Sunday, May 10, 2009

Tabletop Demonstrator

Knot-tying instruction is a difficult subject to film. If you don't believe me, go onto YouTube and just search for knots. The problem is that the easiest angle to film is from the front, but if you try to follow along and tie the knot, everything is in reverse. The best angle for instruction is from the perspective of the knot-tyer. But most videos from that angle are really jerky as someone attaches the camera to their head to get a "point of view" recording.

So I came up with a PVC contraption, originally called the Knot Demonstrator. It allows you to film directly downwards, which works pretty well for filming knot-tying. But then my wife wanted to digitize some artwork that wouldn't fit in the scanner, and we discovered that the Knot Demonstrator works for that, too. So after a lot of experimentation and changes, I've come up with a stable design that allows you to film and photograph anything from directly above. The new name is Tabletop Demonstrator because it can be used for much more than just knot videos.

(All 3/4" sch 40 PVC or fittings)

Legs -- 4x 21.5"
Crossbeams -- 4x 9"
Z-Beams -- 4x 10.5"
Stabilizers -- 2x 7"
Hidden Connectors -- 6x 1.5"
* A note on lengths: These lengths are set up with my specific camera in mind. Depending on how wide of an angle your camera has, you may need to change the dimensions slightly. If, when you have everything set up correctly, you can see any of the PVC, you either need to shorten the legs or make the Z-Beams or Crossbeams longer.

2 End Caps
8 90-degree elbows
8 Tees

By the way, you may notice that there's an extra Tee between the lower crossbeams. I don't know what it's doing there, but it seemed to be a handy place to put a connector (possibly for future modifications).

Price: Around $10.00, unless you have all the parts lying around (like I do)
Build time: 15 minutes, more if you need to adjust the height or width
Availability of materials: Readily available
Durability: It's PVC. Plenty durable for indoor work
Functionality: Works very well for what it's designed for
Portability: Somewhat large and bulky, but it can fold up into a smaller size (see future post)


  1. Instead of using the pair of elbows, would it not be more simple to build the mount into the tee which connects the crossbeam if the tee were attached facing the side the camera would mount? that would save on elbows but maybe the crossbeam would be in the way of your hands as you operate the camera.

  2. Dave,

    In some ways, it would simplify things to eliminate the elbows. But you're right; the crossbeam can get in the way. Plus, this design puts the camera further away from the ground crossbeam, allowing the z-beams to be shorter while keeping the bottom crossbeam out of the shot.

    Thanks for looking at ways to make this better. Keep up your suggestions. I know the designs aren't perfect, and I'd love to get more community support for improvements.

  3. You are so funny. The little song you were doing and the fast talking was is your tabletop thingy. :)

  4. Great video Paco. I think it's an elegant and inexpensive solution. And it really works!

  5. how does the camera attach?