SP GP20 Build, 2023 Edition

I use 91% rubbing alcohol for pretty much all my paint removal. After I've removed the handrails, windows, horn, etc., I soak the shell in alcohol for a few hours. After soaking, the shell gets scrubbed with an old toothbrush and cotton swabs. Some brands of paint require a little bit of elbow grease, but LL paint practically falls right off. Once the shell is clean I rinse off any remaining paint specks with water, and it's good to go.

Other folks prefer other stronger solvents, but rubbing alcohol has minimal risk of harming the plastic (or me, for that matter).

 

Thanks, I had read and bought some of the 'stronger stuff' but was a little reluctant to use it. Good to know that with a little more patience the alcohol should work fine. Do you ever use the 99%? Also do you reuse it or is it a one time use?

Sumner

 

I haven't used 99%, but only because it's much harder to find locally than the 91%. If I'm running low on alcohol I'll strain out the paint flakes through a coffee filter and reuse it, but it's so cheap that I usually don't bother.

 

I have found that older models (Atlas/Austria being a prime suspect) require stronger stuff. I use brake fluid to remove as much as possible, then some very old Pollyscale Easy Lift Off for the remainder. I also use an ultrasonic cleaner; since it only runs five minutes at a time, that may take days.

As he says, high proof isopropyl alcohol works well on newer paints.

 

I found that the paint on old Con-Cors wouldn't even budge with 99% IPA. I had to use AK Interactive Paint Stripper and cotton buds / Q tips. It took days to get the paint off and its still not absolutely clean.

 

Oh yeah, vintage paint is a whole 'nother animal. If I ever strip another Minitrix loco I'm going to give brake fluid or something a shot. Rubbing alcohol might as well have been water as far as that paint was concerned.

 

Try Pinesol, with actual pine in it for stripping paint. It even works on decades old Testor's Enamels.

 

I re-did my model to close in the top, switched from a complicated assembly of shapes to an extrusion of a profile:



I posted the .stl here:

https://glenn.pulpitrock.net/SP_LightBoard_Na.stl

 

Looking good, Glenn! The curve around the top of the hood is pretty hard to scratchbuild cleanly. I might have to go the printed route for my next locos.




For my previous GP20 I used Sunrise air tanks, but those are long gone so I scratchbuilt some instead. 0.080" half-round styrene is just about the perfect size for the job. The bands are aluminum foil tape.



The new frame has a slightly different shaped fuel tank area than any of my other GP20s; I'm guessing LL made the change when they updated the GP18 to use the same frame. For some reason, the updated frame lets the tank rock side-to-side a little bit instead of seating securely like my other GP20s. I'll have to address that when I take the frame apart for decoder installation.

 

Oops, hadn't seen the rounded bottom. Will update...

IMHO resin printing is the way to go for small parts. Most are not hard to model (exception: bell hangar - yikes!), and they're cheap to iterate through until it fits...

 

Updated STL with rounded bottom:

https://glenn.pulpitrock.net/SP_LightBoard_Na.stl

I'm lips-deep right now in D&RGW steam, but you've got me jones-ing SP early diesels now...

 

One of these days I'll get a resin printer. Any specific recommendations for one that can do really small details? I don't know much of anything about 3D printers, I've barely even mastered the 2D kind

I was sure I'd confirmed there was some space between the fuel tank sides and frame of the old-version GP20s. But lo and behold, I ended up having to grind some notches in the frame. Come to think of it, I'm going to have to grind out spaces for relocated headlight LEDs too. At least a Dremel makes the work quick!




I'm waiting for a batch of Miniatures by Eric detail parts I need to move forward, but in the meantime the second Geep is nearly caught up to the first. Its decoder is in, and the nose light packages for both of them are in the test-fitting phase.

 

I bought a Mars 3, 4K resolution at a decent price point for experimentation. On my HOn3 project, it resolves most of the detail nicely, 'cept for the build plate, looks like a build plate from normal viewing distances but you can't read it looking close-up. I'm still using the default layer height, so it may get better dialing that down. The build volume is more than adequate for all but maybe very long passenger cars in N scale; with resin printing tilting at a 45-degree angle helps a lot of things, including fitting the part in the volume.

8K printers are now down in my "experimental" price point, so I'd probably do one of those if starting out now.

Resin is the thing for "decorative" detail, but I think you'd really have to work out exotic resins for mechanical parts. I may yet do that, but for now I'm reverting to brass fabrication for such. You also need weight in a locomotive, and no plastic is going to do that like brass for a frame.

For filament printers, my kid just bought a Bambu Labs X1. OMG, LIDAR bed leveling, in-print filament switching, speedy-quick. Also, just works out-of-the-box, he got tired of fiddling with the Ender 3 Pro with no satisfaction. A bit expensive, but maybe worth it if you just want to git-er-done. Ha, I thought I was hearing the washing machine upstairs just now; turns out it's his printer going at it...

 

Oh, I'm writing up my experiences building a model of DRG #168 here:

https://glenn.pulpitrock.net/blog/

Mainly a capture of what I'm doing so I can remember what I've learned, but I hope it also helps expedite others' initiations...

 

Sorry to hear he had problems with the Ender. That certainly hasn't been the case for thousands of us and if I wasn't happy I wouldn't of bought a second one to use. Printed hundreds of items for the layout with mine.

For what jwaldo is doing I would for sure recommend a resin printer though. One thing to keep in mind when looking at resolution is that sometimes an 8K doesn't have any or much better resolution than 4k or even a lower resolution. I found this video to be very interesting....



Sumner

 

Thought I'd qualify that as I don't think I did a very good job of trying to say what this says in the about the 6th paragraph down..

https://all3dp.com/2/8k-3d-printer-explained/

... where it explains one shouldn't pick or think an 8K will have a better, more detailed, print quality than a 4K. I have a 4K but have yet to use it, bad on me.

Sumner

 

Any loco experts know what this doodad in front of the fuel tank is? I'm guessing it's an air filter/moisture trap, but I can't find one that looks quite like it. Knowing what it is would sure help me find/make the right detail part!

 

I'm only guessing, but likely a water trap and bleed valve on the air feed to the air tank.
Cheers
Steve

 

Could also be a filter/water separator for the diesel fuel too.