Newman Miniatures Crampton

[TangoOscarMike]

Many many years ago, aged about 12, I had an extremely vivid dream in which I unwrapped a Christmas present and found inside a model locomotive. It was something old-fashioned, having a single pair of enormous driving wheels with delicate spokes and intricate coupling rods and valve gear. Such things were not at all to my taste at the time, but nevertheless I was extremely happy with this present, even after I woke up and realised that it wasn't real.

 

This is not the fulfilment of this dream, but it is something similar. These are the parts of the Newman Miniatures 00 LNWR Crampton:

 

 

 

At first glance I am delighted with these pieces - considering the limitations of Shapeways' "White Strong and Flexible" plastic, there is some awfully fine detail here.

 

I'm a little out of my depth with this (and I have plenty of other projects on the go) so I don't expect to make rapid progress. But I'll post pictures here when I do. The first step is to order wheels, I think.

 

[Paul H Vigor]

11 minutes ago, TangoOscarMike said:

Many many years ago, aged about 12, I had an extremely vivid dream in which I unwrapped a Christmas present and found inside a model locomotive. It was something old-fashioned, having a single pair of enormous driving wheels with delicate spokes and intricate coupling rods and valve gear. Such things were not at all to my taste at the time, but nevertheless I was extremely happy with this present, even after I woke up and realised that it wasn't real.

 

This is not the fulfilment of this dream, but it is something similar. These are the parts of the Newman Miniatures 00 LNWR Crampton:

 

 

 

At first glance I am delighted with these pieces - considering the limitations of Shapeways' "White Strong and Flexible" plastic, there is some awfully fine detail here.

 

I'm a little out of my depth with this (and I have plenty of other projects on the go) so I don't expect to make rapid progress. But I'll post pictures here when I do. The first step is to order wheels, I think.

 

I've been looking at those Newman early locomotive printings as well. Must say they are rather tempting! I will watch your progress with great interest, Tom!

[TangoOscarMike]

I'm starting with a plan to put a motor in the tender. On the Shapeways site, @Rudititanic suggests (and provides a chassis structure for) a Tenshodo motor bogie, but also lists drawbacks:

• The wheelbase is slightly wrong
• Limited haulage capacity

But in any case the bogie in question is out of stock at motorbogies.com. So I've been considering other ways to motorise it. Plan A was to use an N20 motor+gearbox with two right-angle shafts, and put the central wheels directly on those shafts. The motor would have to be tilted to clear the axle behind. Plan A wouldn't work because it would bring the motor too low.

 

This is a sketch of Plan B, again with an N20 motor. This doesn't work either because the motor is too long to fit in the tender. And I can't find any other orientation that fits.

 

 

So now I'm thinking of a shaft with worm wheels (driving all three axles) and connected via gear wheels to a motor above it (without the built-in gearbox).

 

I would very much welcome suggestions!

 

[TangoOscarMike]

On reflection, I have a bit more freedom with the motor's position.

 

I'll try a few more variations on this concept to see if I can get it to fit. In fact, if the motor's gear acts on the idler instead of the central wheel, then I'm pretty sure it'll be fine.

 

I'm also pretty sure that I'm mis-using gear wheel terminology.

 

Edited January 18, 2023 by TangoOscarMike

[PaulaDoesTrains]

Have you considered meshing with one of the intermediate gears instead of the gear on the centre axle?

[TangoOscarMike]

9 hours ago, PaulaDoesTrains said:

Have you considered meshing with one of the intermediate gears instead of the gear on the centre axle?

I'm considering it now!

[TangoOscarMike]

Here is an arrangement that I think will fit. The gear wheels are of a type stocked in my local model shop. They have rather large bosses, but I don't think this will be a problem. I've bought an N20 motor (it's so tiny!) so now I must get my act together and buy the railway wheels and the gears.

 

 

[TangoOscarMike]

Instead of the recommended Alan Gibson wheels, I've bought Hornby tender spare wheels - 4 pairs in each case, although that's more than I need. The tender wheels have pin-point axles, which will have to be filed off.

 

 

The locomotive carrying wheels seem to be about right. Fitted loosely like this they (and the drivers) all roll properly when I push it along the track.

 

 

But the axles are 2mm diameter, whereas these slots would accommodate 3mm axles.

 

 

So there is a bit too much freedom of movement.

 

 

I think that I will:

 

• Restrict the fore-and-aft movement with shims inside the slots. I suppose maybe I could try plasticard. I'm not sure.
• Restrict the side movement of the front pair of wheels, either with shims outside the wheel supports ("dummy frames" perhaps?) or with shims inside the axle boxes.
• Not restrict the side-play of the other two pairs of carrying wheels. 

But I would be most grateful for comments or advice.

 

Meanwhile, I'm having a little trouble finding a suppler of gear wheels for the tender mechanism. There are plenty of on-line shops with a huge variety of things that seem almost right. It's a bit of a wearing situation for a procrastinator.

 

[Nile]

Some brass tube, inside diam. 2.0mm , outside diam. 3.0mm or as close as you can get should do the job. Plenty of suppliers on ebay if you cant find any.

[Chas Levin]

1 hour ago, Nile said:

Some brass tube, inside diam. 2.0mm , outside diam. 3.0mm or as close as you can get should do the job. Plenty of suppliers on ebay if you cant find any.

Nile beat me to it - using brass tube would deal with the play but also supply bearings for the axles to run in, so they'd run much more smoothly and safely... 🙂

[TangoOscarMike]

4 hours ago, Nile said:

Some brass tube, inside diam. 2.0mm , outside diam. 3.0mm or as close as you can get should do the job. Plenty of suppliers on ebay if you cant find any.

 

2 hours ago, Chas Levin said:

Nile beat me to it - using brass tube would deal with the play but also supply bearings for the axles to run in, so they'd run much more smoothly and safely... 🙂

 

Thank you both. My initial reaction was that this won't work so well because the axles, bearing against the tops of their slots, are at the right height, and the tube would put them half a millimetre lower.

 

But on reflection, the tube could be cut away where these supports are, or could be wholly inside the inner frames. So I think this might indeed be the right approach. I might already have some suitable tube, but if not my local model shop does.

 

 

[Chas Levin]

Or use a small round file to lift the upper surfaces of the slots? Keeping the tube untouched will help smooth running I think.

[TangoOscarMike]

2 hours ago, Chas Levin said:

Or use a small round file to lift the upper surfaces of the slots? Keeping the tube untouched will help smooth running I think.

The whole locomotive is a single piece of plastic, so the axle boxes make it impossible to get a file in.

 

There is probably an alternative way of abrading away the tops of the slots - perhaps a grinding tool attached to the very motor that I have bought for the tender. But I will avoid that particular rabbit hole for now, while I think about contrivances of brass tube, channel and strip.

 

[MikeTrice]

Would these help? Manufactured by Markits:

https://www.roxeymouldings.co.uk/product/1003/4ma063-axle-bush-for-2mm-shaft-12/

[TangoOscarMike]

2 hours ago, MikeTrice said:

Would these help? Manufactured by Markits:

https://www.roxeymouldings.co.uk/product/1003/4ma063-axle-bush-for-2mm-shaft-12/

Definitely worth consideration. I'll be having the same set of questions again with the tender, as well.

[TangoOscarMike]

I've made a bearing and support, for the front set of wheels, out of brass tube and channel. The tube has cutouts where the axle touches the frames, to prevent sideways movement of this brazen contrivance and to put the axle at the right height. The channel prevents rotation. The tube sticks out past the inner frames, to prevent the sideways movement of the axle.

 

 

 

It's a slightly loose fit, but I hope that with thin shims it will be a tight fit and hold itself in place.

 

 

I'm making two more for the other carrying axles - these will have shorter tubes to permit sideways movement.

 

[Chas Levin]

On 12/03/2023 at 20:42, TangoOscarMike said:

I've made a bearing and support, for the front set of wheels, out of brass tube and channel. The tube has cutouts where the axle touches the frames, to prevent sideways movement of this brazen contrivance and to put the axle at the right height. The channel prevents rotation. The tube sticks out past the inner frames, to prevent the sideways movement of the axle.

 

 

 

It's a slightly loose fit, but I hope that with thin shims it will be a tight fit and hold itself in place.

 

 

I'm making two more for the other carrying axles - these will have shorter tubes to permit sideways movement.

 

Now that is a very good solution! I bet that will work far better than any of the other answers and it'll reward the extra time and effort it will have taken you: top notch! (Oops - no pun intended on 'notch'...).

 

The one thing I'd suggest though is fixing them in place in some way, rather than relying on a friction fit, partly because the two materials - the printed plastic and the metal - will expand and behave differently when their temperatures change and, possibly, under movement too, so you might find that your excellently designed and made bearings work loose or move about. It's also possible that movement of the bearings over time, even tiny amounts, might start to wear the plastic where the metal contacts and moves against it, so that what starts out as a tightly shimmed friction fit may become looser...

[TangoOscarMike]

22 hours ago, Chas Levin said:

The one thing I'd suggest though is fixing them in place in some way, rather than relying on a friction fit, partly because the two materials - the printed plastic and the metal - will expand and behave differently when their temperatures change and, possibly, under movement too, so you might find that your excellently designed and made bearings work loose or move about. It's also possible that movement of the bearings over time, even tiny amounts, might start to wear the plastic where the metal contacts and moves against it, so that what starts out as a tightly shimmed friction fit may become looser...

 

Thank you, that sounds like good advice. Possibly a sturdy plastic strip running up the middle would be appropriate. Perhaps held in place with a machine screw that mates with an epoxied-in nut, because I like to make things that I can dismantle. Hmmm...

 

I'm also thinking of having pickups on the front wheels because (I suppose) the more's the merrier when it comes to electrical contact.

 

[Chas Levin]

11 hours ago, TangoOscarMike said:

 

Thank you, that sounds like good advice. Possibly a sturdy plastic strip running up the middle would be appropriate. Perhaps held in place with a machine screw that mates with an epoxied-in nut, because I like to make things that I can dismantle. Hmmm...

 

I'm also thinking of having pickups on the front wheels because (I suppose) the more's the merrier when it comes to electrical contact.

 

Yep: dsimantleability (is that a word? It is now!) is always good, something I only started to realise on my last couple of builds and definitely where moving parts are involved.

And extra pickups are always good too, particularly with this unusual wheelbase.

 

What's the printed surface like, in terms of smoothness? Do you have plans for priming and painting it?

[TangoOscarMike]

Well, I've just had three weeks without Internet (Vodafone and Telecom blaming each other for the outage), followed by two weeks on holiday. A strange experience altogether. But now I'm back.

 

On 15/03/2023 at 09:22, Chas Levin said:

What's the printed surface like, in terms of smoothness? Do you have plans for priming and painting it?

 

The printed surface is rough and a little bit porous - it takes paint well, without any need to prime. I apply many coats of (tapwater) thinned acrylic, and the build-up of paint removes some of the roughness. Here are some examples (although these are examples of Shapeways' "smoothed" version of this plastic, whereas the Crampton parts are not smoothed):
 

 

 

 

Some people achieve much smoother finishes with several coats of primer and sanding. But as well as being hard work, this approach requires careful handling of the fine detail (or removal of fine detail altogether, with subsequent replacement needed).

 

So I am almost certainly going to take my usual simple approach.

 

[TangoOscarMike]

Meanwhile, I have ordered a print of this, for the tender chassis:

 

 

[Chas Levin]

2 hours ago, TangoOscarMike said:

Well, I've just had three weeks without Internet (Vodafone and Telecom blaming each other for the outage), followed by two weeks on holiday. A strange experience altogether. But now I'm back.

 

 

The printed surface is rough and a little bit porous - it takes paint well, without any need to prime. I apply many coats of (tapwater) thinned acrylic, and the build-up of paint removes some of the roughness. Here are some examples (although these are examples of Shapeways' "smoothed" version of this plastic, whereas the Crampton parts are not smoothed):
 

 

 

 

Some people achieve much smoother finishes with several coats of primer and sanding. But as well as being hard work, this approach requires careful handling of the fine detail (or removal of fine detail altogether, with subsequent replacement needed).

 

So I am almost certainly going to take my usual simple approach.

 

Hello and welcome back to the InterWeb: you didn't miss much!!

 

Very interesting re. surface, finish and so forth, I shall read up those threads...

[TangoOscarMike]

My 3D printed tender chassis has arrived.

 

 

 

The four protrusions are intended to tuck in the corners, and I deliberately left some vertical clearance to be filled with shims. Unfortunately, I enormously overestimated the amount of clearance needed, so the first order of business was to build up these corner pieces by two additional millimetres.

 

 

 

 

 

[TangoOscarMike]

And now a request for advice.

 

I want to paint the wheels, and so I'm looking for ways to mask the tyres/rims. My first attempt was to use masking tape on the whole wheel, then try to cut a neat circle for the hub. This was not so successful.

 

My second idea was to remove the hubs altogether for painting, but they seem not to be removable in these particular wheels.

 

I'm now thinking that if I rotate the wheels (perhaps in a drill) then I could apply some liquid masking agent with a paint brush, and get a fairly neat circle. I'm also wondering if I could use PVA glue as a masking agent, to avoid having to go shopping for the real thing.

 

I would be most grateful for suggestions!

[Chas Levin]

Hello, nice work on the tender chassis!

 

22 hours ago, TangoOscarMike said:

And now a request for advice.

 

I want to paint the wheels, and so I'm looking for ways to mask the tyres/rims. My first attempt was to use masking tape on the whole wheel, then try to cut a neat circle for the hub. This was not so successful.

 

My second idea was to remove the hubs altogether for painting, but they seem not to be removable in these particular wheels.

 

I'm now thinking that if I rotate the wheels (perhaps in a drill) then I could apply some liquid masking agent with a paint brush, and get a fairly neat circle. I'm also wondering if I could use PVA glue as a masking agent, to avoid having to go shopping for the real thing.

 

I would be most grateful for suggestions!

 

Re. painting wheels, I sprayed the wheels - primer and top coats - on a 4-4-2 GNR C2 I built a little while ago and while it took quite a lot of time and work I think the results were well worth it. I note you said that masking didn't work well, but I think it's the only way to be able to spray and it can be done, it just takes some time and possibly multiple attemtps - if you have a look at my post from May 1st 2021 on page 22 from my thread, something over halfway down the page, you can see the various stages I went through to do it and it did take several goes, though I didn't post lots of pictures of the failed ones!

 

Hope this helps...