Against the Clock

As an avid racing cyclist, pitting yourself against the clock is nothing unusual in a time trial.

So what better way to portray time than with a cyclist.

In this project I will create an animated cyclist representing the passage of time.

The will be accomplished using a combination of 3d printing and manual machining.

The timing and control for the animated clock will be accomplish using in the main a previous Instructable.

Micro Binary Clock

With some modifications these being the RTC and the motor controller.

Downloads

TT_clock.mp4

Supplies

Perspex sheet 160mm * 205mm * 5mm - Black

Perspex sheet 75mm * 150mm * 5mm - White

3D Printer

BlocksCAD

Cura

Microbit

Kitronik All-in-one Robotics Board for BBC Micro:bit or similar

Adafruit DS3231 or similar

28BYJ-48 5V stepper motor or similar - Qty 2

Servo Motor 5V or similar.

MF52ZZ 2x6x2.3mm - Qty 8

M3/10mm though hole threaded stand off. - Qty 19

M3/15mm though hole threaded stand off. - Qty 2

Aluminium sheet 6.5mm * 17mm * 1.5mm

Drill bit 6mm

Drill Bit 3mm

Drill Bit 10mm

M3/10mm bolts - Qty 26

LEGO cross axle 55mm min

LEGO cross axle 23mm

Cyclist Design

The cyclist will be 3d printed and was designed using BlocksCAD.

The main moving parts will be the legs and these will pivot at the hips and the knee.

Rather than creating a separate pedal, the foot became the pivot point with the crank reducing the component count.

However as a result the Q factor or 'stance width' needed to be taken account by a spacer between the foot and the crank. This was integrated within the crank.

The hips would be an anchor point for the cyclist in addition to the hand.

The distance from the hips to the toe needs to be such that the leg is not totally straight at dead bottom centre allowing the leg to retract on the upstroke to stop the leg locking out.

Too long a crank will cause the leg to lock out, you will often see this on real cyclist thereby they rock their hips to compensate for the extra length.

Short cranks in this model being less of a problem.

As should be the case in a real time trial situation the upper torso will be static adopting a aero tuck resting on the forearms.

For simplicity there will be no bicycle but this will be accounted for by the riders body position and the wheels.

The wheels will have only one spoke each these represent the hands on the clock the rear representing hours and the front representing the minutes.

The pedals will be connected to a chain ring in this case via a LEGO cog and this in turn will be driven by a larger LEGO cog this in turn will be driven by a motor. 3d printed cogs are included with the design if LEGO cogs are not available but being the same size requires moving the motor up to remove the gap.

You will however, need a cross locating axle or drill this out for a round axle.

Therefore, as the cogs rotate the chainring and foot will rotate around turning the legs.

Everything, is mounted on a single sheet of Perspex forming the background and the support for all the pieces.

The files for the cyclist and wheel hands can be found here:

YouMagine – Against the Clock by chris – YouMagine 🎨

Support Board

Again this was designed using BlocksCAD being a template for the holes.

Therefore, the fact that this board is smaller (top and right edge), than the final support board is not an issue.

The left hand corner is the reference.

This variation of the template is due to the completed board being larger than my 3D printers build area.

It also enabled adjustment during the pre-fit to save wasting a Perspex sheet.

Having done the pre-fit any measurement adjustments were fed back into the template.

A couple of slots were included into which feet would be fitted later, this is a 68mm Perspex circle cut in half and slotted to fit in the support board.

Cyclist Build

Once printed and removed from the brim and trimming applied the pieces were assembled.

Starting with the arms these are attached to the outer torso at the shoulder with a M2.5/18mm bolt this lines up with a similar positioned hole in the central torso so a small protrusion will anchor this the hole are counter sunk to keep the torso elements flush together.

There is a left and right outer torso.

The central torso with the head and helmet is sandwiched in the middle.

To lock this all together a bolt M2.5/18mm bolt towards the hips is is attached.

That's the body complete.

Next the legs.

In order to improve the fluidity of movement and reduce friction the pivot points for the foot and knee uses sealed bearings.

These are a press fit into the outer surfaces of each of these two pivot points.

Using M2.5/10mm bolts with locking nuts and spacing between the centre taken up by adding nuts to the section of the bolt that sits inside the crank foot pivot point to reduce rocking.

Tighten the nut/bolt just enough to allow the joint to swing freely.

The process is repeated for both legs.

This is locked to the support board with two spaces fitted front and back both with cross fixings to prevent lateral movement on a long LEGO cross axle.

Next the left outer torso section the central torso followed by the right outer torso element and a space..

This is held together with a long LEGO cross axle which mates with the outer hip

Initial print colour for the cyclist was grey but for the final figure I added some colour in the form of a yellow jersey, red shorts and grey for the legs and the head/helmet. Optionally, these could have been painted.

Pedal Drive

The cranks are fitted to the bottom bracket and chain ring via a cross axle which passes though a 6mm hole in a thin length of aluminium and a spacer before passing through the left hand crank.

This length of Aluminium is secured to the board by two M3/15mm spacers and the spindle for the motor passes through a 6mm hole to the motor and cog.