Introduction: Simple Drill Jig for Drilling a Perfect Hole in a Sphere.
This Ible was created as a supplement to my last ible Hurricane Balls 3000 rpm + spinning toy. sorry to those who where expecting a more innuendo filled title,
I wanted to make a simple and reusable jig that would allow me to drill perfect holes in metal ball bearings or any sphere.
This is a very simple solution that Is easy to accurately refit to your drill press again and again, this jig is designed for small ball bearing up to about 20mm but could easily unscaled to suit much larger spheres.
To make this simple jig you just need a short piece of box section, 2 clamps and a counter sink drill suitable for metal.
Hope you find this useful.
Step 1: Step One.
To make the jig you will need a piece of box section that is as long as you drill table is wide.
First center adjust the drill table so the drill is directly over the hole and the drill with enough room left so the box section will fit under the drill bit.
Clamp the piece of box section to the table with the 2 clamps and drill a hole right through the box section, Use a drill bit that has a shank that is clear of wear or has burs as this drill will be used to re-center the jig later one.
Remove the clamps and use a countersink bit to remove the burr where the drill bit exited the bottom of the box section.
Step 2: Step 2.
Once you have drilled and deburred the box section you will need to raise the table to a higher position.
Use the drill bit as a location pin and adjust the height of the table so there is enough room left to mount the countersink bit, this is one of those jobs that is tricky and would require 3 arms to do. I find that winding the spindle down a bit helps but this all adds to the number of arms required.
Once you have the table adjusted tighten the drill bit in the chuck and then clamp the box section to the table again.
Once everything is clamped in place loosen the chuck and drop the drill bit out through the bottom of the table.
Now fit the countersink bit and countersink the hole, do not oversize the hole, leave some of the original hole viable as it will help in realignment of the jig when you next need to use it.
Remove the countersink drill leaving the clamps still in place, your jig is now ready to use.
Step 3: How to Use the Jig.
Mount the drill you wish to use to drill the ball with in the chuck, leave only the same depth of twists showing as how deep you want the hole to be drilled.
Now set the ball into the countersunk hole and start the drill up.
Now bring the spindle down in a quick stabbing motion a few times until you get the drill to start.
If the ball starts to spin no the jig you can grip it with some pliers to stop this.
You now should be able to drill multiple balls bead center and to a uniform depth.
Thanks for looking, I hope you find this useful.