but that's another story..... I think we tried every tool shop in Amposta to try to find a simple £5 immersion heater spanner....!
Ahh yesYes, to include a very large expensive slip-ring water pump pliers, for removing immersion heating elements
Like you, I'm hoping to be out there from the second week in June.
Yes please, John
Chapter 2
Joining the Material
OK so lets look at the easy bit first – back welding. That means the whole joint is made on the back of the material. With this type of joint, the extruded material is designed to give a perfect finish on to top side whilst being welded underneath.
Trakmark supply their material in a range of colours and plank sizes with the inter plank caulking already moulded into the extrusion. When making a panel you are most likely to use the “double plank” extrusion. Like in this pic.
Most of the time, planks are joined by welding a 5mm plastic flexible rod onto the back of each joint. Trakmark’s double plank extrusion forms a “V” groove where two double planks are joined. See in this pic:-
To weld two planks together, you heat up the groove that is formed between the planks and at the same time run hot plastic weld rod into the groove. The idea is to melt the plastic so that the planks and the weld rod fuse together without burning through the material.
To do this a hot air welding gun is used. This is mine.
Manually, that would be quite difficult to get right for large areas so a “Speed Nozzle” is used on the welding gun. A speed nozzle looks like this:-
As you would expect, just holding one piece against another and welding won’t work. Before welding I found that it is crucial to squeeze the two planks together so that they are tight enough together that you can’t see any gap. Also, each plank needs to be clamped down tightly to a flat surface before any welding can take place. To do this Trakmark suggested some tools.
A Good Working Surface
Firstly a large flat white base board. Something like Contiboard. I used a couple of sheets of 18mm MDF and stuck some white Formica to them. The base board needs to be white so that you can see any gaps when you place the two Trakmark planks together. I put my working boards onto some old trestle tables that I have so that everything is at a good working height. I suppose you could do it on the floor but I prefer to stand whilst welding.
Weights
I can’t emphasise just how important is it to have lots of weights available. In their workshop, Trakmark use lots of approx 150mm x approx 10mm x approx 75mm mild steel plates joined together in threes. They use these to hold the material down whilst welding.
These are Trakmark’s weights
I chose to make some weights that I could also use when installing the teak onto the boat later. I made mine from some mild steel 40mm x 80mm x square section tube that I cut into 150mm lengths and filled with lead.
These are my weights – I made about 28 of them.
The idea is that you put these weights either side of the groove that you are going to weld. But if you did that, you wouldn’t be able to get the welder into the groove to make the weld. The solution is a tool like this:-
Trakmark now supply these but I made mine from the same components that they use.
Hot Air Gun
Synthetic teak is quite rigid until you get it hot. All you need is a cheap “paint stripper” type hot air gun. I bought this for about 10 quid from Screwfix.
Finally, before I show you how to make the weld, I want to add a little technique that helps me. I also have some 30mm x 4mm x 150mm long mild steel plates that I lay on their side to keep the welded joint tight down to Working Surface.
The following pics show how each joint is assembled before welding.
The Work Table
The joint ready for welding
In this pic you can see my addition of the small steel plates to keep the joint in place.
The Welding Process
Remember, this is how I’ve learned to do the process. There are probably better techniques out there and people who do this every day probably have better methods.
Firstly, I heat the joint using the “pain stripper” heat gun – backwards and forwards a few times.
Then I run a screw driver down the joint to ensure that both surfaces are laying flat on the white surface. I then double check that there are no white bits showing through the joint from below. Then I start the welder, feed some welding rod into the speed nozzle and slowly draw the welder along the joint being careful to make sure that the welder melts the plastic without burning a hole through. You have to push quite hard on the joint with the welder to force the heated weld rod into the joint. Without all the weights holding the joint together the force of the welding process would move the material apart.
Here is a video of the whole process.
In a perfect joint, the weld rod will end up flush with the back surface of the plank. But in the real world, you may have to trim it off to help the joint lay flat when it is the correct way up.
So to finish this post, here is the final result of the weld in the above video.
and when turned over it looked like this
So thats how the bulk of the joints are made – back welding.
The more complicated jointing (top welding etc) will follow in subsequent posts.
I did most of my welding during the winter in my garage in the UK but we had to finish some of it on site. Done during lock down whilst we were stuck in Spain!!!
In the March sunshine – nobody else in the marina – we had the place to ourselves.
I didn't post any pics of the templating process.
Congratulations John
