Building the Martin Finney A3

Discussion in 'Area 51' started by oldravendale, 10 September 2018.

  1. oldravendale

    oldravendale Western Thunderer

    'ere we go again.....

    As threatened here is the start of my thread about the building of the MF A3.

    This is a kit I bought together with the coal rail tender (built by Mickoo and now to be seen in primer on the Finney7 stand) several years ago from Martin before the concept of Finney7 was a twinkle in anyone's eye. I started it by building firebox, coned boiler part and boiler several years ago. The firebox and boiler were both unsatisfactory for reasons which will now become clear.

    Firebox. This went together rather well, I thought. Except that I filed away the cusps on the armature, strictly not in accordance with the instructions. The result of that is that the coned part of the boiler doesn't fit properly. After discussions with Dikitriki it was clear that, rather than compromise the structure by marginally reducing the length of the firebox it was far better to build up the internal structure, which I've duly done.

    As far as the parallel part of the boiler is concerned, I failed to join that properly with the result that it sagged underneath in the middle. As a result I applied the magic fire stick and separated it all in to component parts and have only now cleaned it all up and reassembled as it should have been done in the first place.

    All this, of course, before I'd attempted the "K", from which I've learned much. I'd also previously built the Martin Finney Radial Tank without any boiler problems so any error was due to my poor technique.

    So..... having made appropriate adjustments this is where I am now.

    IMG_20180910_163658012.jpg IMG_20180910_163711188.jpg IMG_20180910_163725530.jpg
    I'm now satisfied with my starting point. Next I'm about to start the chassis, my normal starting point with any loco kit. It'll be built with full compensation.

    Let's see, eh?

    farnetti, 7mmMick, Rob Pulham and 8 others like this.
  2. Yorkshire Dave

    Yorkshire Dave Western Thunderer

    Is the boiler and firebox in one piece now or still in three pieces?

    If the latter then now's the time to consider the speaker location and subsequent installation for sound.
  3. oldravendale

    oldravendale Western Thunderer

    Still in three pieces, Dave. The front two are screwed together but are designed to unscrew. The firebox is there by willpower and two studs.

    As designed the whole assembly is hollow anyway so the decoder and speaker can fit pretty well anywhere. I'll need to fit some weight, though, and that's my major concern. In fitting the weight I will be aware of the need to allow space for "accoutrements".

    The joy of building this after the "K" is that I know all the parts will fit together and in the right order - if I now follow the instructions.:)

    3 LINK likes this.
  4. P A D

    P A D Western Thunderer

    Hi Brian ,
    Having recently completed my Finney A3 I look forward to seeing your take on it.

    When I ran mine on the test track at Doncaster, if was clear that extra weight is needed if the model is to pull a decent load. I still need to do that but I don't have to worry about chips or speakers.

    Richard mentioned a modification to the cartazzi axle box, using two springs, one either side rather than a single central one which I still need to do.
    Rob Pulham likes this.
  5. SimonT

    SimonT Western Thunderer

    Which give two photo opportunities to get the mod into the instructions;)
    Rob Pulham likes this.
  6. Ressaldar

    Ressaldar Western Thunderer

    Good morning Brian,

    I have been asked to install a sound decoder and speaker into a "Duke of Gloucester", as yet I am still awaiting delivery. In the meantime, I have looked at the kit (Scorpio) drawings to see where as you say, the "accoutrements" can go. I would usually, as you seem to be intimating, put the speaker somewhere in the boiler/smokebox area, but this means that should necessity dictate separating the body from the chassis at a later date, having the speaker wires long enough to allow this to be carried out without too much trouble, even allowing for a miniature plug and socket somewhere in the 'line'.

    Studying the drawings, there seems to be a suitable space for a 'double sugar cube' type speaker to be fitted within the chassis, thus overcoming the 'umbilical chord' problem and also in your case, leaving space in the boiler for the additional weight that Peter mentions in post #4. I should be taking delivery of the model sometime this week, I will keep you informed of what I end up doing.

    kind regards

  7. oldravendale

    oldravendale Western Thunderer

    Hi Peter.

    Thanks for your thoughts. Having run the Bulleid Light Pacific and discovered the need for extra weight even in that loco I've made the early assumption that it'll be necessary in the A3. Of course, the DJH A3 suffers no such problems with weight!

    The cartazzi axle box is something I've not spoken to Richard about. However, the rear truck on the Bulleid Light Pacific is controlled by a single central wire spring and holds the track well. I'll probably build again with the same layout for simplicity and modify afterwards if I find it's necessary. I had to do this on the bogie of an Oakville Black 5 which now has proper side control springing and that went from a "fally offy" sort of loco to one which now holds the track perfectly so I have no doubt that there are circumstances where additional control is desirable.

    Are you incorporating this change to the cartazzi box as a result of problems with the track holding, or simply to ensure that such problems don't arise?


    I will, indeed, be interested in your speaker findings. I used a double sugar cube for the first time in the K and am amazed at the performance. As I have the room in the A3 I may go for something more adventurous this time.

    Every loco I have built to date has the speakers somewhere in the body on a flying lead, joined to the decoder by a mini plug. I find that works for me as I prefer to keep the chassis clear of additional bits and pieces, but I'll never say never.

    In fact my comment about the boiler of the A3 being clear of obstructions is actually untrue. Between the parallel boiler and the coned section is a boiler former on both the parallel and coned sections which acts as the interface between the two. It won't be a problem to cut a slot in that for the speaker cables, though, and if I don't put the smokebox door on the loco until the last knockings I'll be able to get in to the space to install both the required weight and speaker. However, I reckon there'll be room within the vastness of the coned section for speaker.

    As ever thanks for thoughts and advice, and please keep 'em coming.

    Scanlon likes this.
  8. P A D

    P A D Western Thunderer

    Hi Brian,
    I have noted a slight tendency for the inner wheel to lift on curves on my brothers layout which does not give much room for running a loco of this size. From speaking to Richard I believe he had the same issue and told me about the dual spring approach, so perhaps he could add some comments. On the test track at Doncaster it seemed OK but showed signs of wheel spin due to lack of weight. So the answer is, I'm going for belt and braces.
  9. Richard Spoors

    Richard Spoors Western Thunderer

    Hi Brian, I'm not sure if you have access to a lathe. When planning to fit the largest possible speaker in the boiler of the Finney 7 V2 I am building I replaced the disc formers between the parallel and coned sections of the boiler with turned brass rings. These were then drilled and tapped at 120 degree intervals to join the sections together before soldering into one unit. This now gives me space for a decent 2W 8ohm bass reflex speaker. For weight I have used lead sheet. This was cut into longitudinal sections, rolled and once positioned inside the boiler opened out to fit as flush as possible to the inside diameter of the boiler. In this way I have retained a core open diameter of 28mm. The photograph shows the inside of the boiler before I fitted the lead.


    Finney V2 boiler.jpg Finney V2 boiler.jpg
  10. oldravendale

    oldravendale Western Thunderer

    Your approach makes very good sense then, Peter. I'd very much have liked to have seen your A3 at Telford and had a chat about the build.

    Having said that I'm exceptionally fortunate in that I have the expertise of my colleagues in Finney7 to fall back on - indeed, as we all do. I really don't expect any further issues from now on though.

    Richard - thanks for your thoughts. I appreciate your elegant solution. I have access to a lathe. It's in my workshop, is Steph's and I'm waiting for some instruction. The last time I used a lathe was at school, 55 years ago, and I lack the confidence to just charge in and see how much I remember. Nevertheless, that's not the issue as, for the K, I created two circular formers for the boiler by hand. Unsurprisingly it took a while, but worked well, using an arbour in my Dremel and filing the soldered together and coarsely cut out blanks into a circle. In this case for the A3 I'd simply need to cut out the centres.

    However, in my normal fashion I've failed to think a.......head. So the blind formers are soldered in place in the back of the boiler and the front of the coned section. At the moment I'm not inclined to remove them and open out the centres as they are such a good fit and in the perfect position. I may, therefore, do as I suggested earlier and cut out a slot for the speaker wire, leaving the smokebox door off the kit until the last knockings.

    On the K, where I'd created a similar situation, I fixed the smokebox door in place with canopy glue despite the rest of the build being almost entirely soldered. The assembly is not dissimilar to the A3 in that the smokebox door mounts on to a brass or nickel silver boiler former. It's perfectly adequate for the purpose and, as I found out later :oops: can be made to release its bond without damage by simply getting a fine blade behind the edge. After cleaning up it can be glued back in position in the knowledge that, if a speaker change is ever needed I can get in to the boiler with the minimum of damage. It is a rare example of where I actually did apply some thinking before taking action!

    Having said all the above, if you are already familiar with my postings, you are quite likely to find that I've heeded the advice and removed the formers in order to modify them as you suggest......

    Rob Pulham and Richard Spoors like this.
  11. oldravendale

    oldravendale Western Thunderer

    Yesterday was spent, mainly, in research. The frames of A3s are a minefield and while I made some progress I'm now relying on Mickoo to advise te refinements. I found out, though, that 60066 was unique in having a higher can roof ventilator than other A3s after the cab was damaged in an accident. Unless I can scratch build something which looks appropriate it'll have the ventilator that comes in the kit!

    I spent some of yesterday afternoon filing back the cusp on frames and spacers, and also making up the coupling rods ready for fitting the hornblocks. Loco will be fully compensated with split axle pick up (again) from the tender. The holes to lighten the frames and the rivet pattern will be decided when I hear from Mick.


  12. P A D

    P A D Western Thunderer

    Hi Brian,
    Looking good. Brings back happy memories of a very enjoyable build. I must get mine painted.

    The forward upward facing bracket on right hand frame will need a groove filing in the rear edge, or it will foul the flange on the front driver, when you fold it down.
  13. oldravendale

    oldravendale Western Thunderer

    Thanks for the advice, Peter. That makes perfect sense.

    I've nothing to add in the way of photos today - I've done a bit more to file off some cusps, drilled the holes for the compensation and brake hangers and opened up the slots for the hornblocks. I'm seriously considering making the brake hangers from screws so that they can be removed such that the wheels can be easily removed. Mickoo has previously described the technique for the Bulleid light Pacific build which may be transferable to the A3.

    I've also started to build up the hornblocks, so not a lot to see until I start to build up the frames.

    I'm hoping that I'll have the opportunity to spend a few more hours in the workshop in the next week but with visitors for most of next week and the beginning of the following week progress will be slow - again.

    Last edited: 12 September 2018
    jonte likes this.
  14. mickoo

    mickoo Western Thunderer


    Very quickly, as far as I know all the rivets patterns are the same, it's the choice of countersunk of domed. 2565 (nee #66) would......should of been all flush when built, but, and it's a big but, it was built at Darlington and they traditionally used pan head rivets.

    I've a fairly good well lit side on shot of #66 at Grantham in BR blue and it appears the original frames, that which is left, are flush, which in your case is the rear hornguide rivets and all frame rivets aft of that.

    2565 had new frames in Aug/Sept 32 using the then 'new' pattern of frame which was four holes 1'-0" in diameter, I see you've already opened the front ones, lucky for you that you need to do that ;), lot's of engines don't have that front hole.

    However, the new frames are butt welded to the original rear ones right between the two rear lightening holes, so we have a mish mash of oval and round.

    I'll try and make the next step as simple as possible.


    On your frames, open out all the red 'round' holes marked and open out the rear only 'oval' hole (see below). Punch all the rivets from the rear hornguides (but not including the rear hornguides) all the way to the front.

    Now make two patch plates (green), the length of which sits between the intermediate and trailing hornguides, it's height goes to the top of the frames but stops short at the bottom to clear the slot for what I assume is that stay with Martin Finney written on it, should be part F4. Each blanking plate shall have two 1'-0" holes, the front aligned with the rear round hole on the new front section, the rear on the same longitudinal axis and aligned over the oval hole.

    Personally I'd open all holes out to the round profile, make my blanking plates, hold in place and scribe the two hound holes using the frame holes as a guide and then open out the rear hole to the oval profile.

    If you cut a slot in the patch then you won't have to trim the width of stay F7.

    Back to #66, it's a Darlington built engine but does not have the fish belly reversing lever, so use the standard Doncaster straight one one.

    Cab, only the ventilator is taller, the rest of the cab is the same as other engines.

    Boiler, you've got the wrong boiler I'm afraid, the kit only does the 94 variants, you need a 107 boiler, same as fitted to the A4 class, the biggest visual difference is the location and number of washout plugs and the mud hole doors, the upper two on the 94 are in a straight line parallel to the track, on the 107 the leading one is lower.....I have photos if required.

    Get rid of those two tabs on the bottom of the frame and have a word with Finney7 stores and get some of the new intermediate steam fed cast sand boxes, there's also a new cast brass sand trap fitting to go in the base. Get some new front outside gravity ones as well whilst you're there. These are renders as I don't have any of the new A3 or A4 ones to hand, just the W1 ones, they're similar so I can post a photo to show the detail they have if you need.


    If your thinking of not adding the blanking plate....don't, the round hole behind the oval hole really shows between the spokes of the driving wheels, same for the firebox details, I've not seen many 107 boilers, people seem to keep the stock 94 layout.

    Moving the mudhole will be fiddly, you'll need to file the original flange flush and fill the recess, then cut a new one lower and slightly further forward....need to check exact measurements and then add the flange plate back on, I can sneak a couple on my next test etch, though I'm sure I've done some before, but can't recall where as yet.

    Unfortunately that's all I've found this evening, but I will have a longer dig around shortly.

    Last edited: 12 September 2018
  15. Steph Dale

    Steph Dale Western Thunderer

    Ruddy hell Mick,

    That's an amazing level of detail and knowledge :thumbs:

    Well impressed :)

  16. mickoo

    mickoo Western Thunderer

    Thank you.

    Sadly these days I can't remember it all, just where most of it is in books etc :D

    The above is a mere grazing of the closest to hand and there's an awful lot about the A3's still not discovered. Brian is lucky as 2565 frame details are actually listed in detail, many of the other engines are simply left to best guessing on their build date, likely hood of a frame change which was almost certainly carried out on all the original oval hole frames, some of the four hole machines and probably not on the single hole machines.

    It's the oval hole frames that's the hard part as they can be rebuilt with two types of front end, in some cases some engines almost certainly had both types, but failures in the older round 4 hole frames seem rare.

    I still have a super detail A3 in my sights at some point, more for the modeling than the running sort of thing.

    BR Tony, Rob Pulham and Dog Star like this.
  17. oldravendale

    oldravendale Western Thunderer

    That's amazing detail, Mick. Thank you.

    That front frame lightening hole is actually in the etch, so lucky that I chose the correct loco! I'll also take a look at the boiler assembly. It sounds as though the modification won't be too onerous - the trick for me will be making any alterations invisible, but it's been done before.......

    The photo I have of 60051, as described in an earlier missive which then went missing, doesn;t quite match your description, but as yours is of the loco I'm building it has to be right, so thanks for that too.

    Yes, creating the flange plate will be tricky, so if you have space on a test etch it'll be much appreciated.

    Rob Pulham likes this.
  18. mickoo

    mickoo Western Thunderer

    Which part of 60051 doesn't match, it's possible they have different details but I'd be interested to know what's different and if I wrote it, I'm not unknown to be wrong so it'd be nice to double check.
  19. oldravendale

    oldravendale Western Thunderer

    Hi Mick.

    Here's the photo of 60051. What do you reckon?

    (Not my copyright and reproduced purely for research.)

    BR Tony, 7mmMick, Dan Randall and 2 others like this.
  20. Peter Cross

    Peter Cross Western Thunderer

    Now that saves lots of work. No boiler, firebox or smoke box to build.