KEMNA street roller in scale 1:22.5

[fspg2]

@Ray
I'm always happy if I get more and more informations

@Russ
You make me a bit embarrassed, it's just normal model making.


As we had met with Helmut recently, we talked about different ways to colorize the steel tire of the roller.

In addition to the proposal to turn off the outer edge and replace it with a stainless steel tire, a more elegant solution emerged:

to nickel electroplated or chemically!

Helmut lent me a kit for electroplating nickel. Thomas Heyl has described on its website the procedure very well: click
In this case, the coating is indeed quickly visible, but the abrasion resistance is probably not as strong given.

Thomas E. then proposed electroless nickel plating. Thanks for the tip - the result is really great!

I was lucky, a supplier right next to me had just re-scheduled his nickel bath. So it took only one day and I had a nice sea water and abrasion resistant surface.


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If the wheels are painted and aged later, you will see only metal and no golden brass shining through in those places, where eventually the color dissolves.
The inner edge and the inserted brass plates should be painted red.


Helmut wrote on 04.20.2018 at Buntbahn forum:

For that real rollers have the ability to tilt the axis, so that the wheels show even on curved roadways effect.

Have you ever thought to realize this in the model?

In the meantime, I got a brochure scan from the former manufacturer of the HATRA Gigant 8 with the decisive hint! (Thank you for your kind support!)
And no, I will not replicate this double swing axle in the model!

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Copyright: https://www.hatra-baumaschinen.de


Hatra_Gigant_Doppelschwingachse_01 (fspg2)

Copyright: https://www.hatra-baumaschinen.de


Hatra_Gigant_Doppelschwingachse_03 (fspg2)

Copyright: https://www.hatra-baumaschinen.de



At the original roller I could make a few shots: here und here

When measuring the width of the chassis, I found that my model was drawn exactly 2.0mm too narrow.

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So I have changed the files... with the result that the old unrolling of the housing was 1.4mm too short now!
Since you are now a confidant: wink: .... it will be milled again.
Indeed you can say that you do not see the 0.7mm per side ..... That may be true, too .... but I know that ... As long as I have the opportunity to improve on my possibilities, so I'll do it.
But the larger width has the advantage that I have 2.0mm more inside. So I can use a stronger and wider battery. To be honest, that was the reason for redrawing.

Between the housing and the rear rolling wheels, there is a metal cover.

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It probably served as protection when tilting the axles.

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[finescalerr]

You are rebuilding some parts because of a 2mm discrepancy on a 1:22.5 scale model? The only one who would know it's too narrow is you!

As for electroless nickel plating, it emerged in the late 1970s-early 1980s to protect pistols and rifles from water and corrosion. For a while, some expensive and sophisticated target rifles and handguns had such plating. Soon, though, stainless steel technology improved and they found ways to make stainless parts harder and more durable. That pretty much ended electroless nickel plating on firearms.

Russ

[Hauk]

Very cool project.
The documentation of this interesting piece of technology history is valuable in itself.
And your experimentation with modelling techniques is both entertaining and educational.

Thank you for sharing!

[Ray Dunakin]

Very interesting. I'd never heard of electroless plating before.

[fspg2]

The drive unit is located in a separate subframe.
Compared with the  first drawings, it was modified and supplemented by two engine bearer plates.


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In order to mount the parts exactly parallel, I have milled small Pertinax gauges.

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[fspg2]

When I came back from my last business trip, two packages lay on my desk.

The first package came from Shapeways and had two small black bags with wheel covers for the rear roller wheels.

Although I ordered them as "brass raw", they came highly polished.

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Originally, I wanted to make the wheel hub on the lathe and solder the small lettering as an etched part.

But then I let it print in the lost wax casting. . I was very curious if the font is clearly legible - it is only 0.2mm thick.



At the beginning, I created and dimensioned a 2D sketch.

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Then the sketch was rotated 360 ° around the central axis to create the 3D model.

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Afterwards I put a new sketch plane on the surface of the wheel hub and copied in a scaled photo (1: 22.5) as background.

Now the outer contours of the black ring and the writing were redrawn and then extruded everything up to 0.2mm in height.

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Incidentally, the lettering stands for Julius Kemna.

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Well, the second package had it in itself: Two small 7.0mm x 4.0mm shackles !!!
(The postage was more expensive than the content!)

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[finescalerr]

The parts look beautiful. Are you surprised that Shapeways gave you parts of such quality? -- Russ

[Ray Dunakin]

Sweet!

[Gordon Ferguson]

Wonderful to watch the process , that front roller carriage is just beautiful ..... as are the rear wheel covers & lettering

[Greg Hile]

Wow! I continue to be fascinated by this incredible project, both in terms of process and workflow as well as the final output.

I have a small project in mind for my train depot: a replica of an early Fairbanks warehouse scale, with some of the parts 3D-printed in brass. I would do the ABS prototypes on my cheap printer and send them out to Shapeways or somewhere for the final product. What you got from Shapeways looks pretty darn good and I was wondering what your thoughts would be on this.

Also, may I ask what CAD software you use? I currently use SketchUp for working with structures and Autodesk Fusion for components.

Greg

[fspg2]

Thanks to all!l

@Greg
The quality of Shapeways (or similar providers) can only be as good as the template.
For a cheap printer, the print resolution is usually very rough. That means you can see clear steps.
I created a stl-file (highest resolution) in my Cad program (Inventor) and sent them to shapeways.
Within 10-14 days I received the finished product.


Meanwhile I had milled the outer shell a second time and also made new bending templates from MDF for the larger radius.
When milling the new brass plate, I noticed that the same cutter (as before) now pulled up the edges ..... MS58 brass was ordered ..... but the behavior was more MS63 brass...
After annealing the brass plate with the flame, I was able to bend the material much better than the MS58 plate.
Previously I had removed the slightly elevated level of the edges with a sandpaper file.

For further assembly of the roller I have milled small lessons from hard paper again.

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Through corresponding recesses I can fix the exact position, as in this example, the rear cab floor plate to the two side cheeks. To keep the 0.5 mm supernatant of the yellow side plates during the soldering by hand, I was too unsure.

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The floor base plate itself was slotted on both sides. For this I have grooved the upper side first. The four 2.0mm brass pins served to accurately position the back side.



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[finescalerr]

Well, that worked out nicely. -- Russ

[fspg2]

The resistance soldering tool just helped to solder the parts together in the hard paper gauge.

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So far, everything fits together. 

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[1-32]

great job Frithjof look forward to the next post Cheers.

[finescalerr]

Impressive. -- Russ