Ok.
nearly there now with a quick re-cap.....please refer to the AM2 picture at the top of this thread
i have done a 10mm dog leg, the first bend at the top where it turns left. I have also done the second bend so the tube now turns out towards the light.
this is a common question from my students....."how do i make it
exactly the right length alan?" When i show them there is a look of amazement around the workshop, but with a tinge of embarrassment. This is how you do it....the "magic" measurement here is 16mm, which is the length of a thread. ( it goes therefore that a coupling must be 32mm)
take a measurement from the back wall to the face of the fitting. i will make one up of 400mm. now lay the tube up against a wall or straight edge and take a measurement from the wall of 394mm. remember the conduit is not lying against the wall, it is held off by the depth of a saddle which is 6mm.
Stage 1 Get your hacksaw and put a scar in the tube on that 394mm mark
Stage 2 Carefully hold the coupling round the back of the tube and mark the tube like me, this being the inside mark. This one is vital, as you will see shortly
Stage 3 Now you should have two marks on the tube, the distance between these being the length of a coupling. next you get your saw and cut, by eye between the two marks. Here i have nearly gone through to complete the cut. that black mark on the right is the 394mm mark
Stage 4 Right, nearly there now! you get your compound and stock/die on the job and keep threading till
three full threads are sticking out the back like this....
when you spin off the stock you should be confronted with this sight, and then it should all become obvious where we are heading with this exercise...
Stage 5 now all you do is screw on the coupling and tighten it to that little scar you did earlier and voila!
It has to be right
As i said at the top clever but simple!
At this stage now the conduit should pop straight in on your AM2 and the bushes should engage without any effort....
When I did the AM2 trailer job that is pictured at the top of this thread, there were all identical bays...i measured one and made 6 and they all fitted
the man who taught me this spent a few years as the chief electrician on the QE2 and later was a tutor at that norweb training school i had to go to.
he always stated that conduit installations should be to a tolerance of +/- 1mm as this is the width of a hacksaw blade.
to the OP i say practice and confidence makes perfect.
