About Comments

Comments are enabled on all postings. Click a posting to find the comment box. Comments are moderated and appear after my review.

Friday 25 August 2023

Ballast Cleaning Train - Part 9

I previously bought two unpainted Dapol grampus wagons that accompanied this train with a view to painting them weathered black, not realising that the Dapol unpainted model is already black! I decided to leave them as is and just fit the numbering. I choose a couple of DB numbers from the Eastleigh allocation since the train shown in the books was on its way to Eastleigh depot. The assumption being that the ballast cleaner was stabled there(?)

The lettering was printed on sticky paper labels and when stuck on the model the white edges were carefully blacked with a fine tipped pen. 

In the book Southern Steam in Action 1 there is a close up photo of the leading grampus in this train. Two 'oil' drums and a ladder are clearly visible in the wagon. Other bits and bobs there are not identifiable. I 3D printed the loads using some of my own designs and some 3D .stl crate designs from Thingyverse.

The second wagon appears in another photo of the same train in Southern Steam from Lineside. It is far too distant to see the load clearly but looks like it contains more bits and bobs. I chose to retain the ballast load supplied with the Dapol wagon on the basis that when the spoil is taken out the remaining cleaned ballast may need to be supplemented. The unpainted (black) wagon load was sprayed with grey primer and then lightly sponge dabbed with brown, white and black acrylics to represent the colour variation of Meldon ballast.

Friday 18 August 2023

Ballast Cleaning Train - Part 8

There were two major considerations in the design of the final spoil conveyor.

1. Negotiating model track curves.

It is obvious that this long conveyor sticks out a long way from the rear of the wagon. If the conveyor was fixed in position then, with the wagon in transit and moving around track curves especially the tight curves of model railway track, it would swing out beyond loading gauge limits and potentially hit a train on an adjacent track. Therefore, I had to make it swivel (as the prototype) so that it can be constrained within the width of the wagons.  An added complication is the hopper that feeds this conveyor. It cannot be fixed to the conveyor. We can see the split line in the photo that allows the conveyor to swivel independently of it.

When designing the conveyor I had to ensure its height kept within the loading gauge and ensure there was no interference with parts of the generator wagon. These constraints set the length of the conveyor. 

The conveyor rests on a yoke frame. I raised the ends of this to limit travel of the conveyor as the train  negotiates track curves. I am pleased to say that the swivelling conveyor works as planned around the tightest curves of my model railway layout. 

2. Interaction with the Power Generator Wagon

As explained, the conveyor rests on the Generator Wagon during transit. Well, that is how it was in the early days. Later on the machine was supplied with a match truck where the conveyor rested on that instead. 

I digress here to explain the orientation of the two wagons. In the photo above the arrangement is for transport. For working activities the power generator wagon is run around the other end of the machine and a high voltage umbilical cable connected between the cabins.

Whilst I digress, how does the ballast cleaning machine move when working? Beneath the buffer stock at the spoil conveyor end is a drum winch with two cables. The cables may have been bolted to the fishplates or chairs of the railway track and the machine winched itself incrementally along. Another oddity is the braking arrangement of the machine. I have found no evidence of brakes or vacuum pipes on this early machine. Maybe the red handles beneath the cabin operated brakes(?) What there is is a long pipe that runs along the girder frame to the buffer stocks at each end. I guess that connected to the pipes of adjacent wagons?

Now, there are subtle differences between between builds of this Matisa 3B5 machine and the generator wagon variant I choose to model seems to be a latter variant that did not support the conveyor (match truck used instead?). Consequently that big box on the end of the wagon causes the conveyor to lift higher than desired and this lead to it being shorter that in should be. The variant I should have modelled did not have the big box. Instead it had two fuel drums laid down and further inboard that would allow the conveyor slope to be less and its length longer so that it sat correctly above the generator unit instead of in front of it.

In Conclusion

I had hoped to get the design of these models right first time but, I'm afraid I have not. I have a list of 10 faux pas of which the most significant is the girder frame that should have been set further in board. Correcting this will have knock on effects of many other parts.  Modelling the wrong generator wagon variant is also disappointing. Also, I am unhappy with the quality of 3D print. It all looks a bit rough on close inspection. Nevertheless, when I placed the models on my scenic model railway they certainly look the part and we do not notice the rough finish as much. So, I am encouraged to carry on with this project.

What I will do is overhaul the CAD design to correct errors and add more details with a view to Resin 3D printing in the future for greater finesse of the models.

Next though I must prepare the Grampus wagons.

To Part 9.

To Part 1.

Saturday 12 August 2023

Ballast Cleaning Train - Part 7

The vibrating sieve box and first spoil expulsion conveyor have been added. When the spoil reaches the end of the conveyor it drops into the hopper and onto the final conveyor, which is the next part to be modelled.

If you stumbled upon this individual posting and wondered what this mess of parts is then best first go and watch it in action at YouTube here.

To Part 8.

To Part 1.

Saturday 5 August 2023

Railway Ballast Cleaning Train - Part 6

It looks like a diesel shunter but, in fact is a 440V electrical power generator wagon for the ballast cleaning machine conveyor motors etc.

There are more details to add to this wagon that will have to wait because there are dependencies on parts of the ballast cleaning wagon that are not yet modelled. In particular, its spoil expulsion conveyor that rests on top of the generator during transportation.

The black radiator grill has a close mesh effect that was created using a trick of the 3D printer. When it prints thick parts it prints a honeycomb for internal layers to save on plastic and print time. I simply programmed it to continue printing the honeycomb through to the outer layer instead of finishing with a solid layer. Parameters of the honeycomb can be manipulated to give the desired close mesh effect.

The two lamps required some ingenuity to make from bits to hand. They were made from the clear end of a Bic biro ink tube and the dome formed by filling the hole with polystyrene cement gel. I was pleased with the outcome until closer inspection of the prototype showed them as being oblong!.

Related Posts Plugin for WordPress, Blogger...