Author Topic: Bogie design  (Read 1555 times)

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Offline MikeWilliams

Bogie design
« on: May 29 2012 11:35 »
On another thread John Witts commented on the G3S's steel bogie sideframes and that has prompted this post.  I've made plenty of bogies in smaller scales, but not in Gauge 3, though I'm sure the same problems and principles apply.  Here are my thoughts and I'd welcome comments and suggestions.  This is NOT a kit, but a batch for private use.

The model is a wagon, the wheelbase very short, and the budget tight, so I'm thinking that springing and compensation may not be necessary.  They have plate frames (not flanged like a Gresley bogie).

1. I could etch the whole thing.  Its short, so should be strong enough and it would be easy to include lots of detail (not that there is much!), but it wouldn't be cheap.  It would still need cast spring and axlebox detail and some solid pivot arrangement.

2. I could cast the whole thing in resin, including springs and axleboxes.  I think this would be too weak.

3. I could use laser cut sideframes (like the G3S ones) and add dummy cast whitemetal or resin skins - a bit like the Walsall whitemetal frames.

4. What I am tempted to do is laser cut the sideframe outline, end stretchers and central transom, solder the whole lot up in a jig to form a really solid base, and then add springs and axleboxes.

5. If I do 4, it would be easy to leave slots for the axleboxes instead of just holes, and have them removable with separate keeps so you can get the wheels out - and if I do that it wouldn't be much more work to include working coil springs like model wagons.

What do members think?  Does anyone have solid unsprung and non-compensated bogies?


Offline John Witts

Re: Bogie design
« Reply #1 on: May 29 2012 15:52 »
Hello Mike

I have used your suggested method 3, the bogies work well provided you use sholdered bolts, not locking the sides to the cross member (this has been used in all scales for many years), I also know of bogies of this type made from 2mm plastic sheet and wooden cross member.


Offline keith Bristol

Re: Bogie design
« Reply #2 on: May 29 2012 18:43 »

I am in the process of making a number of bogies, I have the mark 1 bogie here with folded centre frame and ides with roller bearings, I am also making trailing bogies to attach to the dummy sides of my two car unit and also as part of this I am asking my son in law to make a series of identical centre with different laser icut ides to hold the wheels of modern image wagons.

Being modern image person an adaptable bogie is needed. I have literally just st down fom pouring silicone over two bogie sides tonight.... Sticky mess!

Offline cabbage

Re: Bogie design
« Reply #3 on: May 30 2012 07:18 »

I have uncompensated Bogies on my "S" Motor. They are made from the Computer Cabinet equivalent of "Mecanno"and K&S brass sheet.

The bogies for the NER are spring loaded -but the drivers sit on shaped wedges of rubber (actually carved sections of eraser) not unlike an original Mini suspension. I would go for option 4 as my method. But I would use silver solder -or braze it. However most of my chassis frames etc are made from 2 and 3mm thick BMS....

The axles sit in "sandwiches" and are fixed there and the ball races fit into the wheels rather than the axle. It may not be "prototypically correct" -but it does give a nice smooth running system capable of taking sharp curves.



Offline MikeWilliams

Re: Bogie design
« Reply #4 on: May 30 2012 17:01 »
Thanks chaps.  Useful food for thought.