Part 10, The next batch!
As the new batch of lower spark plug shields for
the Harley XA are ready and available in the webshop, I continued
with the upper spark plug shields. These are the trickiest to
make. The insulator is bakelite and is surrounded by 2 sheetmetal
parts formed from flat pieces of 0.8 mm stainless steel. The originals
were made of regular steel with Cadmium plating, and have all
desintegrated by now. Then there is a threaded piece where the
cable is attached and 3 tiny pins that clamp to the lower shield... |
While pressing the first stage "bathtubs"
I noticed that it made quite a difference how you position the
tooling in the press, and also that the hydraulic jack was damaging
the bottom of the tooling, so I made an alumium cap that goes
between the jack and the tooling, and also added a recess in the
tooling to that the pressure is always exactyly in the middle.
It may seem a bit over the top but these little things all add
up. Finally I stamped an R (for Rightside) on all 3 parts of the
tooling so now the process is completely repeatable with very
constant results. |
After the pressing of the "bathtubs"
the next step is sanding away the excess material on my recently
modified beltsander. I was busy doing that when after a while
smoke started appearing from the electric motor and it stopped.
I quickly unplugged it but the electromotor was beyond repair.
To avoid this happening again I installed a new motor with a motor
protection switch that will shut it down if it draws too much
current. |
The vertical beltsander has made this a lot easier on my back,
and I have experimented with a little "jig" to hold
the parts being sanded at the correct distance from the sander.
They get pretty hot by the way! I also have a little setup for
quickly drilling the holes in the right place, using part of the
old tooling as a fixture to hold the parts in the right position.
The drill I am using is one with a stepped tip (from Wurth), specially
made for drilling in sheetmetal without grabbing or burring it,
it gives a very smooth result. |
|
