Work in progress: Westinghouse boxcab electric

[Hauk]

Birchwood Casey aside, the truck looks terrific. == Russ

Thanks, Russ!

[Lawrence@NZFinescale]

I'm a great fan of blackening compounds, but they do contain strong acids, and are somewhat metal specific (for reasons I've never bothered to fully explore).

I have a formulation that I believe is for the 'lead' in stained glass fabrication that works well on brass and solder (not so well on lead free).  Doesn't really affect steel.  Gun blue obviously works well on steel, and does to a lesser extent work on brass/nickel silver, but is slow.  Doesn't work on solder.  I don't use aluminium in model making, but I guess there is a specific product for this for a reason.  Sounds like I should avoid it.

[Hauk]

I'm a great fan of blackening compounds, but they do contain strong acids, and are somewhat metal specific (for reasons I've never bothered to fully explore).

I have a formulation that I believe is for the 'lead' in stained glass fabrication that works well on brass and solder (not so well on lead free).  Doesn't really affect steel.  Gun blue obviously works well on steel, and does to a lesser extent work on brass/nickel silver, but is slow.  Doesn't work on solder.  I don't use aluminium in model making, but I guess there is a specific product for this for a reason.  Sounds like I should avoid it.

Blackening is a bit of a black art at times, and my results are somewhat mixed. The best results have been achieved with very diluted solutions (1:200) and immersion of the parts for several days.

I think I read somewhere that the aluminum blackening worked really well on brass, and that's why I tried it. I did not stop to think about how it would work on steel.

What was most worrisome is that it looks like that the corrosion process continues after the parts have been thoroughly rinsed.

I have been under the impression that all blackening solutions are acids, and that a strong base solution will neutralize the blackening.

I would be very happy if anyone with more chemical knowledge than me could enlighten me!

[Lawrence@NZFinescale]

My understanding is that gun blue (presumably others are broadly similar) is typically phosphoric acid, selenious acid and a copper salt.

On reaction a coating of copper selenide is deposited. The metal salt and acid strength may well vary for other blackening solutions, but I believe the selenium is a constant.

An online search will turn up the MSDS sheets for exact contents, but it's probably not all that helpful unless you have the knowledge to interpret it (which I don't)

A soak in bicarbonate of soda/baking soda should fix it, but the concern (as with flux) is that some reagent may wick around by capillary action and not be thoroughly washed out.  I tend to use an ultrasonic bath, which helps.

[Bernhard]

This cosmetic truck looks really good. Can you tell me what app you used to construct the gears and what material they are printed from? Is the material suitable for an operational model?

Bernhard

[Lawrence@NZFinescale]

This cosmetic truck looks really good. Can you tell me what app you used to construct the gears and what material they are printed from? Is the material suitable for an operational model?

I've printed gears of various sorts for cosmetic use.  They certainly 'work' (as in mesh etc), but I wouldn't be that keen to use them in something that might see more than light use. Henkel/Loctite make a high impact printing resin (and there are others), that would probably be best for a functional print. It's a bit miserable to use as it's viscous, slow and hard to clean up - but the results are fine.

You could cast them in brass from a print though.  They would need lapping in, but would work for some applications.  I imagine pretty well at low speed.

[Hauk]

This cosmetic truck looks really good. Can you tell me what app you used to construct the gears and what material they are printed from? Is the material suitable for an operational model?

Bernhard

I used the free calculator on this site:
https://evolventdesign.com/pages/spur-gear-generator#google_vignette

The gears are printed on an Anycubic Mono 2 resin printer. I doubt the gears would stand up in actual use. Mainly because the resin is quite brittle, but also because the teeth are exactly to scale. I think there are other printers and materials that are better suited for printing working gears.

[Bernhard]

Thank you Lawrence and Hauk. I almost thought that printed gears were only suitable for decorative purposes.

Bernhard

[Hauk]

Thank you Lawrence and Hauk. I almost thought that printed gears were only suitable for decorative purposes.

Bernhard

I did a quick search, and there are several youtube videos and webpages about printing working gears.
I have not tried this myself, but it looks interesting.

[Barney]

Truly remarkable miniature engineering
I'v enrolled for my flower arranging class again and my stamp collection is growing !
Barney

[1-32]

Hi Hauk.
That frame is amazing such a neat well thought out design.
cheers Kim

[Hauk]

3D printed parts is a great help, but some assembly is indeed required.

The "bell" on the top motor was misplaced, so I needed to sand it away and replace it with a turned brass part. (The bell is a cover over the vent for the hot air from the motors, by the way)

Cables were formed from 0,5mm copper wire flattened and drilled to simulate terminals. Imitations of the plugs on the motor were made from 0,8mm brass tubing.



An overview of the truck before the wires were attached:

[Ray Dunakin]

Beautiful work!

[finescalerr]

Impressive. -- Russ

[Peter_T1958]

Hi Håvard

Although I do not write here about my current work I am lurking around in the background very often. May be you remember my similar project of a narrow gauge loco? That project came to a standstill as technical demands were too challenging for me on my kitchen table workspace.
Your approach (a mixture of brass and 3d parts) is very impressing and I must confess, it is very inspiring too !!!
So today I reopened the cartons with the parts at least.   I hope I will be able to recover this project one day. If so, your work here would have been the key input.

All the best,
Peter