Further wagon & tippler progress

I'm getting very close to full wagon production. After half a dozen test prints with minor design tweaks in between, I've assembled a full wagon complete with couplings so I can do some test running. It will need some weight to be added but there's space enough underneath for a bit of lead sheet.

I'm still not sure if the quality will be good enough. I've learnt a lot about the settings needed and it does seem the original Bambu PLA gives slightly better production than the Sunlu I also bought. Adding a filament dryer from which the filament can be fed directly seems to have helped enormously as well as adding brims to the corners of small elements in Bambu Studio. I'd prefer not resort to resin printing as the PLA is much more robust than most resin prints I've seen. The only part which doesn't print successfully is the brake lever so I'll probably use brass etches for these.

I've also progressed the design of the tippler. Solidworks Xdesign enables me to simulate how the shute can be lowered and wagon on the tippler frame will tip the clay into the SG wagons. This has only been done manually by rotating the elements around pivots and checking by eye, i.e. I haven't used Xdesign to check whether elements actually hit each other which I know it is possible to do.

I did do a test print of the whole tippler frame which came out pretty badly but gave me enough info to realise it will not be strong enough as a 3D printed so I intend making it from brass sections, with perhaps the stairs 3D printed. It also made me realise the frame base will be about 10mm higher than designed. I altered the stairs in the design but I'm not going to bother redoing the tippler frame design as I've got enough info for the brass construction. The viaduct itself will be made from wood sections.

My plan is to haul wagons up the viaduct incline via a continuous chain which will have a link with a vertical pin every 20cm or so. The chain link and associated sprockets will be 3D printed. I intend the chain haulage, shute and tippler to all be operated manually from a crank and levers at the baseboard edge which will hopefully be fun for me and the grandchildren.

Wagon Progress

I've progressed quite well with my tipping wagon designs. I've settled on a design top hinged door with a fixed top plank which would help prevent bowing of the sides - on the prototype that is - it wouldn't really be a problem on the model. My first version had a real fixed top plank, however it quickly became clear that hinges that would be small enough to look prototypical would never be operationally reliable even if I could make them work at all. I had resigned myself to go back to the simple top hinged door which did work well with perhaps a top strap to prevent the prototype bowing. It's funny (or perhaps even sad) the things that can keep you awake in the dead of night, however it was then I realised that although it should look like the top plank was fixed, I could make the whole side tip anyway which I knew would work. When opening this would be largely hidden within the tippler anyway.

A tipping test of the body

A trial assembly

Another issue was the means to hold the tipping door shut. I was originally thinking of operational catches and some means to openin them within the tippler mechanism. Again I realised I could make these purely cosmetic and use other means to hold the door closed. I thought I would try using magnets which will hopefully have give just enough strength to prevent it opening when loaded but not when tipped. I designed pockets to take tiny 1mm dia x 2mm length magnets in the wagon base and 2mm dia x 1mm length in the side. Initial experiments suggest one pair of magnets may be enough, but it may be necessary to provide an additional force when tipping to make the side open reliably. This could be a stronger magnet within the tippler - much simpler than a mechanism to operate catch handles.

Note the tiny magnets in the base and bottom pocket of the side. I designed three holes to allow a single central pair or two either side. One pair looks to be sufficient.

One of the benefits of using Solidworks is the ability to visualise how the tippler could work including how the bits can tilt. I'm now fairly confident I have worked out the height it needs to be, the pivot location and the shute position. I can now proceed to fully design the tippler. In my history this would have been built in the 1930s and would have been constructed in metal with the viaduct made from wood. I also need to think about the means of hauling wagons up the incline. I think it may have to be some kind of cable but I'd like it to be automated.

The tippler schematic with tipping wagon platform and shute.

As an aside, real wagons on industrial railways look well used and abused often with bowed sides etc. The problem with printing from a design is they all come out exactly the same. I plan to have some variation in the design to represent different genres of wagons but wanted to introduce some distortion and wear and tear in the main body. It wasn't clear how to do this in Solidworks so I explored ways to distort the generated STL file. I'm not that familiar with Blender so it took me a while to work out how I could add some gentle distortion to the main body. I haven't tried printing these yet to see how it turns out. If successful I intend to do this from scratch for every wagon I print, some more than others, so each wagon will be unique. Coupled with variations in style it should give me a fleet of unique wagons.

 

Wagon Works

I've at last made a start on my long-planned wagon building program. I want the wagons to be distinctive to the rebuilt PLR, i.e. not copies of wagons used elsewhere. The most important aspect is the need for them to be tipped which I hope to do at least semi automatically. I want to try and build a tippler which has echoes of the original Pentewan tipplers with a pivoted section of track. My first thoughts are that it will be easier to automate if the opening side is full length and top hung. I'm not sure how prototypical this will be so would welcome thoughts from other learned modellers.

I'm designing the wagons using Solidworks for Makers. It had quite a steep learning curve however I'm now successfully producing components and assemblies. Test prints so far have been done on my Bambu A1 using a 02mm nozzle and basic PLA. The detail is pretty good and the PLA is remarkably strong. For full production I may get some parts printed in resin, although I'll need to be sure it will be strong enough.

Update 19/01/2025. After some very helpful feedback from fellow modellers on the O14 Group who pointed out the original design could easily bow in prototype practice and suggested a fixed top plank would be better. Here is a visualisation of a revised design:

Here are some pics of the (earlier) designs and prints: