Boywillie Posted July 6, 2007 Share Posted July 6, 2007 Could you gents please explain how you "centre" up the gun barrel, exhaust or whatever else you are drilling. I have had so many failures (and maybe one or two successes) simply because as I start to drill I find that the drill bit hasn't entered the centre of the piece, or as it enters it splits through the sides. I guess poor eyesight and "wobbly" hands don't help, but I kinda wondered if there was a simple "trick" to making this any simpler. Regards, as always Willie Quote Link to post Share on other sites
Old Blind Dog Posted July 6, 2007 Share Posted July 6, 2007 A miniature awl or some similar thing (a sharp needle, the tip of an X-Acto blade etc) that can create a small indentation for the drill bit to grip into at the start (and thus, stay centered) works wonders. Old Blind Dog Quote Link to post Share on other sites
MickeyThickey Posted July 7, 2007 Share Posted July 7, 2007 Also (if at all possible), drill a pilot hole with the smallest bit you've got. Then step up to a larger bit. The indentation will guide your pilot hole to centre it, the pilot hole will guide the larger bit to keep IT centred. If you start out trying to drill with the proper sized bit, you've got no room for error, but starting small gives you room to play, and the ability to fix mistakes if you DO make them. Quote Link to post Share on other sites
madmike Posted July 7, 2007 Share Posted July 7, 2007 A miniature awl or some similar thing (a sharp needle, the tip of an X-Acto blade etc) that can create a small indentation for the drill bit to grip into at the start (and thus, stay centered) works wonders. Old Blind Dog Ditto here and then what MickeyThickey suggests. It works. MikeJ Quote Link to post Share on other sites
Big Kev Posted July 7, 2007 Share Posted July 7, 2007 My question then would be, how do you find the centre to mark the pilot hole in the first place? Hey, while I'm here, where's the best place in Oz to get really small drill bits? Mike? I've got one quite small one (no idea what size), but it seems to large for many tasks, and I haven't found anything smaller in hardware stores etc. Kev Quote Link to post Share on other sites
Pierre Sacha Posted July 7, 2007 Share Posted July 7, 2007 Boywillie, Make a trip to your local pharmacy/drugstore and ask for various sized syringe needles, these are great for gun/cannon barrels. Be prepared though for some classiclal facial expressions when you tell them what itś for :D Pierre Quote Link to post Share on other sites
Grant in West Oz Posted July 7, 2007 Share Posted July 7, 2007 Big Kev, I start my holes using a scalpel tip, check to ensure it's in the centre. (with my old eyes, that's easier said than done) Then the drill. My standard drills are 'Tip Cleaners' from a welding shop. They look like drills, but small and have a plastic knob to twist the drill. Sizes 0.3mm to 1.2mm. Mine are so old they are CIG branded. You'd need to get them from a BOC Gas centre. My son had micro drills purchased at a hobby shop, about 15 in sizes from #80~#64. No idea what those numbers represent, filthy Imperial measure no doubt. I picked up a set of 10 re-sharpened tungsten micro-drills from a trader on ebay.co.au for $18 recently. They're nice. HTH G Quote Link to post Share on other sites
Big Kev Posted July 7, 2007 Share Posted July 7, 2007 Thanks Grant - great info! Kev Quote Link to post Share on other sites
redruffensore Posted July 7, 2007 Share Posted July 7, 2007 I use a small sewing needle held in a pin vise. Caz Quote Link to post Share on other sites
SBARC Posted July 7, 2007 Share Posted July 7, 2007 On a related note...... If you are drilling out the end of a resin gun barrel....it is best to cut the end off and glue a tiny plastic rod on the end and drill that out instead.....or glue a hollow tube from a hypodemic needle on the end. Steve B Quote Link to post Share on other sites
MickeyThickey Posted July 7, 2007 Share Posted July 7, 2007 Drill bit sizes: http://bobmay.astronomy.net/misc/drillchart.htm Finding the middle... usually just eyeball it. Make a small indentation with a pin, look at the part, rotate it, see if it's 'close enough' for your liking. If it's not, poke another hole closer to where the centre should be. If it is, make a bigger indentation with the pin, then start a'drillin'. If you're really crap at that, you can use an X-acto blade to set your middle. Press it along the width, to make a line, and along the length, to make a second line. If you're going across the middle of the circle, the centre of the resulting + will be where you want to drill. If you're not really precise, and your lines are a little off centre, more lines will help you judge the middle more accurately, so make a * instead. It may not get you exactly, perfectly, dead centre, but should be close enough for modelling purposes. For particularly fiddly bits, it can help to clamp them. Something like this, with rubber pads that won't damage the part (hopefully...) but hold it securely so you can work easily: Quote Link to post Share on other sites
The Loggie Posted July 7, 2007 Share Posted July 7, 2007 G'Day Big Kev. I'm in Sydney. Dick Smith & Tandy have a micro-drillbit set. They are also available from the railway &/or RC section of a LHS, as a set or as loose individual bits. The displays for them is usually a board 15" x 15". They are stored in cigarette-diameter tubes. Finding the centre. I drill the first centre dent with a knife blade point (I use Exacto No. 11/straight blades) then I widen the hole by twisting the knife a full 360-degrees. As the hole gets bigger and you can see that it is off centre, cease keep twisting the blade. Instead, just wriggle it through a small ARC, but ensure that the sharp edge of the blade is against the thicker rim of the hole. This removes the plastic from the thicker side of the rim, and brings the hole back to the centre. STOP when the rim is the correct/desired thickness, and the same width all around the hole. This, and a spot of black paint, should be good enough for most AC guns. I only drill deeper for larger cannon barrels (50mm, 75mm 105's - that sort of thing). Hope this helps you. Good luck. George, out.............................. Quote Link to post Share on other sites
Big Kev Posted July 7, 2007 Share Posted July 7, 2007 Thanks George - great info once again! I'd seen those drill bit sets at Dick Smith, but wasn't sure they'd be adequate, since I know nothing about drill bit sizes and how small though go. I need to get to a larger DS store anyway to see if they sell those tiny LEDs (1.2mm or so). :D Kev Quote Link to post Share on other sites
Boywillie Posted July 8, 2007 Author Share Posted July 8, 2007 Many thanks for all the replies chaps,,,,, much appreciated. Regards Willie Quote Link to post Share on other sites
jrallman Posted July 9, 2007 Share Posted July 9, 2007 one thing that is kind of key to drilling out guns is to sand the end of the barrel flat first. Alot of times the end of styrene gun barrels will have a mold seam or be slightly rounded. it is almost impossible to get centered on that kind of surface. Take a sanding stick or some sand paper, hold the barrel tightly near the tip so it doesnt bend or break, and give if a few swipes, just enough to true it out. Then go on with any of the above methods. Quote Link to post Share on other sites
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