Perspex Light Bulb for the Lamp Post Engine

An article about me making a perspex light bulb for the Lamp Post Engine. Essentially I’m creating a perspex glass light bulb. I’m starting with perspex rod that is 19mm in diameter and around 30mm long. The first operation was to face, drill and thread one end.

machining perspex, 1000rpm on Hobbymat MD65
Machining perpsex in the HobbyMat MD65
perspex drilled and threaded to turn into a light bulb

The 6mm thread will allow me to fit this onto the top of the lamppost, the 5mm drilled hole will accept an LED.

The LED will essentially be the filament in the bulb.

The thread to fix the bulb to the top of the post was then used to fix the bulb in the lathe. A 6mm bolt thread sticks out from the lathe chuck and the bulb blank was screwed onto this stub of bolt.

rough turned bulb
The rough shape was machined at 1000rpm

I roughed out the shape with a mix of turning and using a very aggressive file. Note that when using any abrasives on the lathe it is best to cover the lathe bed. I use a piece of MDF to protect the bed.

I then used sandpaper to get the shape closer to that of a light bulb. Moving to a finer grade of paper I then used lots of cutting oil to keep the temperature down.

smoothed bulb

As you can see, the oil and finer paper starts to reveal the glass like clarity.

turned and polished bulb

I then moved to fine wire wool with cutting oil and spent quite some time polishing the perspex. Lots of cutting oil and 0000 wire wool and I ended up with perspex glass.

Lantern and perspex bulb

The bulb fitted into the lantern and with an LED as a test case in the centre of the bulb.

And so I now have a perspex light bulb for the Lamp Post Engine.

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