Engines > From Plans
Another Pennsylvania A3 Switcher
matthew-s:
Looks AMAZING! Congrats.
I think you are the first person who I’ve followed to make the box. Looks sharp.
And as far as time consumed …. compared to [ahem] some of us, you are flying!!
Enjoy the journey.
JCvdW:
Thanks Kim and Matthew! It took me close to two years to build the tender, so I guess it will be at least four years or so to build the engine. A box to protect the tender in the mean time is probably not a bad idea.
I made an indirect start on the engine by first making the headlights for the tender and engine. I was wondering how to make the curved aluminium reflector, until I consulted Kim's build. Using pre-calculated X and Z DRO coordinates for a ball nose cutter gave excellent results!
The same technique was used with a 3mm ball nose cutter to round the tops of the top covers, as these will be very visible.
The lenses were made from 1mm thick clear polycarbonate sheet, which I could cut with my CNC router.
Two headlights ready for painting:
I modified the inside of the headlights behind the reflector to make room for a PCB that carries a coin battery, a push button toggle switch and a LED. A small hole on the side of the headlight gives access to the switch with a piece of paperclip wire. No need then to route wires from external batteries and switches.
Here is a 3D model of the layout:
Now I just need to figure out how to layout a PCB. I noticed that Fusion 360 now has an Electronics module...
And then I can start to fill in the bits underneath the engine headlight!
Kim:
That's pretty clever for the headlights! Looking forward to seeing how you workout the PCB and all. Very cool!
Kim
JCvdW:
Thanks Kim. I hope it works out!
The headlight detail provides a nice sense of realism to the tender:
JCvdW:
First order of business on the engine is the main frame. Cold rolled bright mild steel flat bar was milled to size for the side frames. The X-axis travel on my RF-45 clone milling machine was just enough to mill the length of the side frames in one go.
The blanks for the two side frames were then bolted together for all subsequent operations. To avoid tedious hacksawing, the cutouts for the fire grid were drilled out.
Eventually the two side frames, pedestal braces and rear axle boxes were complete!
Due to carelessness, an M2.5 tap broke off on the foot plate. Impossible to remove, the broken tap was drilled out from the opposite side with a 5mm drill. An M6 plug was then made from silver steel (drill rod), screwed into the foot plate with Locktite. I am now wondering if the Locktite will be able to handle the heat of the fire?
A 2mm drill bit was initially used for the M2.5 tapped holes. This was then increased to a 2.1mm drill bit, to reduce the risk of breaking another tap in mild steel. This resulted in much easier tapping!
I also noted that tapping the drill rod was much easier than tapping the cold rolled bright mild steel. This made me realise that I should pay closer attention to the type of steel alloy I am using in general. Softer steels will extend cutting tool life, and cutting tools are getting more expensive by the day. Kozo suggests using brass all over, but it is prohibitively expensive.
Any suggestions re preferred steel alloys to use, will be appreciated.
The M3 holes in the end of the side frames were drilled and tapped on the lathe by clamping the side bars onto the vertical slide mounted on the cross slide.
As always, it took much longer than anticipated, but I can finally reproduce Kozo's photo of the completed main frame!
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