Glow in the Dark Keyring

Awesome, Awesome, Awesome mini project that i recently discovered on this web site:

http://start-model-engineering.co.uk/2012/01/glow-in-the-dark-keyfob/

It will be my next project for my after school engineering club. Check the vid to see the key rings in action!




Learning Objective

By following a detailed set of instructions and videos from the Instructables website, yr9 students (13 year olds) will make a glow-in-the-dark key ring. The students will recall previously learnt skills on the metal lathe, e.g. facing off, centre drilling, and drilling to a given depth. This project will introduce the students to a milling machine and an indexable head. The project teaches how to use these precision tools to a high degree of accuracy and the students must aim to work within a tolerance of ⁺/- 0.1mm. To achieve this tolerance the students will have to use basic mathematical calculations of linear measurements and angular divisions.

• Use a hacksaw to cut either Ø9mm brass or aluminium to 90mm long

• Centre drill
• Drill Ø6mm x 50mm deep
• Drill Ø6.8mm x 8mm deep

• Put a M8 tap into the chuck and manually tap the thread. Do not turn the lathe on!
• Once its started remove from the lathe and complete the rest in a metal vice.

• Remove the work piece from the lathe and secure in the indexing head.
• Put in the centring bar (this can be any rod with a known diameter)
• Slowly advance the rod towards the work piece, using a thin piece of tissue as an indicator......keep moving the tissue, when the rod grips the tissue you know its exactly on the edge of the work piece.
• Lower the machine bed and zero the Y axis dial.
• Use the following calculation (Ø of centre rod + Ø of work piece / 2)
• 8mm + 9mm = 17mm       17mm / 2 = 8.5mm
• Move the Y axis dial 8.5mm
• If done correctly you should be within ⁺/- 0.1mm of the centre

• This does not need to be as accurate as the Y axis
• So put in the Ø10mm centre drill and align it over the end of the work piece
• Zero the X axis dial and move it 8mm to the right

• Use the drilling head to drill to a depth of 5mm.....its important each hole is exactly the same depth.....ensure you pay close attention to the numbers on the Z axis dial.
• Once the first hole is drilled rotate the indexing head by 8 holes, drill the 2nd hole
• rotate another 8 positions on the indexing head.
• Move the X axis by 8mm 
• Move the index head by 2 positions 
• Repeat the process until you have four sets of holes

• Put a chamfer on the end of the work piece
• Use 100 grit abrasive paper to clean up the surface
• Part off the component at 55mm

• Measure 15mm into the rod and centre punch 
• clamp the other half of the rod into the v-grove on the machine vice with the punched mark perfectly vertical 
• Use a centre drill to start the hole 
• Use a Ø4mm drill to complete the hole

• Parallel turn the end, Ø8mm x 10mm
• Use a M8 die, start the thread using the tail stock of the lathe 
• After a few turns complete the thread in a metal vice

• Test the thread by screwing on the other half, you will find that the thread is a bit long.....face it off until its the appropriate length.....approx 5mm
• Part off the component, 5mm past the hole
• Screw the two halves together

• Wrap the main body in paper to protect the surface finish 
• Shape the end using the cutting tool
• Use 150 grit abrasive paper to tidy up the surface

• I got this Ø6mm glass tube from the science department....... you can use any glass or plastic tube....even fish tank air hose would work.
• The glow in the dark powder was purchased on ebay.
• Cut the tube to 45mm
• Use the glue gun to seal one end
• Clamp the tube to stand upright....alternatively ask someone to hold it
• Carefully fill the tube using a folded piece of paper 
• Glue the other end to seal the tube
• Put the tube in the brass holder
• Screw on cap
• Enjoy :)