Spoked wheels for decorative model making

As you can probably see on this site, I work a lot with fischertechnik. The parts of that construction system have a recognizable level of abstraction that is excellent for building dynamic functional models. Other construction systems, with their sometimes numerous parts, go much further in pursuing models with decorative realism. This article explores the boundary between functional and decorative on the basis of the classic fischertechnik spoke wheel. Here the 3D printer plays a major role.

Purist or 'creative facilitator'?

Some other construction systems (we won't name names because it's 'Lego') focus with their sometimes countless numbers of specially shaped building blocks on the (re)construction of highly decorative models while with fischertechnik the accent sometimes lies precisely on the technical function. For the builder of decorative scale models of, for example, vintage vehicles, tractors or steam trains, designing within the abstraction level of our favorite construction system is therefore sometimes quite a challenge. For, how do you build the most recognizable scale model possible with the available, sometimes quite far stylized, parts? For some, the challenge here is to work as purely as possible by limiting oneself to the officially available parts without any concessions. But it should be noted that fischertechnik does not always impose this limitation on itself. To build some original models, for example, attachments are required that have to be cut out of cardboard yourself. And with the model of 'Classic Line' steam roller (39050), for example, it is suggested that the roof of the cabin be fixed with double-sided adhesive tape because the springs of the 'Planiger shield' (36908) are on the wrong side. Didn't 'creative facilitation' with this make its appearance well before the availability of the 3D printer?

Spoked wheels

Thus, due to the lack of specific decorative elements, sometimes fischertechnik requires a bit more puzzling and improvisation. Especially when building decorative models of classic automobiles, bicycles, steam trains or other vehicles, one encounters challenges. After all, the standard fischertechnik program is not abundant here. In fact, the 90 mm "Speichenrad" (19317) in the picture to the right actually turns out to be the only openwork spoked wheel with real spokes.

original-90mm

Some spoked wheels with smaller diameters can be found among the fischertechnik car rims, but these are of poor use as true-to-life spoked wheels for a decorative model. Thereby, the 'Felge 20' (143231) is the only one where one can really see between the spokes. The 'Speichenfelge' (31986) is closed and actually all car rims are too thick to be used as a classic vehicle wheel anyway. If you are looking for small spoke wheels (17mm) for a steam train, for example, and like a bit of tinkering, you can find two 'Mini-Speichenr├Ąder' (35171) in the old differential (31043). In short, the conclusion cannot be otherwise that wire wheels play a very minor role in the standard fischertechnik program.

On the contrary, in the range of standard Lego parts available, there are many models and sizes of openwork wire wheels. Although the diameters of these for the construction scale of fischertechnik models are somewhat on the small side. To fill this gap, you can even find online web shops with special 3D printed Lego wheels for models of trains and classic vehicles.

For fischertechnik, I did not yet find this possibility. This was of course a nice challenge for me as the owner of a 3D printer and some 3D skills when I was asked from various quarters to help think about additional diameters, colors and designs of spoke wheels for building models vintage vehicles, tractors and power trains. These requests happened to come at exactly the time when I myself was in need of some 3D printed design variations of spoke wheels.

History

Looking over the product program of fischertechnik, one cannot help but come to the conclusion that the wire wheel does not play a particularly large role here. Thus, apart from the small car wheel mentioned above, there is only one real spoke wheel with a diameter of 90 mm. This wheel is quite far stylized and equipped with eight spokes of 4 mm thickness. The wheel also has a relatively wide tread of 15 mm. Possibly this is a design compromise that allows the part to be used both as a tire-powered flywheel or (with some imagination) as a normal vehicle wheel. But at a common 1:20 scale, this already looks quite crude. Only on tractors, for example, do such wide wheels appear true to nature. In addition, most classic (steam) vehicles often require various diameters of wheels. Anyone looking for other spoked wheel diameters will have to make them themselves.

schwungscheibe

As the only smaller variant, fischertechnik itself proposes the use of the "Schwungscheibe" (39006), in which eight red "spokes" (Rastachse/V-Achse 20, 31690) can be placed, in the "Classic Line" construction sets of steam roller (39050) and the mobile steam engine (19321). This wheel, in Figure 2, has a diameter of ~60 mm but is closed on one side so that one cannot see between the spokes. Purely round spoked wheels with other diameters do not include the parts program, and the spoked wheels made with Statika "Bogenst├╝cken" of 30 and 60 degrees are far too large for most vehicles. Those who want to make other diameters of spoked wheels therefore have to rely on polygons made up of building blocks and angle blocks.

Size variations of the large 'Speichenrad'

While I was restoring an old original fischertechnik model, it became clear that the original 'Speichenrad 90' in black (36916) is no longer manufactured, and therefore very poorly available. It therefore seemed to me a nice finger exercise to be the first to model and 3D print this classic wheel. Since the eight (4 mm) spokes of this wheel cannot be printed flat on the print bed, I experimented with some ways of printing. Printing with a support structure, to be removed after printing, is the easiest. However, the loss of printing time and material is significant at these diameters. Moreover, the spokes on the support side must be reworked and smoothed by hand. I therefore also experimented with printing two halves that could be glued with superglue after printing. This method is certainly preferable for the somewhat larger wheels, or for those that require a high level of detail on both sides.

4-colors-90mm
90-75-60mm

In antique vehicles, sometimes not all diameters of the wheels are the same. Front wheels are sometimes smaller than rear wheels, and even the 90 mm spoked wheel is quite large for 1:20 scale models for this purpose. Similar spoked wheels of 60 and 75 mm would be a nice addition and immediately greatly improve the building possibilities for decorative (and perhaps functional) models. It worked out quite smoothly to design and print some additional variants. Here, the tread width was proportionally reduced to 10 mm instead of the 15 mm of the original 90 mm spoked wheel.

New propulsion options

Inspired by the construction of the first generation automobiles, I designed some additional drive options. For the realization of a chain drive, as in many of these classic vehicles, fischertechnik in itself already offers sufficient possibilities. But with the hub-mounted solutions, only relatively large sprocket diameters can be used, and when mounted with a collet, these require a relatively large installation depth. Moreover, these clamping options are only available in red within the standard fischertechnik spare parts program.

clip-on-applicationclip-on-gear-Z33

To preserve the 'transparency' of the open spoked wheel as much as possible, I designed a sprocket wheel that does not require a separate hub on the central shaft for attachment. This 'Clip-On' Z34 sprocket can be snapped onto the spokes of the spoked wheel by means of four 'Rastadapters' (36227). The sprocket can be driven with another sprocket or with a chain, and of course can be printed in different colors. The picture show the design and an application of this sprocket.

inner-gear-various1inner-gear-application1

An authentic drive method that is still regularly used today is by means of a wreath with inner teeth. With some experimentation, this too could be designed in a suitable modulo 1.5 variant. The result is visible in Figure 6. Because the sprocket is attached directly to the spokes, the wheel retains its open spokes structure. Note that by now I had also printed tires for these spoked wheels. More on this later.

Both drive methods are well suited to building antique automobiles. The wheel itself is an accurate copy of the original 90 mm spoke wheel, because of this the standard fischertechnik hubs can be used.

Colored hubs?

For the larger spoked wheels, mounting in the regular way, with standard hub (31014), is an excellent solution. See, for example, the wheel with a diameter of 10 cm (Figure 9) which, with its narrower tread of 10 mm, is intended as a prototype for an antique automobile.

However, the red hub stands out a lot on this black wheel, and unfortunately no other color hubs are available in the standard fischertechnik program. For this reason, I did some experiments with printing the fischertechnik hubs myself. The preliminary conclusion, however, is unfortunately that the method (FDM) and the printing material used (PLA or PETG) of most hobby 3D printers is not sufficient for this purpose. Due to the method of printing (individual layers) and the brittleness of the material, it is not easy to print parts with a toughness comparable to the injection molded plastic parts from fischertechnik itself. The material is too brittle to withstand the torsional forces during tightening, and the fragile loose lips of the hub part can then break off quickly.

red-and-black-nabe
flachnabe-experiments

The self printed parts made of PLA or PETG have excellent shape and impact resistance, but thus do not possess the tough resilience necessary for sufficient clamping force on the shaft when used as hubs or collets. Perhaps I will continue with further experiments in the future, but for now, for decorative models, it seems to make more sense to simply work the familiar red hubs into the desired color with a spray can of plastic paint.

The photo to the right shows some experiments with printing the hubs in other colors. The blue hub is printed with the flexible "flex" filament. Unfortunately, I did not yet manage to print smaller details (such as the screw thread) with this with the necessary precision as well.

Shaft attachment for smaller diameters

The next step was to bring some variation to the available spoke wheel diameters. Here I quickly ran into the fact that with smaller diameters (smaller than 50 mm) the standard fischertechnik hub starts to take up a relatively large amount of space. A standard hub (31014) already has a diameter of 25.5 mm so the ring in the center of the wheel will soon be about 28 mm. As can be seen in the illustration, at a wheel diameter of 60 mm, this already starts to become relatively large. At wheel diameters below 40 mm, no spokes will even be visible at all.

For this reason, I continued to search for alternative ways to mount the wheel on the axle. Mounting with "Rastaschen" is obvious and would minimize the necessary hub space. Unfortunately, a Rastasche is always somewhat movable in the mounting point and the wheel cannot then be loaded too much vertically and vertically rotating wheels will quickly become visibly 'wobbly'.

60mm-big-naaf
60mm-various-couplings

A lot sturdier would be mounting with collet (35113). The sleeve in the wheel for this would then be limited to only 11 mm. This is a considerable improvement, but it does significantly increase the mounting depth of the wheel on the axle. A completely assembled wheel is therefore almost 22 mm thick at the center. For this reason, it seemed better to me to abandon the fischertechnik click and clamp methods for the smaller diameters and to design a simple sleeve with socket head screw to these wheels. This different mounting method is largely hidden behind the wheel itself, and therefore also hardly noticeable while the wheel can be kept nice and flat on the outside. The latter is also functionally important if, for example in the case of spoke wheels of train models, connecting rods must be able to pass through.

Breaking the monopoly of the "Schwungscheibe" as the smallest opaque (pseudo-)spokes wheel requires that we will have to continue our miniaturization. However, scaling is obviously not infinitely possible. It is important to realize that the size of the standard fischertechnik hub remains the same. Therefore, if the wheel is to remain aesthetically proportionate, things like spoke thickness (standard 4 mm) and tread width will also have to be scaled. The possibility exists that this will take us beyond the instinctive degree of "styling" of the standard fischertechnik parts. For myself, instinctively somewhere around 50 mm there is a step to a spoke thickness of 2 mm and a wheel width of 5 mm, but this is purely subjective of course.

This visual transition is shown in the images below. Note that for the sake of clarity, the black train flange strap has been reversed. After all, usually the axle mount will have to be on the back of the wheel. Both images are visualizations of the designed hypothetical wheels. For 3D modeling, visualization and animation, I used Blender. The wheel on the right I actually printed later and can be seen below.

30mm-8spoke-collet30mm-10spoke-shaft

Where do we draw the line...

Experimenting with spoke wheel variants rekindled an old idea. Quite coincidentally, I had seen replicas of the Benz Patent Motorwagen in museums twice in a relatively short period of time. First at the Technoseum in Mannheim during my visit to the BUGA23, later at the Mercedes-Benz Museum in Stuttgart. This antique vehicle has a type of bicycle wheels with many spokes. The only type of spoked wheel with eight spokes of 4 mm thickness in the fischertechnik program is, even if we were to take the black variant for this, obviously much too far stylized. Moreover, for a somewhat decorative and recognizable model, two different diameters of this spoke wheel are needed.

110mm-40-spoke-vintage

The ability to design and print, allows for a more detailed level of abstraction for these wheels. This led to the spoke wheels with many more and much thinner (1 mm) spokes as shown here.

With a few more bespoke pieces (small Z15 sprocket with Allen screw for the chain drive and a building block with which the front wheel-fork could be made), these detailed spoked wheels made it possible to make a decorative model of the 1886 Benz Patent Motorwagen I. Of course with a (descendant of) Bertha Benz on the buck.

bertha_benz

Treinwielen

30mm-train-wheel35mm-train-wheel45mm-train-wheel-pivot

When building in 1:10 scale, decorative train models actually require even smaller diameter spoke wheels. At the request of a club member, I experimented with diameters of 30, 35 and 45 mm with a shaft with Allen screw for mounting on the axle. For the 45 mm train wheel, I additionally designed a variant with a pivot for the characteristic connecting rods of steam trains (see Figure 19). 'Statika Streben' can serve as connecting rods. For another application example, however, I designed slightly slimmer rods, which more closely follow the design of the BSB Lok Gelenkschieber-Kurbelstange (36917). For experimenting with the chromed metal 4 mm fischertechnik axles I designed an enlarged 'Achsadapter (31422), see images.

drijfstangen1drijfstangen2

Tires and rims

The standard fischertechnik program offers few options for giving spoked wheels tires. Only for the smallest fischertechnik spoked rim is a 'Rennreifen' (31237) available. No tires are actually suggested for other spoked wheels and one is at the mercy of one's own creativity. For the 90 mm spoke wheel, by way of tread, the black rubber 'Raupenband Gummi 230' (31057) from, among others, mot1 and mot2 boxes can be diverted, but it is actually too narrow for this 15 mm wide wheel. The wide rubber tire in the picture here is from other toys and actually too wide, but could possibly be used for a tractor model. All in all, there is a desire to have more useful diameters, colors and types of tires available, for example special tires for trains or tractors.

ft-wiel-banden
60mm-tire60mm-train-tiretractor-tires

Designing a suitable tire, which can then be put around the spoke wheel in question, is obviously relatively simple. For this reason, I experimented with various diameters and widths. In some of the previous images in this article, the results of this are already visible.

Appropriate treads or tires can of course be developed for special applications. Such as "flange tires" for trains or tires for tractor models where the ribs on the tread are similar to the profile on the available fischertechnik tires in the smaller diameters. The tractor tires shown above can be used directly on the standard 90 mm spoked wheels and look more stylish than a simple rubber elastic. Note that the correct direction of tread requires two different tires.

Conclusion

By adding your own colors and diameters of spoked wheels to the standard fischertechnik parts program, the possibilities for building decorative models of antique vehicles or trains can be greatly expanded. Mounting the wheels on Rastaschen is possible, but not very stable in practice, and especially with the smaller diameters it breaks down that the standard hub 31014 (which, moreover, is unfortunately only available in red) becomes more and more visually dominant. Although the 35113 collet has a smaller diameter, it unfortunately requires a relatively large installation depth. Mounting with a small sleeve with Allen screw seems a fine (almost invisible) alternative.

More decisive are perhaps the visual adjustments such as the number of spokes or spoke diameter in the wheel. Aesthetically speaking, after all, with each expansion of building possibilities we seek the limit of the recognizable and familiar level of abstraction of fischertechnik. Everyone will have to decide for themselves whether this is a great opportunity or too heavy a concession. In most cases it will probably be an excellent addition since in terms of spoke wheels at fischertechnik the choices are very limited.

Possible future additions to my self-designed "spoke wheel program," and the spoke wheel types I have already experimented with can be found in the online catalog.