There were a number of things that needed to be done: the whole head/neck assembly tended to point too steeply downwards, the jaws were originally cut out very quickly and were thus a bit rough and the ‘kinked’ neck strut had snapped….The following is a report on how these have been remedied.
The broken kinked strut is shown below.
A new strut was made using welding rod and electical eyelets.
I then made a longer aluminium bar to link the head to the red horizontal neck section with a bend which would make the head agle less steep. I also smothed the rough edges of the black jaws.
Modified head and neck section shown below.
Next task is to replace the 200:1 motor/gearbox that drives the head & neck with a 120:1 version to speed it up.
Modifying the smallest prototype Techno-saurus (the ‘baby’): removing the worm and wheel drive and replacing it with a simple crank with a slip-clutch.
The head and neck lunges backwards and forwards and this causes the mouth to bite as can be seen below.
This is achieved using a worm-and-wheel drive mechanism.
It’s fast and effective but the worm and wheel gears tend to chew themselves up very quickly.
It was decided to use a crank mechanism instead and with a built-in slip clutch similar to that used for the rotating claws.
The first step was to dismantle the above drive system:
Next a motor mounting plate was made:
The 200:1 motor/gearbox was attached beneath this:
The crank spindle was then attached to the motor spindle:
A crank wheel was made with a slot and slip-adjustment clamp that would provide the slip clutch function (and thus protecting the gearbox under excessive loading).
This was then attached to the crank spindle and secured with a split pin. A a crank pin was attached to drive the con-rod (M4 machine screw -actually attached before assembling as shown below).
A connecting rod was made and attached.
The finished crank design…
This can be seen in action below…..
It works but compared to the video at the top of this post it is too slow. This is due to the gearbox ratio being 200:1 which is perfect for the rotating claws but a bit slow for the lunging and biting mechanism. Because it’s slow, there is not the same kind of dynamic effect on the whole device which made it more life-like. I’ll change the motor/gearbox asap.
