Using 3D printers

Produced By- Dave White. Head of D&T Clevedon School

How it works Mix together vinegar (acetic acid) and sodium bicarbonate (baking

soda/powder) and you get a reaction.

It is a neutralisation (acid - base) reaction. Sodium Bicarbonate (baking soda) is a base, it reacts with the acetic acid (vinegar) to produce water (H2O) and Sodium Acetate. In the process it also evolves CO2 (carbon dioxide) as a product.

CH3COOH (acetic acid) + NaHCO3 (sodium bicarbonate) -> NaCH3COO- (sodium acetate) + H2CO3

The H2CO3 is not stable and breaks down quickly to form water and Carbon dioxide: (H2CO3 -> H2O + CO2).

It’s the CO2 we’re interested in!

Information about sodium bicarbonate http://en.wikipedia.org/wiki/Sodium_bicarbonate

Information about vinegar http://en.wikipedia.org/wiki/VinegarOK, so this one works slightly differently

Under pressure Well that’s the theory- but you can have fun with

the CO2 that is produced. If you mix the sodium bicarbonate and vinegar in

a sealed container (NEVER a glass one) you can generate quite a lot of pressure.

If the pressure is released quickly then quite a lot of force can be generated…. Try it for yourself by mixing sodium bicarbonate and vinegar in an old 35mm film case and popping on the lid. Don’t forget to stand back!

Releasing the pressure in a controlled way means that you can use the force to propel a simple rocket

5, 4, 3, 2, 1, Blast off! Here is a design for just such

a rocket by “tastybento” which can be found on Thingiversehttp://www.thingiverse.com/thing:3327

It’s quite an ambitious print but after some experience you should be able to manage.

Parts There are two parts to this

design. The rocket itself and a base.

The clever part of the design is that vinegar is put into the rocket and the sodium bicarbonate into the base. Push the two parts together, shake, place on the ground and stand back.

Design your own If you are proficient at using 3D design software why

not have a go at designing your own rocket?

Things to think about….

How to keep the weight down

The volume of the rocket and base

How to build pressure and release it

Size and shape of the fins

Aerodynamics

Perhaps not so good!

Safety Ok, so it’s only vinegar and sodium

bicarbonate… what’s so dangerous about that?

Vinegar is acid and it will splash about… probably not really dangerous but you certainly don’t want to get it in your eyes. Safety goggles/glasses are a good idea.

Don’t spoil your best clothes… wear something old.

Don’t stand over the rocket… a sharp smack in the face (or in the eyes) is not pleasant.

Keep young children away. Above all do your own RISK ASSESSMENT.

Maybe this is going too far?

Credits Thanks to “tastybento” for the ideas and designs that

he posted onto Thingiverse. http://www.thingiverse.com/thing:3327

Thanks to the other guys on Thingiverse whose designs I have borrowed.

Links, pictures etc…. Wikipedia and others… thanks.