GWR Steam Railmotor Chassis

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Re: GWR Steam Railmotor Chassis

Postby dal-t » Mon Sep 11, 2017 2:24 pm


Thanks for the 'encouragement', I might at least take another look at the actual etch - although, if Jeremy isn't too pissed of with us for hijacking his thread, I'd still be very interested should an updated supplement became available (I understand the 7mm version has been greatly 'improved'). Meanwhile, any time you're ready to reveal your cunning plan for tackling the glitches I'll be watching out for it. As for the finish, I agree Peter G's looks very nice, but having just made a right pig's ear of a David Geen 50' full brake (22 panels per side, plus doors and duckets!) I'm going 'back to basics' with a couple of 6-wheelers before I attempt anything as challenging as the Railmotor.

David L-T

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Re: GWR Steam Railmotor Chassis

Postby GWMark » Fri Sep 29, 2017 9:12 am

Jeremy, having spoken to you at Scaleforum and seeing your test build I'm really impressed by what you have been doing here. I would certainly be in the market for two or three of the motor bogie etches and the diagram Q rail motor as well. I've now tried three different ways to build rail motors, the Mallard ones are a little crude, but nothing on the NuCast, although the NuCast is the only one that runs for me at the moment, albeit with a mix of NuCast and Mallard motion. The NuCast 70 foot rail motor suffers from being a white metal vehicle that makes it incredibly heavy and not the best looking beast - it works well as a way to make sure track work is well bedded down!

Impressive stuff

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Re: GWR Steam Railmotor Chassis

Postby kelham » Fri Sep 29, 2017 3:36 pm

I'm another who would be in the market for a 'proper' railmotor chassis etch as there's a couple of Mallards in my "things to do if I manage to retire before I go gaga/blind/etc" pile.


Jeremy Suter
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Re: GWR Steam Railmotor Chassis

Postby Jeremy Suter » Sun Oct 22, 2017 8:28 am

Hi David
Sorry no plans for an LNWR one at the moment .

Thanks to every one for showing an interest in having a chassis kit. I am slowly trying to get things right.

With Scaleforum and a holiday over its back to work on the Railmotor Chassis.

My 3rd test etch was received just before Scaleforum but have not started it yet.
I added the OO and EM spacers along with the Gearbox which uses High Level gears on a 54:1 ratio. The brakes have been simplified, as although nice when made up they are so small that I thought 4 pieces in 3mm was a bit much for one brake.


I have not been idle while waiting for the etches to arrive and have now made the masters for the castings on the chassis which include 4 Sand Boxes, 2 Cylinder tops and 2 Boiler inserts.


In this photo I have double sided taped them to the chassis.
The body underframe is in the background with the some more patterns for the tanks and vacuum cylinders on, and on the left are a couple of buffers started. I still need to make springs and axlebox patterns for the 8' Fishbelly bogie which the Gloucester built Railmotors had.


And a distant view of my work room with the project on the bench.


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Le Corbusier
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Re: GWR Steam Railmotor Chassis

Postby Le Corbusier » Mon Oct 23, 2017 8:49 pm


Could I ask who does your etching.
Tim Lee

Jeremy Suter
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Re: GWR Steam Railmotor Chassis

Postby Jeremy Suter » Tue Oct 24, 2017 6:44 pm

Hi Tim
I use PPD to do all my test etching. The production etches I have are with Photo etch consultants

Jeremy Suter
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Re: GWR Steam Railmotor Chassis

Postby Jeremy Suter » Thu Feb 01, 2018 7:37 pm

It seems like ages since I have done any modelling for my self but have finally had some time to play.

The 3rd chassis test etch with wider gap between the wheels and slide bars has been put together and all seems well. The wheels go round with the connecting rods on and the cross head in place. although I have still put the bearings on the wrong way round to keep coupling rods close to the wheels and away from the slide bars so as not foul the crosshead as they go round. Actually the crosshead is behind the crankpin.

I have also used the slightly smaller 3'11" Gibson wheels with a shorter crank throw and the correct number of spokes and there smaller size is not noticeable. Although I have painted the chassis there are none of the castings fitted as I have not had them cast yet.


On this side I have fitted the Union Crank and Combination Lever then attached to the Valve Gland box which needs to move back and forth but the Radius Rod which makes the pivot I got the wrong length on the 1st Valve Gear test etch is not attached.
As you can see on the picture below that the distance between the Reverse Lift Lever hole and the Expansion Link hole is much bigger than it should be .This picture is one of David Brandreths who is also working on my test etches for a second opinion. It shows all the cranks fitted together and the valve gland which is made from a fold up box which should slide in and out along the valve rod. I have tried the full valve gear and it does work but keeping the Gland Box level is not working very well. I have just sent a new Valve Gear test etch to the etchers with a few variations on it to see how I can keep it level by fitting the Radius Rod to the Value Rod.

valve gear_2815[1].jpg

This next Picture shows the MK 2 and the Mk 3 versions together from above to show the different distances between Wheels and Slide bars. You can also see the Valve Gland box between the cylinders and the slide bar bracket. I have also fitted all the valves rods on the opposite side but not fitted the eccentric crank yet as I still want to take it apart to put a motor gearbox in which has been done but needs slight alteration to the configuration to get the gears out of the way of the Brake Roding. Also fitted are a couple of Copper Clad strips for he pick ups.


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Re: GWR Steam Railmotor Chassis

Postby JackBlack » Thu Feb 01, 2018 7:42 pm

I would very much like one of these kits when you make them available.

Thanks, Nick

Jeremy Suter
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Re: GWR Steam Railmotor Chassis

Postby Jeremy Suter » Sun Feb 04, 2018 8:18 pm

While waiting for the new Valve Gear etch to arrive. I have been putting together the second test etch for the Diagram Q Underframe. On the whole every thing has gone together well, there are just a few minor tweaks to put right. Like re spacing the under beams as the steps cross one of them, which as far as I can see they should not. I need too look at the Queen posts as the tie bar is flat not round I have used .6mm rod and this will have to be an etched strip. The steps need to be altered as I have still to add the hand rail for the doors.



This next view shows the underframe sitting on top of the chassis. Tomorrow I will make the first set of mounts to mount the chassis to the body. Also seen in this view are the underframe castings. The gas tanks have no straps on as they are on the etch and have not been used yet. I also have not drawn the levers for the brake rigging yet.


Close up of the steps checking photographs I think all I need to do is add an extension with a hole in to represent a hand rail knob



Jeremy Suter
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Re: GWR Steam Railmotor Chassis

Postby Jeremy Suter » Thu Feb 08, 2018 5:37 pm

Now the Mounts are made.

Firstly the outer solebar bracket was cut from 40thou/1mm brass sheet on the Pantograph milling machine. A plasticard pattern was made at 3 times the size and glued down on another sheet. I use a 3:1 Ratio as working at 12mm :foot scale so that 1mm represents 1 inch which makes an easy conversion from Imperial to Metric.

Being Cut.

Cut Out.

Once all cut out I have drilled one end with a .6mm drill so I can fit a .6mm nickel silver rod through it as a mount.

I could, but have not drilled to fit a mounting spigot to go through the hole in the solebar. They fitted the solebar perfectly so I soldered them straight on.

Now with the posts mounted on the solebar. I made the Under Beams in the same way on the Pantograph Milling Machine from 60thou /1.5mm Brass sheet. These need to be shaped in 2 plains. So once I got the profile they need to be cut along the top and bottom.

Mounted in the tool post of my Boley lathe and the cutter in the collett they can be machined.


After first cut.

Once shaped they need to be drilled and a .7mm drill on the outer and 1mm on the inner holes so that the 14ba bolts fit through and then mounted through the .6mm rods on the body.


Now the beams can be fitted to the chassis and height adjusted with the position of the nut on the bolt and a spot of paint to stop them coming undone.



The chassis can be fixed to the body with either a little bend in the outer pins or by a 16 ba nut.

My intention is to machine the body mounts and have the Under Beams lost wax cast.

Phil O
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Re: GWR Steam Railmotor Chassis

Postby Phil O » Thu Feb 08, 2018 7:04 pm

Fantastic modelling, Jeremy. Those Dean style suspension and mounting parts are a work of art.


Alan Woodard
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Re: GWR Steam Railmotor Chassis

Postby Alan Woodard » Thu Feb 08, 2018 7:45 pm

Outstanding work Jeremy.

Looking forward to it's completion. ( and the kit. :-) )



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Re: GWR Steam Railmotor Chassis

Postby andrewnummelin » Sat Feb 10, 2018 4:39 pm

Fantastic indeed!
Any idea what the minimum radius curve for such a set-up will be? I’ve a long term plan to build 0-4-4ST that had this type of suspension.

Andrew Nummelin

Jeremy Suter
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Re: GWR Steam Railmotor Chassis

Postby Jeremy Suter » Sun Feb 11, 2018 7:52 pm

Any idea what the minimum radius curve for such a set-up will be? I’ve a long term plan to build 0-4-4ST that had this type of suspension.

Thanks Andrew
Very good question. Something I had not yet thought too much about.
placing the underframe and chassis on the only turnout I have to hand, I think it will just go through, but it will not go to any tighter radius and will probably jam at this if I had powered it.

To increase the swivel on the chassis there are a few variables to think of. I have used 14BA nuts and bolts which are a bit thicker than they should be to attach the suspension to the chassis 16 BA or lace pins would be better this would allow them to rock further forward and back.
The Under Beams could be slimmer to allow further movement as the rear one almost touches the brakes when straight. Even the position of the solebar mounts could be a fraction closer to each other. and of coarse increase the size of hole in the under beams to allow further swing.

Its really about how much swing I can get on the inner suspension hangers.

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Re: GWR Steam Railmotor Chassis

Postby essdee » Sun Feb 11, 2018 9:35 pm

That is simply superb, Jeremy.

I can empathise heartily, as I am still wrestling with a Falcon Brass MR Railmotor and trailer; started 2012, shelved 2014 and only recently pushed towards completion.

'You are a braver man than I, Gunga Suter'! Although my MkII motor bogie uses the Falcon sideframes, with modified Mallard valve gear (the Falcon version appeared not to be practicable after shooting down from 7mm to 4mm scale), and has had CSB retro-fitted, I baulked at the vertical motor option, and also at the prototypical bogie suspension. I was actually quite happy with the fabricated (and amputated at the base) bogie suspension bracket that I devised - until I saw what a fantastic job you have made of the prototype arrangement.........

Time pressures now preclude me going back to the drawing board on my build; but what a splendidly high bar you are setting!

In total admiration,


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Re: GWR Steam Railmotor Chassis

Postby DavidM » Mon Feb 12, 2018 12:03 am


Just brilliant Jeremy, superb engineering.
For me, this is what our side of the hobby is all about!


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