How to make holes in plastic boxes?

[OM2]

I need to make holes in plastic boxes.
The holes need to be clean and smooth ones.
I've drilled and it comes out looking like a big mess!
I need to be able to do many many times so need to figure out how to do in a quick and clean operation that only takes seconds.

See below for what I've done so far:

Thanks.

 

[JohnD]

What sort of drill did you use? It must be cold.

 

[Harry Bloomfield]

Take a piece of steel pipe, of the correct diameter, heat it up on a gas flame, then offer it to the plastic, where you need the hole.

 

[Stivino]

Why not put rubber grommets on the holes?

 

[Old Salt]

Piece of timber clamped inside the face of the box to drill into.

 

[Nozzle]

Use a stepped drill

http://www.tooled-up.com/artwork/prodzoom/B-S20506.jpg

 

[SFK]

Use a step or Cone drill.
Pre-drill a small 3mm hole first to mark where to use the Cone drill.
I would make a wood template with 3mm holes in it to mark where to put the 3mm drill holes.
And put tape on Cone drill or step drill to mark where to stop.

https://www.screwfix.com/p/erbauer-cone-drill-bits-3-14-8-20-16-30mm-3-piece-set/9031V?tc=MA2

 

[Harry Bloomfield]

Use a step or Cone drill.
Pre-drill a small 3mm hole first to mark where to use the Cone drill.

The plastic of those boxes, is quite brittle, trying to drill it, risks shattering it - which was why I suggested a hot piece of steel pipe.