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.

Step 1: Cut Material to Length

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

Step 2: Drilling

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

Step 3: Tapping the Thread

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.

Step 4: Y Axis (centre)

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

Step 5: X Axis

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

Step 6: Drill

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

Step 7: Finishing the Component

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

Step 8: End Cap

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

Step 9: Threading

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

Step 10: Parting Off

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

Step 11: Shaping the End Cap

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

Step 12: Glass Tube

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 :)