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Demotech News


News Sat Feb 10 (2007) -- Fri Apr 22 (2016)
News Tue Jan 25 (2005) -- Mon Sep 25 (2006)
News Fri Jan 09 (2004) -- Tue Jan 25 (2005)
News Wed Aug 27 (2003) -- Tue Dec 16 (2003)

Welding wood, checking the manual

Thu Aug 14 (2003)

Rogier is now familiar with the technique of welding wood. When I asked him to set up the construction of the new toilet seat, he had no difficulty in selecting the right size nails, width and thickness of sheet metal, and then a good position for the wooden parts to fit nicely together. He does the nailing swiftly, the sheet flows around the wood, and there are no sharp bits sticking out.
Yet this is only the eighth joint he has welded. Does this prove that the system of Welding Wood does what it promises: offering real strength in connections between wooden parts, without the need for professional abilities?
The two interns Leonora and Petz checked it for themselves. They found the welding OK, but had several remarks on the effectiveness of the manual.
I will discuss these with the girls today and make the appropriate changes.

Make it! See it!

Sat Aug 02 (2003)

It seemed the right thing to make the presentations more accessible. So Marc guided me in choosing a good approach for it. The outcome was two menu items which link to the presentations.
Both start-up presentations are now click-able from the menu. Once in 'Make it!' or 'See it!' you can navigate to each presentation.
Specially when working on the presentation of the Bathroom Toilet unit, it became clear that it would take too long to download files as large as this one. So these long presentations will again be split up into chapters. And the first page of each presentation will give the content of the whole.

The sunny side of the NightReader

Fri Aug 01 (2003)

The interns Leonora and Petz now focus on the NightReader. They have another two weeks to go and want to get this design job done. They plan to use their experiences with this design in the presentation they are expected to deliver at their school. However it is still not clear how a number of problems should be solved.
Leonora and Petz discovered two fundamental new approaches for the construction of the box that houses the three batteries of the NightReader. Both ideas help to make the instruction package to make the NightReader thin enough to be sent to users by post in an envelope.
One is to link all parts of the box -if sheet metal is used- with a hinge-like construction so that is is completely collapsible. We have still to explore the possibilities this method offers.
The other approach does away with sheet metal. It makes the box from two layers of cloth, sewn into rectangles made stiff with inserted bits of carton. This approach is promising: easy to make on a sewing machine, looks nice, easy to decorate. But as yet there is no answer to how a number of parts will be joined.
I trust that the continuing experiments, by the two girls, in our sunny garden will provide that answer.

Stills from video

Thu Jul 31 (2003)

Stills are the very few images taken out of the thousands of images that together make a video film. Such stills are just now made accessible in a new presentation on the construction of the BathroomToilet unit.
Some years ago Erik Holthuis has made a video on the actual design of this toilet system for rural use. While I was working on it, thinking, trying out, changing plans and approaches, Erik recorded it on video tape. The one hundred hours of video footage made in this way, Eric and his wife Anneth editted it into a one hour movie on design, called "The Concept". The Concept is a valuable document of how a design grows from idea into reality along thousand of small decisions on construction details and sometimes on the concept as a whole.

Erik and I plan to take some shots out of this movie and put it on this website as a first experiment in using streaming video to clarify our ideas. Many questions have to be answered. Time for download with slow data transfer? The small window of 250 by 250 pixels large enough to see and understand? Very short shots better than pictures with a description? Possible of a kind of slide show of text and images mixed with video?

It is really helpful to be able to rely on the use of high-tech electronic consumer products for Demotech's work. Stills taken from Erik's video recordings are now shown in a set up for a construction manual for the BatroomToilet unit. It took me very long to prepare all the images for it. But they came out in a good enough quality.
When I get some more routine, this way of making presentations holds a promise.

Meeting Hanna

Fri Jul 11 (2003)

Tuesday Hanna Hemmink visited Demotech. Picture Hanna: a Dutch woman deeply involved in rural life in Senegal, engaged in projects to improve life in these rural conditions. She speaks the local language, has lived there a long part of her life, and is now travelling between Senegal, France and Holland while organising support for her project.
Hanna's project concentrates on improving gardening in and around her home village Sangalcam. To this end her project aims at getting more water from existing wells in the area. She works mainly with local means while adding better technology to it. She is currently working on a local project in the area of Sangalcam. The aim of which is to spread better methods of accessing water more effectively and rapidly in rural Senegal.

Hanna already came across the idea of the rope pump many years ago. She got instructions from people of the WOT and had these worked out in in a metal workshop in Senegal, where she knows the people well. Her introduction resulted in many good functioning rope pumps. However, she was not satisfied with the idea of the manually driven rope pump and promoted the use of pedal power. Such pedal driven rope pumps are now produced in that workshop. Now she hopes to introduce real progress in pumping water with the use of solar power. She has got the first one (see picture below) working!

It is a great and inspiring event to meet a person who does the things I am involved in myself, who uses the technology I have taken part in creating, and who wants to move further in the same direction as I want Demotech to move in. I hope she will extend her use of Demotech designs, such as that of the WindDrive, with which she is pictured above.

In order to get more people behind her project, yesterday Hanna made the first steps in the setup of her foundation "ATA, support for rural life in West Africa". As a gesture to express hope on future cooperation Demotech donated our DAF-truck to this new ATA foundation. I hope ATA can use this sturdy truck for the same purpose that Demotech originally intended it for: as a Mobile Training Unit

I was fascinated by the photographs Hanna showed me. They show the rope pump integrated in rural life just as it should be. I hope Hanna allows me to use these pictures for a presentation on Demotech's website.

Deep innovation: long vision, small steps

Thu Jul 10 (2003)

There is plenty progress now with the pulley setup for Senegal. The mockup for the well ring, looking like the one in Senegal, gives inspiration. Rogier and I work on 'welding' the wooden sticks together. Once again the choice for details at the moment of actual making is a different one than what I had in mind only a short time before that. And often the difference is big and consists of real improvement.
It keeps surprising me, that such effective solutions can not be designed beforehand. I really thought I did design an effective solution, but practice offers more, much more. It teaches me what I did overlook and it offers far more opportunities than I could have thought of.
Looking back at the whole process of design for the pulley, I think I was right to be challenged by the worn out locally made pulley, laying useless next to many wells, while for lifting water these pulleys were indispensable. That was four years back in The Gambia
The long vision was:

  • Use locally available stuff to make pulleys in some sort of local craft combined with local trade.
  • Prevent the wearing out that now destroys the pulleys.
  • Produce them in an effective way, easy to learn, easy to accomplish.

    This long vision was -in my expectation- somehow realistic, because of the worn out rubber tires laying around. It seemed probable that the properties of rubber as well as its round shape would offer a starting point.
    Well, it actually did. It did as well offer stiff resistance to let itself shape in something like a pulley. By taking small steps, some progress was gained. What really helped was the interest of Ives Faye for his Keur Moesse project in Senegal. That gave the urgency that I needed to overcome the difficulties I encountered. One of them was bending the rubber in a V-groove like shape and sewing it with bits of wire. An other big obstacle was the way the spokes had to be made. Both problems could not have been overcome in a design made at the very beginning. Only when some of the other problems had found a likely solution, only then these difficult steps could be taken with some result.
    Only when the pulley wheel was introduced in the project in Senegal (Februari this year), only then I got some grip on the problem of mounting the pulley over the well. Again the preliminary ideas of how to solve it with concrete and steel melted away at the moment of having to realize them in practice.
    Though now there is plenty of progress and the present construction looks realistic, there still is al long way to go. First it has to prove to be functional, to give a real good ergonomic working position for lifting water with two bags. I know such a system can be very effective compared to other ways of pumping water from deep wells. The final test can only be done in Senegal, may be in August or September.
    But a harder nut to crack is to create the reserve strength of the supporting construction. The pulley, its axle and the supporting structure have to be strong enough to lift two people out of a well in case of an accident. Such a situation will someday occur. At that time the pulley may not fail to take that load.
    When I set out for the design of the pulley I did not have the slightest idea such a demand would ever be made. But it is also encouraging that this extreme demand can -at the very end- be positively answered.

  • An extra function for the pulley support over a well

    Tue Jul 01 (2003)

    It is high time to create a consistent idea for the set up of the supporting construction for the pulley over the well. It is not so easy, as it has to be rural technology, meaning it has to be made with next to no tools andd very rough materials.
    We do the research in the garden next to our workshop. We made a mockup pf the size and giving the impression of the upper-structure of a well such as at the site of Keur Mousse in Senegal. Experimenting was done by tying bamboo sticks with rubber strips cut from an inner tire.
    Today I worked on an added extra design specification; it should be possible to safely lower and lift a man into and from the well. This puts an extra load on the pulley. But for the construction that supports the pulley over the well, it means it now has to withstand a large force sideways, not only vertical because of the weight of the water. This sideways force is generated when a group of people pull together at the rope away from the well. Such a force is equal to the weight of the person being lifted and should not shift the support itself from the well.
    To get some grip on how to get it right, Rogier and I made three full size models with bamboo sticks tied with rubber. Our final model, a tripod, will Thursday be composed out of sticks, cut from the bush around and put together with the use of "Welding Wood".
    It was high time as well to put the information on the construction of the pulley and the supporting stand on Internet. That is done today as well.

    Old news

    Wed Jun 25 (2003)

    I cleared about three meter archive. Most of it was old administrational stuff and copies of reports that needed not to be kept. They are back in the paper recycling, giving our office some welcome extra space.
    However I also came across many items that I very much liked to see again. One of these items was the front page (sadly only the frontpage!) of a construction manual of the rope pump, such as Valentine Julien and I made, when we still in Ambon after a project on the constructing of wells in Waipia at Ceram/Indonesia. That was back in 1986. Also photographs made in that project of work done on the well cover ring. Pictures from that manual frontpage now help explain how a rope pump can be mounted on the wll cover ring.

    Right now old news is news again. The picture shown here was taken in 1976, showing farmers lifting water from a well with a rope and bucket. Jos Besseling at that time was working on the rope pump in Burkina Faso. He also worked on the manufacring of pulleys to ease the watering of cattle. His approach was different from what we try out now on behalf of the project in Senegal.
    He used a front wheel hub mounted in a disk of hard wood cut to size on a wood lathe. Much water could be lifted from a well using two rubber bags at each end of the rope running over this pulley. His findings in that experiment are very inspiring: the pulley with dubble bag system lift about as much water as the rope pump. Precondition is a good working position for the person pulling the rope.
    A good workng position, that is still lacking for the Senegal project. But not for long! Rogier and I made the first crude version of a support for our version of a pulley. Next week I should be able to report on it with some images.

    Facelift for the Demotech website

    Tue Jun 17 (2003)

    We put more common sense into our home page. It just grew organically. In the beginning I thought it needed an impressive letterhead kind of name to begin with. It took some time to find out this was just a wasting the visitor's attention. Then it took more time to find out how to do it better. The answer: just act functional!
    The menu now is reduced to the bare minimum in height, but located at a place where people will look for it. The name Demotech is still there. Reduced in size, but still making clear this site is Demotech's site and Demotech has something to do with the many pictures and the pump animation. Not hard to get a general impression in a few seconds.
    The width in pixels guaranties it fits well on a 15 inch monitor. The guess is 15 inch monitors is the seize used by our most important clients, the NGO's in Third World countries. There is no need to scroll sideways. A little scrolling up and down helps.

    New, apart from the homepage layout, is "Presentation". Presentation is the database that contains presentations, such as the excursion in pictures in our workshop. More often presentations will be used to create construction manuals such as the WellCover construction manual .What now is visible is just the very beginning. Marc van der Kamp works on integrating and linking "Presentation" with the rest of the database.
    "Presentation" will be used in three different modes:

  • For a sketchy presentation of a recent experiment, meant to keep people informed who somehow participate in that experiment.
  • To show a properly edited version of a construction manual, combining text and illustrations.
  • To make a slideshow to clarify more complex ideas, such as "What is Demotech about". As Demotech's targets are beyond what can be considered 'reasonable', indeed such a presentation better should be clear and impressive.
  • Storing stuff

    Tue Jun 03 (2003)

    Suppport by diagonally placed sticks

    All the stuff we gather in our lives need to be stored, often on shelves. Demotech itself has an enormous mass of small and larger things that has to put away, but have to be within easy reach on the other hand. Such as our book keeping and our kitchen stuff.
    Though we were in dire need of them, in some cases to make shelves proved difficult;

  • Our walls were unreliable to attach something to. They were too soft, or too uneven.
  • To use the floor to stack the shelves on, was unpractical as well. It was not flat, but the real problem: it was not available, as needed for other purposes.
  • Neither offered the ceiling an easy attachment. The beams for the roof were strong enough, but the space between them did seldom match the lengths of the shelves.
    Above conditions also occur in the millions of dwellings in shanty towns, where only the roof beams offer some hold and walls are fully unreliable to fasten anything to. Making this a problem worthwhile to be solved.
  • A frame atteched to the roof beams now take the load

    The way out was to construct a base structure from the ceiling and go from there. Even then we had a long way to go and experimented over the years to find a method, where shelves could be prepared as modular units, to be interconnected by frames, hanging from this base structure attached at the ceiling.

    A problem of stability had to be solved. What hangs down can sway. Shelves with stuff stored on them should not sway. We lined out the spacers between the shelves in a way they all were pulled out of the middle and wanted to sway back, specially when some load was put on the shelves.
    For this reason all shelves want to sway back against the wall, press themselves against the wall, causing this hanging construction to remain fixed in one position.
    Still there was an instability of the shelves to overcome. The lower shelves had the tendency to turn backward over in conditions of load. Our solution for it did not work very well. (first picture). This solution consisted out of sticks diagonally positioned, guiding the load from the front to the wall. It was a messy set up.
    What turns out to works better is to extend the primary frame attached to the ceiling. Now it reaches from one beam to the other, whether these beams run even to the wall or cross wise (lower picture). The trick of the shelves, each swaying back into a stable position, now works well at last.


    News Thu May 22 (2003) -- Mon Mar 17 (2003)
    News Mon Mar 17 (2003) -- Wed Dec 04 (2002)
    News Thu Nov 28 (2002) -- Mon Oct 21 (2002)
    News Fri Oct 11 (2002) -- Tue Aug 27 (2002)
    News Tue Aug 27 (2002) -- Mon Jul 01 (2002)