Seven Models O gauge Duke of Gloucester

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Some months ago I posted some comments regarding the Seven Models DoG on the thread started by Steve Fay. Note it is Seven not Severn Models. Since then I have completed the tender and the loco chassis is on its wheels with the coupling rods and running sweetly. Thought I'd write up the build as there seems to be some interest in how this kit compares to the Acorn Models version.

 

First of all the tender is pure Acorn (Seven Models having purchased a number of kits from Jim Harris on his retirement), but the loco is a completely new and in my view much superior design. The tender goes together fairly easily and if you look on Jazz's 7mm work bench (page 14) you can see the method of construction. I pretty much followed the way Jazz built the tender, although thanks to some  comments in his  thread, I was able to modify the  fitting  of  the  tender sides to allow the bottom edges to fit  under the top plate on the  chassis rather than on top of it, in line  with the  prototype. Thanks to Jazz for the heads up on that. However, I made one or two changes and additions to hopefully improve the appearance.

 

First of all, the lifting hooks in the bunker were moved to the rear of the front bulkhead instead of the bunker sides as in the instructions.  A couple  of reinforcing  brackets were added on the  inside  of  the  left hand side plate, a representation of  the  slacking pipe added above  the  coal space  doors on the  rear of  the  front bulkhead, and  tender tank vents fabricated from waste etch and fitted to the inner rear bunker  sides. The ladder at the rear of the tender was set in a lower position, and the grab rail on the tender back plate lowered, to allow the upper lamp bracket to be fitted lower down.  This will allow the fixing of a BR1E tender plate, when sourced from Guildplates. Additional detail associated with the coal pusher, was also added behind the rear bulkhead on the coal bunker.

 

The two lifting brackets on the back plate were remade with 6 rivets as opposed to the 8 on the etched pieces. I’m not normally a rivet counter but 33% more is a bit much on such a small part. That said I also noted that the number of rivets on the back and side plates is not prototypical, but that did not concern me. What I did not like, was that the first three rows of vertical rivets on the sides, run up too high and meet with the double row of rivets on the curve at the top. The top four rivets on these rows were therefore not punched out. The double row of rivets on the top curves are also incorrect, as they are spaced too far apart, and therefore there are less than there should be.

 

A couple of grease boxes and  piping were added to the chassis side frames behind the  front footsteps and  the water level gauge scratch built  and  added to the  tender front  on the  left  hand side. On the underside, the chassis frame cross members were fixed to the inner chassis via some brass rodding (which is not visible from normal viewing angles) which allows the chassis to be removed. I see on Jazz’s build that he added these also, but I cannot tell how he fixed them. From building  the  Acorn BR1 tender some time ago, I know that the  instructions suggested soldering  them to the  tender  frames which would have  locked  the  chassis in place.

 

There are one two two bits and pieces to be  added to the front  buffer beam but  I’ve left  those  until the  loco is  at  an advanced stage so I can check clearances on bends.  Here are some photos of the build so far.       

[JeffP]

Interesting.

I've been waiting for this one to start.

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Moving on to the loco chassis, the two main differences compared to the Acorn kit are that the rear frame extensions are incorporated onto the main frames (albeit as a laminate), as are the leaf springs. You also have to add three laminated etches to the springs to build up the thickness and provide the detail on the outer surfaces. Personally, I much prefer this approach to white metal castings. Also beam compensation is catered for between the rear and middle diving wheels. The motor gearbox(ABC/Maxon)will have to go on the rear axle so I'm not sure how that will work with the axle being compensated. One small problem encountered was that the brass rivets provided to fit the compensation beams are too small for the holes in the beams and the frames. I overcame this by using a filed down 6BA cheese head bolt after reaming the holes to fit. It is important that this is a precise fit so that there is no forward and backwards movement of the beam. The chassis is quite a complex set up but there are 3 diagrams and extensive text in the instructions which take you through the steps. My brother has an Avonside Works chassis jig which I used to assist in the construction. It was particularly useful in assembling the coupling rods which I will come to later. Here are some pics of the chassis frames showing the the axle bushes and compensation beams, the laminated rear frameextentions and the laminated springs.

[woodyfox]

Very neat, very clean, impressive - This will certainly have a 'presence' when built - can't wait for updates....

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Thanks. I tend to clean up a lot as I go along but it does take more time. In otherwords I'm a slow builder.

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The coupling rods are made up of three laminates and come in two sections which are designed to pivot on the centre driving wheel crank pins. Pivoting on the centre crankpin will work, but I have found that using this method with a triple laminate, wears groves in the crankpin over a period of time, so I don’t use it any more. Where the rods are designed like this I prefer to modify them so that the “knuckle” joint behind the centre crankpin hole can pivot as per the prototype. To do that you need to cut the middle laminate of the rear coupling rod just behind the where the prototype joint is. The piece with the centre crankpin hole and the joint is then soldered between the inner and outer parts of crankpin hole for the centre driver on the front part of the coupling rods. The difficult part is drilling the hole in the forked joint on the rear rod and the “knuckle” on the front rod. It is critical that the spacing between the holes for the middle and rear crankpins remains the same as the driving wheel spacing. If this changes then the wheels will not rotate freely, if at all in extremes. Although I have done this before without the Avonside jig, it was so much easier to do it with this excellent tool.

It sounds complicated so let’s see if I can explain the sequence with some pics. First of all I placed the rods over the crankpin extensions on the jig (which were still set to the spacing of the axle holes after using the jig to erect the frames. They were a perfect fit so now we know that in theory, as long as the spacing remains the same the wheels should run smoothly with the rods in place.

Next I soldered up the 3 laminates of front part of the rod with the middle laminate of the rear part. Here’s what that looked like.

[JeffP]

Nah.......keep it clean, keep us interested.

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Ok,this is the right hand coupling rod. To the right we have the 3 laminates of the front rod, tack soldered to the middle laminate of the rear rod. Above that is the rear inner laminate and below that the rear outer laminate. Now we cut the rear rod just behind the knuckle joint and now have this.

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Next thing is to mark the centre of the outer fork joint for drilling the first hole. (the centre of the circle at the right hand end of the lower laminate) It is not critical if the hole is not exactly in the centre because we will only drill the hole in the knuckle joint and the inner fork when the rods are in place on the jig.

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I then removed 1mm from the front end of the middle laminate to allow clearance for the rods to pivot without binding when complete. The rods are then put back in the jig, squared up, clamped and tack soldered. Remove, solder fully, file clean and polish. Put back on the jig and carefully drill through the out fork into the knuckle. Remove again, place on a flat wooden surface to support the inner fork and drill all the way through. Ream the holes to match your chosen pivot bolt, clean up and smooth. Put a smear of Vaseline on the fork, add the bolt and solder on the inside. Trim back, file flush and oil up. Now we have the completed rod. Check it still fits on the jig perfectly. Turn the jig around and repeat for the left hand rods.

[Grovenor]

I think I would have drilled through the 3 laminates on the jig whilst the rods were in the 12:27 state, ie before cutting the  centre laminate, this would help hold everything solidly while drilling wouldn't it?

The knuckle joint pin can then be soldered solid in the centre lamination before the rear rod laminations are assembled, this works well in 4mm at least.

Keith

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Whoops! Wrong photo. Anyone know how to delete them? Here's the completed rods in place with a few more views of the chassis. After reaming out the holes to clear the crankpins slightly and oiling up, it runs freely. At this stage I spend some time pushing the chassis back and forth on a metre length of track to "run it in". I do not use the motor for running in. Only when the chassis will run freely down the length of track under its own weight on a slight incline am I satisfied.

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I think I would have drilled through the 3 laminates on the jig whilst the rods were in the 12:27 state, ie before cutting the  centre laminate, this would help hold everything solidly while drilling wouldn't it?

The knuckle joint pin can then be soldered solid in the centre lamination before the rear rod laminations are assembled, this works well in 4mm at least.

Keith

Hi Keith, there's more than one way to skin a cat. Your way sound feasible also, but I had no problem with the approach I used.

Cheers,

Peter

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One thing that did catch me out for a while is that the rear frame spacer is tapered (narrower at the back) so that the frame extensions joggle in slightly. There is no mention of that in the instruction and it had me scratching my head for a while. I guess the idea is to give some clearance to the pony truck wheels on the curves.

 

I got the bogie completed also. It is quite straight forward and the only change I made was to add a captive spring to the elongated pivot hole to keep the bogie down on the curves. The bolt screws into a captive nut in the spacer between the cylinders. The instructions suggest doing it the other way around, but it I think is easier to attach the bogie using a screw driver than putting a nut onto a bolt and turning.

 

Here's a photo of the rear spacer, the completed bogie and also the part built rear truck. The rear truck is a big improvement on the Acorn one being of etched construction, and designed with a screw in frame for the wheels so that they may be removed if necessaary.

This is as far as I have got so far, so won't be posting for a while.

Cheers,

Peter

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I took somw pics with my camera of the etches and cast parts before I started the build but the files are too big to upload. Just worked out how to resize them so thuoght I see how it looked in the forum.

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Above are some some of the etches for the tender. I'll posy some more when i get them resized.

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Ok, better late than never. Here's the full set of etchings, cast brass, nickel silver and white metal parts. Plus the wheels. I still have to get the ABC gearbox and Maxon motor I intend to use.

[N15class]

As far as mounting the motor on a moving axle, all I do is make sure there is no side play on the axle, then fix a 0.7mm wire from a hole in a frame spacer and either a hole or handrail knob mounted on the gearbox. This acts a torsion bar and stops the motor rotating but lets it move.

 

The wire on my LBSCR A1 can be seen between the left hand and centre drivers, this is on a fully sprung chassis. It is only about 25mm long but gives plenty of movement with little rotation.

 

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Thanks for the comments. I have a similar set up on a Connoisseur Jinty and that runs very well. The difference, is that I will have to drive on the rear axle. Not sure how well that will work but will give it a try.

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Managed to do some work on the trailing truck this afternoon but did not make too much progress. Unfortunately, the cast coil springs are too large in diameter so decided to replace these with copper wire wound around brass rod. I used copper as it is easy to coil around the rod held and turned in a pin vice. I then removed the coiled brass from the rod an ran solder along its length. This to keep the coil from distorting when cutting into 4 suitable lengths to represent the springs. These then needed filing to the correct length and 4 suitable lengths of brass rod prepared. I'll post some pics when I get the chance.

 

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Got the replacement springs made as per the attached pics. The first one show the new springs and brass rod insert. On the right is the cast brass spring included with the kit. Looks nice but far too thick. Got the springs in place along with the cast cross beam above. The castings for the axle boxes were also fettled up but ran out of modelling time.

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Back tracking to the tender, I noticed on some photos of BR1D tenders that they do not have the 2 double rows of rivets on the side curve near the front on the right hand side. On the left hand side the rivets are to fasten some reinforcing brackets inside the bunker, which I guess is to strengthen the side at this point. On the right hand side they are not there on the BR1E tender either, which I guess is due to the fire iron tunnel offering support, so the brackets are not needed. I'll press these out as best I can then file smooth.

[Sandy Harper]

I do like your spring imprvements. Neat.

Sandy

[JeffP]

What tender will you be running?

 

Didn't DoG run with the sole BR1J?

 

And yes, those springs are excellent. Far nicer than the cast ones. Just a shame they don't work............LOL

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I do like your spring imprvements. Neat.

Sandy

Thanks Sandy. Been looking at your S15 build. I know nothing about S region stuff apart from rebuilt Bulleids, but it looks a quality build. Look forward to seeing it finished.