first attempt at making igniters

[web/gag.com] / rockets / research / 2017-batch-02.mdwn

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+# Batch 2017-batch-02 #
+
+We're nearly out of [Quickburst](quickburst.net) igniters, they haven't been
+great at lighting erythritol grains anyway, and they're kind of 
+expensive...  So we decided to experiment with making igniters, and the
+first ones we decided to try are "epoxy fire" using a formula from 
+[Scott Berfield](http://www.berfield.com/igniters.html).
+
+For our first attempt, we made up a 10g batch with the following formula:
+
+* 68% KNO3, 6.80g, hand ground with mortar and pestle to fine grain size
+* 7% magnesium powder, 0.70g
+* 1% air float charcoal, 0.10g
+* 24% West Systems 105+205 epoxy, 2.40g
+** 2.01g 105 resin
+** 0.39g 205 hardener
+
+Two folded papers were used to weigh out the KNO3 in one, and a mixture of
+the magnesium powder and charcoal in another.  The epoxy was mixed in a small 
+disposable plastic cup with a popsicle stick, then the magnesium and charcoal 
+were poured in and mixed until complete wetted.  Then the KNO3 was added and
+mixed until everything became a homogenous mix.  It was a dry-ish, crumbly
+consistency, but packed into lumps easily.
+
+We used Chinese made e-matches with 2m leads, and used plastic drinking straws
+about 1/4" in diameter cut into 1" lengths.  The procedure was to slide the
+ematch through the straw, pack material into the straw from the "back" end 
+until it was mostly full, then pull the ematch lead until the match head was
+just at the forward end of the straw, then pack more material in the front 
+end of the straw until the match head was just covered.  Using nitrile-gloved
+fingers, it was then easy to mash on both ends simultaneously to make sure
+we had good packing with minimal voids, leaving both ends flush with the 
+straw.  
+
+The matches were left to cure overnight, and then the straws were carefully
+sliced lengthwise with a razor blade and peeled off, revealing what looked
+like very solid cylindrical igniters.  They look a lot like the Quickburst
+ones.
+
+These igniters were made on 17 May 2017.
+
+## Results ##
+
+## Observations ##
+
+A 10g batch was just enough to make up 6 igniters, and the pot life seemed
+a little tight.  Next time, it seems like trying a 15g batch with the slower
+206 hardener might be a good plan?
+