Livingston Posted April 21, 2015 Posted April 21, 2015 So I made a few 3/4 crossetes with the round cavity. Inserted a folded a small piece of BM added my flash capped and rolled and Kraft and capped again. I don't know why but they didn't break!! I like to know what I'm doing wrong.
gregh Posted April 21, 2015 Posted April 21, 2015 I have had zero luck with them as well without containment. However making a holeshot that small is very tedious.
Livingston Posted April 21, 2015 Author Posted April 21, 2015 (edited) They were contained very well. Whsts is the holeshot? If that's the small hole within the cavity than are your saying I should make it deeper? Edited April 21, 2015 by Livingston
Wiley Posted April 21, 2015 Posted April 21, 2015 (edited) It's a tiny, handmade paper firecracker fused with BM and filled with dark report comp. Edited April 21, 2015 by Wiley
gregh Posted April 21, 2015 Posted April 21, 2015 When the comet burns down and exposes the cavity, the flash comp just burns and vents through the hole. If you are lucky, they might make a cool jetting motion. I never had one break just by putting BM and flash in the cavity loose.
pyrokid Posted April 21, 2015 Posted April 21, 2015 In my recent experiments with round cavity crossettes, I had the flash comp burn as a silver star when it was inside a c6 comet, and then, after I lengthened the timing pin, it completely destroyed a green comet when it ignited. The green burned much slower than the c6, so I think differences in confinement are responsible. As soon as I can figure out how to cut a cruciform tool properly on my lathe I think my problems will disappear. What is the optimal cavity length relative to overall comet length?
Exo Posted April 22, 2015 Posted April 22, 2015 I made a crossette pump with a square cavity, works well for a 4 break comet. I fill the timing pin hole and the bottom part of the cavity with very fine bp left over from making my lift.I wrap the flash comp in a small pice of tissue paper to stop it mixing in with the bp or going down into the timing hole. If your breaks are to hard just add less flash and more bp to fill the cavity.
enanthate Posted April 22, 2015 Posted April 22, 2015 (edited) In my recent experiments with round cavity crossettes, I had the flash comp burn as a silver star when it was inside a c6 comet, and then, after I lengthened the timing pin, it completely destroyed a green comet when it ignited. The green burned much slower than the c6, so I think differences in confinement are responsible. As soon as I can figure out how to cut a cruciform tool properly on my lathe I think my problems will disappear. What is the optimal cavity length relative to overall comet length?The length of the comet depends on what timing you want (before it breaks). Here's how to make your tool:https://www.youtube.com/watch?v=XDSc8ftzgso Edit: Livingston, notice the tip of the tooling in the video. Im guessing your tool doesnt have a small tip like that? This makes the difference between an explosion and just burning. Edited April 22, 2015 by enanthate
Livingston Posted April 28, 2015 Author Posted April 28, 2015 The length of the comet depends on what timing you want (before it breaks). Here's how to make your tool: Edit: Livingston, notice the tip of the tooling in the video. Im guessing your tool doesnt have a small tip like that? This makes the difference between an explosion and just burning.I do have tip like this but as long. So maybe that's the problem? I was talking with my mentor and he says that I might have confine it to much.
pyrokid Posted April 28, 2015 Posted April 28, 2015 Since we're talking about crossettes, how does everyone paste their comets? I had a hell of a time trying to wrap the pasted paper onto the charcoal comets. It kept slipping and didn't want to bind to the star.
dagabu Posted May 5, 2015 Posted May 5, 2015 I am confused, I hear the word "crossette" with cavity comets in the same sentence. While there is much discussion as to origins of words, crossette is certainly not one of them. Crossette comes from the French, not Italian, meaning "A return in one of the corners of the architrave of a door or window." such as the one on the far left in the picture below. This return on the corner causes a square shape as seen in figure 1135 with the center post. The term "cruciform" (crux) has been used to describe an overall shape of a cross, therefore the word crossette and cruciform with a four segmented crossette are much more closely associated than a round hole cavity comet with a small charge. The overall effect of a cross (crux) in the air is not normally created by a round hole, 3-5 pieces are common while four, even pieces are rarer to make with any consistency without the help of the cruciform shape within the comet. Can you use the term crossette for a cavity comet? Perhaps, but why? http://justinstorck.free.fr/c/image/1133-1135-crossette-chambranle.jpg
dagabu Posted May 5, 2015 Posted May 5, 2015 In my recent experiments with round cavity crossettes, I had the flash comp burn as a silver star when it was inside a c6 comet, and then, after I lengthened the timing pin, it completely destroyed a green comet when it ignited. The green burned much slower than the c6, so I think differences in confinement are responsible. As soon as I can figure out how to cut a cruciform tool properly on my lathe I think my problems will disappear. What is the optimal cavity length relative to overall comet length? Not as easy to answer as one would think: In Wolters pumps, the length is X2 of the inner aspect of the cruciform, not the wings BUT this changes according to the OD of the comet. If the comet were 100mm OD, the cavity would be 50mm long and that is a LOT of flash! There is no need to overpower the break, a cavity need only be large enough to propel the sections out and away from the core fast enough to make a cross from the segments. 1
pyrojig Posted May 6, 2015 Posted May 6, 2015 Some find hot glue attaching the end cap to help followed by masking or paste paper leaving 1/8-1/4" exposed for ignition. the paper (or tape) is then pasted over the end cap to secure it. I have found flash diluted with 4F bp to work great. You can then adjust your power by ratio of bp-FP
calebkessinger Posted May 6, 2015 Posted May 6, 2015 I just found this post tooo... I talked to him over the phone. I believe he had wrapped the comets with dry paper before pasting... at least thats what I understood. My shot holes are pretty large on some of those first pumps I made. I believe they could be broken with bp even.. I made some and even a little amount of benzoate whistle shattered them. I need to press some more and give it another go..
Mike Posted May 6, 2015 Posted May 6, 2015 I had the best results when i used gummed tape to paste the crossettes. Cut all strips to size, wet them quite good so that the paper fibres swelled a little bit. Then wind them as tightly as possible. After drying they where tighly pasted in. The biggest issue was if i didn't roll 100% straight, then small channels could form, after a couple crossettes you will get the hang of it. But in the last time i started using mainly wax dipped crossettes. 1
pyrokid Posted May 6, 2015 Posted May 6, 2015 Mike, does wax really provide adequate fire protection? Could you please go into a little more depth about this method?
Mike Posted May 6, 2015 Posted May 6, 2015 The crossette itself gets pressed with +2 binder. For the wax dipped crossettes i fill the cavity with burst up to about 4mm to the rim and close the cavity with hot glue. Now take some pliers and dip in wax, 1-2 Dips are needed, depending on the wax an temperature/comp need (hot wax = more dipps, metal = less adhession of wax. A problem with charcoal stars can be hot wax that absorbs into the comp). Thats all to it, the biggest issue i feel there is, is that the hot glue creates a bulge at the top, so stacking can be a pain. The wax provides enough fire protection. 1
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