fowler a7 2" scale traction engine steam mikes models

Having reviewed all the work undertaken to date on the Fowler traction engine (from castings
available from MJ Engineering - see links page) I seemed to have missed some important early
work. Therefore my action plan to continue the build is to go back to the start and complete the
missing links. This involves the making of the dummy manhole which will then be soft soldered
to the boiler itself.

The starting place is a a simple gunmetal casting (see the gallery below) which has two
brass/bronze studs, tapped 4BA. Upon these studs two clamps are bolted. These clamps are
made from 1/8th" plate and a BMS rod is turned and drilled to fit the stud.

The first attempt at making the clamps was by making a template and then cutting it out.
The first attempt was made using the Proxxon bandsaw but due to the thickness of the
metal it was very slow progress. I then remembered the beneifits of chain drilling, and the
task was done. It then remained to file the part to shape. However before putting too
much effort into the making of the clamp, I considered if there may be another way.

On reflection I considered using the rotary table to machine the top and bottom curves,
then milling the ends to shape. After drawing out the curves and dimensions it seemed this
would be a possible solution, so the first attempt was ended.

After sourcing some 1/8th" plate from the scrap box the markings required were then
transferred to the plate. The rotary table was secured to the table of the mill and a centre
was placed in the rotary table. Using the 'ruler' method the centre point of the rotary table
was found. Put simply, the ruler is gently trapped between the mill and the centre on the
table. If it is out of position the ruler will not be square too in both planes. By simply
moving the x and y axis until it is level, the centre is found. Next the position is recorded
by zeroing the digital readouts.

Once this position is secured, the punched hole for the top curve is placed centred. From
this position it is a simple task to move the radius dimension required. Taking a very light
cut first to see if the milled path runs true to the marked line, it was then a case of taking
light cuts with a small slot drill, until the cut is completed.

The next curve was measured out and again a practice cut made but it was wrong! I had
forgotten that the second centre punched hole should be located in the central position
and once the clamps were removed and the piece located correctly, then the correct
curve was made. It only remained for the two edge cuts to be made to complete the part.
The second was then completed in a much shorter time!

The next parts to finish will be two studs and two central round parts that will be soldered
on to the clamps.......more to follow........

Session2 17/08/2008

Today I took a long time to achive a relatively simple task! I needed to cut a slot in two
rods. My first attempt was to use slitting saws but because of the thickness it was
unsuccesful. I then considered cutting them with a hacksaw, then chain drilling and filing
the slots. So a cup of tea and a think revealed the most sensible way.....Good old
Tetley......Why not mill the slots? It was then a false start because my first set up with the
rotary table, I used the chuck holding the turned bar. The difficulty though was the 1/8th
end mill(didn't have a slot drill small enough) wasn't long enough without fouling the chuck.

It was then a case of changing the chuck to the Myford ER25 chuck adaptor made for
the ML10. This allowed for the correct clearance so it was full steam ahead at
last.......Well it was slow steam ahead as the cuts were very small until a channel was
made then they could be increased, but not by much. However it did produce what was
needed and I was quite pleased with the results. It does show however, that a simple
thing such as this dummy manhole plate can be very time consuming, especially for a
novice! It does add to experience I suppose and perhaps next time I will come up with
the solution sooner. I hope so.

Once the two barrels and the two clamps were made they needed to be silver soldered
together. To start I cleaned up the four parts with emery tape, then degreeser. After that it
was a case of mixing up some Easyflow flux powder and coating the parts to be joined.

I then cut some lengths of silver solder rod to size and placed them alongside the joins.
After heating the surrounding metal to cherry red the solder then flowed into the joins.
After turning the part over, fluxed sections of rod were placed on the other joins and the
heating resumed.

The next stage was to put the two newly soldered clamps into the pickling solution (citirc
acid) for thirty minutes before washing in clean water. Then over to the rotary wire brush
to clean up the clamps.

Thats were we are. The next job will be to drill out the central hole in each clamp, then
make the studs to tap into the casting, which has yet to be properly cleaned up.

All this work for a "dummy" boiler manhole...........but it is fun!