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KEMNA street roller in scale 1:22.5

Started by fspg2, April 07, 2018, 12:15:28 AM

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my new milling machine is down to the suction shoe fully operational ... only I`m myself currently not quite mobile.
What can I do when this machine is not so easy to reach by foot?

Not really a problem, there are still many things that I would like to build as a model in scale 1: 22.5.

The research for this ran and always runs besides, so that I could gather some pictures and measurements to a rail- and a street-bound model.

In my youth the cobblestone street in front of our house were torn open and and sewer were installed. I can remember I often watched as a young boy, as the cable dredger dropped his shovel onto the ground, then the crunch when closing and lifting ..... unfortunately I have no paper images, only the memory.  When the road was closed again with the paving stones, there was a loud metallic rumble ... a street roller leveled the surface.

Of course at this time my dearest wish was to get such a roller...
at Christmas I got the SIKU-roller.

In recent days I started with two new projects on the computer.

Now to the first new venture:
It is a KEMNA-stree roller Gigant 8 (or 10 - both have the same dimensions).
Over the years I had collected some pictures and information that I have looked at more closely now. In various forums there were now and then a few pictures and descriptions of the Hatra / Kemna-rollers, for example at bauforum24
Images you can find for example here: click

Some info at  Hatra
Here  about the history of the company. From 1949 the company produced at Lübeck Kemna-rollers in license and did further development for the three-wheeled street rollers.

On this page there is also a roughly dimensioned sketch of the Giant 8-roller. This, however, has different height and aspect ratios.
I scaleded this sketch in Photoshop to 1:22.5.
Agreed the length, the height was too great - agreed the height, the length was too short.
There are another black and white sketch in the head of Hatra page - top right. A screenshot of this image has been scaled to length ... and lo and behold, the result was better than before.   :)

Kemna_Walze_Grundriss_000 (fspg2)

found at:https://www.hatra-baumaschinen.de/

This page plan was mounted together with a scaled front view in 90 °  in the CAD program.
The lines roughly traced and dimensioned according to the following table:

Kemna_Walze_Abmessungen (fspg2)

Two days ago it looked like this:

Kemna_Animation_001 (fspg2)

Now it gives more pictures:

Kemna_Walze_Grundriss_009 (fspg2)

Kemna_Walze_Grundriss_012 (fspg2)

Kemna_Walze_Grundriss_013 (fspg2)

Kemna_Walze_Grundriss_014 (fspg2)

The space for drive elements inside are: width = 29,0mm  -  length = about 133,0mm and height = some 55,0mm.

Kemna_Walze_Grundriss_015 (fspg2)



Please post updates as you build the model! -- Russ

Greg Hile

Yes, please! I'm looking forward to seeing more!


@Russ and Greg
But gladly!

Since I know only the coarse outer dimensions of the roller, but also want to position the details in the right place, I have taken images from the Web to help.

The following video clip on YouTube shows the roller from all sides, as well as to get a good sound impression:


I created several screenshots and equalizes and scales them to parallel.

www_youtube_com:watch_v_SonE63gse1k (fspg2)

equalized and scaled excerpt from video clip: https://www.youtube.com/watch?v=SonE63gse1k

With Photoshop, the image was scaled to a known height and width. Through the help lines, I could then determine the proportions and transferred to the Cad program.

This is how the drawing looked today:

Kemna_Walze_Grundriss_016 (fspg2)

Kemna_Walze_Grundriss_018 (fspg2)

Kemna_Walze_Grundriss_019 (fspg2)

Kemna_Walze_Grundriss_021 (fspg2)

Kemna_Walze_Grundriss_022 (fspg2)



It was just a little bit drawn in the last few days.

Kemna_Walze_Grundriss_028 (fspg2)

First, a stl file of the retaining bar of the front roller has been prepared for 3D printing:

Kemna_Walze_Grundriss_024 (fspg2)

Thanks to a nice contact, soon I will be able to obtain more detailed documentation from the Hatra / Kemna Gigant 8 roller.
That pleases me a lot, because then I can not only scale the positions of the many small hexagon screws in addition to the exact external dimensions.
Before the data goes to the router, I can adjust the dimensions and get an even more coherent model.

Kemna_Walze_Grundriss_035 (fspg2)

I'm not just counting the rivets

The roller had 3 gears at the following speeds:

Kemna_Walze_Grundriss_036 (fspg2)

The current drive is an existing high-cut 2225 Faulhaber geared motor.

Kemna_Walze_Grundriss_034 (fspg2)

It can be operated with up to 24 volts - at about 12 volts at idle he has around 30 rpm and decent power ... under load, he might drive the roller well prototypical.

Kemna_Walze_Grundriss_029 (fspg2)

However, the space for a 12 volt battery is then a bit tight. Let's see if it works with a StepUp controller then to drive with a 3.7Volt Lipo cell .....

Kemna_Walze_Grundriss_030 (fspg2)

Kemna_Walze_Grundriss_032 (fspg2)

Kemna_Walze_Grundriss_033 (fspg2)

I had an interesting discussion in the last few days with some friends regarding the rear axle drive:

a) Drive with a motor on the rigidly connected rear roller wheels (the simplest solution)
b) Drive with a differential or planetary gear to prevent the roller will moving straight ahead when cornering (for a differential is down too little space)
c) As above, but with one motor per rear wheel to reduce the speed of the inner wheel, or to increase the outer wheel when cornering over a corresponding controller (the most expensive solution)
d) split rear axle with only one driven rear wheel. The front steering wheel must be built accordingly heavy. (I would like that most - at about 20cm top speed / min right and left cornering probably should not turn out so differently fast)

Would be glad if you still have tips, or can tell from your experience.


Oh, that will be a beauty! And those Faulhaber motors are superb. -- Russ

Ray Dunakin

Wow I didn't realize you were planning to motorize this! Very cool.
Visit my website to see pics of the rugged and rocky In-ko-pah Railroad!

Ray Dunakin's World

Franck Tavernier

Hi Frithjof,

Nice futur project! As always, perfect technical study!



Franck, nice to see you again. What have you been doing? -- Russ


Thanks for your comments!

It continues with many pictures!

The roller will receive a differential, I found it at AFV. They have a " FleXaxle Differential Steel Set" which can be a good compromise with the dimensions, if I cut the bottom of the roller below the input bevel gear.
The diameter of the input bevel gear is 28mm, the differential case has 19.0mm - at a width of 22,0mm (just fits!)

I have already installed it virtual:

Kemna_Walze_Grundriss_037 (fspg2)

Kemna_Walze_Grundriss_040 (fspg2)

The lower cover sheet will be tuned in the width to the input.

Kemna_Walze_Grundriss_041 (fspg2)

Kemna_Walze_Grundriss_043 (fspg2)

In order to be able to better service all RC components and the motor with drive axle, everything will be pre-assembled on a subframe and inserted from below into the roller.

Kemna_Walze_Grundriss_056 (fspg2)

Kemna_Walze_Grundriss_054 (fspg2)

The suspension is not yet drawn!

Kemna_Walze_Grundriss_044 (fspg2)

Kemna_Walze_Grundriss_057 (fspg2)

Kemna_Walze_Grundriss_062 (fspg2)

Kemna_Walze-Gigant_8_066 (fspg2)

Here the differential from AFV:

Kemna_Walze-Gigant_8_076 (fspg2)

With the drawings I'm done except for a few small details, such as the hinge of the middle hood cover ... I would like to do it quite flexible.

You can see an animation it  shows the assembly of the subframe into the roller.:

Kemna_Walze-Gigant_8_067 (fspg2)

Kemna_Walze-Gigant_8_072 (fspg2)

In addition to the differential, further parts for the roller construction have arrived recently.

I had sent a STL file of the front roller retainer to two 3D printer companies.
Within 10 days I got the part printed by Shapeways in Brass Raw.

Kemna_Walze-Gigant_8_073 (fspg2)

Above, as it was delivered. The outer surfaces were already been polished by Shapeways ...
and below after sandblasting, the visible steps were no longer a problem.

Kemna_Walze-Gigant_8_074 (fspg2)

Earlier printed results from this provider had some strong stairs on the curves, so I asked Kalle Stümpfl to print the file on his printer in plastic parallel. I saw some very clean printed surfaces from this provider before.

Also this part has arrived shortly.

Kemna_Walze-Gigant_8_075 (fspg2)

Apart from the fact that I hold a plastic part in my hand, there is no reason to complain about it.
But I will continue to stay with brass, the experiment with the Dutch provider made me very positive. I think, I'll print a smaller part soon ...

Also more brass raw material came and wants to become as a model.

Kemna_Walze-Gigant_8_077 (fspg2)

The first plates for the inner frame and the bearing blocks for the rear axle you can see as follow. 

Kemna_Walze-Gigant_8_081 (fspg2)

Kemna_Walze-Gigant_8_082 (fspg2)


Gordon Ferguson

I just love watching the way you work and develop yours ideas and drawings in beautifully crafted parts ...... I really do wish I had just a little of your skills and talent

Makes the way I constructed my "roller" amateurish in the extreme



Gordon, your statement is completely incorrect. Go stand in the corner.

Frithjof, your engineering and execution impresses me beyond words. Question: Does Kalle Stümpfl (or anyone else) print parts of higher resolution and/or quality than Shapeways? Is the material durable?



I have to agree with Russ, your models are unrivaled, they are built so well. It does not matter if you build in plastic or brass - it counts the result ... and I will never reach your aging effects ;-)

Kalle Stümpfl (Impressum) used the Formlab 2-printer
He has a lot of experience, so he mixes different printer fluids for example. He can adjust the pressure parts as customers want. A thin railing of a scale 1:45 locomotive is so flexible that it still has not broken off after a year, although many customers have touched and bent this part at several exhibitions. Kalle treats the printed parts in such a way that they will be able to stand in the sun without being painted.

The roller retainer from Shapeways was build by lost wax methode. You can choose different materials. I took brass raw (44,00€ incl tax). The outer surfaces were still polished.
The quality of the plastic material is good enough for a stand model. However my roller will drive with RC control, so brass is more welcome as material for me.
Both surfaces are comparable. The plastic part of Kalle cost 33,00 € incl. Tax.

More and more parts are coming from the milling machine.

Kemna_Walze-Gigant_8_085 (fspg2)

The pendulum frame has a model height of 5.6mm and a thickness of 1.3mm.

To customize it, I had two options:
a)Milling an unrolling of the file. For this purpose, a corresponding part of a 1.5 mm thick Ms58 sheet would have been planned off by 0.2 mm in order to obtain a 1.3 mm material thickness - then drill holes and mill out the outer contour. After that I would have bent the frame over a template and soldered together at the interface.

I opted for b) .
Use found a 90mm x 60mm x 6.0mm MS58 rest plate.
First, a 3.0mm deep pocket with the dimensions of the brass plate was milled into an MDF board and the part inserted. After that the 8 holes to hold the milling piece came into the material. It is not possible to clamp the plate in a small vise, because only a gossamer edge remains at the end.
Now a 0.4mm deep pocket was milled into the brass over the frame area to then mill the outside and inside contours.

Kemna-Pendelrahmen_Fraesdatei_01 (fspg2)

For further processing, I left several thin holding webs inside..

Kemna-Pendelrahmen_Fraesdatei_02 (fspg2)

For the exact positioning of the 0.6mm, 0.8mm and 2.0mm holes in the frame I have milled two templates of 10.0mm Pertinax.

Kemna_Pendelrahmen_Bohrschablonen_01 (fspg2)

Kemna_Pendelrahmen_Bohrschablonen_02 (fspg2)

Kemna_Pendelrahmen_Bohrschablonen_03 (fspg2)

Now the remaining holding webs were separated with a 0.3mm saw blade and the interfaces were smoothed with a sandpaper file.

Kemna_Walze-Gigant_8_086 (fspg2)

In the interior space of the scooter must be placed beside the engine a receiver, a servo for the front axle and a control shaft to the handwheel in the cab .... if then a battery should give enough power, it may not have only 200mA.
Oh, sound with speakers, lighting and then a driver - there is not much room left. Let's see what comes out in the end.

Kemna_Walze-Gigant_8_087 (fspg2)

Kemna_Walze-Gigant_8_088 (fspg2)

Kemna_Walze-Gigant_8_089 (fspg2)

Kemna_Walze-Gigant_8_092 (fspg2)

Ray Dunakin

Brilliant design! I like the way the mechanical parts will fit into the model.
Visit my website to see pics of the rugged and rocky In-ko-pah Railroad!

Ray Dunakin's World


After all parts are milled for the inner frame, it continues with the outer skin. It is completely made as a unrolling of 1.0mm MS58.

Kemna_Walze-Gigant_8_094 (fspg2)

All holes, recesses and depressions are taken into account.

Kemna_Walze-Gigant_8_093 (fspg2)

The front tip will be annealed and bent over a template later.

Kemna_Walze-Gigant_8_095 (fspg2)

The lower part of the front filler was milled, which will take up the rotation axis of of the front roller.
Since it has a height of 13.61mm, but my longest small cutter only has a cutting length of 12.0mm, I shared the part.
From a 10,0mm MS58 material, the lower part was built.
The upper brass part came out from a piece of 4.0mm MS58 rod. Then the five center holes were drilled and the outer contour milled. In the holes 1.0mm brass pins for precise positioning will be mounted for soldering.
Subsequently, the brazed parts are milled to the height of 13.61mm.

Kemna_Walze-Gigant_8_096 (fspg2)

Kemna_Walze-Gigant_8_097 (fspg2)

Kemna_Walze-Gigant_8_098 (fspg2)

Lower section with 3.0mm sintered bronze bushing.

Kemna_Walze-Gigant_8_099 (fspg2)

Kemna_Walze-Gigant_8_100 (fspg2)

Kemna_Walze-Gigant_8_101 (fspg2)

The unrolling of the outer skin I milled shortely.

Kemna_Walze-Gigant_8_102 (fspg2)

After the sheet was machined from the inner side (0.5mm indentations on the lower edges and the two sides of the cab), I milled a pocket of 1.0mm depth into a MDF board so that I could machine the milled brass sheet from the outside. It was fixed with Tesakrepp and then I milled 0.2mm deep pockets. Later I can position the lamp holder and the round nameplate "Klöckner" exactly.

Kemna_Walze-Gigant_8_103 (fspg2)

To bend the settlement, I've milled two bending templates made of 20mm thick MDF.

Kemna_Walze-Gigant_8_104 (fspg2)

In the first template, I chose the radius of the previously milled brass block and bent the sheet annealed in the middle with the help of a hard wooden stick. The second side was not parallel to the angle, so I could bent the outer skin more slightly.

Kemna_Walze-Gigant_8_110 (fspg2)

Kemna_Walze-Gigant_8_105 (fspg2)

As can be seen in the following picture, the curve of the sheet does not yet lie exactly on the curve of the template.

Kemna_Walze-Gigant_8_106 (fspg2)

Kemna_Walze-Gigant_8_107 (fspg2)

So a new stencil was milled without further ado, now with a smaller radius and a slightly stronger angle of the second side.

Kemna_Walze-Gigant_8_108 (fspg2)

It fits better now!

Here's a first non-virtual impression of what the roller will look like. The parts are put together only loosely - the brass block hangs something wrong in the rounding.

Kemna_Walze-Gigant_8_109 (fspg2)

As a last point today a look at the router:
It's great to be able to put several things in parallel.

P1-Montage_125 (fspg2)

P1-Montage_126 (fspg2)