Garden Railway Forum

Rik

And now I have something which looks like a coach. It also looks remarkably like the one I made by hand!
Back to the bogies.

Trevor

Most impressive!

It is indeed very very impressive, full marks for that one

The bogies are now working.

I settled for this arrangement in the end:
You can see the spring between the axle box and the bogie. So the axle boxes move as per full size, but when fully loaded I expect the springs to bottom - and act more to keep the wheels in contact with the rail than to actually make the coach properly sprung.

Printed couplings which are reasonably close to the ones which these coaches were originally fitted with. The only difference as far as I can work out is that mine have a coupling hook at both ends whereas I think the originals had only a hook at one end:
Trevor

The couplings installed:
The ring is a bush to hold the coupling pivot ring up - and preventing it interfering with the bogies movement. There is a brass loop in the bottom of the coupling to take coupling hooks - so that wagons can also connect to the chopper couplings.

and the bogie fitted:
I have used a 6BA brass bolt fitted into a tapped hole in the bottom of the coach. Tapping into the ABS seems to leave the thread a bit tight, and that is helpful as it locks the bolt without resorting to lock tight. It is interesting to note how far the bogie will pivot, I think it is going to go round quite tight curves!

Trevor

With the coach on the test track I have tried connecting it to the other bogie coaches. The ride height seems perfect - with the end platforms both at the same height (pure fluke). In this photo the coupling on the new coach is a bit higher than the other - so I remade the couplings with the height adjusted to my standard coupling height. The basic coupling is a component that I use on all my models - I just change the way it connects to the model. In this case the long shaft and ring.

As far as the springing is concerned there is about 2mm of spring left to compress when the coach is on the rails (less its roof) and the couplings are of course a touch high.
I have now made the roof in 4 sections. I tried ABS but the section curled up along the length of the coach, so I made the 4 sections from PLA (using a new nozzle which is now reserved for use only with PLA). This resulted in far less curling. I printed the sections flat on the bed by the way. I know I could have printed them on end - but I am going to fill and sand this roof to hide the joints so the steps are going to be filled in anyway.
I printed the oil lamps as part of the centre sections of the roof. However I made a mistake in centring them on the roof and when I cut the middle one in half, printed the roof section with the lamps on twice, and tried to join them the two halves didn't mate up. So oil lamps have been cut off - and I will make separate oil lamps to glue on. At least it will be easier to sand the roof now.

And now there is just over a mm of spring to compress, so the model is actually near enough fully sprung and sitting at the correct height on the track. It will be interesting to see how it handles on the track in the garden.

Trevor

Fascinating that the couplings swing independently of the bogies. Presumably, there are lugs on top of the bogies to align the coupling with the swing of the bogie?

Rik

No Rick there is nothing to make the coupling swing with the Bogie. They are totally independent of each other.

In fact I am pretty sure that they have to be independent - in that I think the couplings won't always align with the bogie angles. Think of a slate wagon hanging off the end of the coach coupling for example. When two couplings are connected the hooks hold the couplings in alignment.

Trevor

That's very clever, I like it!

Trevor Thompson wrote: ↑Thu May 20, 2021 3:05 pm No Rick there is nothing to make the coupling swing with the Bogie. They are totally independent of each other.

In fact I am pretty sure that they have to be independent - in that I think the couplings won't always align with the bogie angles. Think of a slate wagon hanging off the end of the coach coupling for example. When two couplings are connected the hooks hold the couplings in alignment.

Trevor

That is interesting. I suppose I follow railway modelling manufacturers' practice of mounting my couplings on extensions of the bogies rather than prototypical practices of mounting them independently. Having the couplings on the bogies means that auto coupling is easier on curves as they align with each other. Presumably, with independently mounted couplings, the guard will have to manually align each coupling when coupling-up?

Rik

I suppose I have been influenced by looking at photos of the real thing. I noted that on the double fairlies, now that they have buck eye couplings, there is still a swivel in the coupling even though they are mounted on the bogie. I wonder if there is a centralising spring in side the real thing which isn't obvious?

I hadn't considered auto coupling - although I can understand why you would want it (I read your description of running trains to a timetable etc).

So yes in this case I will have to align the couplings and manually connect them.

Trevor