Being quite intrigued by the Babington burner, I’ve decided to take on the task of building one. I’ve collected what I think is most of the parts, we’ll find out if I’m right once I get them more assembled. I seemed to have found a possible source for the ever-elusive hole making device. After trying Home Depot (hey, I can walk there from my house, and needed some other goodies from there for the burner anyway), I decided to follow the advice from the list and look for a PCB drill. I visited Radio Shack and a local electronics parts supplier.
Radio Shack didn’t surprise me with their lacking, but the electronics supplier did, since they had un-etched PCB and other board production goodies. Anyway, they pointed me to a hobby shop next door to them. It seems that hobby shops might be the place to go looking! I found some nice X-ACTO drills, sold in an assortment. Found an 0.018″ bit in the set (the shop was nice enough to dig out their digital dial micrometer from the back, and measure them for me). So, I bought the assortment, along with a ‘Pin-Vise’. The pin-vise is meant to hold the small bits as a drill chuck would, but it designed to be operated by hand (twirl it between your fingers like a screw-driver). The guy at the shop said he had put a bit in the pin-vise, then put the pin-vise in
a 3/8″ drill chuck with success.
So, I got my new goodies home (about $25 worth, by the time it was all done, for the bit assortment, plus a pin-vise (that included another bit assortment, so I probably spent more than I *had* to)) and was very excited to put them to use. I had purchased a brass cabinet knob at home depot (not sure the exact size, but some of the images on yahoogroups show one like it, about 3/4 sphere, semi-hollow back side).
I also picked up a tap, to cut some threads in the knob, and install a 1/8″ brass pipe in the back of it (for the air supply). Mounting the ball in a small vise, I set it on my drill press. I drilled the large hole to be tapped for the brass pipe, and drilled it almost all the way through. I used the stops on the drill press, and left about 1/16-1/8″of brass left. I then opened up my new bit assortment. With all the bits in my hand, I found the one we had measured in the store. I also notice a smaller one, and grabbed my micrometer. I measured the one we sized up in the store… sure enough, it was 0.018″. I measured the smaller bit… 0.013″! I suppose I had never though about how small this was, so while I was at it, I pulled a hair out of my head… 0.002″. Okay, so now the small bit doesn’t seem as small to me. Still, I feared breaking it on my first drill attempt, and remember reading that Archibald had increased his hole to 0.020″ successfully.
It seems that X-ACTO isn’t so exacto (sorry, couldn’t resist). Installing the 0.018″ bit in the pin vise, it had a bit of wobble in it (well, a LOT of wobble, I could notice it just twisting it in my fingers). I reset the bit a few times, finally got it *pretty* true. Just to check, I mounted the pin vise in the drill press (it’s a little mini-press, not one of the 6′ industrial jobbers), and dropped the drive belt down to the 870rpm range. I know, small bit, high speed… but, it’s so fragile!! I turned the press on and… still wobbling. Not that I didn’t expect this, but it might have made my life easier (or not, I dunno). So, I pulled the pin-vise out of the drill press, and began to drill through my ball by hand (keeping the ball in the vise, so it would stay square).
I had to drill into the rounded side of the ball, as the pin-vise was too fat to fit in the hole I had drilled for the 1/8″ brass pipe. I would have lubed it up with some oil first, but, the ball was already WELL oily from drilling the tap hole. I turned away with my fingers for a few seconds, then pulled it off to wipe it clean (it was building up a *relatively* large amount of shavings). Once the hole was about 0.080″ deep (I didn’t measure, I’m just guessing), I decided to mount the pin-vise in the drill press again… the wobble wasn’t THAT bad, and I figured the little hole I had drilled should hold it stable, and keep it from breaking. I edged the bit into the hole, far enough so it was in, but not all the way to the bottom of the hole, and turned the drill press on. I gently turned the handle on the drill press, and could hear when the bit made contact with the ball. I nudge at it, backing off after about 1/2 second of contact each time. Within about 10-15 nudges, I was through, and my bit was still in one piece!
So, now that my hole is drilled, I’m pretty close to being able to fully assemble this thing. The only thing that’s going to hold me back is my move (new house, acre lot, big garage, no HOA, yeah!!) I figure I’ll buy some more balls and 1/8″ brass pipe, and make some extra jets, once I get this first burner working. Might be fun to play around with the hole sizes, patters, quantity, whatnot. Anyway, I’ll post some more news on that when the burner is doing something exciting.
Now, for what I was thinking for modification. It’s actually based on the answer to a question: what kind of exhaust gas velocities do these things have? Why do I ask, you ask? Well, has anyone thought about taking an automotive turbo, and mounting it on the exhaust stack, and using it to increase the intake airflow? No clue if it’d be feasable. If someone thinks it might be, and I can get my burner running, I’ll try to dig one up and see what I can do with it. I just figure that if we can easily increase the intake pressure, we might get a cleaner burn? I figure it might take some playing with where the turbo injects it’s air too… behind the ball might be bad, if it blows the fuel stream away from the ball. In front of the ball might be good (inlets on the side of the tube), but how far? Just behind where the flame starts (2-3″ in front of the ball)? Right at the seat of the flame? Anyway, maybe it’s a worthless idea anyway… or, maybe it *will* work, and we can rig a turbo to turn a small generator, to power the fuel pump :)