How to Drill or Bore Round Objects, Safely.




Ever want to drill out a pool ball for a paintball pump, shift knob, or door pull? Maybe just a really cool and tactically sound walking stick. We do custom laser engraved shift knobs (as seen in the first photo) and needed a repeatable way to drill out the balls for them.

Clamping down in a vice on a sphere is pretty difficult, especially when yo are trying to keep a surface finish correct. Being able to index is even more crucial, so repeated operations can happen, which is not always possible when you are wrapping things in rags and scraps of leather.

What you will need:
A block of Sculpy modeling clay
car wax
Your vice
an oven

Milling is optional.
Techshop is optional, but a big help. I did this at Techshop Pittsburgh
I first got the idea from a fellow on

Step 1: Prep Your Sculpy

for this jig, I used 1/2 a block. Take and work it a bit, until you have a few balls of material. You will need one for each side.

Step 2: Wax Time!

Take your object, in this case a pool ball, and apply a generous amount of wax. this will help it release from the sculpy.

Step 3: Prep the Vice

We want a clean surface on the vice, so we don't contaminate the sculpy, nor the vice with clay.  Clean off any chips an inconsiderate user may have left, and then give both jaws and the bottom a good coating of masking tape.  You can then wipe this down with a bit of wax as well if using a liquid version. Just a dab will do ya!

Step 4: Molding

Put the scuply or clay on either side of the vice, in ann L shape, and then press the ball into it. We then lightly close the vice in order to make sure the material is gripping the object with sufficient surface area.

Sculpy is good for this, being that it stays just a bit plasticy once cured. I havent had a ball slip yet.

remember, we want a bit of clay to fit over the top, and we want to keep both halves of the jig from closing in. You may want to use a bit of tape or a bit of wax in order to keep them apart, I didnt have an issue with this.

Step 5: Remove the Mold, and Bake!

Next, remove the ball (should be easy because of the wax, and take care to separate the 2 without deforming the clay.  Place it onto a surface that is flat and will alow for it to be heated, I used some scrap aluminum, and placed it in a powdercoating oven.

Follow the instructions on the box. I baked mine for about an hour to be sure.

Step 6: Thats It

Let cool, remove, and test fit.  You may want to chuck it back up and use an end mill to clean up the sides, but that is optional.

Good luck, and I hope this was useful!



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    28 Discussions


    5 years ago on Introduction

    You need to sculpt it so it looks like teeth... and use pink and white sculpty.

    Just saying... ;-)


    5 years ago on Introduction

    Ingenious. Thanks for sharing. This would work with any odd shaped and difficult to clamp object too.


    5 years ago on Step 4

    How are you guaranteed to drill straight toward the center with this rig?

    3 replies

    Reply 3 years ago

    Just saw this comment / question...

    Before we would drill, we would laser them with a crosshair. Prfect placement every time.


    Reply 5 years ago on Introduction

    Danzo, First thing is make sure the drill is true vertically, then just take a piece of thin flat metal and a small ball from a ball bearing and place the flat metal on top of the ball to be drilled. Close the drill chuck small enough that the bearing ball will not go inside the chuck and place the bearing ball under the chuck jaws and bring the chuck down on top of the flat metal and move the lower ball until the flat metal is level in all directions and you then know that the drill is centered on it. Raise the drill after clamping the vise down, catch the bearing ball, insert the needed drill bit and turn the drill on and drill the hole as needed. It will be true and centered.


    4 years ago

    I drill a center hole in hundreds of 2" composite balls as part of a production process.
    I never imagined it to be so complicated.
    I simply center the drill bit to the 1 1/2 hole in the center of the press table, lower the table, place the first ball in the table hole, hold ball by hand with slight downward pressure and begin drilling.
    If table hole size too large or too small, drill correct size hole in 2X4. If additional grip required use tool box liner, etc. to prevent spinning. This method can be easily adapted to drilling on a mill compound table.


    5 years ago

    Simply center round object by placing it in the hole in the drill press table. Can also use old bearing race, a tin can, etc.


    If your drilling a round object I use ABS pipe 1.5in to rings cut about 1inch long then heat up the inside edge and press it into a round object like a tow hitch ball let cool and keep near drill press for use..hint lightly sand edge Nd dip in plastidip tool grip to protect from marking

    1 reply

    5 years ago on Introduction

    you appear to be working on a mill, do you not have V blocks?...if not, you can make V blocks out of wood, they will be more effective. btw, i'm a certified machinist, which is why i'm asking.

    1 reply

    Not sure. Worth a try. Like that JB weld epoxy clay? One of the nice things about Sculpy is the surface feel after it is cured. Its just a hair plasticy, and still sold. Almost like a very, very hard rubber.

    Yes, it is like JB. I have never used Sculpy..but will try. I was thinking about what I may have in my bag of tricks w/o having to go shop. Tnx, appreciate ya


    5 years ago on Introduction

    Nice idea. :)

    Depending on the difficulty of drilling, could this also work without baking the clay and using it "wet"?

    1 reply

    5 years ago on Step 6

    This is a nifty idea pity that it came just a wee bit late for me but something the younger crowd must file and keep it when needed. I had a Volkswagen Golf (also known in other countries as the Rabbit) gear selector knob actuator at the steering box under the engine for reverse. The price of the part was exorbitant so I made one out of the control valve lever knob of a Lansing Bagnall lift truck