Wiley Posted June 12, 2015 Posted June 12, 2015 I will be making a bunch of draw-outs this year, and I've always primed both ends of my time fuse with a thin coat of BP/NC slurry. However, when you're making a lot of inserts, this step can be a bit tedious, and I think it hurts my timing a little. My question for those who have done this is, can a square-cut end of Kingshine time fuse reliably light 7:3:1 (perc:5413:sulfur), if the fuse is solidly in contact with it? I'm pretty sure both psyco and wonderboy do this, but I can't remember where I read that.
mikeee Posted June 12, 2015 Posted June 12, 2015 Wiley, That is the method I have used for several years, when using quality time fuse it works fine.
Wiley Posted June 13, 2015 Author Posted June 13, 2015 Ok, that's what I thought. To test the theory with my materials, I took five lengths of my time fuse (about .75" long), taped a piece of visco to one end, and put two turns of masking tape around the other end with about .5" of tape hanging off the end of the fuse. Into this tiny compartment thus created, I charged a tiny amount of 7:3:1, maybe about 1/8" in the bottom of the little masking tape tube. Crimped the end of the masking tape shut (you could hardly see that there was anything inside it when this was done), took the little devices out to a safe location, and fired up the visco. Each and every one gave a nice, low-pitched little pop completely unlike the bang you get from a class C firecracker and a bright flash, visible even in broad daylight. Not only does the time fuse appear to be perfectly adequate for lighting this particular composition, I also discovered a neat little device that isn't particularly loud, but is still fun to light when I feel the urge to "smell the smoke."
RichardH08 Posted June 15, 2015 Posted June 15, 2015 I've always primed both ends of my time fuse with a thin coat of BP/NC slurry. However, when you're making a lot of inserts, this step can be a bit tedious, and I think it hurts my timing a little. A while back I did some burn tests on time fuse. My results suggest that priming one end can add up to 0.4 seconds to the delay time. 1
Mumbles Posted June 15, 2015 Posted June 15, 2015 Richard, did you notice the priming adding a consistent or somewhat variable amount of timing to the fuse?
RichardH08 Posted June 16, 2015 Posted June 16, 2015 For what it's worth, here is the write-up I did of my trials: http://www.pyrobin.com/files/TimeFuseInvestigation.pdf In the main trial, priming both ends gave a total additional time per end of about 400ms, with a variation of about plus or minus 30ms. For unprimed time fuse, I estimated the corresponding additional fire-transfer time to be about 50ms, but I didn't measure the variation. Given the size of the effect and the differences caused by different priming methods, my feeling is that priming either end increases the variability of the timing.
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