Category: 2012

System Building turned on its head!

It’s no secret that one of my favourite television programmes is “Grand Designs”. My favourite episode is “Ben Law’s house in the woods”. If you are not in the UK, then this may not make that much sense to you.

It’s also no secret that, as an engineer, I like system built construction, but I don’t particularly like system built houses. So far, the ones on “Grand Designs” which have impressed me are: “The Huf House” (http://www.huf-haus.com/en/home.html) and “The ADApta-house” (http://www.adaptahaus.co.uk/).  After last night’s new episode (19thSeptember 2012 on UK Channel 4) I need to add another one. I’m afraid I don’t know the name of the system yet, but I’m going to find out. I also don’t usually enthuse about television programmes, but this one is worth watching, even if you don’t particularly like Grand Designs and Kevin McCloud (http://www.channel4.com/programmes/grand-designs/4od).

Description

If you haven’t seen it yet, here’s my summary and thoughts:
The clients are a pair of lady university professors in a civil partnership. They’re obviously approaching retirement. What is admirable is that they decided to act as patrons to a small industrial design firm with a big idea. I don’t especially like the house, but I do like the method of construction. The house is very “Modernist” and the method of construction suits that kind of design. The method reminds me, very much, of techniques suggested for constructing things on the Moon or Mars!
The designers had a “big” idea, but had never built a house before. This was going to be their prototype. The deal that the clients and the designer had was that the clients paid for the construction, but the “thinking” and “error-fixing” was done for free by the design team. The design team did the construction themselves. The site was awash with degrees of various kinds, and lots of enthusiasm.
Most system-building relies on using standard modules which are constructed off-site. Often this means “the bigger the better”. That way most of the work is done in the controlled environment of the factory and all that happens on site is the final assembly of the modules. In many cases the modules are fully fitted out before they leave the factory. Great on site, but it does mean that the client has to make all the decisions before construction starts and that may be months in advance.
This new technique stands all this on its head (or “inside out”, or whatever metaphor you like). Everything is made on site!
Let me describe the process for this particular house.
The foundations were screw-piles, topped by an engineered wood framework (timber “I” beams) and a plywood base floor. So far, so ordinary.
The “factory” arrived at site inside a steel container with a drop-down side. All it needed to get going was some concrete slabs to stand on and an electricity supply. Even that could have been a mobile generator.
The raw material was sheets of 8×4 construction plywood. The house was built of semi-standard modules. The factory used a computer controlled milling cutter to cut a sheet into the components for an enclosed box. The box was assembled by the workers as the components were finished. It typically took 4 minutes (give or take) to assemble a box and fasten it together with a nail gun. Each box was (usually) constructed from a single sheet of ply and was therefore of such as size and weight as to be easily handled by 2 people.
Once a box was completed it was carried to the house and fastened into place. Each box is numbered by the mill (number routed into the surface) and manufactured as it is required. The assembly drawings tell the workers where it has to go. The boxes were fastened together using wooden staples made by the mill, from the same plywood sheet as the box components.
This was a two storey building, and once the shell was finished, it was roofed, rendered and clad fairly conventionally.  Plumbing and electrical first fix was done conventionally but made very convenient by having the routing for the services built into the boxes. Windows and doors are subcontracted and fitted into openings built into the shell. Once the building is watertight and secure the boxes are filled with blown recycled newspaper insulation (so that’s a foot of insulation on all walls, and the floor and (I think) the roof).
The show followed the standard Grand Designs format and identified problems on the way through, but actually, especially considering it was such an experimental construction method I didn’t see that many.

Problems and Vulnerabilities:

Like all building using precision, factory built, components, you are very dependent on the quality of the foundations and initial setting out. It has to be square and level because there is no opportunity to adjust things later. This wasn’t a problem on this occasion because whoever did the groundwork knew what they were doing (probably not the designers of the house).
Before the first floor was up there was some heavy rain and the designers were concerned that the dampness might mess up the dimensions of the boxes. It doesn’t seem to have been a problem in practice.
On the ground floor, the modules turned out to be “a bit of a tight fit” in places. This was because the designer had not allowed for a proper fitting clearance. It wasn’t too severe a problem, and was rectified for the first floor by an adjustment to the cutting design. Probably achieved by a single parameter being adjusted, or alternatively, by re-dimensioning the first floor boxes (if done that way, it probably turned into an all-nighter, which we didn’t see).
The windows were a perfect fit in their allotted places, but the client didn’t like the proposed fastening method. Actually, neither did I; screwing through the frames even when the screw heads are covered with caps, seems a bit crude for such a high spec building. The alternative (much better) involved hidden brackets, and required some manual chiselling to make rebates for the brackets. The designer said he would adopt the new attachment method for future buildings and the rebates would be routed into the components by the factory.
The flat roof didn’t have quite the correct fall to drain properly. The additional drain had to be modified to satisfy the building inspector that it had sufficient capacity. Once again, this was a problem with experience and detailing, and the solution has now been accepted into the design parameters used by the designer.
One of the clients fitted the blanking plates for the holes used to install the insulation herself. She said they were too tight a fit. Again, a detailing and dimensioning problem with can be solved for future constructions.
The clients felt that at times the designer took too much control of the design. They said that they felt “they should have been more assertive” at times. They also said that they felt that part of the deal was to give over some control to the designer, and that they were entirely happy with the result. This seems to have been a good client/patron, maker relationship.
The project ran slightly over budget (15% ?), but don’t they all?

Strengths

  • What I like about this method is the way that everything is made on site. There is considerable flexibility.
  • It seems to mix good bits from traditional building: first fix and fitting out on site, inside a weather-tight shell.
  • The client is not committed to anything until the actual cutting starts. I wouldn’t recommend making changes at the last minute, but they would be possible.
  • The client is not committed to decorative finishes until the shell is up and they can walk around it. This solves the problem of people visualising spaces. It also creates the possibility of adjusting the finish to suit the budget.
  • Stock and material control is easier. There is one main material: sheets of 8×4 ply. Building component boxes (which do not have to be all the same) are made as they are required. The bill of materials from the design program (don’t know what it was) handles the quantities required. Made components are numbered by the factory to match the construction drawings, so identification should be straight forward (no looking for “right handed hoople-grommet”) and components are constructed just before they are needed for construction, so there is no stock-yard to search through.
  • The “factory” is just the contents of the shipping container, plus a covered assembly area on site. No need to pay for the costs of a large factory area when it isn’t working.

 

Limitations

  • The method lends itself to boxy “modernist” construction. All right if you like that sort of thing.
  • I suspect that the 8×4 sheet imposes some limitations, like the maximum height of ceilings (think about it). Even this can probably be got round, with imagination. Similarly, total number of storeys may be limited. None of this is at all serious. I would regard it mainly as “characteristics” of the method and the material.
  • It is probably easiest if the factory is building parts for one building at a time. That may represent a limitation on “utilisation efficiency”, but frankly I don’t see it as too serious. If you have two or more buildings on the same site (they don’t have to be identical, just make them in sequence, and maybe move the factory to each one as you build it).

 

Overall

 I like it! I may not like the product, but the clients did, and that is what matters. I can see this carving a niche for itself. Similarly, I think the idea of moving the precision factory onto the site, making custom components just-in-time and then assembling them as required is very interesting. The added-value chain might be interesting too (sheet of ply, component box, house shell, finished house etc).

I’ve just been racing a tractor pulling a slurry tank

(Thursday 13th September 2012 Signed on 17:39)

It all happens where I live. I really have been racing a tractor pulling a slurry tank this afternoon and I’ve been to the Garda station.
Let’s start with the tanker: the house where we live has a septic tank. The Irish Government have decided to comply with European regulations and have all septic tanks inspected. My septic tank is registered, but there have been lots of complaints in the press about the process. Many people view it as a “tax on rural Ireland”. They’re probably right but I believe in “render onto Caesar that which is Caesar’s”, so I registered early and will be helpful to whoever turns up to do the inspection.
With any kind of inspection or examination one always has concern that something bad will be found. In this case that might mean a new septic tank, which would be enormously disruptive and very expensive. If something nasty is going to happen, I would rather find out sooner than later, so I arranged to have my tank emptied and at the same time asked the fellow emptying it whether he thought it would pass.
I found two suppliers who empty septic tanks. Both offered good service (registered, etc) so naturally I chose the one which was slightly cheaper. I will comment, that it may be a dirty business but the people in it seem to be very easy and pleasant to deal with. I arranged for him to call at my house in the early evening, and to ring my mobile when he was on his way.
I had to collect my daughters from their school just before 4 o’clock and on the way home I dropped into the supermarket to buy a packet of cereal that I had overlooked in today’s shop. While I was in the check-out queue my phone rang. I could see from the display that it was the septic-tank man, but I couldn’t hear what he was saying. Hoping that I was saying the right thing, I said that I was on my way home and that he should proceed there.
On the way home, on the way out of the town I drive through a tee junction (in front of the library for anyone who knows). As I  was in the traffic queue I saw an enormous 4 wheel drive tractor, pulling a proportionately large slurry tank crossing the “tee”. I said to my daughters, “I bet that is our slurry tanker”. They agreed, but we couldn’t be sure, and there was nothing practical we could do about it in any case, because we were waiting in traffic.
When we turned into our road (a long, winding country road), the tractor was nowhere in sight, but soon enough we caught up with the queue of traffic which had accumulated behind it. I was now “racing a tractor pulling a slurry tank”.  Fortunately he pulled over to let the traffic clear and to get his bearings before he reached my house, so I was able to overtake him and pull into my drive.
The driver was extremely skilful. Backing the tractor into my driveway and then around the corner of the house was like threading a needle.
The actual emptying was done quickly and efficiently. The driver said that the tank needed emptying and I would see that there was large proportion of solids in the stuff that he was pumping out. Yuck!
As he was leaving I noticed something lying in my front garden. I thought it might be his, so I walked over to it, picked it up and waved at him. The thing I had picked it up was a brown ladies’ handbag which had been discarded in my front garden. I realised that it might from a robbery of some sort. There was nothing to be done about my having picked it up, so I dropped it in a plastic carrier and took it to the Garda Station. The Garda looked at it, inspected the contents: a recipe, a cigarette lighter, a receipt and two Mass cards (For anyone who doesn’t know, a Mass card is printed to commemorate someone’s funeral).  I hadn’t noticed the Mass Cards, but the Garda seemed to think that they suggested that the bag belonged to someone local. The receipt was from a local supermarket (actually the one where I had bought the cereal just a short time before, and had the “Rewards Card” number on it, so it should be easy for the Supermarket to identify the bag’s owner for the Gardai. I left my name, address and phone number and went on my way.
(Signed off 19:13 800 Words, a little over 1 page)

Priorities: Important versus Urgent

Recently, an acquaintance sent me a note in which he referred to “The Seven Habits of Highly Effective People” by Stephen R. Covey. One habit he thought was particularly useful was: “Doing ‘Important, Non-Urgent’ things ahead of ‘Non-important, Urgent’ things”. This prompted me to think more about this suggestion. I think it is a good one, and it appears in different guises in different places.

We are all guilty of doing the “urgent” but ignoring the “important”.

Different people live their lives in different ways. Some people, procrastinate to such a degree that they never do anything, important or un-important, until it has become extremely (maybe even, frighteningly, urgent). Then, galvanised by fear, they race  to complete whatever it is. Once they have done the task they heave a sigh of relief and subside into inactivity again, until the next crisis. These poor souls exist in states of worry (about what they should be doing), fear (about what they haven’t done), and exhaustion (having forced themselves to do it). Very rarely do they enjoy peace, or the satisfaction of a job well done. I do not recommend this as a way of living.

The difference between “Important” and “Urgent” is crucial. Importance may come from within, or without. Most urgency comes from the outside. It is important to establish ones own priorities. We may not always get our way and we may sometimes choose to do things which we do not consider important, but if we have priorities, we can always return to them.

A final thought is to look for activities which create more options for the future. Which make us stronger, which allow us to deal with everyday tasks more effectively and allow us more energy and time to deal with the important things.

Talking with blokes in pubs – 3d Printing

OK, so one of my hobbies is “going to the pub”. As I happen to be on holiday, and living less than 100 yards from a pub (well, really a hotel bar) then it is natural that I have been in there a few times. It’s also natural that I should make the place my “last port of call” before going home to bed. Go out, visit a pub (or two) in the town, drop in at on the way home. As a result, I’ve become friendly with the owner, and a couple of the regulars.
I knew that one of these “regulars” knew something about software and engineering and was from the North-East of England, where I worked a long time ago. I thought that he was in Fife on business. It turns out that he lives there. He works nearby for a company that makes surgical devices among other things. He also makes a lot of use of 3d scanners, printers and CAD (Autocad, Solidworks and others).

He told me a number of things that I did not know about 3d printing. Here we go:

  • 3d printed ABS (I think that is what he said) are approximately 80% of the strength of injection moulded parts.
  • 3d objects can now be scanned accurately with hand-held scanners, rather than a turntable scanner. Presumably some clever software compensates for the operator not holding the scanner steady. 
  • The accuracy of scanning and printing is now about 0.1mm, which is adequate for surfaces which are not touching other things or are going to be machined. 
  • Shapes which would be unstable during construction (for example, large overhangs) can be made by constructing in two materials. One material (which he said was like “sugar glass”) is used as scaffolding to support the real material and then dissolved away. This is rather like “Lost wax” or “Investment casting”, except that the temporary material is around the shape being made, rather than part of it.
  • This technique can also be used for making parts which are going to interconnect, could be moving parts. You design them, then interconnect the 3d models, and then use the filler material to fill the gap between the interconnecting parts. Finally, when the parts are finished, you dissolve away the filler and, “hey presto” the two parts are connected or interconnected. No further assembly is required!
  • Finally he told me a little about commercial 3d printers.

I’m going to try and “bump into him” next week. I’d like to add him to my list of contacts.

Laundry, sightseeing in the mist, and a change in the weather

Today we went to a launderette to do a week’s laundry. We went to Rosyth as there is not washing machine in the cottage. I found out later that one of the dry cleaning shops in Burntisland takes in service washes. The sat-nav made finding the place again a piece of cake.

The laundry took a little time, and while it was finishing we had lunch in a little cafe. Noreen was a bit dubious about it, but I thought it was pretty reasonable for the kind of place that it was.

I asked Noreen where she wanted to go. She didn’t know, so I suggested going to look at the Forth (railway) Bridge. Initially I said “South Queensferry” but then changed my mind to “North”. We found it without any difficulty. The bridge is impressive, but was concealed by the “Harr” (sea mist). At this time of year the harr feels strange. Not cold as you would expect, but warm and damp at the same time. To me it felt a little like being in a luke-warm turkish bath. Quite suddenly the mist started to clear, and we could see the top of the bridge structure.

Since returning home I have been to town and back, prepared tea (poached egg on toast, followed by a doughnut) and tea has been eaten. In the meanwhile the weather has turned quite nice. Both the sky and sea are blue. It’s nice and warm.