7mm Mk1 castings

Discussion in 'Coaching stock' started by 28ten, 19 November 2012.

  1. Bob Reid

    Bob Reid Western Thunderer

    I've not forgotten you Tom, just as it turned out no time this evening....

    I'm on the case!
     
    tomstaf likes this.
  2. Bob Reid

    Bob Reid Western Thunderer

    Here you go Tom. If you need more detailed dimensions let me know.
    Vent 3.png

    As used on the Later Mk1's early Mk2's....
    ..
     
  3. tomstaf

    tomstaf Western Thunderer

    Thanks Bob,

    They're going to make creating them much easier. To me the shaped looks like a sphere cut centrally and mounted on a thin base plate. Am I right there?
    More detailed dimensions would definitely be helpful please.:thumbs:

    Cheers

    Tom
     
  4. Bob Reid

    Bob Reid Western Thunderer

    What is it you are planning to do Tom?

    Think two semi circular hollow domes, one inner and one outer over the top of a round tubular port, all cast in one piece onto a base curved to match the profile of the vehicle roof, originally in Cast Iron and later in Aluminium. The inner dome sits over the tubular port and is slotted to allow air to be drawn from the vehicle without dust and rain getting in.

    Vent3 cut.png
     
  5. tomstaf

    tomstaf Western Thunderer

    Thanks Bob,

    Must have been a hard one to cast.

    I was more meaning dimensions if you have anymore - eg the openings/cut outs?

    I'm going to draw it in 3D and print some. No one produces one in O gauge and I need plenty.

    Cheers

    Tom
     
  6. Bob Reid

    Bob Reid Western Thunderer

    Apart from dimensioning up the drawing of the full size'd 3D model Tom, what program are you creating the files in? It would be easier for me to redraw it scaled down and send you a 3D file.... It'll only cost you an RMB's worth ;)
     
  7. Dog Star

    Dog Star Western Thunderer

    In cast iron that would be a gravity cast into a sand mould with (probably) a single core... after cooling the core would be broken in place and then tipped out. Not sure how the fettler would break the core around the outside of the central tube sufficiently to ensure all the grog was removed. Bob, were there a couple of holes in the base of the vent which enabled a rod to be poked into the space adjacent to the tube?

    In Aluminium there would be a choice of low-pressure or high-pressure die-casting - more likely to be low-pressure than high-pressure as the sections are thick enough and there is no surface detail. Low-pressure die-casting could have been done in the same manner as cast-iron...

    Which company supplied the Aluminium castings Bob? I do not recall seeing anything like those vents when wandering around High Duty Alloys in the 70s and I had the impression that HDA did a fair bit of work for BREL.

    regards, Graham
     
    Bob Reid likes this.
  8. Bob Reid

    Bob Reid Western Thunderer

    There would be room to poke around the tube via the main port in the base I'd imagine Graham. If he was still alive I'd have asked my dad - he worked for Dewrance & Co. in the 70's (who'd at one time produced amongst other things Guage protectors and Valves for the GWR.....

    As far as the vents Graham - the early cast iron ones came from Derby works - the Aluminium version though may well be the product of Swindon where a lot of BREL's internal casting work was done latterly.
     
  9. tomstaf

    tomstaf Western Thunderer

    Sure Bob. I'm using Blender and I find that most people who print in 3D ask for stl. files.

    Cheers

    Tom
     
    Bob Reid likes this.
  10. lancer1027

    lancer1027 Western Thunderer

    This is a very interesting thread.

    Tom, Will these become available for others and if so basically how much for how many etc.

    Rob:)
     
    Bob Reid likes this.
  11. tomstaf

    tomstaf Western Thunderer

    Yup, that's what I've done with all the stuff I've made so far Rob. Too early for cost etc at the moment. But I know that prints are priced according to the volume of material that is required, set up etc. As it progresses I'll update here.

    Cheers

    Tom
     
    lancer1027 likes this.
  12. lancer1027

    lancer1027 Western Thunderer

    Cheers Tom:thumbs:

    Rob:)
     
  13. Dog Star

    Dog Star Western Thunderer

    We took a couple of EZ MK1 coaches to a recent S7 Group meeting - one bodyshell / underframe / bogies and one with just underframe / bogies so that those interested in the breed could handle the product and examine the fittings attached to the underframe - with an impromptu discussion about the merits of JLTRT, EZ and HJ, sorry David there was no MMP offering on display (nor any Bachmann coach...).

    I was asked about which fittings were from EZ... which from JLTRT... and which from other suppliers. We have replaced some of the EZ offerings as the quality / accuracy is not as good as comparable items from JLTRT, or we have added parts where the part is not supplied with the EZ kit (parts shown in italics). So here is a list of what bits-n-bobs Peter and I are using with the basic EZ bodyshell.

    From CPL:-

    Passenger Communication gear (the "butterfly" and vacuum valve on one end of a coach)

    From EZ:-

    Dynamo and dynamo bracket;
    Battery boxes;
    V-hangers for brake cross-shaft;

    Interior kit as appropriate.

    From JLTRT Mk.1 kits:-

    RCH electrical cables and covers;
    Passenger Door handles;
    Water tank filler and pipes;
    Water tank overflow;
    Fire extinguisher;

    Buckeye couplings;
    Steam Heat / Vacuum Brake pipes;

    Regulator Cradle / Regulator / Fusebox;
    Distribution Fusebox;
    Vacuum Cylinder from JLTRT GUV kit;
    Vacuum Cylinder Trunnions from GUV kit;

    From JLTRT Mk.2 kits:-
    Brake Distributor and the spirax air valve;
    Buffer Beam Air Brake & Main Reservoir pipes and valves.

    Air Brake Cylinders / Actuators.
    Main Air Reservoir.
    ETH cables, connectors and sockets

    The parts from JLTRT Mk.2 kits are required because our models are to represent dual brake / dual heat Mk.1s in the late 1980s era.

    Why GUV fittings? Interesting question... the vacuum brake cylinders in the JLTRT Mk.1 passenger coach kits are of the "rivetted" cylinder whereas the equivalent in the GUV kit is the "welded" cylinder and we feel that the welded cylinder is more appropriate to our "period".

    Why change the vacuum cylinders at all? Partly because the JLTRT offering is a better representation than the EZ part. Partly because the EZ part has fixed trunnions and hence, as supplied, the part represents a vacuum cylinder in the "on" position. Partly because the EZ part has "welded" trunnions as per early Mk.1 builds whereas the JLTRT trunnions represent the "bolted" trunnion of later Mk.1 builds. Overall, the JLTRT separate trunnions allow us to represent the prototype with a better appearance than the EZ alternatives.


    So whilst the above seems to be a long list there are still some Mk.1 carriage fittings that are not available from the trade - or if you know different then please provide details. For example:-

    Emergency charging / lighting socket;
    ETH distribution fusebox;
    Sheep's Head drain for steam heating pipe;
    WC outlet pipe.

    regards, Graham
     
    Last edited: 6 October 2015
  14. Dog Star

    Dog Star Western Thunderer

    Eagle-eyed WTers and sleuths of other persuasions may have noticed that I did not mention the DA valve in my previous posting... truth is that I forgot until today and that is because, probably, I have yet to fit a DA to an underframe. There are two options which are easy to obtain:-

    * from EZ, supplied in the kit;
    * from JLTRT, as a bought-in spare.

    Which I use is likely to be decided by the visual appearance of the part and the easy of fitting to the underframe (plus ease of making the connection between the DA and the vac cyl).

    The nicest route is a MMP DA part which comes with a bendable vac hose.

    regards, Graham
     
    Bob Reid likes this.