Slaters MR/LMR Johnson '1262' Class 0-4-4T 7L011 in Scale 7

Discussion in 'Area 51' started by John Walker, 8 March 2017.

  1. John Walker

    John Walker Active Member

    This is my next build for HMRS in Scale 7.

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    As with the Kirtley Goods described here, Slaters MR/LMS Kirtley 0-6-0 Goods (Johnson) 7L007, there is less than no clearance between the splashers especially across the smaller section over the coupling rods. I have sent the O gauge wheels to Colin Dowling for reprofiling with a request to reduce the width as much as possible. When I get them back I can have another look and see whether the splasher fronts will have to be removed from this etch and refitted. I am not sure how far up into the splasher the coupling rod and crankpin extends.

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  2. Scale7JB

    Scale7JB Western Thunderer

    I had to take quite of material off for the Connoisseur G5..

    Not end of the world though..

    JB.
     
  3. Colombo

    Colombo New Member

    John,
    When I decided to build a GCR class 11A, LNER D6, in P4 from a White metal DJH kit, I had a similar problem with getting the wheels into the splashers. I solved it by using Stuarts Micrometer Engineers marking paste. I smeared this blue paste onto the flanges and tried them in the splashers. When I removed them, I could see where they had touched and I ground off the tell tale blue marks with a dental burr. After many repeats I succeeded in obtaining sufficient clearance. It helps that with a 4 coupled engine you do not have to allow for lateral movement of the axles.
    Keep up the good work,

    Louis
     
  4. Ian@StEnochs

    Ian@StEnochs Western Thunderer

    John,

    You can turn Slaters wheels down to very close to scale thickness at the rim but sometimes it can be difficult getting the boss to size without spoiling the spoke profile. The crank pin bushes, if using the Slaters ones, can have the flange reduced to virtually zero, just enough to stop the coupling rods from rubbing.

    On my Caley 19 class, in S7, I have zero sideplay on the front splashers but inside the side tanks the sky's the limit, well not quite but you know what I mean. The motor drives on the 2nd axle and the whole assembly can slide sideways. The bogie is on a fixed pivot just in front of the first axle with plenty of swing at the rear.

    Ian.
     
  5. Scale7JB

    Scale7JB Western Thunderer

    Good thing with this kit is that it's etch, so you'll see straight away if anything needs taking away..

    JB.
     
  6. John Walker

    John Walker Active Member

    Progress has been slow but prompted by a trip to HMRS next week I have fitted the pickups for a test run. I hadn't realised how much I had done since my last post. The chassis ran first time with the footplate attached on my 6ft long 6ft radius S test track.

    There is no sideplay on the front drivers because of the limited clearance in the splashers and that seems fine. That has allowed me to use Slaters plunger pickups set off from the frames with two of the etched packing washers.

    The rear drivers have maximum sideplay. Slaters pickups don't have enough movement to work effectively in that situation. I soldered double sided PCB to the inside of the frames. 0.3mm phosphur bronze wire was soldered to this and wrapped round in a U to pick up off the treads. There are two on each wheel, front and back. I wasn't sure this would work but it seems OK so far. They will need to be tidied up if all is well next week. The tread is only a little bit wider than the sideplay so they need to be accurately positioned. On the 6ft radius the full sideplay is used.

    I have not included the centering spring mechanism on the bogie reasoning that there must be no resistance to sideways movement because it is so necessary.

    Since I wasn't using the plunger pickup holes for the rear drivers I soldered a rod through the holes to fill them and provide a convenient chassis spacer. My intention is to fit dummy inside motion.

    I will post some more of my activity to date after next week's test.

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  7. Peter Cross

    Peter Cross Western Thunderer

    Just wondering why so much side play on the drivers. It's not particularly long between bogie pin and front driver. Mine was built minimal on the drivers and with the limited side play on the bogie it went through A5 points without a problem.
     
  8. Ian@StEnochs

    Ian@StEnochs Western Thunderer

    Hi John,
    I find that you don't need very much side play on the 2nd axle but it does need to have free movement.
    The Slaters plungers work well when the wheels have no side play but as soon as the wheels move sideways one plunger slacks off and the other increases the pressure. To get over this problem I use a sliding plunger arrangement for the pickups, which moves with the axle and keeps a constant pressure on both plungers. The picture below explains the principle. But further explanation here Simple loco to fill a space!
    In your case the pickups would fit in where your rod spacer is and if painted black will be invisible below your dummy valve gear.

    Ian

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  9. John Walker

    John Walker Active Member

    Ian, I like your elegant solution for pickups. I'll keep that in mind for next time.

    I am working on a nominal radius of 6ft with no gauge widening for running on Dewsbury Goods in Scale 7. Even at that the trackwork is challenging!

    I am in two minds about whether to allow sideways travel on the bogie pivot. At the moment it is not restricted but I don't yet know if any fittings will compromise that. I am mindful of the problem I am having with my O gauge Finney M7 on 31.5mm gauge. There is virtual no room for movement between the balance pipes. Martin acknowledges this in the instructions. However the wheelbase on 1262 is much shorter.

    John
     
  10. Ian@StEnochs

    Ian@StEnochs Western Thunderer

    John,

    My caledonian 0-4-4 tank is a similar size to your loco. It has no side play on the front axle, some on the 2nd, and the bogie pivots just behind the 1st axle. By doing that the rear bogie wheel swing a bit more than they would full size but not noticeable on the model. The rear weight is carried on the centre of the bogie which is 3 point compensated. I had it at the S7 agm a couple of years ago and it ran ok on Dewsbury.

    Ian.