It is Wedding time again

No no, not for me.
A friend is getting married: the sister of my Mums godson (is there an english word for that? There is none in german :-)
Sister-of-godson is basically family.

Calling for a present

And so it is time to make a wedding present.
Make, not buy – bying is only half as much fun.

Usually the part made is a packaging for another present.
This worked well over a decade ago for Ela and Michi and the version 2 of the Brio-lock packaging was a full success some time ago again with Susanne and Toby as seen on Tobykiste.

This time was a bit different, though, just read on.

For the impatient:
When I tested the opening and closing using the internal mechanism, I did record that with my old Nikon Coopix.
Its not cinema-quality movie, but You'll get the idea of what the box does.

Project start

As in every project, there is the first step: the kick-off.
Here I decided to

Ideas

Next step: analyse the prerequisites and environment.

Using something electronic in a wedding contraption is actually a new idea.
So far I made a point of not using electronics but just electromechnical stuff (switches, relais and motors) in the presents.

This time I wanted to use electronics, probably a microcontroller.

One of my favourite online-shops Pollin (www.pollin.de) had a special recently.

They offered what is known in Germany as a „Nummernschalter“ (if you do understand the buerocratic lingo of Deutsche Bundespost Telecom, that is). The non-initiated German would probably call it a „Wählscheibe“.

Yes, indeed it is an old-fashioned rotary dial from a telephones. The ones offered by Pollin were used units but working fine.

Decoding the output from these is a few lines of code for a microcontroller, so this makes a very nice input device.

I had two of these sitting around for a while and no project to use them on – so this project needed to use one.
When using an input device like a rotary dial it is probably a good idea to use some kind of display as well.
I thought about not using a display since good old telephones did not have one either.

Two reasons made me use an LCD anyway

I had already used LC Displays before, so it should be a no-brainer to use one on this.

I even had a small type lying around. The 2 lines of 16 chars each it shows were a little small in other projects, here it would be perfect.







Other ideas.

I just love modding existing stuff. Preferably stuff people will immediately recognize.
This is usually true for anything Ikea.

Whether you hate Ikea or love it, whether every room in your house/flat/cardboard box hase some Ikea stuff in it or none – you know Ikea.

http://www.ikea.com/de/de/catalog/products/30032387

is one of hte well known products many people immediately recognize as Ike or as Ikea-style.
So it should be a wonderful base for modding.
I simply bought one and then started thinking about what to do with it.

The original idea was to put a motor inside so it would open one drawer (or both) and close it again.


To cut a long story short, I could not figure out a simple but efficient and reliable way of opening and closing a drawer without rendering the other one useless.
Actually I had a couple of ideas but none seemed to fit in the remaining time budget.
Unidirection motion is more simple to create.

So I went for the obvious solution: move one way only and use gravity for the other direction.
I found these sprockets and the chain in the catalogue from www.conrad.de

The chain looks just like a bicycle chain, just much smaller. It is about 6mm wide and the links are also 6mm long.

The sprockets match this, so they can be used to pull the chain or make chain transmissions.

The plywood in between the two drawers of the Mackis thingy is 5,6mm thick. In theory a 6mm wide chain would not fit in there, but actually it does because of the tolarances of the drawers.

Ideas summary

So we have some components and an outline of the overall idea

That is a good start. Looks promising.
So lets make the thing.

Continue