I just bought a new-ray helicopter diecast toy. I want to modify it a bit, and one of the plan is to make holes for the windows (square, around 5mm by 5mm). What I'm thinking is to use dremel to drill a small hole (around 2mm diameter) and then enlarge the hole using dremel metal grinder bit. However, I'm not sure how to start. Dremel bit catalogue has drill bit for metal, for soft metal. I am not sure what kind of metal the diecast is. The thickness of the diecast is around 1mm. I also checked dremel speed guide chart, but could not find the speed for drilling.

Is it ok to use these drill bits for that purpose? What speed should I use?

3 Answers 3


For delicate work in soft materials, I still like to use my old wheel brace (hand drill). I've used it on plastics, wood and aluminium when I don't want to risk marring the surface as I break through. Securing the workpiece is an absolute requirement as it's a two-handed tool. I'd start with a 2 mm drill bit, then use a 4–4.5 mm bit so you've got the minimum at the next step.

You could then square off the corners with a needle file. My square needle file is about 2–3 mm at the widest point. This will give you much squarer corners than any rotary tool can provide. Even if you start with the dremel, you may need to finish off with a needle file.


It is zinc, it will drill easily but a dremel is very high RPM. I would suggest an electric drill , battery or plug, and a regular bit. Then square off the corners with a dremel. Zinc is so soft a hand crank drill could do it but I don't think anyone has them anymore. A small chance that it is aluminum - all comments the same.


I agree with @blacksmith37 that the material is certainly soft and drilling will be quick and painless.

The (typical) speed of a Dremel is just fine for a drill bit of such small diameter in that material, especially since the material is thin. If your Dremel is variable speed, you can run it about half-speed to be conservative.

I would center-punch (gently and with backing if possible) the intended hole location just enough to locate the drill bit tip so it doesn't wander.

Any drill bit of the right size will work fine here. 1/16" might be easiest to find at a hardware store (depending on your country/location) and is roughly the right size (1.59mm). 1/8" might work as well, but might be pushing it for the high Dremel RPM and may have more of a tendency to grab when going through. In any case you should secure the work somehow (perhaps using a clamp or padded vise) rather than hold it in your hand while running the Dremel with the other.

  • As OP uses mm in his question, you can expect that his tools are also in metric. It would be nice if you converted your imperial sizes to metric for that reason.
    – Willeke
    Sep 27, 2018 at 18:36

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