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