First attempt on shell launch:)

[Visco]

I think their could be merit to drum moisture. The first time I ran it my drum was outside 55 degrees and my ingredients were stored inside 75 degrees. As we all know it clumped. I wanted to run the mill dust again for a bit to see if it got any stronger only this time both drum and mill dust was were same tempature outside and after running for two hours comp was very powdery no clumps at all. I'll granulate this weekend dry and test as soon as possible.

[Col]

Hi Mum

I think it may be the tyre has a lot more give in it than the dense hdpe. The cascading lead may create a constant vibration in the tyre wall itself so nothing gets a chance to stick or stay stuck for very long.

Moisture can build up in the jar over time, especially if you leave the lid off. I wash and dry the media every so often and switch out the tyre for a clean dry one (i have a pair of fronts and a pair of rears)

Edited October 25, 2016 by Col

[NeighborJ]

Drum moisture is a concern but I believe most people are underestimating the amount of water contained in the air and the relationship between relative humidity and temperature. A given amount of moisture may represent 60% humidity at 75degrees but lower the temp to 55degrees, in that same container and it is below saturation temperature and humidity is 100% even after condensing most of the water into a puddle on the floor.

It is not even a lot of moisture needed to create clumping, the fact is that the moisture will collect on the coldest surface available( media) and saturate a small portion of comp which spreads until either all the comp is collected or there is no longer enough moisture to spread any further.

The key to preventing this is to ensure your media and drum are warmer than the comp you intend on puting in it. This will prevent clumping even if humidity is hi.

Edited October 25, 2016 by NeighborJ

[Col]

A cubic foot (7.5 gal) of air at 75F and 60%, dropping to 55F and 99.9 % RH would result in 0.05g of water condensing out. In comparison, 100g of charcoal will hold 3g without showing any sign of being damp

Edited October 25, 2016 by Col

[NeighborJ]

Col, what I'm saying here is that the clumping occurs at the saturation point. This is what is happening, the amount of water is of little consequence because it needs to condense on the colder surface and will be a much higher concentration around the media and for a short time on the walls of the drum.

Put some recently dried stars in a sealed ziplock bag, it will form condensate on the cooler bag surface when set in the sun. It is a very tiny amount but it is enough to cause the loose prime to stick. This is my method of testing how dry the stars are.

Edited October 25, 2016 by NeighborJ

[Col]

I cant see it being the cause Consider everything is bone dry and the only water entering the jar is from the air. To accomodate 1ft3 of air you`d be looking at something like a 20gal jar and 16Kg+ of comp. If the resulting 0.05g of condensed water just coated the media it wouldnt be enough to cause a problem. I doubt you could dry 16kg of comp to that level of moisture content without resorting to a vacuum

The moisture coming from the stars in a ziplock must change phase from liquid to gas (water vapour) before it can be transported (via the air) to the cool surface of the bag. If you leave the stars in a sealed ziplock without replacing the air, you`ll eventually reach a point where no moisture is lost even though the stars may not be completely dry. Potentially they could re-absorb some of the moisture trapped in the bag. A mill is like the ziplock, an airtight container with a finite amount of moisture locked in for the ride.

Edited October 26, 2016 by Col

[memo]

drying my mill and media, plus all my chems for making bp works for me. i dont clean my mill either. my mill has been sitting for about a month. i am going to dry it at the same time i am drying the charcoal and kno3 bet it doesn,t clump. the rh is in the hi 80's.

 

memo

[NeighborJ]

I wouldn't bet against you, in the end if the methods are proven then the reasons why are irrelevant.

[MadMat]

I used to get clumping problems in my mill. I haven't in a while now. After thinking about it, the only thing that has changed is the fact my milling jar has been run about a dozen times. My milling jar is PVC. and I wonder if there were some volatiles (plasticizers?) in the PVC that are "used up" on the inside surface. Since my jar is dedicated to black powder only, I have never actually cleaned it. Well, I can't say I never get clumping; when it is very humid out, I get some very minor clumping, but it is nothing like I used to get.

Edited October 27, 2016 by MadMat

[steveair2]

Hello group, Steve here from Dallas Texas making my first post. I've decided to build a ball mill for the BP needed for ejection charges for my sugar rocket motors.

I've learned a lot already since I found this site two days ago. I feel like I have a good handle on making my first batch now. I'm still collecting parts for my mill.

So far I have a five foot section of 6" green PVC sewer pipe from my plumber neighbor and a whole house fan motor from a fan I removed from an old house.

I may post my construction progress on this forum. Thanks for all the good advise.

 

Steve

[Visco]

Just wanted to let everyone know I tested my bp this weekend and it was awesome. Worked perfectly! If good spruce bp does this and Ceder is better I can't wait to make ceder bp. I'll try that this week. This time I used cold water and 25% alcohol. Nice black hard as a rock grains. I'm happy.