Bachmann B1

davebradwell
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Re: Bachmann B1

Postby davebradwell » Sat May 30, 2020 8:57 pm

The Thomson A2s are just too long for my curves - the A1 is bad enough. Can't think what they'll look like on standard 00 layout. Anyway Chris P has done both of them so no point. We've nearly got an A2 test etch if I can manage to interface ancient cad system to new etcher.

No V2 either once I've finished my Finney.

DaveB

DougN
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Re: Bachmann B1

Postby DougN » Sat May 30, 2020 10:17 pm

I have wondered about some manufacturers of etched kits and the way it may be possible to just do chassis etches. I have even heard of a professional loco builder saying, of the Finney A4, build the chassis and match it to a hornby body as he and others couldn't improve on the RTR. The V2 is a case in point the chassis bits are mostly on 2 main etches but there are details spread through out the othe 3 body etches. So the possibility is a non starter unless there is an experienced cad draft who is willing to do all the cutting and pasting into new layouts which would be doubtful if the number of kits sold would repay the effort and cost.

DaveB I am surprised that the etches can't upgrade the CADs to the latest. I know the architects I am dealing with have placed all the files as dwgs but are using rivet. At uni I used CAD but I think it was very well set up but I would have no idea today!
Doug
Still not doing enough modelling

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barhamd
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Re: Bachmann B1

Postby barhamd » Sat May 30, 2020 10:33 pm

Once again, thanks for that Dave. I'm aware that it is often hard to get the balance between 'teaching grandmother to suck eggs' and 'presuming the builder has made one before', please don't take my dumb questions as criticism. I'm also aware of the likelihood of unwittingly causing offense online by not using the right words on forums...

After some fiddling the alignment between the radius rods and the valve spindles is much better and I've worked the joint and given myself more movement (but not more slop). I also soldered on the cylinder covers which finishes things off nicely.

I have been using a jig with vertical holes drilled in it. It does make the assembly very much easier.

I think I understand your instructions re; the return crank, have I interpreted them correctly?

IMG_8011b.jpg


Thanks
David

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Horsetan
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Re: Bachmann B1

Postby Horsetan » Sat May 30, 2020 10:51 pm

davebradwell wrote:....We've nearly got an A2 test etch....


Believe me, I've waited a long time for this.
That would be an ecumenical matter.

davebradwell
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Re: Bachmann B1

Postby davebradwell » Sun May 31, 2020 9:19 am

We're getting there - make a single bend near the end so that the bent end meets the rod at an angle and forms a but joint and leaving the fork clear. The external fillet of solder to be smoothed to make the flowing curves typical of motion. The drawings attempt to show this.

I trust more movement=amount of movement shown on diagram. Getting enough free movement in the joints is fundamental to success.

I think the knack with kits is to think ahead to the next bit - so by thinking that the eccentric rod fork has to fit the expansion link tail you would see that 0.7 is too wide (it dates back to mk1). Front of radius rod fits combination lever so 0.7 here is correct. I don't build many of other people's kits but certainly have to adapt my thinking as I don't have that vision of the whole that comes from designing the model. There's more chance of a surprise.

Can't say I remember what the other part25 is for - possibly an alternative for the eccentric rod in case of over-etching. Use it if half etched bit is too short.

I'm told the way to assess an A4 model is to note where the valence curve is highest and the r-t-r bodies fail here. They also make some errors on the front view. Apparently, the way to success is to get a copy of the boiler cladding drg and not base the shape on the GA which isn't meant to convey such subtleties, rather to show fitters where to put the boiler, brakes and all the other bits.

If there's an expert with Bentley Microstation 1995 out there, why doesn't it export recognisable filled lines? Previous etcher required open lines so ok so far.

DaveB

Crepello
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Re: Bachmann B1

Postby Crepello » Sun May 31, 2020 10:11 am

davebradwell wrote:I'm told the way to assess an A4 model is to note where the valence curve is highest and the r-t-r bodies fail here. They also make some errors on the front view.

None of them has so far matched Martin's powers of observation of the smokebox doors either. Even the most exotic r-t-r have the doors flat in the transverse direction, whereas Martin incorporated the subtle bow at the lower hinge line, easing progressively out to straight at the top hinge line. Hornby's CADs for the W1 rebuild show they haven't as yet cottoned on, despite full-scale Bittern being 'downstairs'.

davebradwell
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Re: Bachmann B1

Postby davebradwell » Sun May 31, 2020 10:30 am

It's because they all start with the wrong drgs. I'm told there was also a drg prepared showing all the frames - all dimensioned of course - that were attached to the boiler first but this hasn't turned up. They were an engineering job and should be fully defined by numbers on paper, although I wouldn't be surprised if there were some blocks of wood at Doncaster for forming the buffer housings and the like. I once stumbled across the thread on RMweb about the shape of the then proposed 0 gauge rtr A3 and A4 and no mention of searching lower levels of drgs. They may have come close by eye but what hard work.

DaveB

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Re: Bachmann B1

Postby davebradwell » Sun May 31, 2020 10:32 am

Just to add that Martin used the boiler clothing drg.

DaveB

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Re: Bachmann B1

Postby Crepello » Sun May 31, 2020 1:54 pm

davebradwell wrote:I'm told there was also a drg prepared showing all the frames - all dimensioned of course - that were attached to the boiler first but this hasn't turned up.

If you mean the crinolines, then I have a copy! Think I got it from NRM.

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barhamd
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Re: Bachmann B1

Postby barhamd » Sun May 31, 2020 10:34 pm

I made a lot more progress today thanks to Dave's pointers.

I made up the return cranks and the eccentric rods and tried fitting them, I was pleased it was relatively straight-forward.
After not too much fiddling I managed to get the cranks moving smoothly and much to my amazement things go round and round and backwards and forwards as appropriate.

IMG_8012a.jpg


IMG_8013a.jpg


IMG_8014a.jpg


The return crank is actually at a the right angle, the first couple of photographs just make it look as if the angle isn't enough.So I'm rather pleased with the progress..

David

davebradwell
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Re: Bachmann B1

Postby davebradwell » Mon Jun 01, 2020 8:13 am

That's looking much more encouraging. The head of the rivet in the eccentric rod/return crank joint will probably need the front filed flat to clear the cover casting. I don't go for a full soldered joint when fitting this and make do with a quick tack with 145 each side. Clean casting joint face carefully first.

I'll emphasise again the need to check angles of swing with the combination lever as this is a notoriously troublesome area. I've already mentioned the top 2 joints and the bottom joint and union link take up an extreme angle when piston at front centre.


A4 crinolines drg - that's the word and good to see it's turned up now the NRM drawings have become more accessible. Wonder if Hornby have the version for the W1 - hmm!

DaveB

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barhamd
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Re: Bachmann B1

Postby barhamd » Thu Jun 04, 2020 9:19 pm

The last few days have been quite an effort.

I had started making up the valve forks which consist of an etch and some 1mm nickel-silver rod. I tried to put these into the valve tube which had been soldered into the cylinder much earlier in the construction. Trouble was that the bore of the valve tube was way less than 1mm.

I contacted Dave Bradwell and it turned out that a bad batch of tube had made it into some kits, he kindly offered to send me a replacement but also suggested that I could try and drill the existing tube out in place by removing the valve spindle cover. I gave it a go and succeed on one side but broke several drill bits on the second. In the end I had to disassemble the cylinder wrapper, cut out the existing valve tube and replace it with a new piece of tube which I had drilled out.

So after several steps backwards I was able to continue with the rest of the valve gear.
IMG_8019a.jpg


After a good few more hours I ended up getting to the part of the instructions where, as Dave Bradwell so eloquently puts it, you should sit back and watch mesmerised as it all wobbles about. The chassis has had several hours on my DCC concepts rolling road it is running quite sweetly. I have still to tidy up the cylinder wrappers again and put back on the valve spindle covers.
IMG_8020a.jpg


I now have the lifting arm to add and then things get cosmetic..

David

Julian Roberts
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Re: Bachmann B1

Postby Julian Roberts » Sat Jun 06, 2020 1:52 pm

Well done Dave. Celebration would be in order. How about a video of the mesmerising wobbling about?

davebradwell wrote:The Thomson A2s are just too long for my curves - the A1 is bad enough.


What radius is a suitable minimum for a Pacific I wonder. I'm dreaming up a layout for my locos and I would like to design in capability to handle something bigger than my humdrum types.

Philip Hall
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Re: Bachmann B1

Postby Philip Hall » Sat Jun 06, 2020 2:36 pm

Julian Roberts wrote:What radius is a suitable minimum for a Pacific I wonder


A bit debatable this one. So long as you don’t want the engine to go around the edge of a dinner plate there’s probably no reasonable minimum. With huge amounts of gauge widening we had Alan Ketley’s rebuilt Merchant Navy around a 2ft 3in radius curve on my old Taw Vale layout, and Alan didn’t build ‘em sloppy. It was dead slow though.

More seriously, it’s what it looks like really. Big engines speeding around tight curves look silly, but that can be built so that they will, within reason. 3ft 6in is a useful minimum, most things will happily spin around that, but I am pleased that I have been able to have a minimum of 4ft 6in, maybe 5ft, on the new layout which will make building engines (and converting them) much easier.

Philip

davebradwell
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Re: Bachmann B1

Postby davebradwell » Sat Jun 06, 2020 4:06 pm

It depends whose Pacifics - the LNER types have a Cartazzi rear truck which places an absolute limit on swing, unless you start widening it, of course and I think my own A1 has an extra 0.3 per side at the very rear but the double bend is correct width. I suspect a Stanier or Bulleid rear truck disconnects itself from the supporting bits and looks daft. Making the front bogie load bearing with close to scale frame cutouts doesn't help either. You can get the front bogie shorting on the brakes and if you try and go really silly then wheel flanges touch the brakes. Min radius just depends on how much distortion you build in. I get everything round a metre but it's not the way to approach it and coach gangways can complain just as much as locos. I haven't succeeded with cab doors which rather spoils the look. It's always a compromise, of course and assumes your curves are perfect arcs.

B1s whizz round my curves, though!

DaveB

Julian Roberts
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Re: Bachmann B1

Postby Julian Roberts » Sat Jun 06, 2020 7:19 pm

I have 4ft minimum radius in my head - sounds like you both think that is practical? A Princess is what I have in mind. It is the fiddleyard design that is my less enjoyable daydream. The main part of the layout won't have any such bends. Sorry this is tangential to your thread David.

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Re: Bachmann B1

Postby Philip Hall » Sat Jun 06, 2020 11:40 pm

I would think that 4ft is fine, Julian. A Princess doesn't have a Cartazzi truck to complicate the rear end. I might find out one day as my first Triang engine was a green Princess Elizabeth. I quite fancy one now Hornby make a decent model. But in Devon in 1954...?!!

Philip

DougN
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Re: Bachmann B1

Postby DougN » Sun Jun 07, 2020 12:41 am

Phillip remember rule 1 it's your railway! So you can have anything you want. Prototypically correct is one thing but your own enjoyment is the primary rule to what any one builds or does. :thumb
Doug
Still not doing enough modelling

Crepello
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Re: Bachmann B1

Postby Crepello » Sun Jun 07, 2020 3:32 pm

The overall wheelbase sets a fundamental limit. The bogie on earlier LNER Pacifics helped to guide the engine into curves, but Mr Thompson seemed to send his bogies so far enough ahead as to form a scouting party!

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barhamd
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Re: Bachmann B1

Postby barhamd » Wed Jun 17, 2020 11:09 pm

It may seem like I've been idle for the last two weeks but I have managed to get the lifting link in place and also the drain cocks and drain cock linkage. I've also stuck the balance weights in place and built the tender chassis.

IMG_8031a.jpg


Dave Bradwell has kindly sent me some scans for the 'plumbing' which he suggested I might add to this thread in case anyone else can also benefit from them.

Img120.jpg

Img121.jpg

Img122.jpg

Img123.jpg


I've put up a little clip on Youtube to show it working.



I think it is almost at the 'taking it all apart to paint it' stage.

I have made up the replacement locomotive footsteps so need to start thinking about the cosmetic bits. A couple of things I'd be interested in folks views on.

1) lining, the photographs I have of 61046 at Clare are not clear enough to show lining on the locomotive but I can see it on the tender. A picture of 61048 at Cambridge in the similar era shows lining on the cab side and tender but none on the cylinder sides or boiler. Was the lining simplified in the 1950s or were the locos just too dirty to see it?

2) The photo of 61048 seems to show a speedo bracket on the left hand side, was this a common feature add does anyone produce a casting/etch or should I fabricate it from scratch?

speedo-bracket.jpg
speedo-bracket.jpg (93.01 KiB) Viewed 599 times


3) I think I need to add some wires for sand pipes, particularly in front of the rear axle where they would seem quite visible.

4) really dumb question, did the tenders have guard irons?

thanks
David

DougN
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Re: Bachmann B1

Postby DougN » Thu Jun 18, 2020 2:04 am

Looks great David. The running is great, your layout looks very interesting too. :thumb
Doug
Still not doing enough modelling

davebradwell
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Re: Bachmann B1

Postby davebradwell » Thu Jun 18, 2020 8:41 am

Sorry about the lack of a speedo brkt - my Hornby body had one (but I've cut it off recently to do "Sassaby"). Not sure if I have information - I did one for the K1.

Boiler bands are always an issue with plastic bodies as they should be around a thou' thick and 0.7 wide wide with 2 lines on them - not to the side as on the Replica. The proper way is to remove them completely and replace with strips of Scotch tape pre-painted and lined. For the more cautious, like myself, I stick strips of Scotch tape either side of the bands and file them down to the tape - one of Dave Franks' tips. In service, it was rare to see the lining much above the handrail and with Blaydon or Gateshead engines below as well, except where rubbed by overalls. I would expect Cambridge engines to do better. Cylinders don't appear to be lined.

Sand pipes make a difference and I can remember attacking the rear sandbox to make it more convincing.

The issue of tender guard irons is certainly not dumb on LNER where battles were fought over them. In the NE, most sheds were roundhouse type with locos stabled around turntables, smokeboxes facing. The tracks had the ends bent up in lieu of buffers and any guardirons could hook over them until freed by a fitter with cutting equipment. I suspect your answer is possibly/probably at Cambridge.

Can I suggest you notch the gear up a bit - bring the radius rod up nearer to the centre of the expansion link. This would be more of a running position. Perhaps get a bit more throw on the return crank when you assemble it finally. Does the tender just need some weight? I usually stick some in the sides and it stops them drumming.

DaveB

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Mike Garwood
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Re: Bachmann B1

Postby Mike Garwood » Thu Jun 18, 2020 9:23 am

Fair play David, that looks excellent. Something to enjoy. Look forward to seeing it painted and another video.

Mike

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45609
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Re: Bachmann B1

Postby 45609 » Thu Jun 18, 2020 11:42 am

davebradwell wrote: Cylinders don't appear to be lined.


Stratford were the only ex LNER works that habitually lined the cylinder clothing on their overhauls / repaints

Great looking model David. I've always liked B1s but I have a bias. I spent a fair bit of time getting footplate rides on 1306 Mayflower as a youth volunteer at the GCR in the mid 1980's. Had one very memorable light engine trip from L'boro to Quorn to fetch the breakdown train on a cold January evening where the driver just let her rip. Once out onto the straight and rising gradient the regulator was jammed wide open and she was progressively linked up as we accelerated away. 1306 didn't have a speedo but I'd guess at 40 to 50 mph before we sighted the shunter's bardic lamp being waved furiously to bring us to a stop. Regulator slammed shut and brakes applied progressively and hard we pulled alongside to get instructions on what to do next. I can't remember much of the trip back to L'boro. Back in those days the light railway order speed limit of 25 mph was more of a guideline than a hard rule. You could get away with a lot in the dark without a train behind.

Cheers...Morgan

Dave Holt
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Re: Bachmann B1

Postby Dave Holt » Thu Jun 18, 2020 1:35 pm

David.
A fine looking model you have created. However, I would reinforce Dave B's comments about the valve gear cut off and eccentric throw. I'm not sure of the precise figure for a B1, but typically an offset of about 2 mm ahead of the axle centre would be in order.
Thanks for posting Dave's pipe & rod drawings. They will be most useful when I get around to my B1model.
Dave.


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