November 2016 – Mechatronics Workshop

I thought I would offer some ideas on different ways to open box lids. My main motivation has been finding a good way for lifting the lid of small Halloween coffin props, but the techniques can be used for many other applications as well.

I love to play around making these things as a hobby, but I need to make smaller versions of these because I don’t have enough room for full-sized ones. Here’s an example of a nice full-sized one by MrTmartindale on YouTube.

Seeing as I was recently playing around with pulleys I thought I would start with probably the most basic way to lift a lid — with a string!

There are a lot of potential problems with this arrangement:

It’s visible.

You need to reverse the polarity on the motor for up and down directions.

It takes up a lot of space.

It needs a lot of parts: string, string pulley, pulley support, motor, motor pulley, motor mount, and some way to reverse the motor direction.

More ideas and videos coming soon…

Today I’m starting to experiment using pulleys. They’re not used all that much in animatronics. I’m guessing it’s because they’re not as strong, predictable, or reliable as gears. But sometimes they can be useful. I see them a lot on the outside of gearboxes like this one, where the inside is chock full of gears (click photos to open larger versions in a new window):

I’m guessing this is the case when they don’t have room inside a standard gearbox (if there is such a thing in animatronic toys) and when speed, direction, or power transfer are not critical. Although, I wonder why they just don’t re-design the gearbox to accommodate this arrangement with gears? I have come across two toys where the drive belt has broken and rendered the toy’s animations useless.

Now these little gearboxes are tremendous to use in small animatronics, but it’s not possible for most of us to design our own gearboxes on this small of a scale. So pulleys are one way to drive our own hobby animatronics.

Enter my beginning learning design!

The first thing I had to do was get myself a little hobby motor. They are easy to find in just about any animated toy. They are pretty generic can usually run on anything from 1-1/2 to 6 volts DC or so. The problem with using just the motor is that they spin way too fast (around 10,000 RPM), and they have no power. Gears, or pulleys, are used to slow down the rotation and increase power.

To be continued

Month: November 2016

Ways to Lift Lids (as in opening coffin lids for Halloween props)

Playing with Pulleys