jrin0630 Posted June 29, 2009 Posted June 29, 2009 What's the rule of thumb as far as burst charge goes? I'm in the process of making some 3" ball shells. It'll be filled with 3/8" cut stars. How many grams of burst should be used? Is there some sort of formula? I'm using Goex 4FG.
TheSidewinder Posted June 29, 2009 Posted June 29, 2009 I'll move this to the Newbie Section, since that's the best place for this question and you're more likely to have it answered there. I've not heard of a set formula for burst, only for lift. In the past, when I've made 3" cannister (not ball) shells, I simply filled a 3/4" center cannule with my BP. But perhaps someone has the info for ball shells, and can share it with us.
jrin0630 Posted June 29, 2009 Author Posted June 29, 2009 I'll move this to the Newbie Section, since that's the best place for this question and you're more likely to have it answered there. I've not heard of a set formula for burst, only for lift. In the past, when I've made 3" cannister (not ball) shells, I simply filled a 3/4" center cannule with my BP. But perhaps someone has the info for ball shells, and can share it with us. Thanks......
Bonny Posted June 29, 2009 Posted June 29, 2009 I think the most common method is to make up load of BP burst on a carrier. (I use BP coated vermiculite, approx 5:1 BP to vermiculie) Place your stars in the hemis and fill the remaining space with the burst. You may or may not want to add a booster such as dirty flash or whistle.
Swede Posted June 30, 2009 Posted June 30, 2009 Bonny, how do you like the vermiculite as compared to rice hulls? Easier to prepare and handle?
Bonny Posted June 30, 2009 Posted June 30, 2009 Bonny, how do you like the vermiculite as compared to rice hulls? Easier to prepare and handle? I've never tried rice hulls, but I like the vermiculite. I started using it as I couldn't find rice hulls ( didn't look very hard though) and vermiculite is very cheap and easy to find. You do need to be a bit gentle with the dry vermiculite until it is coated as it will break up. I screen out the fine crap before coating in BP. After they are dry, you can screen out a few sizes if needed for different shell sizes. I use the fine junk in 1" shells as filler with the rest saved for the 3" and larger.
qwezxc12 Posted June 30, 2009 Posted June 30, 2009 What's the rule of thumb as far as burst charge goes? I'm in the process of making some 3" ball shells. It'll be filled with 3/8" cut stars. How many grams of burst should be used? Is there some sort of formula? I'm using Goex 4FG. I use 4:1 BP coated rice crispies + some booster as burst. My general rule of thumb for ball shells is: 3in shell..........30g4in shell..........105g6in shell..........450g Some take less, some more depending on the qty and size of the stars/inserts. I've never used straight BP for ball shells (only for filling cannules in can shells) so I have no idea how much to use.
jrin0630 Posted June 30, 2009 Author Posted June 30, 2009 I use 4:1 BP coated rice crispies + some booster as burst. My general rule of thumb for ball shells is: 3in shell..........30g4in shell..........105g6in shell..........450g Some take less, some more depending on the qty and size of the stars/inserts. I've never used straight BP for ball shells (only for filling cannules in can shells) so I have no idea how much to use. Can you share your process for making BP coated rice crispies? This would be my first time making it so the more detail the better. Thanks!
qwezxc12 Posted July 1, 2009 Posted July 1, 2009 Can you share your process for making BP coated rice crispies? This would be my first time making it so the more detail the better. Thanks! It's pretty easy... I mill my BP with +1.5% CMC for binder. First, I throw 300g of generic rice crispies into my star roller (ATX power supply driven BMW windshield-wiper motor turning a cut down 5-gal Home Depot bucket). Spray dampen (75/25 water/eTOH) and coat with 1200g milled BP in double tablespoon increments, making sure that all the BP is picked up each increment and leaving the last coat a bit dusty. I turn out 1500g in about 25 min. and let dry a few days in full size baking trays.
jrin0630 Posted July 1, 2009 Author Posted July 1, 2009 It's pretty easy... I mill my BP with +1.5% CMC for binder. First, I throw 300g of generic rice crispies into my star roller (ATX power supply driven BMW windshield-wiper motor turning a cut down 5-gal Home Depot bucket). Spray dampen (75/25 water/eTOH) and coat with 1200g milled BP in double tablespoon increments, making sure that all the BP is picked up each increment and leaving the last coat a bit dusty. I turn out 1500g in about 25 min. and let dry a few days in full size baking trays. Would Goex 4FG commercial powder work in place of meal powder to make coated rice hulls for burst charge? Or would it work better just using straight 4FG as the burst? I'm not at the point of making my own BP yet so I don't have a mill etc.... thanks.
Seymour Posted July 1, 2009 Posted July 1, 2009 I very much doubt that the rice hulls or other inert carrier would pick up much, because it's not a powder, and there is no binder. However you could certainly mortar and pestle it to a powder and add 2% dextrin. Using it as-is will certainly work, but you may use a bit more than you need, thus wasting an expensive product.
qwezxc12 Posted July 2, 2009 Posted July 2, 2009 Would Goex 4FG commercial powder work in place of meal powder to make coated rice hulls for burst charge? Or would it work better just using straight 4FG as the burst? I'm not at the point of making my own BP yet so I don't have a mill etc.... thanks. jrin, The whole point of using BP on a carrier is to bulk up the burst; a 4in shell where 105g of 4:1 burst on carrier is used only has ~80g of BP in it. If you used straight BP, you'd probably use 3x the amount to fill the same shell. Instead of trying to rework perfectly good commercial powder, why not try to bulk the BP up? Try X amount of Goex mixed in with an inert carrier (rice hulls, vermiculite, oatmeal, puffed wheat, etc). The risk I see is that the BP might not stay homogeneous and may settle out and cause a lop-sided break.
jrin0630 Posted July 2, 2009 Author Posted July 2, 2009 jrin, The whole point of using BP on a carrier is to bulk up the burst; a 4in shell where 105g of 4:1 burst on carrier is used only has ~80g of BP in it. If you used straight BP, you'd probably use 3x the amount to fill the same shell. Instead of trying to rework perfectly good commercial powder, why not try to bulk the BP up? Try X amount of Goex mixed in with an inert carrier (rice hulls, vermiculite, oatmeal, puffed wheat, etc). The risk I see is that the BP might not stay homogeneous and may settle out and cause a lop-sided break. I like that idea. I'll try bulking up the Goex with a carrier and see how it works. Thanks.
Swede Posted July 2, 2009 Posted July 2, 2009 Since I don't have a star-roller (it's on my to-do list), I made BP on rice hulls fairly easily using a plastic gallon paint tub with lid. The rice hulls were weighed, soaked, excess water squeezed out, and added to the tub. 4X or 5X the weight in BP is set nearby, and the BP added incrementally to the hulls. With the lid on, some gentle shaking and agitation coats them nicely, and the process repeated (you can add water if needed with a spray bottle) until you get the ratio you want. After they dry for just a short while, any clumps are broken up by hand, and it's all set on a screen to dry. It's really pretty easy to do, but works best IMO when the binder is milled into the BP rather than added later. I like the idea of CMC gum for this. You can do it with KP and other burst comps as well.
jrin0630 Posted July 11, 2009 Author Posted July 11, 2009 Since I don't have a star-roller (it's on my to-do list), I made BP on rice hulls fairly easily using a plastic gallon paint tub with lid. The rice hulls were weighed, soaked, excess water squeezed out, and added to the tub. 4X or 5X the weight in BP is set nearby, and the BP added incrementally to the hulls. With the lid on, some gentle shaking and agitation coats them nicely, and the process repeated (you can add water if needed with a spray bottle) until you get the ratio you want. After they dry for just a short while, any clumps are broken up by hand, and it's all set on a screen to dry. It's really pretty easy to do, but works best IMO when the binder is milled into the BP rather than added later. I like the idea of CMC gum for this. You can do it with KP and other burst comps as well. I'm going to use Dextrin as the binder and I understand the rule of thumb to be about 5% by weight. However, I noticed in the process published on Cannon Fuse they use 375G of BP with 75G of Dextrin to make coated rice hulls. Isn't that like 20% Dextrin? Or am I missing something?
Seymour Posted July 11, 2009 Posted July 11, 2009 I suggest less than 5%. 2 or 3% will be sufficient with anything but very poor dextrin.
Mumbles Posted July 13, 2009 Posted July 13, 2009 The cannonfuse thing is a direct copy from United Nuclear, which has some questionable things. Stick with 5% or less.
jrin0630 Posted July 13, 2009 Author Posted July 13, 2009 The cannonfuse thing is a direct copy from United Nuclear, which has some questionable things. Stick with 5% or less. That's good to know. thanks.
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