barrel/exhaust drilling help

[Gwyn]

I am looking for some help/guidance on the technique of drilling the ends of gun barrels etc.


I am sure that having a hole at the end of a barrel or exhaust pipe is necessary to make a model as realistic as possible.


I can also see the problems of getting the hole central and also not to drill out through the side.


How deep does the hole need to be?


What equipment and techniques do people use to overcome my perceived problems.


Thank you in advance for any submitted help/guidance.

[eddiesolo]

I do a centre punch hole and then use a small drill bit either on a slow speed in a cordless drill or using a pin vice, if the hole needs to be bigger go up a size in drill bit until you get a good hole. I hold the barrel in a vice-gently but enough force to create a centre punch, you do not need loads of pressure for this as it is just to get a central point and a guide for the drill bit. Use the vice or even hold by hand, if using a pin vice, to gentle do the turns to create the hole. As for depth depends on the scale, but 90% of the time just a couple of twists will give the look of a bore on a small barrel.

[Gern]

Hi Gwyn. You're absolutely right to say it improves the look of a kit.


You will definitely need a pin vice and a set of small drill bits (John has both of these in his shop. I'd recommend the Microbox set and the double ended pin vice). They're not expensive and you will find other uses for them. Whatever you do, DON'T use any kind of power tool for this. The holes you're trying to drill are tiny so you're not going to save any time or effort, and power tools will be much harder to control accurately.


1) Make sure the end of the pipe is flat and square.


2) Mark the centre of the piece you need to drill out. I do this by eye using the point of a No 11 blade in my knife, but you could use a needle or sharp pin. Try to get this as accurate as possible. Your mark should create a tiny hole in the plastic which will make sure your drill bit doesn't slip when you start to drill.


3) Start with a fairly small diameter drill bit and drill out a pilot hole 1 - 2 mm deep. This will enable you to check you're drilling straight and in the middle - if you're not exactly centred, don't worry, you can fix it later (see part 6). Gradually increase the size until you get the desired result. Keep your drill lined up straight with the pipe to ensure you don't drill through the side.


4)  Unless you're very steady and sure about what you're doing, don't try to drill the hole to get the walls of the pipe very thin and to scale. It's much better to leave the walls of the hole slightly too thick rather than risk the plastic tearing or going through the side.


5) You only need to drill your hole a millimetre or so deep - the larger the diameter, the deeper your hole needs to be. Even with the larger sizes (up to 1.6mm in your drill box) you will only need to drill 3 - 4 mm deep.


6) If you find your hole is not absolutely in the centre, use the point of a No 11 blade and gently enlarge the size of the hole by spinning it like a drill and scraping away the plastic. Keep the sharp side of the blade at the place you want to remove the plastic until the hole looks central. GENTLY DOES IT with this bit!


Sounds difficult I know, but a little practice will show you it's nowhere near as hard as it sounds. For practice, cut some short lengths of round sprue of different diameters - don't use hollow sprue sections: that's cheating!

[Guest]

My technique is much the same as Si. I use a pushpin to get the initial hole & then a micro drill bit to begin the process. I move up the scale of micro bits until I'm happy with how it looks.


I only use hand power; motorized tools can get away from you & bore too much too quickly.

[Gwyn]

Thank you for your quick replies. Sounds a bit scary but take it slowly and i should be alright. This is a great site and I am pleased that I joined.

[Guest]

Great advice; I would add only one thing: a drop of black wash (I use watered down India ink) down the barrel can add to the illusion of depth.