Bronica ETRSi Battery Compartment Cover Replacement Part

The Bronica ETR series were 6×4.5 film SLR medium format cameras manufactured by Zenza Bronica in Japan from 1976 to 2004. The series consisted of the original ETR (January 1976), the ETRC (October 1977), the ETRS (January 1979), the ETR-C (January 1979), modified ETRS (July 1982), and the ETRSi (October 1989) (Gonzalez, 2016). Production of the ETRSi ended in December 2004; full technical support for the ETRSi ended seven years later, in December 2011.

The ETRSi incorporated a number of changes over the preceding ETRS, namely improvements in the focusing screens, shutter speed dial, and in sound and light-deadening material in the interior of the camera (Gonzalez, 2016). One other relevant change was the enlargement of the battery cover over that of the ETRS (#2912) to that of the SQ-A (#1912) (Gonzalez, 2016).

The battery cover in place on the bottom of the Bronica ETRSi

The battery cover in place on the bottom of the Bronica ETRSi

As is often the case, various parts of such a camera system can go missing – the eyepiece, the winding lever, the battery cover, and so forth. In the case of the battery cover, replacements are hard to find. The only other (efficient) way to obtain a replacement battery cover would be to buy a broken ETRSi camera body. Though this is useful from a long-term repair perspective, it is not entirely feasible if just the battery cover is needed. The intent here was to create a 3D model of a ETRSi battery cover in order to allow for 3D printing of replacements.

FreeCAD screenshot of battery cover 3D model

FreeCAD screenshot of battery cover 3D model

Using the original part as a guide, I constructed a 3D model using FreeCAD. I decided to keep it close to the original part in terms of design. That said, the grip/groove pattern was changed slightly, in order to make it easier to shift over. Because of the lack of a finish on the replacement battery cover, it is easier to remove from the camera body, as compared to the original battery cover (due to the rougher, as opposed to smooth, surface finish).

The part was test printed by Sculpteo (Paris, France). The total cost, with shipping, ended up being €6.00 (~$9.00 CAD; ~$7.25 USD).

The materials and related characteristics were:

Process: Multijet Fusion
Material: Nylon PA12 (Black)
Finish: Raw

Original and replacement battery cover

Original (bottom) and replacement (top) battery cover

Part Download

The part can be downloaded from Thingiverse.

References

Gonzalez, D. (2016). Bronica medium format cameras. Retrieved from http://bronica.org/start/bronica-medium-format-cameras.html

CV-35 Light Tank – 3D Model – Part 1

The Carro Veloce CV-35 (CV-35, L3/35) was an Italian tank (tankette) that was produced and saw combat prior to and during World War II. It was, and still is, Italy’s most produced tank (upwards of 2,500 built). The CV-35 was a two-man tank – one gunner and one driver. Throughout its combat use the CV-35 was surpassed by nearly all other armour it encountered. Despite early failures, it still saw widespread use until even after World War II. The CV-35 was used by a number of different forces, not just the Italians – e.g. following the Armistice of 1943, numerous CV-35s were seized by the Germans. Decades later, a nearly intact CV-35 was found by US forces in Iraq during “Operation Iraqi Freedom” (presumably one of 16-20 sold to the Kingdom of Iraq prior to WWII). For more information on the tank, you can find Wikipedia’s entry here: http://en.wikipedia.org/wiki/L3/35.

The intention behind creating this model was to have it included in a video game, in particular the award-winning Battlefield 2 mod “Forgotten Hope 2.” The other (larger) purpose is to make available the necessary vehicles that would have been used during the Italian East Africa campaign – an often neglected area of World War II (certainly in terms of video game coverage).

The tank was modeled primarily with Autodesk 3ds Max 2013 (NB: screenshots of the wireframe show parts of the 3ds Max interface). The renders here were all done with Maxwell Render.

The first step in creating the model was to gather reference images (a collage of some of those is below). One issue that I encountered right away was the variation amongst CV-35s – differences in vision slits, hinge types, muffler types, differences amongst nominally identical gun models, and so on. The model that I made has what is (in my understanding) the most common of each separate variation. In fact, I have images of one tank that exhibits all of the represented features, so I will consider my model historically accurate on that basis. Generally speaking though, all the CV-35s that I’ve come across are roughly similar to each other (ignoring sub-types, of course).

Reference image collage. This is a sampling of the roughly 140 reference images collected.

Reference image collage. This is a sampling of the roughly 140 reference images collected.

Being a model destined to be used in the Refractor 2 game engine (which is now ten years old), there were certainly polycount limits to observe (both due to the engine but also general requirements set out by the mod developers). In the case of vehicles, the advised limit was 10,000 polys or less. My initial model (front and back renders below) had about 25,000 polys – these were mostly in the parts with curves (e.g. wheels, muffler). The hull itself (everything but the wheels, tracks, and suspension) was just over 9,700 polys. Once the wheels, mufflers, gun barrels, and so forth were optimized, the total poly count went below 6,500. The tracks, as shown here, were done fairly quickly, and as such don’t quite fit the tank properly (the ones below are the non-optimized ones). In the Refractor 2 engine, the tracks are fairly low poly (and are actually static).

The initial model of the CV-35 - front 3/4 view.

The initial model of the CV-35 – front 3/4 view.

The initial model of the CV-35 - back 3/4 view.

The initial model of the CV-35 – back 3/4 view.

Having received input on the initial model, and its optimized form, I added a few details in (with the spare polys that I found myself with). I also altered a few parts (e.g. the gun barrels and turret).

Current model without wheels or suspension.

Current model without wheels or suspension.

Wireframe of the current version of the model.

Wireframe of the current version of the model.

Suspension detail.

Suspension detail.

The next step for this model is to do the UV unwrap and then the texturing. The import into the game is done by someone else on the FH2 development team.

Future work would entail modifications to the model for the anti-tank variant/sub-type (with the 20mm Solothurn S18-1000), one of the flamethrower variants (CV-35 LF with the over-engine fuel tank), and the command tank variant.