shell size vs mortar tube

[Carbon796]

You should screen your lift or polverone, at a minimum of 3 times through your course-est sizing screen. Somewhere in the vicinity of 6.6 lbs water to 26 lbs BP/polverone iirc. The first screening only, should be forced through. Subsequent screenings should be sort of tumbled through. Controlling the drying speed is also important. And, can make a noticeable difference, in performance. Edited May 18, 2021 by Carbon796

[ronmoper76]

You should screen your lift or polverone, at a minimum of 3 times through your course-est sizing screen. Somewhere in the vicinity of 6.6 lbs water to 26 lbs BP/polverone iirc. The first screening only, should be forced through. Subsequent screenings should be sort of tumbled through. Controlling the drying speed is also important. And, can make a noticeable difference, in performance.

i used a 12 and forced the larger harder grains twice,then shook it through two more screens,a 20,and a 30.The sun was hot here today and it dried fast So i basically have a bag of each each.,its does burn instantly like flash powder and everything i have made to to this point has burnt like fast cannon fuse,lol I"m wary about how much of it to put into anything.That benzolift i have is bullshit compared to the new bp. I need to mess with it for a bit before i even begin to build something,it's like i just found a whole new substance.

Edited May 18, 2021 by ronmoper76

[Piccaso]

If you are using SYP as your charcoal for lift then thats the issue.

[ronmoper76]

I no longer have issues with it being to weak,against my better judgement i tried the same shell with 24 grams of the new stuff and it was like a cannon,The power and sound was off the charts ridiculous,the concussion echoed through the mountain all i had was burning embers floating out of the sky and the shell hit the water 20 seconds later,it failed to light for whatever reason. My black powder is fine now,it sets off car alarms,lmao I just need to find out how to use it effectively,you could easily blow just about any device sky high with this stuff,not used to something that acts like this.I see why some of you are so stubborn about using BP for most stuff.I never realized it before and kinda looked at BP as meah at most. This stuff is nasty and deserves respect,im blown away....thanks guys

Edited May 19, 2021 by ronmoper76

[BetICouldMake1]

Yeah buddy. Good BP is the foundation of good pyro. Now that you're making hot stuff you probably want to consider using coarser grains if you are lifting anything bigger than the shells you're building now. If you keep with the small grains for these shells you will probably need way less powder, but you should keep in mind that using the coarser stuff is a little easier on the shell. Because it burns a bit slower it gives the shell more of a push than a sharp kick. It's less of an issue for small shells, but the bigger they get the more likely it is to cause issues.

 

You don't need to puck and corn to make binder-less bp. IMO there's really no reason to puck and corn bp unless you're making it for firearms. The binder-less bp made by granulating with alcohol is VERY hot. It's awesome for burst but can actually be too hot to use as lift, especially for bigger shells. I've been making two batches of powder, one granulated with 70% isopropyl alcohol that I use for burst charge, and one granulated with water and 1.5% SGRS that I use for lift. I granulate through a 3 or 4 mesh screen and then sift out the different cuts once it's dry. Since I mostly build large shells I'm looking to get more of the coarser power in the -3+12 range. If you wanted more of the finer stuff I'd go with an 8 mesh for granulating. Anything smaller than that is just a huge pain in the ass to work with, IMO.

 

In terms of milling the optimal load for a rebel jar is about 700g, though there are some guys who run 1000g and get good results, but that's running an optimized mill. I built my mill to run the correct RPM for rebel jars and I get good powder in 2-2.5 hrs running 700g loads. Even with a stock rebel I'd guess that 12 hrs is excessive. If you look at power relative to mill time there's a steep curve for the first few hours and then things level off. So you might see a big difference between milling for 1 hour vs 2, but not much difference between 2 and 3. Milling a few test batches for different times should give you an idea of where that cutoff is for your mill.

 

Oh, and using too much binder when granulating will slow the powder down appreciably. 1-2% is plenty.

[ronmoper76]

I noticed what you said tonight. I took one of those empty shells,plugged one end,and put 1/2 teaspoon of BP in the bottom and covered the bottom of the tube with a piece of clear tape. That thing went way up in the sky... I removed all containment and used a fraction of the powder,its amazing. I also saw some damage to the tube from such a small amount,too much would definitely destroy a shell.Your right I think i did make it finer than it needs to be as well. I need to test weighted shells next to get a starting point.... I'm thinking i should probably try 10 grams and go from there? 25 was absolutely way to much.

Edited May 20, 2021 by ronmoper76

[ronmoper76]

I don't want to start a new thread just for this when you guys already helped me thus far,so i added it here... I have a 6lb dvc set from woodys i have been dying to use,i plugged and fused one today following his youtube video and was preparing to fill the bottom with lift. However i weighed how much powder it takes to fill the bottom of one up and its ALOT,35 grams actually. From my experiences above with a mortar tube and the powder i have, i envision a massive explosion,LOL and not much else. What would you guys do? He makes really good tools,so i'm sure he intended the cavity to be that large,but i'm still nervous to just load and fire one.

[BetICouldMake1]

Well the cavity doesn't need to be full for it to work. That said, DVC require more lift than a similar size/weight shell because they don't have the benefit of being confined in a mortar. Using a lot of lift is kind of the idea--double voice--a boom at lift and a boom up top.

 

It will probably take some dialing in to figure out how much lift you want/need relative to how long the timing is. The up side is, if the lift is too hot you just end up with a big firecracker and don't need to worry about blowing up a mortar. And if you're shooting in a large open space, as you should, even if there's not enough lift they shouldn't go high enough to drift too far off course. I would probably start by just filling the lift cavity and putting a small charge of bp in the report section and fill the rest with something inert that approximates the weight of a normal device. If it works then you have an idea of the overall timing, and if it fails you have a much less energetic failure.

 

Side note: are you a member of PA Pyro Artists? You should look into joining if not. They're a good club and have lots of open shoots all over the state. We don't have many builders in the club, but there's a few.