Introduction: IPad Stylus Tip - (How to Turn Small Parts on a Jet Lathe), I Made This at Tech Shop!
Make this brass tip for holding stylus rubber nibs! This is the hardest part of making your own capacitive stylus! I needed a brass tip to hold the rubber nib for my pressure sensitive stylus I'm developing. This instructable will show you my stylus tip plans and tips for how to create this on the metal lathe at tech shop. I made this at Tech Shop San Jose! http://www.techshop.ws/
Step 1: Gather Materials
3/8" x 12" Brass Rod -- I picked this up at OSH (Orchard Supply Hardware) in Northern California USA
Cheap iPad Stylus w/ Rubber Tip -- You need this only for the rubber tip, the one I used is the "rocket fish" brand from best buy
lathe cutting tools - Carbide Triangle Tip and Straight cut-off tool
six sided collet holder
3/8" 5C Collet
M4x0.5 Tap and Die
Step 2: The Plan
These are the drawings for the brass tip and the nut at the end. Please use them as a guide, since I did not cut custom tooling for the lathe I could not make the small gap in the middle, on my part it is more of a V shape.
A note for stylus tip design for the iPad: The brass tip is 6mm diameter and with the rubber it's about 8mm , and this is the smallest you should go. If you go smaller than this the screen will not detect the touch, or it will only detect the touch if you squish down the tip to spread it out.
Step 3: Bevel the Edges!
When making this part make sure your bevel the edge at the far left in the drawing, otherwise the sharp square edge will cut through your rubber tip. Guess how I figured this out?
Step 4: Let's Get Started on the Lathe!
Ahh yes, the Jet lathe. This thing is awesome and costs about $14k, it will make amazingly precise parts if you follow these tips.
Warning: Do not just throw your brass rod into the Three jaw chuck, it will not center with such a small piece and will chew up your brass!
First - Go find the correct 3/8" 5C collet -
The easiest way to find the right one is to just drop it in the collet holder with the closest fit, but remember do not force it into a collet! If it won't go in, it is the wrong size.
Step 5: Use a Six Sided Collet
Now that you have your collet, find the six sided collet holder and it's retaining ring.
Slide the collet into the front of the holder.
Slide your brass rod into the collet.
Screw the retaining ring onto the back of the collet and tighten with spanners or a wrench.
Step 6: Turning the Part
Now mount the collet holder in the 3 jaw chuck on the lathe.
I don't have pictures of the actual turning, I may add some later when I make the next one.
But, here are some tips.
1.When you turn the part start on the right side of the drawing (the parts with threads) and work to the left.
2. Do not cut off the piece when you are done! Instead add the threads to the end of the piece with a M4x0.5 die
while it is still on the lathe.
3. After adding the threads, only cut off the piece half way then add a small bevel to the end of the part, then cut off the part.
This bevel will help the rubber tip last longer
Step 7: Good Job! You Made a Sturdy Stylus Tip!
Now just pop the rubber tip on and you should be good to go!
If made precisely this stylus tip should feel very solid, and make good contact with the tablet screen.
Mine has a screw on back since it acts as a plunger to press on a sensor so that you can use the stylus as a pressure sensitive brush. I hope to polish my prototype and have it on kickstarter in the next month or two