I got really sidetracked.... PRR B8A

[drosera88]

So awhile ago I posted about doing a bash on the Bachmann K4 to turn it into a poppet valve variant. I started modeling the parts and ended up being sent out on a trip for work and no longer had the Bachmann K4 as a reference to model off of while I was away. Still wanting to work on learning 3D modelling, I started another model and it's more or less engrossed my free time ever since, so the K4 bash is on hold. It took a long time to figure out, and now I am getting the hang of this stuff. What I've been working on is a PRR B8A 0-6-0 tank locomotive (a shop goat). I've already modified a Minitrix B6 0-6-0 chassis with my mill to fit the model and I've done several test prints for fitting. The main thing about this is redoing the motor due to how much smaller this shell is vs the B6 shell (will be using a tiny 12v coreless motor I got from Japan), as well as getting enough weight into it so that it can actually pull something.

The shell is mostly finished, and right now I am in the tedious process of adding small details like rivets, and the cab is the closest part of the model to being finished detail wise. I also still have to work on redoing the cylinders as well to match the prototype, which looks different from the B6 cylinders. Will also need to add coupler pockets to the rear and some underbody details. Probably going to redo the sand dome as well, as it doesn't look quite right compared to the prototype.

I've attached a render. Once I get this done, I'll probably finish the K4 parts. After the K4, I think I'll move on to getting Moose's tank engine (I haven't forgotten), though I may change my original plan and go for a larger tank locomotive using the Kato C11 as a base for a Boston & Albany 2-6-4T.

[mg_thomastx]

Nice sidetrack!

Mark

[badlandnp]

Sidetracks, rabbit holes or branch lines, they are all probably the most interesting part of what we do! For fun!

Looks like a neat steam loco!

[drosera88]

This is my first rough (really rough) test fit for the shell on the chassis. The detail in resin prints is amazing. You may not be able to see it, but there are rivets on this thing, they're just so fine that you need to look at the model from a certain angle or with a magnifying glass to see them. The pump also turned out nicely. As you probably noticed, the shell didn't come out quite right though. The shell warped a bit. I don't think I cured it correctly because when it first came out of the printer it was straight. It was only after sitting overnight that the shell warped.
Had to mill a millimeter or two off the top of the Minitrix frame to get the shell to sit lower on the chassis. Also milled off a significant portion of the rear frame to get rid of the Minitrix side tanks and make room for the stairs and coupler pocket.
Also I found that the hole in the top of the steam dome is too small for the screw. I measured it out fine, so I think this is due to shrinkage, which I will have to compensate for.
Next up is going to be the cylinders.

[ChicagoNW]

If you have the capability to do serious milling, have you considered creating your own chassis from a metal heavier than Zamac? You could even create some parts to enhance the weight rather than light resin. Shapeways does do metal as well as resin and plastic. While you might not be able to put rivets on the metal parts, Archer 3D decals can provide them.

[drosera88]

If you have the capability to do serious milling, have you considered creating your own chassis from a metal heavier than Zamac? You could even create some parts to enhance the weight rather than light resin. Shapeways does do metal as well as resin and plastic. While you might not be able to put rivets on the metal parts, Archer 3D decals can provide them.

I have considered a custom milled chassis, but this is something I am going to sell on Shapeways as a conversion kit so I want to keep it as simple as possible. That said, I didn't realize Shapeways did metal. That could be useful for adding weight. One way I can think of is to make the saddle tank out of metal. Some B8A's had riveted tanks, but the one I'm basing the model off of seems to have a welded tank, which means I wouldn't have to worry about adding rivets to the tank at all. It would also make working on it easier if the tank was a separate part.

I'm still working on it so things could change.

[drosera88]

Got the cylinders working. The wheels spin nice and smooth. I'll be working on some tweaks to the main shell and moving on to some of the undercarriage detail. Also got my eye on some potential motors for it. I'm leaning towards the Bachmann motor out of either the K4 or the USRA light mountain as both seem small enough to fit, are easily available for purchase from Bachmann as a separate part, and only cost around $20.

[tomcook]

That's looking sweet. Good job.

I would highly recomend motors from Tramfabrik https://tramfabriek.nl/motors.html They are smooth and powerful and very strong. He also sells adapters, gears , worms etc. I've used them in a bunch of locos and am happy with them.

[drosera88]

That's looking sweet. Good job.

I would highly recomend motors from Tramfabrik https://tramfabriek.nl/motors.html They are smooth and powerful and very strong. He also sells adapters, gears , worms etc. I've used them in a bunch of locos and am happy with them.

THANK YOU!!! This is great. I've been struggling to find a place that has a consistent stock of these motors.

[drosera88]

Got the rear pilot, steps, and air tank done. The pilot and stairs are a bit thicker than the prototype for added strength and printability. Next I'll need to get going on the motor mount.