ESM Hooker 8k Gallon Acid Tank — design thoughts

[chessie system fan]

I would think that if the tank walls on the top and bottom were the same thickness then the shrinkage would be the same. 

[bbussey]

Again, if we were talking about designing injection molded parts, it would be easy. The only way to achieve an exact seamless fit otherwise is to rapid prototype the parts, which is not feasible for a cylindrical surface with relief detail due to the stepping of the layers. An etch body wrapper with the relief detail insures a smooth surface. If anyone has any suggestions on building a two-part master for casting that fits precisely, has no layering, has the appearance of being injection-molded and is not labor-intensive (which will add to the cost), I'm all ears.

Also, this is only a deco issue (as opposed to an assembly issue) for models with multiple paint colors. It's not difficult to assemble this model, and it's not an issue to decorate for all black cars.

These are the original four cars that Hooker purchased and they were lettered for Niagara Falls. I am uncertain if they were later lettered for Tacoma, or whether they received the more common orange scheme.

[learmoia]

... Likely a stupid question.. but..

Can't you paint the sub-assemblies (Tank, Frame, Tank Wrap, Dome walkway/handrails) before you assemble.. then touch up as needed?

... Duhh in re-reading your first post.. that was your initial idea, which seems fine to me..

No different than your pre-decorated etched car sides.

~Ian

[Missaberoad]

Both variations in the same kit.  It will be possible to represent each of the four Hooker tankcar prototypes.  Of course, other acid tanks also can be represented accurately including the Shippers car, but the decals won't be included.  The trucks will be wrong as well, as only the Hooker tanks ran on National B-1 trucks.  You would have to procure the MTL truck frame of choice on the medium-extended bolster (same truck bolster as used on the B end of the drop-end gondola), as that design is the only one with a centered bolster hole.  Using another manufacturer's trucks could possibly affect the ride height (and coupler height) of the model.

If painting one-color cars, this becomes academic.  This is a problem specific to the Hooker scheme

Thanks, excited to see how this develops, Decals and trucks shouldn't be an issue, I'll be converting them to TSC anyways so I'm sure there will be some modifications involved. Sounds like it will be a well detailed model...

[Chris333]

How do you form the etched sheet into a tube without deforming it?

Asking for steam smokebox wrappers.

[bbussey]

What I have done in the past is:  Leave the part attached to the fret if possible.  Place the sheet on soft cardboard to start, outer face down.  Use a large handle X-Acto as a rolling pin to start the curl, keep rolling back and forth until you have a distinct curl.  Tape the edge of the fret to a solid rod that is the desired diameter.  Slowly roll the rod over the cardboard to form the wrapper.

Note that with the Low Side Gon, you will have to roll the ACL floors to remove the curl.

[Chris333]

I tired that here:
https://www.therailwire.net/forum/index.php?topic=42082.0

[peteski]

I was thinking of producing a single-piece resin cast tank.

[bbussey]

I tired that here:
https://www.therailwire.net/forum/index.php?topic=42082.0

I've never worked with sheets that thick.  The tank wrapper will be .004" thick over the bulk of its surface.  It will be anchored at the seam by the tank brackets over the bolsters and the spacer block, all secured to the tank core through the wrapper with #00-90 screws.  So it won't have to perfectly conform to the core before application.

[AlbertSpor]

Bringing back an old thread, I am looking for any updates on this project, especially now that you are experimenting with 3D printing.

[bbussey]

Dead at the moment. May revisit it down the line but I haven’t been able to get results to my satisfaction.

[AlbertSpor]

Sorry to hear that, thanks for the update.