I dug through a number of EMD manuals, and these drawings are repeated in several. I couldn't locate one for the GP20, though.
Consensus is it's an air filter/dryer, bolstered by some photos of SSW GP20s that more clearly show the plumbing connection between the air reservoir and filter: The trick now will be making the correct style filter. All the air filter detail parts I've found are the grooved centrifugal kind instead of this pill-shaped version. It shouldn't be too difficult to make (famous last words! )
How about modifying a freight car air tank - ? It has generally the correct shape The size - ? I think - worth checking out Regards, Wolf
That was one of my first thoughts, but on all the cars I turned over the air tanks were maybe 20% too big. Big enough to not fit well between the tank and truck, even. Come to think of it, a Z scale freight car air tank would probably be just about right, assuming I can find one!
ooohhh!!! Gotta love a good loco detailing thread! I used to do lots of detailing 10 to 15 years ago, but like you, I've pretty much ran out of all my Sunrise, NSN, ect older parts. Trying to find what I need on shapeways is next to impossible, so I've gotten better with "accepting" certain things, or the omittance of others. Awesome work, can't wait to see your finished product!! -Mike
Likewise, I've got one pair of Sunrise MU stands left, and about five locos in my queue that need them. Not to mention the wish list of parts that are gone altogether. The loss of so many detail part makers put me off detailing for a while, but at this point I've just about come to terms with it and am challenging myself to push through and make whatever I can't buy anymore. Speaking of details, I've added the nose lights and a few more bits while I hunt down appropriate air filters. But all the staring at underframe details I've been doing to find good air filter references has me thinking about one of the LL GP20's big flaws: the big ugly swath of daylight visible between the trucks and body: Most of the problem is because part of the locomotive's frame should be visible under the side sill, a detail that N scale locomotives have mostly omitted until quite recently. But I think I can fix that. I quickly fabricated some more-or-less correctly shaped strips out of styrene, and glued them to the frame of #4075: Now I just need to test it out on the club layout's veritable rollercoaster of a mainline. If it can still navigate that without the new frame causing problems, I'll replicate it on #4061. If not, it's back to the drawing board.
The unit with the underframe detail doesn't seem to have any problems traversing uneven track, but the frame pieces get knocked loose pretty easily when I'm manhandling the chassis, so the second unit's frame will wait until I'm done hacking at the chassis. And moving the headlight to the nose involves a bit of hacking out room for the LED. At this point I'm hoarding my last SP detail parts. Loco 4075 gets my one remaining bell and MU stands. I can't find old-stock Sunrise SP-style MU stands anywhere, not even marked up to extortionate prices. A 3D printer's not going to be in my budget for a while, but as soon as it is I plan to be ready:
Cut levers and wind deflectors have been found and ordered, bringing this project into the home stretch. Meanwhile, I test fit some spare fan grilles from a Gold Medal Models GP9 detail set onto 4061: They aren't exactly the correct grilles for the GP20s' cap-top fans, but their relative simplicity makes them easy to bend into the correct slightly-domed shape. Whether or not I want to try bending some more accurate (and delicate) fan grilles is still something I'm unsure of, but either way I'll need some fan blades, so I'll have to order some kind of fans. And on the front of detail parts I can't order, I'm working on an air dryer to print some day. Everything from the flange up is a best guess, since the part lives in the shadowy darkness under the sill. And like the MU stand, it's not scaled yet. I suspect it would print about six feet tall in its current iteration
That air filter should be plenty good enough (well, except for the six foot part) since the top part will be hidden.
My search for a local resin printer came up empty, but it's a rainy weekend and I've got plenty of time to kill:
Perhaps it might be something to consider on the TrainBoard level to add a directory to the resource section listing folks with resin printers and their geographical area?
One more for today. Both units got an antenna stand and… antenna shield? Baseball cap? Whatever the round protruding bit of cab roof is. With that, 4075 is ready for the paint booth. 4061 will have to wait a little longer while I sort out the fans and MU stands.
I'd be real interested in any thing you would share about the paint process, especially your taping procedure and the sequence you take in painting, taping, painting, etc.. Sumner
The protruding, semi-circular platform may provide for a symmetrical, electrical "ground plane" for the antenna, which can improve antenna performance (including omni-directionality), especially for an antenna designed to be mounted atop a flat(ish) metal surface.
I always tell myself I'm going to take paint process pictures, but it always slips my mind. At least this time I have two shots at remembering This makes sense, especially since the antenna is located right in the center of the semicircle. Whatever its purpose, it's flush with the cab roof and getting the model that way was a real adventure!
Fitting flush, and seamlessly extending (both electrically and physically) the cab roof would be important to the antenna's performance, if in fact it is fulfilling the circular ground plane.
I'm at the point that I have a number of reminders on my phone. Some daily some on dates in the future. Maybe a daily one near the time of day you might work on the project or a number of us could send reminder texts Sumner
First everything gets disassembled, washed with soapy water, and dried: Next everything gets primed. The larger brass parts get Rustoleum etching metal primer. The shell gets a coat of Mr. Surfacer 1000. The handrails, trucks, and other bendy plastic parts get a coat of Rustoleum plastic adhesion promoter and then a coat of Mr. Surfacer 1000. Assuming I don't find any flaws in the parts that need to be fixed and re-primed, everything is now ready for paint: I always start by spraying the lighter colors first. It means a bit more complex masking is needed, but it's much easier to cleanly spray a dark color over top of a light one than vice versa! So the handrail ends get a coat of white paint, and the hood ends get SP Scarlet: A few light coats, and the red and white are done. That's a paint spill in the background by the way, not a medical emergency The paints I'm using (Mr. Color and True Color) cure very quickly and can be masked and painted over within a few minutes. But I'll let them cure overnight and spray the gray tomorrow.
Thanks, a big help. I read one review say the following about the 1000..... "When mixed 1:1 with Mr Surfacer Leveling Thinner and applied with an air brush it makes an excellent primer". I also saw that it can be sprayed out of the bottle and also that is is a higher build primer. Are you thinning it and if so like above? I'm assuming you are spraying the Rustoleum plastic adhesion promoter from a rattle can. Is that right? So far I've only found the 1000 in 40 ml bottles. Is that the size you are getting? Are you spraying the 1000 in multiple very light coats until there is coverage? That is it for now. I'm really interested in the masking. Sumner
I thin my Mr. Surfacer 1:1 with their leveling thinner; I keep a pre-thinned dropper bottle of it ready to go at all times. Out of the jar it's quite thick and I can't imagine it spraying well, but once thinned it airbrushes perfectly. The 40-ml jar goes a surprisingly long way too, especially once thinned. I start by spraying on a light coat of primer to give the plastic some texture, then once that's dry I spray one or two quite heavy coats. The Mr. Color lacquer paints can be applied shockingly heavily, almost to the point of running, and still dry in a thin smooth coat. The Rustoleum adhesion promoter is a rattle can, but it can also be sprayed quite heavily. As far as I can tell it doesn't have any actual pigment/binder, it's 100% solvent that evaporates and leaves the plastic slightly tacky. Incidentally, the Mr. Color leveling thinner also thins True Color paint very well, and costs significantly less than True Color's own thinner!
