Ok, I foolishly mentioned in another thread that I would do this, so here it is! I'm particularly interested in seeing what implements people use for their tiny cannon/mortars.
Here's what I have - the good, the bad, and the ugly:
(Click for a larger image)
I'll start at the top with the Bad. When I first built my brass BB mortar I was using a fuse that barely fit into my vent and I had ignition problems. At the top of the picture are a couple of pieces of 1/16" drill rod that I used to scrape out burnt fuse (with care after waiting several minutes). These are BAD because they're made of steel and therefore a spark hazard, particularly if used on a steel vent. The second one from the top worked best - if you look close you can see that I ground the end like a D-bit reamer. I need to make another one of these in brass.
Below those is a piece of pipe cleaner, which works great for cleaning out vents 1/16" or larger after firing. Unfortunately, I'm now trying smaller vents and the pipe cleaner is too large! Right now I use the paper clip to push gunk into the bore where I can clean it out with a Q-tip.
I still haven't got around to turning down a dowel the right size for a ramrod (working tiny pieces of metal is fun, but turning small pieces of wood is not my cup of tea!), so I'm using a Q-tip w the cotton removed - UGLY!
Finally we get to the two GOOD implements, but the first is definitely Ugly as well. The blue thing is my vent charger made from disposable micropipet tips (used for measuring tiny amounts of liquid in chemistry labs). I cut the end off of a recycled tip so that the hole is just big enough for 3F powder to pass through easily into my vents. It works MUCH better than bare fingers and mandatory reading glasses, which was my former technique! I melted the end of a second tip closed with a burner and cut it off to make a cap. I just wish it didn't look so much like something slapped together in a chemistry lab!
At the bottom is the only tool I'm completely happy with. My 2-grain powder scoop is a chopped off .22LR casing soldered onto a scrap of 3/16" brass rod. I found that I can reliably scoop between 125-130mg of 3F with it (130mg = 2gr). In a pinch, I can use the handle as a ramrod with my firecracker cannon.
Oh wait! I forgot my bore gage. I guess I have 3 tools I'm happy with...
Before I made the BB mortar I wanted to know the actual diameter of typical BB's, but I couldn't find the info on the net. I miked 20 BB's and found that most were between .172" and .173", with none larger than .174". I made my BB bores with this assumption in mind, but started thinking that 20 BB's is not a very large sample. A bore gage seems like a good idea anyway.
I decided to make a gage that would fit into the standard Daisy tube as a cap, so I could dump out the BB's and then drop them back into the tube through the gage. I tried to make the cutoff .173", and in the end I got a bore that passes BB's smaller than .1732". I had to forge a 1/8" boring bar and a holder for my boring head, and make a second gage after I screwed up the first one
, but it was a good learning experience! I screened 272 BB's (counting by weight) and found that only 35 were larger than the gage (the largest diameter was .1749", in case anybody wonders!)
OK, that's what I've got. I'd love to see what other people are using so I can copy your ideas!
andy
