Drilling rubber / silicone stoppers

In many experiments one needs (e.g. for simple distillation without a dedicated distillation column / Liebig condenser) a stopper with a glass tube through it.
Most stoppers sold through labware shops either direct or via ebay sell the stoppers without holes of holes with the wrong diameter. There are stopper drillers available on ebay for $20-$30 but according to reviews, the results are moderate. A simple approach with basic hardware store items can be done yourself. If you have a lathe (most don't) it is even easier. But without lathe a simple cordless drill and a vise can do the same.

What you need (assumed glass tubing outer diameter 6mm)

• Thin steel or brass tube of same O.D. (6mm in this example)
• Wood / metal drill bit of tube O.D. +2mm (8mm in this example)
• Strong gloves for safety
• Gripping or combination pliers
• File + sandpaper
• Freezer or cooling spray
• Soft burner
• Metal pin which fits in the tube (e.g knitting pin)
• Lathe, if not available, these:
• Vise
• (Cordless) Drill

When you do not use a lathe you can make a fake 'lathe' by putting the drill into a vise (with pieces of wood or plastic to protect the drill against the hard steel jaws). In this case the tube should be not too long so when it is in the chuck of the drill it extends no longer thqan twice the height of the stopper, The lathe or workbench should be placed firmly on the floor / against the wall otherwise your pushing results in moving the workbench / lathe rather than pushing the stopper over the tube.
Set the lathe at a low speed (< 600 rpm). Put the tube into the chuck so that about a few centimeters are left. Start the lathe and hold the file a little skewed over the end to sharpen the end. Then scour with sandpaper to remove the file grooves in the tube end by pushing it gently towards the spinning tube. Stop the lathe and now pull the tube bacck so that it extends about twice the height of the stopper from the chuck. Put on the gloves and hold the stopper FIRMLY in your hands. When you use pliers, then hold the stopper FIRMLY in the pliers. Then and start the lathe. Now, SLOWLY push it with the wide side towards the chuck, as straight as possible towards the chuck. It tends to spin in reverse directon (with the chuck + tube) but prevent this. Be aware that the pliers / your hands may slip off towards the chuck with the resulting damage / injury. When the tube comes out of the other end then move it a bit left / right and then reverse it (narrow side towards the chuck) and now it gets a lot easier. Now stop it.
You can optionally freeze the stopper now (or cool it by spraying 'gas duster' on it which cools down to -26°C) for easier drilling but is not required. Put the drill bit into the chuck and start the lathe again. Again push the stopper over the drill and it will now mill out some more rubber from the hole. Test it by pushing it over the tube which should be with not too much resistance. Otherwise, when you do this with a glass tube it will break and when you do this with bare hands injury will result.

Now the rubber remains might be inside the tube which can be removed by heating SOFTLY (not over 100°C) the tube end and then pusing the knitting pin intom the tube and push out the then soft rubber. When it stinks badly it is too hot !