Chuffer Davies

This is the first I've seen of it. It certainly looks fine from this picture. At first glance the only compromise I can spot are the wheel centres. The Dapol Mogul's wheel centres are correct in comparison. Inaccurate wheel centres are my pet hate which is why I spotted them immediately. Sadly this loco is too modern for Hungerford so I'm not tempted. Thanks for showing this. Frank

Hi, apologies for not fully explaining the point I was making.... If the Hornby’s slide bars were positioned correctly then the connecting rod would foul the bottom slide bar as it would on the prototype without the milled slot. I’m not sure which compromise I prefer, wrongly positioned slidebars or a chamfer, neither is ideal. I’m going to attempt to reproduce the slide bar’s slot when I build my replacement EM chassis but I’m not 100% confident I’ll be able to pull it off. If it doesn’t work I’ll go for the chamfer. Frank

As already stated, the reason the Mogul has this problem is simply because the slidebars are too close together. What Dapol have got correct is the relative position of the piston rod (2 inches above) to the centre line of the driving wheels. The Hornby model has the piston rod (incorrectly) inline with the centre line of the driving wheels but the spacing of the slidebars is correct. Frank

Hi, I am still at the CAD design stage. I have all the design for the gubbins in the tender sorted and am now working systematically through the design of the replacement locomotive chassis. I still have to draw up the cylinders, slidebars, crossheads, etc. as well as the pony truck and then I'll be ready to arrange all the components into their respective etch frames before sending it off to the etchers. I have described my design work to date on the Dapol Mogul's dedicated blog so rather than repeat myself here I'll provide the following link to the first entry and then you can scroll a couple of pages to find the 2nd entry. Frank

Whilst the model comes with quite a detailed hand book, no where does it describe how to drop the chassis from the superstructure. I had to work it out for myself but it was fairly obvious when all was said and done. Personally I had to admire the ingenuity of the design particularly the use of the drawbar as a four way electrical connector. Two wires are to bring the current from the tender pick ups, and the other two are the loudspeaker connection running from the DCC chip in the smokebox to the loudspeaker in the tender. The loco is therefore not permanently coupled to the tender. Frank

Hi Sandra/Tony, I'll try and summarise the general reaction to the new Dapol Mogul. In many ways this is an excellent model and the best GW Mogul from the RTR manufacturers. There are one or two disappointments that prevent it from being at the top of the game: The shape of the slide bars has already been mentioned here but to summarise they are too close together and as a result Dapol have chamfered the ends of both the top and bottom slidebars to clear the connecting rod. This was a problem in the prototype which the Great Western got round by milling a slot in the end of the bottom slidebar to clear the connecting rod. I have previous experience of building a Perseverance chassis for a Mainline Mogul conversion and with correctly spaced slidebars I only needed to chamfer the very end of the bottom slidebar to obtain the required clearance. The front of the crosshead is flat and lacks detail. The loco is quite light and so will dissapoint those wanting it to pull anything like prototypical length trains. The gearing is very low (16/1) which makes control at slow speeds a bit 'iffy' and it also results in an excessive top speed. Otherwise there are many positives including dimensional accuracy, excellent detail, nice looking wheels (and centres) and a good paint job. One contributor mentioned a lack of rivet detail on the valances but these could be added with rivet transfers. I look on it as an excellent candidate for Hungerford as the first thing I'll do is throw away the chassis and replace it with a bespoke etched chassis of my own design including utilising my 'motor in tender' system to allow me to completely fill the loco's body with lead. This will get rid of almost everything negative that has been said about the model in one fell swoop. One last point to Tony: The chassis is released by removing three screws, one under the pony truck and two under the cab. The chassis will only finally drop out once you have unplugged the DCC PCB by pulling it out through the smokebox door. I think that about sums it up. Frank

If you refer back to the pictures I posted : you will see that the chassis almost completely fills the space available within the moulded body. There is a small void in the smokebox but this is used to house the DCC connector so would only be available for ballast if the aDCC wiring regime was first modified to remove or relocate the DCC facility to the tender. Frank

That has been available since the 1950's from Marklin (3 rail only), but I can only assume that it was not universally liked because it never became more widely adopted. ..... I think what you are suggesting is effectively what DCC delivers. The DCC track feed I believe is AC but the power supplies are DC so there must be some jiggery pokery ging on iin the command station to convert the DC feed back to an AC supply to the track. No doubt an electronics expert could explain how and why DCC does this. An alternate method might be some kind of remote control system and there is a system currently being developed commercially. This system promotes the use of batteries but I see no reason why the power couldn't come from the track instead. In reality we are spoilt for choice but train manufacturers have understandably stuck to the two most popular systems of DC and DCC and leave it to the dedicated hobbyist to implement any other system they might chose for themselves as well as absorbing the costs associated with them. After all, in the end it is all driven by cost v's benefit as in any other type of business.. Frank

Hi Jesse, that other casting looks like the fire door handle to me. Frank

Hi, no not a typo but an error on my part none the less. I’ve just checked and it’s more like 35:1 for the Portescap unit. So it’s slap bang in the traditional range of gear ratios. Sorry for the error.... Frank

HI Richard, from the picture above it would appear that the crankpin is not fully inserted in the wheel and it is for this reason that it is hitting the crosshead. I suggest you compare it against the pin on the opposite wheel to double check. With regards slow speed running I have been able to check the gearing on mine and it would appear to be an unusually low gear ratio at 16:1. My experence of building kit loco's is that gear ratios usually come in at 30:1 or higher although the Portescap units were more like 28:1 due to the lower revving of the motors chosen for the units. The lower the motor speed the less benefit will be gained from the flywheel and in the case of the mogul the flywheel is quite small in the first place. This is by no means a criticism, just an observation.... Regards, Frank

That would depend on whether you are happy to change the wiring regime? The smoke box is currently used to house the DCC cicuitry. If you did away with the printed circuit board then the there is probably 25+mm depth inside the smoke box where ballast could be added. If you still want DCC you could then put the chip in the tender by re-jigging the draw bar's 4 way wiring to carry the track feed from the wheels to a chip in the tender and then the connections from the chip to the motor. It all depends how brave (or foolish?) you are. Frank

I don’t have a GA drawing for the mogul but do have a drawing for the County 4-4-0. According to that drawing the distance between the inside faces of GW slide bars is 1’4” (5.33mm). I would agree that the Dapol slide bars appear to be too close together which explains the need for the excessive tapers at the ends of their slide bars. It’s still a very good model but it does seem an unnecessary compromise on the part of Dapol. Frank

This is part 2 of my explanation into how I intend to go about converting a Dapol mogul to EM gauge: I took delivery of my 63xx on Monday and as I have no facilities for OO models I immediately set to and invalidated any warranty by significantly dismantling the loco and tender. The tender frames sit in a rebate around the inside of the valance. There are four small screws, one in each corner, that attach the frames to the body and then two further screws that allow the speaker housing to be removed from the top of the frames. Detail is excellent and whilst there are a couple of things to put right on the whole I'm delighted with the tender. In the following picture I have already removed the brass shim pickups from the top of the frames because they were preventing me from taking some of the measurements I needed. The locomotive splits down into three main parts: the chassis, the footplate and the cab, boiler, smokebox assembly. The chassis is retained with three screws, two small ones under the cab and one between the front of the cylinders. It is necessary to remove the circuit board for the DCC chip through the smokebox door opening before the chassis will drop away from the superstructure. As you would expect the bottom of the boiler barrel comes away with, and is part of the chassis's casting. The superstructure comprises a cast metal (Mazak?) footplate and a plastic moulded cab, boiler, smokebox assembly. Once the chassis has been removed this reveals a single screw under the centre of the cab floor to release the back of the plastic assembly from the footplate. There are four small clips that also hold this assembly to the footplate, these release very easily once the screw under the cab has been removed. I still need to study the model in more detail but I do foresee some immediate challenges for my conversion. As far as the tender is concerned I think I may end up retaining the brake hangers because removing plastic from behind the frames to make space for etched hangers will be difficult without damaging the external detail. Fortunately the brakes are not aligned with, and are significantly outboard of, the OO wheels so should line up reasonably well with EM wheel sets. The good news is that there is clearance (just) for a motor inside the tender albeit approximately 0.2mm. The loco is going to be more challenging because the metal footplate curves down to follow the bottom of the cab sheets. This means that the metal of the footplate's rear will occupy the space I need for the universal joint in the drive train. I'll need to think seriously about how to mitigate this but its not going to be insurmountable I'm sure. The next stage is to finalise the components for the tender before taking on the challenge of designing how to install the drive train under the cab of the locomotive. Watch this space..... Frank

8' 6".....

Hi Izzy, Thanks for the pictures. I have to admit the P4 wheels do look superb. Your pictures allow us to compare the new Dapol offering to the old Mainline body. I have to admit that there's not a lot in it, both capture the look of the prototype convincingly. So the Whitbourne chassis was a product of the 80's, I might well have been a customer had I known of them at the time. I certainly built a number of Perseverance chassis around that period. I've looked at the S4 Society data sheets before but the critical measurements for spacing the slidebars are not provided and can not be reliably determined. Your post triggered a distant memory and I remembered that I have a set of P4 mogul wheels (Ultrascale) that were included in a kit I purchased years ago, so I'm going to gauge up a pair with the appropriate crank pins so that I can measure the distance across the faces of the lead crank pins. I'll then add 0.4mm to allow for clearances and this will give me the dimension required between the backs of the cross heads. Thanks, Frank

Hi Izzy, I’ve not heard of the Whitbourne models chassis... There are so many small businesses, it’s hard to keep track of them all. I’ve only designed a replacement chassis for one outside cylinder loco before and not Great Western, but for that I just scaled down the prototype’s dimensions over the cylinders and slide bars. As you indicated this then required the leading crank pin to be recessed to avoid the cross head interfering with the crank pin in EM but as yet I’ve no dimensions for the distance over leading crank pin faces in S4. If you can provide them I can ensure that the slide bars are set far enough apart for S4 even if this means off setting them slightly in the cylinders. The Dapol wheels do look rather good but commercial wheels tend to be too wide causing problems with clearances and so I’ll have to wait and see if they are suitable. I have a set of Ultrascale wheels in stock so these are what I’m expecting to use. Regards, Frank

You beat me to it. That's just what I was going to suggest, albeit that I didn't know about the Mogan Gilbert expansion links. There must be enough room in a Hornby body for significant amounts of ballast especially if you are careful to minimise/optimise the space occupied by the motor/gearbox unit. Best of luck Sandra. Frank

Ken asked me to keep him posted on my progress towards converting the Dapol mogul to EM with the added challenge of locating the motor in the tender so that the Dapol loco's body could be filled completely with ballast to obtain maximum traction. I am still awaiting delivery of my mogul from Kernow but have been advised that it was despatched on Friday so in the meantime I have started doing some preparatory design work in CAD. The intention is to prepare a set of etches for replacement loco and inside tender frames. Whilst I'm doing this principally for my own benefit I will ensure that the design is suitable for any other EM or S4 modeller who might want to do the same thing. The first stage has been to photocopy a set of line drawings for the mogul and to import them into CAD. These drawings have then been scaled so that they are exactly 4mm / ft in the tool. I tend to do a lot of my initial design work over the top of the line drawings so that I can be sure that the components are as accurate as I can make them. In this specific case the burning question is whether I can actually fit a suitable motor and drive mechanism into what is the quite restricted height of the Churchward tender. As you can see from the first illustration, by using a small but powerful coreless motor (13mm x 20mm) as supplied by Chris Gibbon at High Level Kits I can just squeeze it in the available vertical space. Of course, once I take delivery of my model and take the tender apart I may find that there is something inside the body of the tender that will skupper my plans, but hopefully not! This first illustration highlights the planned position of the drive shaft which will sit just below the level of the tender's valance and will be tilted very slightly upwards to align with the back of the gear box on the rear axle of the loco. The drive shaft will be driven through a pair of high level spur gears and will rotate in small ball races attached to the same mounts as the motor. The gearbox in the loco will use the gears from a High Level RoadRunner+ unit but I have drawn up a new frame to house both them and two further ball races in which the drive shaft holding the worm gear will rotate. The 2nd illustration is of the various components that I have drawn up so far for the tender, along with the gearbox frame for the loco. These will be organised within an etching frame once I have all the components prepared. The black indicates where I require metal. The red indcates where the metal is to be half etched down from the top surface and the blue indicates where I need the metal to be half etched from underneath. I'm now going to turn my attention to the replacement frames for the loco. I could use Comet frames but as I've got to do bespoke etches for the tender and gearbox I might as well go the whole hog and do the loco's frames as well, along with what has become the controversial replacement slide bars and crossheads. I hope that this has been of interest (to Ken at least) and I will include further installments as I go along. Regards, Frank

Would I be correct in thinking that this topic has attracted a significant number of those modellers who follow things Great Western on RM Web? Over the last 3+ years I have been a regular reader and poster on but since most of my recent modelling is focused on the club's new LNER layout the main blog I have been following is Wright Writes. This seems to be a focal point for both amateur and professional LNER modellers as evidenced by its 2000+ pages. I may be mistaken but I have yet to find a similar focal point for Great Western modellers on RM Web. Is there a candidate blog already in existence that I'm just not aware of, and if not would there be any interest in a new blog specifically for that purpose? Here's a picture of Hungerford to wet your appetite: Regards, Frank

Have you tried removing the chip and running it on analogue? If the loco runs acceptably under analogue then the issue is with the DCC set up, if not you would be justified in sending it back. Frank

A word of warning. If the slide bars on the Dapol Mogul are made of Mazak then it is highly likely that any attempt to straighten them will result in their destruction. I learnt the hard way on my Heljan 47xx. Frank

Yes very useful thankyou. Not only have Dapol put an excessive taper on the ends of the slide bars they have added an extra (and in my opinion quite un-necessary) bend as well. All very strange as I feel either solution would almost certainly have been sufficient on its own. I believe the three loco types that share the same relationship of connecting rods to lower slide bars are the large prairies, the moguls and the 47xx's. According to J.H.Russell the moguls were a tender version of the 31xx prairies, and the 47xx are effectively a mogul with attitude - an extra set of driving wheels and a very large boiler. GW standardisation in action. Frank

Hi Ken, Yes I remember seeing a picture of the drive mechanism for Guy's 28xx, it was quite amazing in its simplicity but I know it works because I've seen it performing on the Dartmoor scene in the flesh. I have been dabbling with this type of drive system for some of the loco's I'm building for our club's LNER layout. This layout recreates the 1:50 gradient of the prototype location and because of that we need as much ballast as possible in the locomotives to enable them to pull representative trains. This is the system I've developed based around reuse of High Level gears and Markits ball and socket joints. The J1 loco chassis as shown here illustrates how it is possible to contain the gearbox completely within the frames of the loco. Unfortunately the motor and gears as I've designed them are much too tall to fit in a Churchward 3500 gallon tender and so whilst the concept is right I will need to rethink how to shoehorn a similar system into the lower tender. I think 13mm is about the maximum height available above the tender frames so I'll plan to use one of Chris Gibbon's coreless motors. If I manage to successfully design something suitable is this something you might want to use yourself Ken? Regards, Frank