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P4ing the Flying Scotsman

The Fatadder



Not really a lot to say on this, other than its a much more difficult conversion than Clan Line was. The big problem at the moment is that there is not enough space inside the splashers to fit the new wheels. Off the top of my head the 'front to front' width of the new wheels is 22mm, the rear and centre splashers have a clearance of 22.5mm between them, whereas the front wheel only has 21.5mm clearance.


I can see 4 possible courses of action:

1) give up - not really an option given that it will take so much effort to rebuild the chassis to get the loco in a sellable condition, unless I could make back what I paid for it this just isnt an option.

2) file out the splashers to get more clearance on each one, by my reckoning the middle and rear splasher are each about 0.8mm in thickness, I hope to be able to reduce this by half without weakening them too much (thus getting 1mm or so clearance on those two axles). The big problem is the lead axle, while the rear/centre splashers are attached to the boiler, the lead one is attached to the running plate (thus a lot harder to remove and less of an indication as to their width. in order to get enough materiel removed I am worried that it will go through the plastic

3) I know that with other wheels Gibsons are often a bit wider than the alternatives, it would be interesting to know the width of the Ultrascale option. The final option would be the Exactoscale product (which from experence are normally a scale width and will fit where other wheels wont. But I doubt they could be made to work with the Hornby chassis

4) which leads to option 4, by far the most expensive option, use the exactoscale wheels along with an etched chassis


For the time being I think the best course of action is going to be to put it all to one side and concentrate on other projects. Firstly I really should find out just how well Clan Line works before starting another large loco, secondly the Hornby A3 chassis has taken a backward step from that in the MN in that they have got rid of the sprung rear axle. This does result in a bit of a worry as to how well a completely solid chassis will run (baring in mind that it has 4 fixed axles). Tis all a bit of a shame really, as I really fancy getting a Castle at some point and that suffers from the same issue what wheels probably wont fit.


Hopefully Gibson will soon have the drivers for City of Truro available and I can get on with converting that instead!


A quick question, just to set my mind at rest. what should the distance be between the outside face of the splasher and the outside edge of the plate it sits on?



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It really is a matter of whether you want to hang onto this particular model or not.


For an out-and-out P4-compatible engine, you're either looking at filing/cutting clearances, or putting it aside in favour of a Martin Finney kit, which has the proper clearances designed in.


Having seen the assembly diagrams for the Exactoscale drivers, my initial thoughts are that they don't look particularly friendly for RTR conversions.....

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PM doesn't appear to be working, so I'll mention here that Comet do a front bogie, SR pattern, 6' 3" wheelbase, which is suitable for a MN. Ref LS11.



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A couple of issues, here.


1) Splasher width. It might be possible to make replacement splasher fronts from thin metal and cutting the moulded plastic fronts away completely. That way you'll gain the full plastic thickness each side. A bit drastic and I don't know if there are beading issues with the splasher fronts on A3's - saw loads but didn't notice that level of detail - only the numbers!!!


2) In my experience, Gibson drivers are slightly narrower than Ultrascale, but the Exactoscale will be dead scale width (but solution (1), above) might obviate the need for this route.


3) I well remember a P4 converted original Hornby Stanier 8F (die-cast with ringfield motor in cab), which simply had P4 wheels packed out with washers and the rigid coupling rods re-fitted. Never saw it derail once - but the track was exceptionally well laid and flat (Pendlebury layout). I think that the narrow "oo" frames allow a little bit of slop, magnified at P4 gauge width, which allows for slight track irregularities. A very accuratly machine made chassis block and a bit of weight help. I would suggest copying the Hornby dummy rear truck wheel idea by having a fixed axle with wheels raised slightly above track and the bottom of the flanges removed. Sounds horrendous, but I've seen an EM converted Britannia done this way and it was barely noticable, in practice. It might be worth raising this issue on the P4 forum, as I know Phil Hall has done several (GWR) P4 conversions, including a Hall (might give ideas for a Castle) and appears to have had great success.






PS. Do I understand from another blog that you were at the leamington show last Sunday? Wish I'd know as i was there too (I live locally) and would love to have said "Hello" - and discuss Clan Line conversion.

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Thanks dave, some interesting thoughts there.


The A3's splashers have got beading around the top edge (would that be the beading issue you mentioned?), and are lined as well, both tasks Im not to happy working on, however this is going to be my backup option if all else fails. Given that I plan on using this as a backup, I have set about attacking the inside of the splashers with a file, so far I appear to have got the rear set sorted (so the middle set will be a pretty straight forward job, needing slightly less plastic removing) the front set is the one thats proving to be an issue.


So far I have removed enough plastic to get it to the width the other two were at when I started, the wheels will now fit in (just wont rotate.) still another 0.25mm needs to come off each side, which I worry will take me rather close to breaking through.


The other problem I have suffered is that in gripping the body to hold it in position while filing, I'm starting to cause damage (one smoke deflector is now half broken off.) not a lot that can be done to prevent it as the details are glued in too well to remove, and light handling just means the file is not effective. Still shouldnt be too difficult to repair when the time comes.....


The final problem I can see is going to be with the balance weights, my first thought had been to etch a set out of 5thou stainless next time I do a test etch (the idea of cutting an accurate semi circle just dosnt appeal) the problem is that I worry this would further increase the width of the wheel (and hence make all of my hard work filing of little use...)


I think I will continue trying to use the Hornby chassis for the time being, and consider a complete replacement

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