Easy to print 1:87 H0 "Finnish" Passenger coach

prusaprinters

Thumbnail Photo credit: Tapio Keränen About the prototype(s)… GeneralDuring the early 1920s, the Finnish state railways was starting to struggle with its rolling stock with the ever increasing amount of traffic on the lines and the older 2 axle  and 4 axle stock were starting to show their age. So to combat this the state railways acquired some new motive power. Notably The Hv1-Hv3 class 4-6-0s for express passenger train use and the Tv1 class heavy 2-8-0s for freight workings. This was an opportune time to introduce more of these new generation of coaches for these much stronger engines since they could pull them better. One of the new Hv1 engines in 1929 pulling a typical consist of its time with a smårgåsbord of rolling stock of that era. Photo credit: unknown/Jyrki Längman Although some examples of the Ei coaches were already being produced in small batches in the 1920s, production really started to kick in the 1930s as the withdrawal of the older stock started and more of the new said motive power became available. These quickly proved their worth on finnish metals and were produced en masse from the 1930s to all the until 1950s with numerous variants based on the same chassis.In the 1960s however, newer steel coaches were being introduced and them having a higher maximum operating speed of 130km/h (later modified up to 160km/h) meant that they were better suited for the speeds that the big diesels at the time could achieve thus reducing trip times. The wooden coaches were restricted to operate at 95-110km/h. initially, long distance trains consisted of a mix of these newfangled steel coaches and the old wooden coaches. But as more steel coaches became available for long distance workings, they were gradually relegated for regional train services around the capital of Helsinki and the occasional rush hour addition to some rakes out of Helsinki. The commuter versions with more capacity and 4 doors per side and bigger hallways saw action in smaller branch lines up until the 1980s as some of the rail busses that were used on those lines were being withdrawn for scrapping. So these were used as a stop gap measure while new stock was being thought out.Luckily, due to the high production number many of these have been snapped up by preservation groups. With the materials and spares being somewhat easy to come by, repairs and maintenance is somewhat easy to do providing a reliable and comfortable journey for many enthusiasts and public alike for many more years to come. There is even a completely “new” type of generator/support/luggage coach converted from old mail coaches!Technical infoThe coaches had a wooden body construction with steel reinforcements in crucial spots and a chassis made out of steel. some earlier variants had stove/water heating but later on were fully retrofitted to steam. Wood was perfect for a coach for the climate of finland, it was  warm, easily processed and readily available. This proved especially crucial the years following the WW2 as Finland had to pay war reparations for USSR and steel was used mainly for that and couldn't be used to rebuild the fleet lost during the war.The roofing fabric was made of a mixture of linseed oil varnish, resin, chalk, dyes and silver crystals drawn over burlap, on which roofing sand was placed. This had a distinctive grainy and sandy texture that you can replicate using a mixture of some black paint PVA glue and fine sand! (like the kind you can find at beaches)Interior was somewhat modest consisting of 2+2 seating with cushioned plush seats. When third class was still in use, some of the commuter coaches had only simple wooden bench seats. This was phased out later however.Lighting system used a 24 volt incandescent lightbulbs which got their power from a simple generator fitted to an axle. Some coaches however were equipped with gas lighting systems using coal gas where available and in some cases acetylene gas where coal gas was not available. The print itselfI was kinda inspired by Sam's trains to make my own printable rolling stock. I was thinking about making some quite a while a go but never really got the inspiration kick before his video series so thank you for that Sam!  Of course this isn't a 1:1 recreation nor is it intended to be but i find to be a nice enough piece for building nice rakes and use as guinea pigs for detailing and weathering techniques. Also designed to be somewhat modular as they share parts between different “versions”. Feel free the bogey design on your own wagons or use the blank coach to make your own custom variants or improve on the original! That's what it is there for! Printing and assembly Material and layer height0,20 or finer layer height should be fineCan be printed with PETG or PLA although i'd recommend using PLA for crisper detailSupports and orientationThe bogies need supports on build plate only and the main bodies need supports everywhere but they should be removed easily enough on 190mm+ build plates. However with the Mini you have to print the main bodies in a 45 degree angle, making the supports a bit harder to remove as they are in a weird angle and have a bit more material.all of the detail can be printed without supports with correct orientation.  The bogies, roof and detail can be printed on the same build plate on the Mini so it should take you 2 prints in total to get all the parts you need  for assembly. compatibility There are two different types of bogies: one with a rigid NEM pocket mount and one with a pivoting one for more slim and close couplers. Although these have a low clearance between the bogey and the track bed so it might get caught up on switches and such (might tweak it a little before release). The bogeys will fit H0/00 gauge standard NEM wagon wheels (should work with märklin pizzacutter wheels) along with any NEM couplers. A little drop of oil is recommended to put in the bogies but it should roll fine without it too.AssemblyUsing this very scientific diagram™ glue the “detail” under the body. Batteryboxes marked in yellow, frames in orange and the airtank in blue. The interior if printed separately can be just glued in after painting and detailing. The bolt holes in the body should be wide enough to just simply drop the bogies in and secure them by using M3 nuts and washers until desired tension is achieved. Buffers should just push in fairly easily and can be just a push fit depending on your printer tolerances, however a drop of glue wouldn't hurt. The roof is just a snap fit and can be glued in place if desired. Stuff you will need:2x M3x10 or longer bolts (4x if you opt in for the pivot pockets)2x M3 hex or square nuts2x M3 washers (optional)4x NEM wagon wheelsets2x NEM coupler of your choice (I used the märklin relex type coupler. Or in other words, the standard european hook and loop.)Some Loctite (modelling glue can work too but the hold is quite weak)Closing thoughts and resourcesthis was my first “real” project in Fusion 360 that came to fruition and i learned a lot doing it. I plan to do some more complex stock in future too but I try to focus primarily on printability rather than being exact replicas but hey who knows! I already have a few ideas floating around for completely different wagon types using the same parts to some extent. I'm also currently studying to be a mechanical engineer so that comes with its perks too i guess, mostly in the shape of Siemens NX which is another can of worms to learn again :DI do look forward to your makes and any questions you might have about the prototypes or the models themselves. Oh and please do post makes if you do decide to print some! It would really make my day!Below is a link to a popular Finnish railway enthusiast site with a lot of pictures of the prototypes (in Finnish though but everybody can read pictures!)(http://vaunut.org/kuvat/?tag0=9%7CEi%7C) Edits12.11.2022 Edit 1: added some info about material and layer height that i forgot