Sparkie

[cabbage]

I am currently (!) working on writing the Scad files for an electric C0-C0 loco based on the BR E77 class. These worked the Sheffield Victoria to Manchester Piccadilly 1500V DC route.

The panels are being "proofed" at the moment and then I will begin to print them.

As everyone knows the printer is on top of the piano...

Regards

Ralph

[cabbage]

All the Scad files have been uploaded to the G3WiKI. The GCODE conversion and then print run will start in the morning.

Regards

Ralph

[AshleyW]

bruce lake has a part 3-d printed em-1 and one of the huddersfield railway model club has done that, so he may be able to help in some way.

[cabbage]

That's interesting! Butterley allow people with cameras and tape measures over their collection but the roof of Elektra is forbidden territory!!!

I have started printing the biggest part of Sparkie which is themain coolant roof. This is going to take 11+ hpurs... I am using PETG at 225°C with 0.125 layer height. The second attempt is going better as the bed has to be frigid cold and the filament at third degree burns temperature.

PETG is more expensive than PLA but I seem to get better quality surface finishes, it does look like metal sheeting and rock - looks like rock!

Regards

Ralph

[cabbage]

Well that went as expected for a first test print... The results show that the layer height is too low and the head temperature needs to be higher.

So, ayt the moment I am using 0.2mm layer with a 250°C print head. In another six hours I will be able to examine what has been done.

Looking at the initial base layer on the bed I don't think that I am that far off.

Regards

Ralph

[cabbage]

There are times when you are building a model when you look at it and think " why the hell is that bit like that ?"

Sometimes it is not obvious like the carbon resistors smoking on the roof of an NYC S Motor, or the 10° inclined water tanks on the Hagans thpe 'J'...

The "hump" in the middle of the class77 I had assumed to be the aero cooling system for the switch gear, and arc blasters as it seemed obvious air was forced down the small mushrooms and out the large mushrooms.

No! (Try again!)

Yes it did contain switching gear and Dutch Railways Technical Archive has provided the answer.  The switching system was enclosed in oil. The big round roof sections are oil tanks and the fans blasted air through oil radiators fitted to the roof vents. The side louvres were there to provide clean air and allow Ozone to dispate through the air blast of the roof vents.

Pre semiconductor power switching must have been a designers nightmare. The NER EE-1 used graphite rods plunged into a bath of Mercury. Italian locos used salt water as the conductor, pump more brine in the switch tank to go faster. The Penn RR GG-1 used Poly Chlorinated BiPhenol as a switch arc breaker and coolant.

That sound you just heard was the Jealth and Safety Executive having a siezure...
..

So now we know!

Regards

Ralph

[cabbage]

Ok... Production of parts is now underway. This loco uses the same bogies as the LMS 10,000 series DE. I do have four bogies for the LMS DE loco but I have sat and looked at them and I have to admit that I do not know how to put them together...

So, having studied the "Wild Swan" book on the LMS loco I am going to duplicate the equaliser arm method used. This will entail a double frame with equaliser bars moving within it. Ideally they should be tensioned by stretching springs as they have no fulcrum pin to act through. Yes, they just move around as they feel like it!!!

Regards

Ralph

[cabbage]

The fifth roof panel os now printing and I have been playing fun and games with Hookes Law... At yhe moment I have only the vaguest idea of how much the loco will weigh...

This has to be divided by 32 to get the downward force on each spring. Each equaliser arm needs four springs, four arms per bogie and two bogies - hence 32.

The lever split ratio is one to two with the longer arms acting on the outside axles of the bogies. The arms will be 3mm laser cut steel and the frame sides 2mm.

The hprn blocks I will probably make from brass strip.

Regards

Ralph

[cabbage]

Last of the main roof panels is pn the bed. Once this is done it will be the two end cabs that have to be printed. The front faces (two pieces) have LED "lamps" inset into them. These will be 3mm LED inserts with a 5mm holder and an 8mm flange to them.

I will need a yellowish white LED to be "in period" as these would have been Tungsten filament in Nitrogen rather than Krypton.

Regards

Ralph

[cabbage]

Tje last of the wall "tiles" has come off the bed. Now I have to sit down with calipers to work out the sizes of the internal frames that will have to be printed. I think that I will only need four, one at each end of the body and two for where the hump is.

Then it on to printing the quadrants...

Regards

Ralph

[cabbage]

Yesterday I made the mistake of looking for the paint... Only one of the class 77 locos got painted in BR "Electric Blue" livery. This was "Minerva".

Well I thought it would be a common paint! But No! Craftmaster had never heard or seen it. They did find an old British Standard definition for "Electric Blue" - so this is what I have ordered.

The cost of the paint is four times that of the filament used to print it...

Regards

Ralph

[cabbage]

All the OpenSCAD files have now been uploaded to the G3WIKI. With the exception of any file marked "quadrant" all the other files can be printed at normal resolution with 20% fill. The quadrant files are best printed at 100% fill. These are not very large pieces but need to take the strain of the polystyrene strip. These  pieces are used to join the roof tiles.

Regards

Ralph