For newcomers - the story so far. Hymer habitation doors are held on by 4 aluminium hinges. Many never have a problem, but it is fair to say that a significant number do. The biggest culprit is the wind catching the door and either slamming it open or shut, and after many years one or more hinges break.
A temporary repair can be effected by using a large washer, but until recently it was easiest just to order spares from Hymer/Brownhills.
Then several years ago the news came out - don't know whether it was true or not, that the hinges were no longer available because the supplier no longer possessed the tooling.
The technical background to this is that in order to produce a hinge with the relatively complex profile of the Hymer one, you use a process called aluminium extrusion. This is where you take a lump of solid machine tool steel and carefully carve it out until you get a hole of the exact same shape as the profile you want - ie hinge shape! Then you harden it in a furnace, and polish it up. Then you mount this special "tool" in a bloody great machine called an extruder which takes lumps of raw aluminium and under huge pressure forced it through the hole in the tool. The pressure is so great that the aluminium becomes plastic and flexible just as it passes through. Then out the other side of the machine pops long lengths of perfectly shaped hinge and all you have to do is to chop it to the right length and insert the steel pins and voila - thousands of little hinges.
This is how aluminium windows are made, and thousands of other everyday objects made from aluminium. The same process is also used to extrude plastics.
The problem is that the tools are very expensive to make - several thousand pounds usually, depending on size and complexity. Usually the cost is borne by the customer, and amortised over the life of the product. So the Hymer people would have projected how many hinges they would need over the life of the design, and divided the cost of the tool by that. Example - £4000 of tooling divided by 10,000 hinges = 40p plus cost of material - probably another 40p, plus labour and overhead say another £1, plus profit and then greedy markup as it goes from manufacturer to Hymer through wholesale and retail and eventually us poor buggers end up paying £20 a hinge!
AND NOW THEY SAY THEY HAVE LOST THE TOOL!! This sounds like it's worse than leaving the baby on the bus, but the reality is that small companies get gobbled up by big ones, things do get lost. Personally, being half engineer myself, I reckon that the original tool was modified to make a different profile, in the mistaken belief that the original tool was obsolete. Or some bloke at Hymer stores had such an enormous bucket of them that they thought bloody hell we'll never shift all these....so they never got re-ordered for many years until slowly but surely us lot used them all up.
So now we are all unhinged ... Hymer understandably don't want to pay out for a new tool because they won't sell enough to cover the cost. They may only sell 1000 over the next 10 years, so using the same formula, That's 40p in tooling, which doesn't sound a lot, but the extruder won't set up the machine for such a small quantity - so the whole job becomes uneconomical.
However it is new news to me from Brownhills that Hymer are maybe going to do something about it - there is a PR element at play as well. So maybe the problem will go away.
Meanwhile, there are other methods of making hinges in smaller quantities, and Peter Curry is looking into this.
My own solution, when my entire door blew off in a sandstorm in the Sahara, and ended up 200 yards away....was to cruise around Moroccan hardware shops until I found a standard steel hinge that did the job. I'll post a photo in a separate post.
