, 2009 by Xtreme Pyro

[FrankRizzo]

Swede,

 

I've had one of those Lortone jars pop open on me too a few years ago (a QT6 jar). In my case I *was* milling BP, but the jar somehow didn't jam the rollers, so there was just powder everywhere. I think what happened in my case was that the BP caked to one end of the jar (like it had a habit of doing previously), and the mass of the the lead media slamming down in an slightly off-center fashion caused the rubber wall to compress just slightly enough that the metal cover came in contact with the rollers and was torqued off.

 

There's nothing quite like going out to check on your mill to find powder *everywhere* and the motor humming along like nothing happened. I've since switched to milling just single components in my Lortone jar because of this failure mode. We've had this discussion on Passfire a while back, and some guys believe this to be impossible.

Edited July 20, 2009 by FrankRizzo

[qwezxc12]

I had that happen too, when I first made my mill. The jar lids will pop off when milling anything after a while if secured with the nut only. Maybe it's because the friction of milling raises the internal temp enough to make the lids pop off from internal pressure; I know my 12lb. jar gets warm after a few hours of milling a full charge. Perhaps it's not an issue with lapidary tumbling because of the water acting like a heatsink... or maybe they all leak, who knows?

 

Anyway, after putting the lid on and tightening the nut, adding a strip of masking tape (I use blue painter's tape because it's leave no residue behind) will keep the external metal lid on nice and tight. No further mishaps since.

[deadman]

When I moved on from the Harbor Freight tumbler to a beefed up ball mill running at the "appropriate speed" and fully charged it happened to me as well. I now tape it everytime and haven't had a problem since.

 

When using the harbor freight tumbler though I had no problems.

 

I was milling BP as well, thank goodness I have a shield, because like you said the motor was acting like the energizer bunny.

[Swede]

Interesting that it has happened to so many people. Milling single chems is reasonably safe, but imagine a couple of pounds of barium nitrate dust spilled all over. It might not explode, but that would be a nasty, toxic mess. All I can say is, I'm glad it was CMC gum and nothing else. I got lucky.

 

Now I know to tape or secure the lid on the lortone rubber jars. Checking the status of the tape and lid every hour or so would probably be smart, too.

[Weasel]

I have that style of jar, but i haven't had the jar pop open ever. I think it's because i'm using small ceramic media, which is way lighter than lead. If I had big lead balls this might happen. I will be sure to tape the lid closed now anyway. By the way, if any of you do have those harbor freight mills, just wrap electrical tape around the shaft and you can easily get 90 RPM.

[Gunzway]

I've had it happened twice, I was milling two hundred grams of black powder one time. Luckily I was in the room again when I heard it happen (distinctive sound of brass bouncing on the floor) and I rushed over to pull the plug to ensure nothing catastrophic happened. I've also had it happen with air float charcoal and I wasn't there for another hour in which I came back to a mess which is a pain to clean. But I haven't had it happen anytime recently, which is a relief. But I'll definitely remember to place some tape over the lid just to keep it more secure.

[lodcomm]

I had an experience today that could have been disastrous. I had a small lortone-style jar on my crappy ball mill, and was away for several hours. When I returned, the jar was open, the media everywhere, and the powder in a huge pile all through the mill.

 

One of the media had jammed the roller bar, and the motor had smoked itself with high current.

 

The composition - chunky CMC gum. If it had been BP, I strongly suspect it would have gone up.

 

Lesson: The rubbery lortone-style jars are not foolproof. Maybe a strip of electrical tape around the lid, or better yet, use a PVC style jar, or one that cannot open under any circumstances. No harm done in this case except the motor, but WOW it could have been bad.

 

Be careful.

 

Heh - I've had the exact same thing happen with the Lortone bottles (metal cap, washer & plastic thumb nut things)... somehow the thumbscrew came off and the lead media pushed the rubber inner lid right off.. I believe I was milling tigertail or spider.. it was a mess... I have no idea on how it unscrewed but it did!

 

-t

[Arthur]

I had this happen when I lost the washer between the nut and the drum lid. If I put the drum on lid to free end of the mill the nut loosens, If I put the drum on the other way round (lid to pulley) it doesn't loosen. IMO it's a vibration issue! The nut shakes and rotates, one way it will shake loose the other way it will not.

 

Since then I have bought a bigger mill (2.25 kilos (rock rating!)) from Manchester Minerals, it mills faster and has all rubber fastenings -no nut to loosen.

 

This sort of incident is why we advise people against washing machine motors!

[andyboy]

This sort of incident is why we advise people against washing machine motors!

 

 

The washing machine motors are alright if you make sure the spill can't reach the motor.

[pyrogeorge]

today i want to mill some BP with inoxia jars..guys be careful with this jars because the powder run out from the jar..i saw powder on the mill,i mill only 30min and i stopped the ball mill..

 

edit:i forgot t0 say that i used it without the inside cover.

Edited August 27, 2009 by pyrogeorge

[Swede]

This thread is as good as any other for a bit of off-topic discussion. What are people using as mill jars? Most know about or use the style of rubber lortone jar that started this thread. I still like and use them. I've also made and used jars crafted from pieces of PVC pipe fittings... an end cap, a short straight section, a reducer, and a rubber lid secured with a hose clamp.

 

What other options are there for a mill jar? I'd think a heavy HDPE 1 gallon food jar would work. It is also possible to take a section of straight PVC pipe, seal one end, and add a lid that is held down by studs and thumb nuts. A lot of work, but definitely a superior sort of mill jar.

 

Any other thoughts?

Edited August 27, 2009 by Swede

[tentacles]

Swede, I'm using straight sections of PVC water main pipe (same thickness as sch 80) with studs and PVC disks for lids. "Bonny" acquired for me some die cut rubber sheet for seals, it's like 1/8" neoprene rings. You're right about it being a lot of work, but IMO it's worth it - as long as you get the wingnuts tight and make sure there's no crap between the seal and the lid, they never leak. Mine are actually watertight. For the bottom of the jar, I glue the disc to the bottom and use countersunk screws to hold that on.

[Swede]

Xetap, that is a damned clever mod. I like the way they can drop into the pipe. The only thing that concerns me is the metal on the removable plug. Is there any way that you can see to perhaps glue a plastic disk onto the metal portion, forming a reasonably tight fit? I have a few of those end plug devices and they do work well.

 

I like the idea (in general) of taking straight sections of PVC pipe and modifying them for use as mill jars. The hard part is engineering them so that there are not deep crevices and areas where a comp can gather and avoid the media. Schedule 80 pipe should have a wall thickness that would allow studs. Or, how about this?

 

Take your pipe section, glue in a disk at the bottom so you have a clean profile internally. At both ends, take a standard PVC cap, with the end parted off so you have rings. Glue these rings onto the body of the pipe, so there are two areas on the jar that bear on the mill rollers, and if necessary, turn or sand off the irregular ribs that are often found on moulded caps. At the lid end, you now have a double thickness of PVC which will easily take 1/4" or #10 stainless studs. The lid is made from one of the parted end cap pieces. I did something similiar when I was making that two-chambered chlorate cell.

 

http://www.5bears.com/perc/tc035.jpg

 

http://www.5bears.com/perc/tc035a.jpg

 

If 3 or 4 of these were made at the same time, the machining/tooling setups would allow for a more rapid construction. Buna o-rings would be adequate for a mill jar. This might be a worthy winter project, definitely labor intensive.

 

Or, the lid could simply be one of those pipe plugs.

Edited August 28, 2009 by Swede

[Bonny]

I've been meaning to make up some new jars. I'll be making them from a PVC pipe,end cap, reducer and rubber cap...just haven't got around to it. Until now (several years) all I've been using is empty peanut butter jars. They actually last quite a few batches before they wear out.

[TheEskimo]

I've been using PVC. A glue-on endcap that is slightly curved, 4inch dia PVC and a rubber endcap that fits tightly: http://www.lowes.com/lowes/lkn?action=prod...&lpage=none

I don't use the metal hose tightener, it stays on just fine by itself. In fact, the rubber endcap is a bugger to get on, it fits so tightly. This way I can maximize on available volume on my mill, without a reducer. The rubber end-cap also has ridges in it, so I never have anything leaking.

Here're some pictures:

[Swede]

^^ I really like that. Very simple to do. I'd like one in 6" or even 8" if the rubber caps are available. Any reason not to use two rubber caps? That would avoid the annoying seam between pipe section and PVC cap.

[TheEskimo]

I only mill BP, charcoal stars, and I don't mind if a little bit gets caught. I use the glue-on endcap because it gives me something sturdy upon which to brace the barrel while putting the rubber endcap on. If you cut your PVC straight enough, there shouldn't be much of a seam anyways. I never thought about having two rubber endcaps, 'cause I was low on money when I made the barrel, and the PVC ones were cheaper. I have only seen 4 inch, and smaller endcaps; you may have to search a bit. This thing is very strong, and never leaks; you guys should try it.

[KruseMissile]

I just use a large jar from protein powder after i finish off the powder. like this http://www.answerfitness.com/wp-content/up...hey-protein.jpg And it is perfect for ball milling(havent had an issue yet, just make sure u tape the top).

[Swede]

I've often thought those thick HDPE protein jars would make a decent container. Do they stand up well to the abuse?

 

A day ago, I picked up a section of 4" PVC pipe and two of the standard rubber end caps that are normally held on with a hose clamp. I am going to try a benign milling with something safe, using heavy media, and just the rubber caps alone, one on each end. Perhaps if there is the slightest sign of a cap loosening, a wrap of duct tape would be all that's needed. Two caps, plus the pipe section, should equal the ultimate simple mill jar.

[TheEskimo]

Swede--you shouldnt have them wiggle off. I really have to jostle, and shove the rubber heads to get them on. Good luck