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k22009

GNR Large Boilered C1 in 4mm

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I've started preparing 4mm Arrangement drawings of 2 Ivatt's Henry's C1 and George's 2MT Tank. These will eventually be developed for myself into plan drawings as there's no etched kit available to my knowledge, but only once i've acquired all of the castings and misc bits and bobs so that any dimensional changes necessary can be made.

 

The 2MT hasn't been a problem see below shown with High Level Loadhauler+ gearbox and 1428 Mashima motor

 

post-24421-0-07469100-1523386035_thumb.jpg

 

but George's father Henry's C1 is proving to be a headache.

 

Initially i have 2 hurdles to get over.

 

1. The drive wheels at 6'-8 diameter 20 spoke are so close together 6'-10 centres. Fine for full size but for 4mm with over sized Gibson flanges there's no chance of it working, even P4 would be very very tight and getting a pair of brake levers and blocks in between would be impossible.

2. The rear pair of bogie wheels once again is very close to the drivers 5'-3 1/4" centres, it will probably be ok for P4 but OO or EM in which i model the over sized flanges with Gibson wheels mean a clash.

 

So what do i do? There's probably other difficulties i haven't come across yet but these will do for starters.

 

Plan A - Use smaller non prototypical drive wheels say 6'-6 diameter 20 spoke, using these i would still need to open the driver centres up slightly as the flanges would just foul and it would make getting the brakes in a lot easier.

 

Plan B - Use the 6'-8 diameter wheels but move the drive wheels 4 1/2" towards the cab (1.5mm) and move the bogie 1 1/2" (0.5mm) towards the front. Doing this alters the position slightly of the rear splasher interface with the firebox.

 

Plan C??

 

Any advice would be appreciated

 

Dave

Edited by k22009

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I've started preparing 4mm Arrangement drawings of 2 Ivatt's Henry's C1 and George's 2MT Tank. These will eventually be developed for myself into plan drawings as there's no etched kit available to my knowledge, but only once i've acquired all of the castings and misc bits and bobs so that any dimensional changes necessary can be made.

 

 

1. The drive wheels at 6'-8 diameter 20 spoke are so close together 6'-10 centres. Fine for full size but for 4mm with over sized Gibson rims there's no chance of it working, even P4 would be very very tight and getting a pair of brake levers and blocks in between would be impossible.

2. The rear pair of bogie wheels once again is very close to the drivers 5'-3 1/4" centres, it will probably be ok for P4 but OO or EM in which i model the over sized rims with Gibson wheels mean a clash.

 

So what do i do? There's probably other difficulties i haven't come across yet but these will do for starters.

 

Plan A - Use smaller non prototypical drive wheels say 6'-6 diameter 20 spoke, using these i would still need to open the driver centres up slightly as the rims would just foul and it would make getting the brakes in a lot easier.

 

Plan B - Use the 6'-8 diameter wheels but move the drive wheels 4 1/2" towards the cab (1.5mm) and move the bogie 1 1/2" (0.5mm) towards the front. Doing this alters the position slightly of the rear splasher interface with the firebox.

 

Plan C??

 

Any advice would be appreciated

 

Dave

Most of the issues relating to the C1 were covered by the late Guy Williams in his book "More 4mm Engines" published by Wild Swan.

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The preliminary set out for the C1 showing the clashes

 

post-24421-0-94998500-1523395802_thumb.jpg

 

Dave

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Most of the issues relating to the C1 were covered by the late Guy Williams in his book "More 4mm Engines" published by Wild Swan.

 

I must see if i can get a copy.

 

Cheers

 

Dave 

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It might also be worth looking at what the previous kits and the RTR designers have done and what the resultant effect was on the look of the loco. We have examples (I think) of every version on Grantham and they are quite different when you look hard.

 

The WSM one has bizarrely bulging firebox sides and is really only kept for sentimental reasons.

 

The Ks ones look OK on their own. When doubleheaded with a DJH version there's quite a visible size difference - the DJH one is larger in almost every dimension. I know it's too high if built as supplied and it may be stretched lengthways as well.

 

The Bachmann one looks the part, but as I don't own one I've not had the chance to compare it to a drawing and see where they've compromised.

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It might also be worth looking at what the previous kits and the RTR designers have done and what the resultant effect was on the look of the loco. We have examples (I think) of every version on Grantham and they are quite different when you look hard.

 

The WSM one has bizarrely bulging firebox sides and is really only kept for sentimental reasons.

 

The Ks ones look OK on their own. When doubleheaded with a DJH version there's quite a visible size difference - the DJH one is larger in almost every dimension. I know it's too high if built as supplied and it may be stretched lengthways as well.

 

The Bachmann one looks the part, but as I don't own one I've not had the chance to compare it to a drawing and see where they've compromised.

 

Thanks

 

I've just read some of the rather large thread on the release of the Bachmann version a few years ago.

 

It would seem that there has been some compromise in the driver diameter, however, i'm not sure if they have kept the correct profile for the splashers which would look oversized for the the smaller diameter wheel, but with the generally thicker mouldings inherrent with plastic bodies it may look ok. 

 

I will have a play on my pc with various options and see what i think will be the best compromise. 

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I've started preparing 4mm Arrangement drawings of 2 Ivatt's Henry's C1 and George's 2MT Tank. These will eventually be developed for myself into plan drawings as there's no etched kit available to my knowledge,....

 

OT but, as far as I can remember, there was the old Crownline conversion kit which had quite a lot of etched parts to turn the old Hornby Ivatt 2 into a 2MT tank, but it never made the jump into a full kit.

 

Ace Products might do a C1 etched kit (shot down from their 7mm range) but it's difficult to tell instantly as they no longer operate a website.

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Ace products used to do a 4mm one, but I'm really not that bothered about having every version......

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I've started preparing 4mm Arrangement drawings of 2 Ivatt's Henry's C1 and George's 2MT Tank. These will eventually be developed for myself into plan drawings as there's no etched kit available to my knowledge, but only once i've acquired all of the castings and misc bits and bobs so that any dimensional changes necessary can be made.

 

The 2MT hasn't been a problem see below shown with High Level Loadhauler+ gearbox and 1428 Mashima motor

 

attachicon.gif3.jpg

 

but George's father Henry's C1 is proving to be a headache.

 

Initially i have 2 hurdles to get over.

 

1. The drive wheels at 6'-8 diameter 20 spoke are so close together 6'-10 centres. Fine for full size but for 4mm with over sized Gibson rims there's no chance of it working, even P4 would be very very tight and getting a pair of brake levers and blocks in between would be impossible.

2. The rear pair of bogie wheels once again is very close to the drivers 5'-3 1/4" centres, it will probably be ok for P4 but OO or EM in which i model the over sized rims with Gibson wheels mean a clash.

 

So what do i do? There's probably other difficulties i haven't come across yet but these will do for starters.

 

Plan A - Use smaller non prototypical drive wheels say 6'-6 diameter 20 spoke, using these i would still need to open the driver centres up slightly as the rims would just foul and it would make getting the brakes in a lot easier.

 

Plan B - Use the 6'-8 diameter wheels but move the drive wheels 4 1/2" towards the cab (1.5mm) and move the bogie 1 1/2" (0.5mm) towards the front. Doing this alters the position slightly of the rear splasher interface with the firebox.

 

Plan C??

 

Any advice would be appreciated

 

Dave

 

Dave,

 

Locomotive driving wheels could lose up to 2 1/2" from their diameter, through normal wear or through re-profiling, before they were re-tyred. It is, perhaps, not commonly known that the real things had steel tyres placed onto the wheel castings which were replaced when worn! During the life of a wheel tyre it would be re-profiled, from time to time, on a wheel turning lathe, which was done at the larger and better equipped sheds.

 

It is reasonable to assume that similar wear was experienced on the bogie wheels, trailing wheels and tender wheels, though I don't know what the allowable wear tolerance was on these wheelsets.

 

Again, this would allow the legitimate use of slightly smaller wheels.

 

So, your nominally 6' 8" diameter driving wheels could be worn down to 6' 6" diameter and still be serviceable. That would add another 1 x 0.66 mm to the distance between the wheel rims and would probably allow the use of Gibson wheels. I'm not sure where that would leave you with space for the brake hangar attachments?

 

Cheers

 

Mike

Edited by mikemeg

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Thanks Mike,

 

I have had a fiddle around with various set ups and the best i can come up with for now is using 6'-6 driver wheels and opening the centres up by 1 1/2" or 0.5mm. The front bogie has also been moved forward by 0.25mm just to give clearance for the flanges. The flanges on the Gibson drivers are coming in at around 0.7mm which gives and o/d of the wheel of 27.4mm or thereabouts.

 

post-24421-0-39033900-1523470862_thumb.jpg

 

 

Dave

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Thanks Mike,

 

I have had a fiddle around with various set ups and the best i can come up with for now is using 6'-6 driver wheels and opening the centres up by 1 1/2" or 0.5mm. The front bogie has also been moved forward by 0.25mm just to give clearance for the flanges. The flanges on the Gibson drivers are coming in at around 0.7mm which gives and o/d of the wheel of 27.4mm or thereabouts.

 

attachicon.gif2.jpg

 

 

Dave

 

Dave,

 

Opening up the distance between driving wheel centres will clearly affect the coupling rods. So will you just enlarge the holes in these rods to allow 0.5 mm  of extra play or will you remake or modify the coupling rods to the extended wheel spacing?

 

I guess the splashers on the model won't be a problem if they are designed to take the wider flanges of OO wheels!

 

Cheers

 

Mike

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Thanks Mike.

 

Once i'm happy with the CAD drawing of the C1 i'll start dissassembling piece by piece as it were and preparing the artwork for all of it. So the coupling rods/connecting rods will be to suit slightly stretched frames.

In preparing the drawing i have found that the crosshead is some distance from the cyinder with a very long piston rod. The stroke isn't huge by any means as the crankpins are on a 11 1/2" throw. I'm not sure if there was a good reason for this?

 

Dave

 

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Most of the issues relating to the C1 were covered by the late Guy Williams in his book "More 4mm Engines" published by Wild Swan.

 

Just received in the post this morning a copy, so before i go any further i will digest what Mr. Williams did with his build.

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Just received in the post this morning a copy, so before i go any further i will digest what Mr. Williams did with his build.

If I remember correctly, he lengthened the wheelbase very very slightly.

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It's been a while but with time to spare during the last few months i've resurrected the build of the C1. I picked up a copy of Locomotives of the LNER part 3A which gives an excellent history and comprehensive building details which is impossible to extract from the Isinglass drawings. Like Guy Williams i will hopefully use the London Road Ivatt self trimming tender so i'm just concentrating on the engine.

 

Updated plans and elevations with a motor and high level gearbox combo vertically into the firebox. It will also work with the motor horizontal too. I'm in two minds about the trailing wheel, i've shown it as though it were to sit in a slot for the axle which will have tabs on the bottom with wire to stop the axle  dropping out as Comet tender chassis do, the axle will then have be restrained by a pivot rod from the rear spacer which will allow some vertical movement as well as a little side play. The big concern however is the clearance between the bogie and the cylinders. I guess i'll just have to see how it goes. The driver spacing has been opened up slightly to accommodate Gibson wheels.

 

1466285471_gnrc1a.jpg.9781675c4dbc13fc2fa98ac20b136ff5.jpg 

 

I've also laid out most of the constituent parts so that they can be used as templates for cutting out.

 

6474901_gnrc1.jpg.00ee44d29c24d7c011808b8df7046c41.jpg

 

Dave

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I cut the frames from 0.38 thick nickel silver sheet with a slitting disk, piercing saw and files to finish off. I omitted the springs as i'd a few from old Comet etches leftover that i could solder on rather than try to cut these out too.

IMAG5715.jpg.18e837acd5674ff3a6fb62e603bca5e0.jpg

 

The springs were added, the rear driver shouldn't be a leaf spring but i believe they were coiled, however they will not really be seen behind the wheels so this will be fine. If i find some old etched parts in my box of bits i may retrofit them later.

 

IMAG5716.jpg.195ea592ce8ab4beeeb5fc2f0c7ab6ac.jpg

 

and with a strip of 12mm nickel silver flat i made up several spacers. The axle bushes were attached before the spacers. I used the poppy's jig here to make sure the frames went together square.

 

IMAG5725.jpg.6d2372ec1a90c1278af8e253b70c8e93.jpg

 

I'll probably have a look at the cylinder/motion bracket support assembly next.

 

Dave

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Thanks, yes as i mentioned i have some etched coil springs somewhere but have added the leaf type for now, they're shown on the drawing in the post above.

 

 

Edited by k22009

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Thanks Mike, the photos are always a useful resource for close in detail.

 

On with the cylinders and motion bracket tomorrow.

 

Dave

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