Johnster's Comet Colletts

[The Johnster]

Hi Johnster, I’m looking forward to seeing this progress. Just a couple of things to consider: Assuming you are using the Comet/Wizard underdrame decide whether you are going with the flat fold down trusses or replacing them with angle.

Either way I’ve found a bit of scrap etch soldered across the floor where they are etched stiffens things up nicely. Just make sure its not

I’m the way of anything else.

 

Thanks for the tip, Darwinian; you are obviously a decent bloke from the loco featured in your heading!  I hadn't considered doing anything but using the fold down trusses as part of the plan to build the kit according to the instructions.  I can see how a cross-piece in the right place would stiffen the situation, and will be doing this when I get to that stage/

 

Apropos stages, I am now at the 'sides soldered to ends in 2 L pieces' stage after a bit of fettling and piecing together earlier.  Next job is to solder the 2 Ls together and get the roof on; this will be a bit of a relief because the thing will be a lot more structurally strong when that is done.  Given my appalling soldering, I have been superglueing parts together to hold them in position while I solder, a bit belt and braces but it seems to be working fine so far.

[The Johnster]

Hornby's announcement has changed the plan a little, despite the new Collet bowender suburbans being not quite right for South Wales; they're good enough for me!  One of each will be bought and the number of Comet kits reduced to this all third, a flat ended B set, and an A44 auto trailer, which plan will cost about the same and involve a lot less work.  The order of things will be that this coach will be followed by an A44, and then the B set.  My existing antediluvian B set will be retired when either the new B set is completed or the Hornby coaches are available, and I will be looking at using it's bogies under an ersatz A27 from a spare Hornby trailer.

[Taz]

Be careful using superglue when soldering.

 

I believe that if you heat superglue it releases cyanide. This is a great hobby but it is not worth dying for.

[Philou]

@taz

 

Oo-er ..... don't want any of that, thankyouverymuch! Noted.

 

@ The Johnster,

 

Aw go on - just a couple of piccies. You never know, some kind soul may suggest another of doing it and be a cleaner/simpler job. I want/need to learn.

 

Good luck,

 

Philip

[The Johnster]

Be careful using superglue when soldering.

 

I believe that if you heat superglue it releases cyanide. This is a great hobby but it is not worth dying for.

 

I've been wearing a face mask just in case, but the technique is to spot glue to hold the parts in position and apply solder further along the seam/join.  Cyanoacrylate or whatever it's called does indeed contain cyanide, but I am no chemist and do not know if it is in a form that can be released as cyanide; taking no chances, though!  Dying would be counter productive and not progress the build in the way that I want...

@taz

 

Oo-er ..... don't want any of that, thankyouverymuch! Noted.

 

@ The Johnster,

 

Aw go on - just a couple of piccies. You never know, some kind soul may suggest another of doing it and be a cleaner/simpler job. I want/need to learn.

 

Good luck,

 

Philip

Laters, Philip, busy with one of my other lives today!

[melmerby]

The problem is proper locomotives usually have the numbers on the front anyway....

 

 

Jason

Unless one of many LNW classes, that didn't even get them in the BR period

 

Keith

[The Johnster]

The problem is proper locomotives usually have the numbers on the front anyway....

 

 

Getting back to Comet coaches. I had a look through my pile earlier and wondered why I had so many sides. Then I remembered that I bought loads of sides to alter RTR coaches, then found it just as easy to build the kits. I haven't built one for quite a while though. Some of them must be getting on for being nearly thirty years old. 

 

 

Jason

 

Those improper locomotives that did not have numbers on the front in pre-nationalisation days had them on the buffer beams fore and aft, so you can't really get away with this cheat on steam locomotives; diesel and electric locos are another matter.

[The Johnster]

Ok, photos.

 

Nuts glued then soldered to the 'end box', which was then folded up into shape and the end glued and soldered to it.  Side glued on but not yet soldered; in fact the joint seems quite solid as the glue has gone off in the form of a bracing fillet piece, and I may leave it as it is.  I have 2 of these assemblies ready to be glued together and then the roof goes on; we will then have the basic shell of the body.

 

The 'end box' has to stand out proud of the bottom of the actual end by about the thickness of the brass sheet, and it is recommended in the 'Comet Way' instruction to use a piece of scrap from the underframe to hold the end off the work surface when you are doing this job; I just used the entire etch and then put it back in it's bag until it's needed.  

 

The very first job was to drill out the holes in the actual ends that the white metal jumper cable castings will eventually locate into.  The sides are predrilled for handles but not hinges. and I am intending to simply glue pieces of wire into position to represent these.  

 

The roof needs to be trimmed to length and cut to fit before it is attached; this will be glued and soldered when it is eventually permanently put in place, but I want to drill the ventilator holes first so that the whole assembly does not have to be handled during this process.  The kit includes a paper template for the holes, which are off centre; the template also acts as a 'drill steadier' on the convex surface.  'Cutting to fit' seems to involve taking off a short length of the guttering at each end to enable to roof to 'sit' properly on the side/end corner.  

 

There are small tabs left on the etchings where you remove them from the fret, and on the sides which are supplied 'free standing' but were presumably cut out of a fret at one time, which have to be filed off before you fit the parts, the sort of job you can do on the sofa watching the telly!  I cut the ends and end boxes from their fret with a slitting disc in a minidrill

[The Johnster]

The sides do not attach to the end box as I initially thought they did; they are a 'butt joint' to the sides.  This is why I am keen to get the roof on, as the structure becomes much more solid at that point.

[The Johnster]

Actually, to fit the roof, you don't take any guttering off; what I think I should have said is that you remove the flange beneath it to the thickness of the coach's end so that it sits neatly on top of the bodyshell.  I might have a go at glueing the sides and fitting the roof later today, but we are out carousing over the pub later!

 

I likes a good carouse, I does...

[The Johnster]

I've glued the two L shaped sides and end assemblies together, trying to line them up as best I could at right angles by eye.  The next job is the roof. and I've cut it to length (measure as many times as you like and cut as many times as you like so long as you don't cut short) using a piece of gaffer across it as a guide for the fretsaw, then cut it across with it held in a vice.  My favourite vice is drinking, but that's another story...  Again, trying to get as close to a right angled cut as possible.  You then clean up the burrs on the cut end of the roof with a file; this file is going to do quite a bit of work in the next stages!

 

There are two proper measured right angles to work to ultimately, those on the factory cut end of the roof.  When it comes to assembly of the sides/ends unit and the roof, I will work upside down (the work piece will be upside down, not me) (most of the time anyway) and align the sides and end at that end.  I follows that the sides/ends unit will then be close enough to square for jazz at the other end, and I can then trim the slightly off-square and overlength roof down at that end with a file to sit properly on the end.  I've done a bit of filing to correct it's off-squareness already but feel that the final adjustment is best done to fit the bodyshell.  

 

The sides bow in and out a little over the length of the coach, hardly surprising given the thin-ness of the brass and amount of space taken by the window and droplight reveals, but I am hoping that attachment by glue and solder to the roof will cure this.  The roof is clearly the main structural component of a Comet coach, like the keel of a ship, and is a quite solid aluminium extrusion that I am confident will be up to the task.  But the final fitting is going to need a good deal of time and care to get it right, and I am not going to do it until tomorrow at least!  A square and solid bodyshell will, I hope, be the result; this is probably the most critical part of the build, and while it is not particularly difficult, it needs careful fitting as once done it will be difficult to rectify any faults.  The theory is that, once the roof is on and the shell is a reasonably rigid structure, 5 sides of a 6 sided box, I will be better able to file the errant roof end into shape.  I can probably not achieve perfection (apparently, Persian carpet weavers deliberately include a small error in their design, as perfection is only for Allah, and a human achieving it affronts him), but will be happy if it looks right to my view.

 

But the thing is beginning to take on the appearance of a Collett C66/75 coach bodyshell.  Photos tomorrow before I fix the shell to the roof and during the process.  

Edited January 9, 2019 by The Johnster

[gwrrob]

I would now you have cut the roof to length, mark the positions for the vents and then drill them 1mm diameter as pilot holes. Use the sketch in the destructions as your guide. Mark the coach ends A & B so you don't fix it on the wrong way.

[The Johnster]

Advice that I will take, Rob; thank you!  I'll drill the holes but not put the vents on yet; there may be some roughish handling in the offing!

[Steamport Southport]

Unless one of many LNW classes, that didn't even get them in the BR period

 

Keith

 

I did say usually.

 

LNWR and L&Y were special cases.

 

Jason

[The Johnster]

More work done tonight, but having trouble loading photos from iPhone for some mysterious reason; Cloud not working properly.  Anyway, taking Robin's advice, I have drilled the pilot holes in the roof ready for the vents, using the template supplied with the kit.  They look to be in the right place, and, more importantly, in line and evenly spaced. I stuck the template paper to the roof with more gaffer, for no better reason than it was to hand...

 

Then came the clever stuff.  To get the roof to sit properly on the bodyshell you have to cut little notches at the ends of the fillet piece beneath the gutter to which the top of the sides attach so that it will sit between and not on top of the ends.  This was done with a slitting disc; mark the position with a scratch from a file and cut vertically upwards from the bottom as far as, but not cutting in to, the gutter, then slit along from the end until the unwanted metal drops out; what drops out is only a sliver as most of the material you want to remove has been ground to dust by the disc!

 

The roof should now drop in neatly, which mine did!  Turning the whole thing upside down, I then superglued the sides to the roof from the inside, applying a drop of glue in the corners and every other compartment divider position between the windows along the sides so as to leave room for strengthening the think with solder tomorrow when the glue's gone properly off.  As the side is not perfectly straight, make sure you press gently inwards so that it contacts the glue along it's whole length and rubs against the fillet part of the roof; it will be pretty straight once the glue goes off.  Then do the other side.  A dab of glue in the angle between the end and the roof does no harm.

 

You now have a unit consisting of sides, ends, and roof, which is much more solid and less flimsy than previously and looks a bit like a coach's bodyshell.  Mine had an overhang of roof at one end which I removed most of with the slitting disc and filed the rest to shape.  The result is a bit of a relief, square, level, and solid, and I am happy with it so far.  Enough for tonight, though (this was about an hour's work) as I need to read up on the next stage in 'Comet Way' before proceeding further. 

[Taz]

You won’t be able to solder the roof to the sides and ends as normal solder / flux does not work with aluminium.

 

I strengthen my roof / side joins with araldite. If you do the same be sure to leave enough clearance for the glazing.

[The Johnster]

It may be strong enough as it is, but thanks for the tip Brian.  I'll make a decision later today when the glue's gone off, and if it feels a bit flimsy I'll apply more superglue.  This is turning into a very superglued kit and not a very soldered one so far!

[Siberian Snooper]

It may be worth considering a fillet of epoxy resin along the joint. If you can rough up the surface of the Aluminium first to give a bit of a key.

[Budgie]

I stuck the roof on mine with Evostik.

[The Johnster]

Actually, it seems all pretty solid as it stands, and there is no mess around the window reveals to be a nuisance when I come to glazing it, so I'm gonna leave it as it is.

 

Bought a pair of Bachmann Collett 9" bogies for it today, the advantage of these being that they have tension lock couplers (NEM profile, but not in NEM pockets) already fitted at the right height and spacing.  I was about to buy a bag of NEMs, but the pair of bogies was cheaper...

[The Johnster]

Ok, back to work.  Last week was fairly successful, and we ended up with a bodyshell though no floor, as per the photo, IMG.1211jpg.  

 

Having regrouped and collected my thoughts over the weekend, the next stage is the underframe, and I have made a start on this today.  Following 'Comet Way', the first thing to do is to cut the main floor pan out of the fret, and I very nearly messed this up!  The piece is complete with the fold up tab to which the bottom of the sides eventually attache, and I came close to cutting this off thinking it was part of the solebar etch.  I realised the mistake before to much harm was done, and the 2 tabs I cut out have been strengthened with a solder fillet.  The piece is an oblong + shape with a fat centre and short arms when you've cut it correctly, not a simple rectangle.

 

You then fold up the tab to 90 degrees and test fit it to the body.  Mine fitted with a little persuasion and clearing glue from the slot between the sides and the 'end boxes', but left me with an unanswered question.  The floorpan, the main underframe component, is designed to be used with several different kits, and has etched lines showing where it should be cut to length, but none match this coach.  As you can see from IMG.1213jpg, there is a lot of surplus brass sticking out the end.  I assume that the proper procedure is to trim the piece as suggested in 'Way', but there is no mark for it on this coach and I will have to measure a position to cut.  I've marked out the position of the actual outer surface of the ends, but the cut needs to be approx. 0.5mm clear inside the end, so about 0.75 mm inwards from my mark at each end.  I cannot fathom what the marks on the surplus floor are for, unless they are to mark the cut or fold up to a shape for some other kit, in which case where is the mark for my coach?

 

And ten there is another question, about bogie centres.  Various pilot holes are provided on the floorpan for different models, but the instruction sheet that came with the kit sides (not 'Comet Way' instructions) state the bogie pivot centres to be at 39'9" apart, and the innermost pilot holes are for 41'6".  This has to be got dead right, and I assume that I can use the diagram in the sides instructions as a template.  The holes have to be to size for the 2.5mm bolt that acts as the bogie pivot; I read this as a 2.5mm diameter hole first off and am glad I considered this much to large to be attempted without checking what I was doing!

 

So the watchwords for the moment are minor doubt and mild consternation, but I am fairly confident that things will sort themselves out. 

 

When this is done the next jobs are the solebars and buffer beams, then the trusses and glued on bits.

 

Then we start on the interior.

 

 

 

 

Edited January 14, 2019 by The Johnster

[The Johnster]

To update, I've trimmed the ends of the floorplan with a slitting disc to something very close to the correct size, and it fits nicely inside the bodyshell.  Solebars next, but busy tomorrow (later), so not til Wednesday earliest.  Also drilled pilot holes using the underframe diagram's as a template to mark the 39'9" positions.

 

I'm starting to feel confident again, and thank you for the 'Craftsmanship/Clever' rating, Ian.

Edited January 15, 2019 by The Johnster

[sjrixon]

I hate to give this advice at this stage of the build.. But.. I would have done the handrails and hinges on the side while they could be placed flat on the table. I just did a simple overlay of my coach, but it was much easier to work on when it was free to move about, only bringing it all together at the very last stage. 

 

Looking good though. A brass coach is quite an undertaking. 

[The Johnster]

I did think of this, Scott, but decided that I'd better do things in the order suggested in 'Comet Way', at least for my first outing.  I was also a bit worried about damaging such detail while handling the coach during construction, and have held back on fixing the ventilators for the same reason, though I have drilled pilot holes for them.  Once finished, the coach will receive much less handling, which can be more delicate; it'll only have to be occasionally craned shunted in the fiddle yard.  I may radically alter the order of constructing things on future Comets, as my feeling is that my original intention to build from the bottom up, as I reckon the sides/ends assembly would be just as rigid attached to the underframe floor's fold-up tabs, and I would be, I think, more comfortable building the interior with the coach in this condition, as I think I can 'fit' the compartments better that way. 

 

Further update; I have today separated the solebars from the fret and folded them, a faffy job for which I used my small vice.  Tomorrow's job is to attach these to the floor, and solder the buffer beams on, possibly followed by the trusses and the other details, we'll see how we progress.  The footboard is made from pieces of the fret's outer frame, but I can't see how unless one is supposed to solder up a butt joint in this awkward position.  Wooden coffee stirrers may be a better bet.

 

I've also done the first layer of grey undercoat primer on the bodyshell, which will highlight any areas that need tidying up.

[Taz]

The way I fix footboards to my coaches is to drill .5mm holes into the solebar and solder stubs of .45mm wire through. You can then solder the footboards on top of the wire.

Edited January 16, 2019 by Taz