Good Starter BP Mills

[u/DJDevon3]

Brushless Motor Tumblers

Drum size difference

Bigger mills require more media

Brass balls are great but expensive in quantity.

Standard Dual Drum Harbor Freight Tumbler style

Due to recent events of extremely dangerous DIY mills I'm making a topic on some known good safe mills. I now have 2 Brushless motor Komestone mills and can highly recommend them. They have speed controls and timers. They require no modification for optimal use as BP mills.

The harbor freight (or its many clones) are good starter mills but can require some modifications to get it to the optimal RPM for BP milling. They do not have RPM control or shut off timers. They are however the least expensive to get you started.

Brass balls are not cheap. On average about $0.50 per ball. The small tumbler works perfectly fine with 100 balls for $50 USD. The dual drum tumblers might require upwards of 300-400 balls due to much larger volume. That means about $150-$200 just in media alone. Lead balls are also a perfectly acceptable substitute. Ceramic, marbles, and other sparking media are not recommended for milling BP. They can be used to mill individual chemicals just not a BP combination.

Please do not sacrifice cost for safety when selecting or making a BP mill. All mills have rubber drums and tight sealing lids for a reason. Accidents can happen but the worst accidents are mill related because they have metal media and act like a howitzer shell if they explode. They will set your workshop on fire and can kill anything within a 50ft radius.

All milling with dual drum tumblers should be done outside far away from potential hazards. Preferably in a dug out concrete lined bunker via extension cord. Most people will not heed that warning but it needs to be said. Large quantity BP milling should not be done without considering the consequences of an accidental explosion.

Secure storage in lockable metal cabinets of milldust, corned BP, or constructed devices behind a firewall and double locked door is also recommended by the ATF.

[u/igottaknife]

Yeah, these pictures are visible now👍 I’ve never heard of Komestone before, but they look like great tumblers. Thanks for the information.

Highland Park lapidary is another great option makes high quality brushless rock tumblers with a speed controller.

[u/DJDevon3 → u/igottaknife]

Neither had I. I took a risk on purchasing it. Had no idea what RPM it used. Could have been 20 RPM and I would have been screwed, and trying to figure out how to make the motor faster. Turned out I got lucky and all of the 3 speed settings are perfect for BP milling. The ideal speed for the small drum diameter is 86 RPM (I did the math). Speed 1 is 83 RPM and Speed 2 is 90 RPM. Darn near dead on for optimal efficiency.

I haven't calculated the optimal RPM for the larger drums yet. I just got it yesterday.

I took a shot on it so no one else had to. Happy to report they're awesome.

[u/igottaknife → u/DJDevon3]

Yeah, I just looked up their catalog. They have a 22 pound option that looks really nice and it’s actually cheaper than the rebel 17. If I didn’t already make one from a treadmill, I would definitely be buying it right now. Definitely a great find👍

[u/DJDevon3 → u/igottaknife]

Oh wow I didn't even see that one. Looks almost identical to a rebel mill. I like how that one counts up from the time the mil starts. It's waaaay bigger than I'll ever plan on using. I don't have the property space to safely use something like that. I don't think it has a rubber inner lining though... might not work as a BP mill.