635 replies to this topic

[spanner]

As to the milled compound sticking to the walls of the jar, even with just a few percent moisture content, once milling begins and the compound is compacted- sticking can occur.

This can be alleviated in several ways. One is to pre-dry the substances being milled. Not an option if you subscribe to the "add water to your black powder to avoid sparking" idea.

Another is to add a "bump" to the milling operation. Depending on your mill, this can be accomplished by adding an eccentric to either the jar or to the roller that drives the jar.

If adding to the jar, it should be done in more than one place to avoid repeated "bumps" in exactly the same place in the jar's rotation.

[BrightStar]

As to the milled compound sticking to the walls of the jar, even with just a few percent moisture content, once milling begins and the compound is compacted- sticking can occur.

For a number of reasons I prefer damp milling BP with 3 - 4 % of water / IPA mix . The comp does start to compact and stick to the jar after 90 minutes or so, but with a thinish jar you can just pick it up and squash it a bit to make the caked comp crumble, shake it and put it back on the mill... repeat every 90 mins until your milling is done...

Edited by BrightStar, 10 January 2007 - 05:45 PM.

[Asteroid]

I was joking, however I suppose an old wahing machine could be modified, although that sort of capacity would probably be unecessary

[newtoolsmith]

If someone modifies an old washing machine, he could build a jar with a large diameter but very short. Lets say 40cm diameter and 10cm length.

The media volume would then be 4 litres - thats big but also effective!

MfG
newtoolsmith

[bonzoronnie]

BTW anyone out there know enough about electronics to tell me how to work out the power requirements of the motor so I can search for a suitable power suply? 3 hours with a 1 hour down time is boring to have to keep remembering on and off times?

I also use a 12v dc motor for my mill

I use the 1.3L jar from inoxia with 1kg of media

The power requirement for this motor is just above 4.6v dc ( below this the motor will stall)

I have achieved this by using a fixed resistor of 1 Ohm. and a further Variable resistor of 1 Ohm Max

Running at 1.75 ohms resistance, the mill seems to turn the mill at a reasonably slow speed. I do not experience too much trouble with clumping.

I guess, If you can find a 6v dc power supply, Very little extra resistance would be needed

Motor cycle battery charger seems to spring to mind

[cooperman435]

Hey if anyone is building a ball Mill I have 4 sets of rollers for sale cheap

They are stainless steel rodded centres with rubber outers measurements are as follows:

total length 300mm

rubber roller length 235mm

rod sticking out at the ends is eccentric 26mm at one end and 39mm at the other end and 8mm diameter.

the rubber part is 25mm diameter.


They are all brand new and I would like a £9 for a pair including postage?

I have a set of 4 bearings for them too but I bought these so Ill want £16 for them not inc postage (ill include it if you are buying rollers too)

If anyone wants them please PM me and we can sort it out

Phill

[cooperman435]

Here is a pic of a roller and the bearings





Say hi if your interested Ive already been asked about 1 pair

[barra69]

Just a quick question on ball mill construction. What is the optimum position for the shafts in relation to the jar? If we assume that the jar has a 6inch OD would it be better to have the shafts at about 2inch seperation rather than 3 or 4 inch, therby ensuring the shafts are at 7 and 5 oclock where 6 o clock is directly under the jar?
Many thanks.

[cooperman435]

Just a quick question on ball mill construction. What is the optimum position for the shafts in relation to the jar? If we assume that the jar has a 6inch OD would it be better to have the shafts at about 2inch seperation rather than 3 or 4 inch, therby ensuring the shafts are at 7 and 5 oclock where 6 o clock is directly under the jar?
Many thanks.

If the rods are going to be BOTH driven by the motor then the wider they are apart the better (within reason) so that would be 4 and 8 o'clock If you only intend to have one shaft driven then closer is better so 5.15 and 6.45 o'clock.

THis will give the best grip on the jar

[barra69]

Many thanks for that Cooperman 435. I am building a substantial unit so the intent was to power one roller. What I may do now is to power both.

[Caramanos2000]

I just bought the Chicago Electric Rock Tumbler for $25, this thing any good?

[Mumbles]

The rock tumbler is mediocre. You can get BP of acceptable quality, but it takes nearly twice as long. I also find a fully charged jar does not spin well due to excessive weight. I had to lower the media to approximatly 1/3 full. It takes 8-12 hours where 3-4 hours in a good mill would do.

[treefingers]

Just a quick question... I recently bought a rock tumbler which seems to mill fairly well. The only problem is the jar is a specific shape and fits to the mill so I cannot have seperate jars for incompatiable chems. So far I have only milled BP but I still have a few corse metals powders i.e magnesium I want to mill but im slightly wary.

Would vigirously washing out the jar with an appropriate solvent be enough or should I just leave it.

[seymour]

Adding various solvents will more likely damage the seals on your barrel than effectively remove the metal powders. I recomend that you get a new barrel and set of media for milling metals, but as you have stated the reason for not doing this, I would use the metals as they are, buy finer ones or get a new aparatus for milling metals. Milling BP in a jar with even trace amounts of metal powders in it or on the media ( I believe even hardened lead is quite skilled at having metal powders stick to it, only to be abandoned back into the jar at a later date) makes the procedure a whole lot less safe.

[EnigmaticBiker]

I was joking, however I suppose an old wahing machine could be modified, although that sort of capacity would probably be unecessary

What washing program would be appropriate for BP?

Wouldn't a full cotton program followed by 1100 spin tend to cause sticking to the drum?
I'd start at wool and work up to synthetics with a 500 spin.