4mm Brassmasters Black 5, 45232

Discussion in 'Area 51' started by Dave Holt, 30 August 2019.

  1. Dave Holt

    Dave Holt Western Thunderer

    I have run into a small problem with the cosmetic frame overlays and the spring and axlebox castings. Whilst I decide what to do, I thought I'd make a start on the body. To this end, I've assembled the base plate and inner sides/back. The fixing arrangements were altered by use of smaller nuts and screw, as these seemed to suit the etched holes and slots better than those specified in the instructions.
    Here's the assembly mounted on the chassis and with the front and back bulkheads just slotted loosely into place.
    BM_Blk5_45284_136.JPG

    BM_Blk5_45284_137.JPG

    BM_Blk5_45284_138.JPG

    The frame/casting problem alluded to above is that the spring and axlebox w/m castings have locating pips on the rear, which do not really match up with the holes in the etchings. I've managed to open out the spring locating holes enough to get them to engage, but the axlebox locators appear to be on a slightly different pitch. I've opened the holes for one box (rear on the LHS) to 1.5 mm to suit the pip diameter, but the centres are different, so the box still does not sit down properly. If the holes are opened further, the edges will be visible outside the castings and it is almost impossible to move the holes in the inner chassis frames because the horn guides are right behind them.
    I wonder if anyone else has experienced this problem?
    BM_Blk5_45284_139.JPG

    The only solution which comes to mind is to file the pips off and simply position the castings by eye.
    Dave.
     
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  2. Dave Holt

    Dave Holt Western Thunderer

    Some further progress has been made and the coal space chute and the front bulkhead have been formed, fitted and fixed. I decided to add some of the smaller details to the front bulkhead before fitting as it was easier to work flat on the bench. The details include the lamp irons and protective cover, water level gauge and a representation of the tender coal spray piping.
    Still quite a bit to do, but it's definitely coming along.
    BM_Blk5_45284_140.JPG

    BM_Blk5_45284_141.JPG
    BM_Blk5_45284_142.JPG

    Dave.
     
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  3. Dave Holt

    Dave Holt Western Thunderer

    Just had a fairly disastrous morning's modelling. Spurred on by recent progress, I decided to fit the half-etched overlays to the tank sides. I started by soldering the front turned in edge and then along the top, working from one end. I noticed that the bottom of the etch was not hard against the inner side so soldered along the bottom. As I returned to the top edge, a bulge started to occur which I could not eliminate. Disaster.
    I then struggled to unsolder the overlay and feared causing permanent and irretrievable damage.
    The only silver lining is that having final detached the overlay, both it and the inner side have cleaned up well without much visible damage, so the overlay lives for a further attempt.
    I'm seriously considering glueing the overlays on next time. What sort of adhesive is best - 5 min epoxy (hard to spread a nice thin film) of 10 second superglue (not much time for adjustment). Do I then solder round the outside edges with lower melt solder or run in low viscosity super glue, bearing in mind there's still some soldering work to do.
    Any thoughts and suggestions welcome.
    Dave.
     
  4. J_F_S

    J_F_S Member

    Hello Dave,

    Sorry to hear you had trouble, but it is sort-of reassuring that even someone of your experience also has issues...

    I would have to be really desperate to use glue. The first loco I built was a Mallard Duke in 1972 and I glued all the overlays using the then-new superglue. One by one they gradually fell off. I still have the loco, but it has all been soldered since.

    I have never attempted to do a tender side that big but have done quite a few tanks sides - like the Finney 51XX - which is also tricky. I notice that the frame you are soldering to has no cutouts in it and I think that is unhelpful because any flux which gets trapped inside has the potential to cause issues later - but you are stuck with it.

    If I had the job to do, I would try a method that would put almost no heat into the overlay - hard to describe - but I just do a series of very light "tacks" at points round the edge until you have done so many that they are continuous. Only when it is fully tacked in that way, gently re-heat a bit at a time until the tacks flow slightly. I would not try to do the job all at once - do a few tacks then leave it all to cool off. Same with the sweating.
    First problem is ensuring that the overlay is perfectly located and completely flat against the side. I would try to engineer some kind of clamp to hold it in place (that is easy to say! It might not be too bad if there are decent cutouts in the bottom of the tank). Needless to say, if the overlay and base are not in perfect contact all over, the job is going to go wrong so avoiding that before you start is key. Obviously, one problem you might have is that the recovered overlay might have stretched a bit so re-fixing that as the last job might be best, once you have "practiced(!)" with the "good" ones... I would also be very worried about how the side and back overlays meet at the back corners - some dry-runs might be needed to know what the right location is.

    Looking at the pics, I think the worst bit is getting the bottom edge right where it meets the bottom plating. For that reason, I would put my first tack in the middle of the bottom edge and make it as light a tack as possible.

    Having got (say) three tacks spaced out along the botton edge and let it cool off, I might go to the middle of each vertical edge and then a couple along the top edge. If you get that far and the overlay is still completely flat and in the right place you are halfway to being halfway there. Then randomly halve all the gaps with a further set of tacks. And so-on. Only when you have no gaps left move on to gently sweating the tacks into a joint. The key for me is keeping the whole job cool - since brass conducts heat better then N/S, it gets hotter and so expands more. Worse, the frame has a greater mass. It would be nice if you could use that fact to create an overlay under tension but I know not how! More likely it just buckles!

    It is a bit hard to explain what I mean by a "tack", but a way of thinking about it, is that they are joint which is so poor that it could be easily broken apart without adding any heat. The way I do them is to have a bit of solder on the iron and some flux on the job, then just very quickly touch the solder to the job and remove it ASAP. The result is a rather ugly dry-joint with no mechanical strength, but it is good enough. Because you are joining N/S and brass it is doubly tricky as the tack will probably take on the brass but not the N/S. After you have these tacks all the way round, sweating them up makes them look a a bit more professional. Again, go a bit at a time and randomly from place to place.

    Just a couple of further thoughts.

    Personally, I would use a tallow flux (like Fluxite). That stuff has a million drawbacks, but it will not rot the finished job if it gets trapped.

    Don't let the job run away with you - if the first tack is not perfect, break it and redo it - after the first few you are comitted!

    Don't be tempted to release a tack by heating it up - that just causes the solder to flow and make it into a strong joint!

    I hope that lot (a) is in some way understandable. (b) is not too much patronising twaddle (c) gives you some ideas you did not previously have in mind!

    If all that sounds like a right royal PITA then I have it about right - I hate the job!

    Good luck and hope it all goes well!

    Best Wishes,
    Howard.
     
    Last edited: 9 June 2020
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  5. Dave Holt

    Dave Holt Western Thunderer

    Howard,
    Thanks for your comprehensive and thoughtful reply.
    I had been thinking about whether I should have started in the middle of the sides and worked out, so that the un-soldered sections are free to expand and contract until they are dealt with.
    I do have a tin of Fluxite but generally only use it for electrical work. For general soldering I use LRM Phosfux 12 which, I'm lead to believe, becomes non-corrosive after boiling off during soldering.
    Dave.
     
  6. oldravendale

    oldravendale Western Thunderer

    I'm no chemist, Dave, but I believe superglue releases cyanide if you get a soldering iron near it. Not a good mix with the hot stick.

    Perhaps one of our chemists will comment.

    Brian
     
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  7. J_F_S

    J_F_S Member

    I hope it has a few ideas Dave.

    I normally use phosphoric acid also, and often in strengths up to 50% at which strength it does not fizz and spit all over the shop!! (at 85% the stuff is almost solid - a bit like lard!)
    But with laminations, it is the bit which does not boil off which is the issue - bearing in mind that we are trying to keep the job cold! (at least for the tacking stage). At the end of the day, I doubt any residue is going to rot a hole in anything, but I have certainly seen examples where corrosion has caused thin laminations to bubble up after a while.

    Certainly, I think getting the order of the job is probably the key to the job.

    But not glue - you would never live that one down!

    Looking forward to hearing how it goes!
    Best Wishes,
     
  8. Dave Holt

    Dave Holt Western Thunderer

    Thanks Howard.
    Phew. My second attempt at attaching the tender side overlays has gone much better and they are now fixed in place to my satisfaction. Despite dallying with thoughts of using adhesives, in the end I persevered with solder but using the approach suggested by Howard. The overlays were held, by fingers, in the correct place and very small tacks made around the edge, starting the the middle, using 145 degree solder and allowing the parts to cool before progressing. I did stick to my normal 12% LRM phosphoric flux, so I hope it doesn't rot away.
    Before placing the overlays, I drilled a couple of vent holes through the inner sides, which might help a bit.
    I might run some low viscosity superglue along the bottom edge as the soldered joints are not continuous along this edge.
    It doesn't show in the photos, but I've taken the sharp corners off the etched beading in the hope of making it look less flat, though obviously not as good as the half round stuff used by some of the 7 mm guys.
    The front platform and a representation of the bunker spray pipes have also been fitted.
    BM_Blk5_45284_143.JPG

    BM_Blk5_45284_144.JPG

    BM_Blk5_45284_145.JPG
    The tender isn't sitting flat on the mat because, before closing up, I fitted some lead sheet inside which was glued in place, but with a nut and set screw for added security. The screw head protrudes from the flat base but misses all the chassis parts so the body sits down properly on the chassis.

    Dave.
     
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  9. Dave Holt

    Dave Holt Western Thunderer

    Today's progress limited to some of the front bulkhead details.
    BM_Blk5_45284_146.JPG

    Dave.
     
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  10. Dave Holt

    Dave Holt Western Thunderer

    Some further progress, mainly on the front bulkhead. Fire iron tunnel, coal space tank vents and front hand rails also attached.
    Just the hand brake and scoop handles to do at the front end.
    BM_Blk5_45284_147.JPG

    BM_Blk5_45284_148.JPG

    BM_Blk5_45284_149.JPG

    Dave.
     
  11. Dave Holt

    Dave Holt Western Thunderer

    The tender body is now finished except, perhaps, for filling in the half etched bend lines at the turn-ins inside the upper sides. I'll use filler if that happens.
    Finishing touches include brake and scoop handles, bulkhead coping strips, vents, scoop dome, filler and lifting lugs on the rear tank top and reinforcing angles and the three lower lamp irons on the rear edge of the footplate.
    BM_Blk5_45284_150.JPG BM_Blk5_45284_151.JPG BM_Blk5_45284_152.JPG

    Back to the chassis, now.
    Dave.
     
  12. dibateg

    dibateg Western Thunderer

    Nice work Dave, I think Howards comprehensive suggestion was excellent, and thats sort of the way I would have tackled it, but a very good point about letting it cool, I hadn't really thought about that too much. I use a citrus based flux and wash the model frequently. It also sits in the water for a while and that must penetrate everywhere and hopefully dilute the acid. After several weeks, they must eventually dry out. Hopefully if there is any corrosion I'll be long past caring when it happens! It looks like the model is nickel silver and of course there are less expansion problems than with brass. Getting big overlays on is always tricky.

    Best Regards
    Tony
     
  13. Dave Holt

    Dave Holt Western Thunderer

    Thanks, Tony.
    Very modest progress since the last entry. The front and rear buffer beam overlays have been fitted, along with the front rubbing block and buffer housings (w/m buffers still to do), rear buffer housings and coupling hook. There will be no shackle as I use Alex Jackson couplings. Buffer heads will be fitted after painting.
    BM_Blk5_45284_153.JPG

    BM_Blk5_45284_154.JPG

    No modelling tomorrow as I'm back working on 35006, P&O, at Toddington (GWSR). First working party since lock-down and loads of risk assessment conditions to comply with.
    Dave.
     
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  14. simond

    simond Western Thunderer

    I’d second the comment Tony made, sit it in water for a couple of days. Possibly even change the water each day. It will draw out most of the residual flux. You can look at it as the modelling is progressing even if you’re at work...

    Atb
    Simon
     
  15. Dave Holt

    Dave Holt Western Thunderer

    Thanks for the suggestion, Simon. A thorough dunking might be in order.
    Not much progress, but the loco and tender are now connected. The loco and tender kits are from different periods of design and manufacture and the adjustable draw bar supplied with the loco is far too long for the later tender. The fault really lies with the tender because the draw bar pivot is far too close to the buffer beam whereas the earlier tenders were about scale in this respect. The more recent tender is not easily modified to correct this aspect, so the only solution was to make a hybrid draw bar using the etched bar at the loco end and a new part, incorporating a formed eye, made from 0.8 mm brass wire at the tender end. It took a couple of goes soldering the two pieces together to get just the right pivot centre distance so that the rubbing blocks touch but allow the required movement between loco and tender. Although the gap between loco and tender is almost scale, the fall plates on the loco do not land on the front platform on the tender, so some further work is required on this aspect.
    BM_Blk5_45284_155.JPG
    Dave.
     
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  16. adrian

    adrian Flying Squad

    That is all coming together rather nicely - it certainly captures the presence of the loco.