Trying photo-etching: A tower crane (among other things...)

[JR East]

platform & pallets look really great ! 

 

Thumb up !

[Wolf]

Wow, results so far look amazing!

[tossedman]

Cool stuff Marc! Design looks great. Make me think, how could I make these with a laser cutter? Looking forward to the end result.

Edited April 25, 2022 by tossedman

[Madsing]

Some progress this (long) weekend.

I have painted the platforms, the tower crane and the catenary.

 

 

The crane's platform is too glossy but I will correct that later.

 

For comparison, this is the photo-etched catenary (left) compared to the Kato 23-063 (right). I prefer mine and I think that I will use it on the layout. 

[cteno4]

Excellent Marc! Really came out well! Kudos!

 

so he crane was painted with a paint pen? That did well on all the detail and nooks and crannies.

 

you really knocked it out of the park on your first shot. When are you opening the business?

 

cheers

 

jeff

[Martijn Meerts]

That's looking really good.. I really need to give this a go as well to get some fish plates made at some point (and possibly other things ....)

[Madsing]

19 hours ago, cteno4 said:

so he crane was painted with a paint pen? That did well on all the detail and nooks and crannies.

I first primed the whole stainless steel sheet with Tamiya Metal Primer (because that's the one I could find at the hobby store) then all parts have been airbrushed.

 

The crane has been airbrushed with a mix of Tamiya X7 Red (two third) and X8 Lemon Yellow (one third). Maybe it's still too red and not enough orange... I used the glossy X paint, not the flat XF, and I applied a few coats so it's really glossy. I'll tone this down a notch later.

 

The platforms have been painted grey, then the details have been highlighted with blue and yellow POSCA markers. This is also acrylic paint, easy for detailing parts...

These are my reference photos: https://trafficnews.jp/photo/79813#photo7

 

[Madsing]

Trying photo-etching: Lessons learned

 

What worked well

The photo-etching process is really precise. You get exactly what you have drawn, including the surface finish.

Example: I could get nice anti-slip patterns (right in the photo), similar to the Finemolds AE-03 I usually use (left in the photo). Of course, in addition, you get to choose the size and contour of the tiles. So this works very well for all flat parts.

 

 

Drawing a half-etched groove on one side makes the part easy to fold. This worked really well for relatively small parts, like those of the tower crane. A bending tool like this one and a good light with a magnifier are more than recommended:

 

 

For more complex parts that are more difficult to just imagine in 3D, 3D modeling really helps. I have used Autodesk Fusion 360 (which is available for free to hobbyists). Check https://www.autodesk.com/products/fusion-360/personal. This is (from my point of view) an advanced professional tool, so the learning curve is a bit steep, but it's worth it.

 

What didn't work well

 

I should have paid more attention to the warnings from @cteno4 and @Kamome442 in an earlier post. I have pushed too much too far with the catenary poles.

 

 

Here, I have a 100mm-long, 0.2mm folding line in the middle of a very thin 0.8mm beam... That's nearly impossible to fold right, even with the bending tool and all the patience in the world. As you can see in the photos above, the catenary poles still look quite ok but I am not happy and one day I will redo them.

I see two solutions:

1. Avoid having to fold these and make four separate parts, probably with slots so that they easily fit together.

2. Replace parts of the folding line (which is now half-etched) by holes (like a dotted line) to weaken it.

 

Any idea?

 

Thanks.

 

Marc

 

Edited May 4, 2022 by Madsing

[Martijn Meerts]

What World Kougei for example does with large areas that need to be folded, is to just have a couple of half etched connections between the parts that need bending. Kinda hard to explain since I don't really know the technical terms 🙂

 

I'm guessing in your picture of the catenary cross beam, the blue line is a half etch line? Now, instead of doing a whole line (even if it's dotted), just have 4 or 5 spots where you have a say 5mm half etch, and a full etch the rest of the line. It'll be easy to fold, and if the etched lines are thin enough, once folded you won't get any gaps either.

 

I have some kits around, I'll see if I can remember and take a picture of what I mean when I get home, it'll make much more sense that way 🙂

[Madsing]

17 minutes ago, Martijn Meerts said:

What World Kougei for example does with large areas that need to be folded, is to just have a couple of half etched connections between the parts that need bending. Kinda hard to explain since I don't really know the technical terms 🙂

 

I'm guessing in your picture of the catenary cross beam, the blue line is a half etch line? Now, instead of doing a whole line (even if it's dotted), just have 4 or 5 spots where you have a say 5mm half etch, and a full etch the rest of the line. It'll be easy to fold, and if the etched lines are thin enough, once folded you won't get any gaps either.

 

I have some kits around, I'll see if I can remember and take a picture of what I mean when I get home, it'll make much more sense that way 🙂

 

Thank you very much Martijn. Any information is welcome. I am using 0.125mm thick stainless steel.

Yes, the blue line is an half-etched line.

I think I see what you mean, that's my "solution #2". It's good to know that there won't be any gap between the two folded parts, I was worried about that.

 

Marc

Edited May 4, 2022 by Madsing

[cteno4]

Yeah arunine uses the dashed line approach for long folds, alternating between full etch and half etch. Seems to make a pretty seemless looking 90 fold compared to butting two pieces together with tabs and far less fiddly.

 

again still amazing for a first whack!

 

Cheers,

 

jeff

[maihama eki]

Very well done.

 

Does the Fusion 360 you are using work out the "bend allowance" automatically? For example, if you wanted to make a 1 cm square box, you would need something different than a 4 cm x 1 cm rectangle to get the 1 cm box after folding it. This bend allowance stuff always gets me when I try to fold up even card stock accurately. I guess the thinner the material and sharper the bend, the less it matters.

 

http://sheetmetal.me/formulas-and-functions/bend-allowance/ 

[Martijn Meerts]

Here are a couple of examples from the IMON H0j Kiwa 90 kit (which I believe is actually manufactured by World Kougei)

 

 

 

The fronts fold, and then you're supposed to solder it all together. That's why they have really small little folding tabs here.

 

 

 

Here as well the tabs are small, since you're supposed to solder things.

 

 

I found this kinda interesting. They made 1 large sheet of brass, and added the folding tabs just for packing it all in a small box 🙂

 

 

You probably don't plan on soldering your catenary, so these tiny tabs are likely a bit too fragile. But making them a little bigger should add plenty strength, and it should still be easy enough to bend.

 

[Madsing]

8 hours ago, maihama eki said:

Very well done.

 

Does the Fusion 360 you are using work out the "bend allowance" automatically? For example, if you wanted to make a 1 cm square box, you would need something different than a 4 cm x 1 cm rectangle to get the 1 cm box after folding it. This bend allowance stuff always gets me when I try to fold up even card stock accurately. I guess the thinner the material and sharper the bend, the less it matters.

 

http://sheetmetal.me/formulas-and-functions/bend-allowance/ 

Thank you!

Yes, Fusion 360 computes that automatically, and much more (I believe). It will take the type of material, thickness and K factor into account. You can also choose different types of bends and corners.

There are some screenshots of the parameter settings here: https://mgfx.co.za/blog/engineering-manufacturing-design/fusion-360-sheet-metal-settings-available-far/

Edited May 5, 2022 by Madsing

[Madsing]

3 hours ago, Martijn Meerts said:

Here are a couple of examples from the IMON H0j Kiwa 90 kit (which I believe is actually manufactured by World Kougei)

Thank you very much for the photos! I will try this next time.