This was a project to try and create a filming dolly, basically a trolley to support a filming tripod with a suspension system to absorb shocks from uneven ground to allow for smooth filming in straight or curved lines.
This was actually built and the there was a full detailed project report covering the construction and how many construction issues were dealt with a full set of component plans. This has been lost due to hard drive failure. In addition whilst parts could be designed precisely,limited tools & materials I had were too crude to produce this to the tolerances needed & in particular the drilling of large holes just ripped the plywood. It does show CAD work though.
This task is often done with very heavy expensive wheeled dollies running on tracks with a team of grips. It is also done using very heavy and expensive steady cams. This project was to try and come up with something similar on the cheap with scrap wood and bolts behind our shed using some similar principles rather than rent this gear.
Product Design Specifications
Support the lightweight filming tripod I had.
Hold the legs steady at the tripod base in a with shock absorbing anchored feet.
Have a braking system.
Have a suspension system on each wheel as well as some form of tires which would also help to silence and smooth the hard castor wheels.
Be able to be folded to take on public transport.
To be mostly made from materials I already had and tooling to minimise cost.
The steadycam was considered far too complex to attempt but a flat trolley similar to those found in a DIY store, with a crude suspension system using rubberised castors, springs and foam lying around, using plywood, some bolts and washers did appear doable.
Proving Principle Prototyping
One of the product design specifications was the dolly/trolley needs to be able to be folded down to be taken on public transport or a small car to be taken to a location. Experiments to work out the mechanics of this were done using Lego Technic.
The primary purpose of the film dolly was to dampen the effects of an uneven surface and human movement to create smooth straight line or curved movement in the camera. This was to be done with a cheap and budget suspension system using items around the home where possibly minimising purchases.
I had 4 casters from an old damaged office chair, some springs and various pieces of foam from packaging and prop making.
100mm elastic bands were purchased to form tires on the hard plastic casters. This would not only dampen minute imperfections in the ground surface, it would also act as grip and sound damping.
The casters were to be connected to the base of the trolley on sprung plungers held in a shaft to prevent buckling and hold it in the X-Y axis. The spring was to absorb much of the vibration and movement in the Z-axis. In addition to the spring plunger the caster is backed with soft foam above and behind the caster wheel. This is to be encased that supports the foam and spring system, making sure the caster wheel is held in place. The top of the plunger is held in place with a holding pin inserted from the front.
The caster casing also holds swinging break arms on the outside. In the bottom picture the breaks are held in the off position. These also used the rubber bands on the break arms.
Thus each when unit operates independently where the wheel unit casing is bolted to the base of the trolley while the caster wheel is connected via the springs and foam.
This is further boosted by the soft foam block shoes the tripod legs will be fitted into.