Ok, I’ve read articles and seen pictures of modellers drilling out gun barrels, etc, but I seem to struggle getting the bit centered on the piece.
I’m trying to drill through .040" rod with a #76 drill bit. It doesn’t seem to be an issue of the drill bit wandering, I just can’t get it aligned and centered properly. I’ve tried using a needle to make a “starter” hole, but I still have the same alignment issues.
How do you guys do it? Do you have a jig, or do you just hold it in your fingers?
Chris
No jig that I’ve ever seen for something that small. The only “tip” I can offer is hitting the end of the rod with a sharpie first. Sometimes it can make centering the needle tip easier, to make the pilot hole.
Hope it helps.
If you are not using some sort of magnifier it’s gonna be tough to see that he starter hole is in the center. I use Opti-Visor. Take your needle, pin or whatever you are using and make a very shallow hole as close to the center as you can get. Looking with the magnifier you should be able to see where you need to re poke the end of the rod. Sometimes I use a pencil to darken the end of the rod then wipe it off the see the little dimple better.Once you get it dead center make it deep enough to guide the drill bit. Always start with the smallest bit you have. For most that #80. I have some bits that go down to #96 so very tiny little holes indeed.
A thought just occurred to me about a jig of sorts. If possible, get a short piece of tubing that the rod will fit in snug. Take a drill bit that also fits inside the tube. Put the rod in the tube, drill a tiny bit from the open end. That should make a a dimple in the end of the rod to make the pilot holes easier to start… Hmmm… gotta try that myself[whstl]
.040 thou rod? your eyes must be better than mine, even with a visor!
Thought about getting some alloy/brass tube instead?
You are trying a REALLY tight job of precision machining. I might try a block of styrene about an eighth of an inch thick. Drill a hole as perpendicular as possible through it with the #76. Then drill a hole forty mil in diameter (don’t know what drill that is off hand) 1/16 inch deep. Put the barrel in the 40 mil hole, hold it in while inserting 76 drill from the other side. Still may be undoable. My pinvise will not even hold a 76 drill! Personally I don’t drill out a barrel that small. You might consider simulating a cover on end of barrel if they used contrasting color for gun covers.
Thanks for the tips, guys. I’ll let you know how it turns out.
I guess I figured everyone drills out 48th scale gun barrels, but maybe I’ve only seen it on larger scales?
Now about using tubes, I am having trouble finding brass tubes small enough. Anyone know a good source of small (1.5mm and less) tubes in USA?
Chris
buy your tubing from Micro-Mark, that’s where I get mine, lot’s of sizes, lot’s of other neat stuff too.
Marc, that is a brilliant idea,I am going to try that next time I need to
it would work for large round stock that needs tiny holes in the center, also
just put tubing inside of tubing until you are small enough for a drill bit
centering fuze holes on Napalm tank fronts just came to mind
I buy syringe needles from the veterinary supplies section at the local feed-store. They offer a wide variety of sizes and I just cut them to length with a cut-off wheel in my Foredom motor tool. One can match the needles to mostly whatever size MG or cannon barrel needed.
Gary