New build. Decided against the new scare gun, I'm making a thundermug instead.
And I need it, soon, the birds have renewed their assault of my shop.
Backstory: When the new roof was installed on the shop where I work, a flat metal roof was simply built above the old arched wood/shingle roof. Holes were cut in the old roof for the supports. The arch is open on the back end, where it extends into a shelter, and this lets birds into the shop. The holes give them access to the space between the two roofs. An extremely tempting nesting area.
So most every spring I am invaded by birds that perch on the roof beams and do what birds do. All over the equipment. If you scare them out while they are nesting, they'll stay out.
Firecrackers don't scare them at all, they ignore them. Black powder, OTOH, scares the tailfeathers off'em. And since I retired the old scare gun, nothing can make the boom that the birds so love to hate. Acetylene bombs are close but dangerous, and have been declared off-limits.
So the thundermug will be the new bird scare device.
Got the steel tube done, save for a little polishing. It's bored and turned from a solid piece of the same chrome-plated 1045 hydraulic cylinder rod I used for my GB mortar.
Still needs to be vented so it can be test-fired outside. One ounce of Fg should do nicely. Then it'll be loaded with a reduced charge and start earning its keep in the shop. It'll need to be fired daily for a few days, then a couple times a week for the next month or so.
The tube is 8.625" OAL (dictated by the length of this piece of stock). The bore is 1" in diameter, 7.250" deep, with a hemispherical bottom. The reason that the bore doesn't extend deeper is that I didn't completely remove the center drill spot on the bottom, I left it to be used during machining. That meant the the bore would have to stop at 1" from that hole, not the bottom of the tube. The section between the base and the first band, over the chamber, is 3" in diameter. So nowhere in the chamber area is it less than one caliber thick.
That photo shows the scale, but because of the camera angle it doesn't really show the taper well. Here is a more direct shot.
I haven't decided whether I'll install the flash pan underneath the vent. If I use it, it'll be cut from steel plate and welded on. And of course, it'll need a handle, but these are things that can be added to it after it's made functional.
I hope to have it firing Monday, and finished by the end of next week.
