An Experiment, with compensation...

[petermeyer]

I've alluded on a couple of occasions to start a thread on my Brassmasters LNWR Experiment build so I thought I'd better start one before I got too far with it. Here's the first instalment. It doesn't start at the beginning but the chassis, bogie and compensation elements are relevant to current discussions on the forum, so here it is.

Here's the chassis which, as can be seen, is articulated ahead of the drivers leaving the bogie in it's own sub chassis.

IMG_0821.jpg

The instructions instruct for a rubbing plate to be attached to the top of the chassis/bogie assembly that rubs against the underside of the running plate. Hopefully the friction in this will be sufficient to control sideways movement. Any extreme movement would be stopped by the flimsy LNWR valance. There is no provision for springing in the kit.

Brassmasters also do/did a Precursor which shares the same bogie on the prototype. Brassmasters supply a separate etch of said Precursor bogie of which I have acquired a few. However, despite being from the same stable and presumably the same designer, the two loco differ particularly as to how the bogie is attached to the separate sub-chassis. So I could not use the complete Precursor style bogie on the Experiment but I did use some parts to beef up the springs and the compensation beams but the core is the Experiment bogie. Here's a close up showing the compensation beam in place.

IMG_0822.jpg

As can be seen from the first photo, getting the brake gear between the drivers is quite a challenge so that will covered in the next instalment.

[davebradwell]

I must say, this seems an awful arrangement, with or without compensation. Biggest concern is the height of the slide above the track - it would be like trying to open curtains which have a sticky rail when sat down. Bogie frames dip down in the centre to get the slide as low as possible. If the bogie can't turn at all with respect to the forward sub frame then there will be track formations where it's not pointing in the direction it would like to. You'll probably tell me it works well - these things can't be predicted easily - and in that case I'll just say you're starting at a disadvantage.

It's not clear how this is part of the compensation as bogie slides are usually part of springing or of a sprung bogie at least.

Many early bogie locos appear to have frames behind the bogie wheels limiting any possible side movement. Looking through my drawing collection I see that on ex-NB D30 & 34 there was a large frame cutout clearing the wheels with a thinner inner layer behind the hole. The Caley put a set in the frames just behind the rear bogie wheel to reduce frame width then bent the frames inwards further forward to give the front wheel more clearance. It should be possible to design a model that will go round a reasonable curve but the kit will be from the days when layout curves were rather tighter and the designer would be looking to the EM and 00 market.

If clearance is very tight around the brakes you'll need to fix them very securely in case they get knocked, perhaps in a derailment. The usual arrangement, seen recently, is rather feeble here so I would suggest you fix the cross beams to the keeper plate (if you have one) and slot tops of hangers so they push up into grooves in hanger pivots. These can be produced with wire and tube if no lathe.

As it's come up recently - I can't see your gearbox restraint!

DaveB

[Philip Hall]

Re the brakes: I would think there is a strong case here for the shoes to be of plastic or paxolin, although it's not clear whether you have done this already?

Philip

[Daddyman]

Many early bogie locos appear to have frames behind the bogie wheels limiting any possible side movement. Looking through my drawing collection I see that on ex-NB D30 & 34 there was a large frame cutout clearing the wheels with a thinner inner layer behind the hole. DaveB

Just visible here.

20190318_115459.jpg

[petermeyer]

First a rewind to the beginning. Herewith a photo of the frames and as can be seen I drilled the brake support holes to allow for tubes to be fitted.

IMG_0695.jpg

With a fixed driven axle, I would normally drive the rear axle but, as that one is halfway below the cab floor with little room to play with, I elected to drive the front axle rather than employ a number of drive stretchers. So I also drilled the hole for the beam before soldering in the spacers. There are alternative spacer positions depending on whether the front or rear is driven.

This kit is dated 1982, which is now 40 years ago, but must have been quite advanced for it's time. It is generally arranged for 18.83 but will accommodate OO. However, the mainframes were etched for "Studiolith" hornblocks - which I've never seen. It also allows for "Maygib" or Gibson sprung hornblocks. Neither of these appealed and I used some more modern alternatives; MJT in this instance. Other brands are available.

The front bogie frame attaches to the mainframes via a 10ba nut and bolt. I like to build the running plate quite early on to check the arrangements for attaching the chassis. As the front bogie frame is allowed to freely swing, the attachments to the body are all on the main frames, fore and aft.

The bogie wheels are AGW and the drivers Sharman which I got from London Road Models who stock them for their Precursor Tank which shares the same wheel size. All was set up on my Hobby Holidays jig. Motor is a Mashima 1425 driving a High Level RR+ gearbox. The kit provides 16ba bolts for the coupling rod split by I used AGW rivets. Having got everything running it was then onto the brakes...

[davebradwell]

So the footplate doesn't rest on the bogie/sub frame after all because it's held up by the fixed axle and beams on the coupled wheels?

DaveB

[Jol Wilkinson]

Unfortunately John Redrup at LRM is no longer able to supply Sharman wheels. However, this particular wheel is still listed on the PPP Sharman Wheels site in OO/EM and P4 profiles (while stocks last).

I believe that Sharman Wheels are no longer manufactured, unless you are willing to order a large quantity of any particular type.

[petermeyer]

I must have been lucky and got the last few Sharmans then. Hi got a set for a Precursor Tank too for which I intend to use the BM chassis.

[petermeyer]

Jol Wilkinson wrote: » Mon Jan 03, 2022 10:51 am

Peter,

presumably this is the Brassmaster Experiment kit. I have one to build and thought I would probably follow the same approach I used when I built a LRM Precursor Tank kit, which were originally supplied with the Brassmaster chassis. BM never got around to doing the "body" kit so LRM produced that and after initially using the BM chassis now have their own dedicated etched frames kit with a sprung bogie.

With the BM chassis, on which the bogie is pivoted longitudinally and compensated, I attached a wire spring the the underside of the body which ran forwards and then located in a hole in the top of the pivoted front frames. This provides some vertical load on the bogie wheels and some lateral control, probably more important on the 4-4-2T than on the 4-6-0.

As you have found the 4-6-0 works okay, I may therefore just stick with the BM chassis as designed, possibly with a bit of weight added to the front frames

Jol

Jol,

On the bogie, the kit provides 14ba bolts for the compensation beam pivots. I replaced this with brass pins running in tubes. I also used High Level mini hornblocks. Now the Experiment bogie is soldered to it's frame, you can no longer see the inner workings. So these first photos are of the bogie I did at the same time for the Precursor but it shows the idea.

IMG_0831.jpg

IMG_0832.jpg

|'ve been reminded that it might have been better to have fitted the hornblocks the other way round with the wings facing out as the Experiment bogie is rather narrow and I had to employ substantial spacers to get the wheels to gauge.

IMG_0869.jpg

You can see from the top side of the bogie/frame combination that there is a substantial void into which some weight could be added to the bogie assembly if considered desireable:

IMG_0868.jpg

However, reading the instructions and in the final paragraphs, the "20thou nickel silver packing" piece is required to make the whole assembly level and the bogie is thus bearing the front weight of the loco. So that is what the designer intended. The jury is out as to whether this will actually work but I guess by leaving the packing piece out, the bogie might be free to move.

[Daddyman]

It's a similar design on the 52F Models kit of the ex-NBR C16s and C15s, but the whole front frames forward of the drivers pivot - a much longer section than what you seem to have here. The bogie has compensated wheels and is free to move in all planes, except across the centre line of the front frames in the horizontal plane. I initially built it in 00 and it worked fine as far as I can remember - though as Dave says, it perhaps shouldn't have.

If Peter Stanger used the same system in his A5 kit, then he may have described the design and working in the one of the two articles he wrote for the MRJ on that model.

[petermeyer]

davebradwell wrote:» Mon Jan 10, 2022 5:12 pm

I must say, this seems an awful arrangement, with or without compensation. Biggest concern is the height of the slide above the track - it would be like trying to open curtains which have a sticky rail when sat down. Bogie frames dip down in the centre to get the slide as low as possible. If the bogie can't turn at all with respect to the forward sub frame then there will be track formations where it's not pointing in the direction it would like to. You'll probably tell me it works well - these things can't be predicted easily - and in that case I'll just say you're starting at a disadvantage.

It's not clear how this is part of the compensation as bogie slides are usually part of springing or of a sprung bogie at least.

Many early bogie locos appear to have frames behind the bogie wheels limiting any possible side movement. Looking through my drawing collection I see that on ex-NB D30 & 34 there was a large frame cutout clearing the wheels with a thinner inner layer behind the hole. The Caley put a set in the frames just behind the rear bogie wheel to reduce frame width then bent the frames inwards further forward to give the front wheel more clearance. It should be possible to design a model that will go round a reasonable curve but the kit will be from the days when layout curves were rather tighter and the designer would be looking to the EM and 00 market.

If clearance is very tight around the brakes you'll need to fix them very securely in case they get knocked, perhaps in a derailment. The usual arrangement, seen recently, is rather feeble here so I would suggest you fix the cross beams to the keeper plate (if you have one) and slot tops of hangers so they push up into grooves in hanger pivots. These can be produced with wire and tube if no lathe.

As it's come up recently - I can't see your gearbox restraint!

DaveB

Dave B

Thanks for the input. The chassis might be flawed but I acquired it with a reputable brandname expecting that it ought to run in P4. It's probable that the arrangement was devised to suit OO and works fine in that guise.

I started this thread firstly as a couple of people I know, both more accomplished modellers than I, have this kit and expressed an interest in my build. It was also in response to Will's thread on bogie springing where I'd already stated that the chassis worked (albeit light engine with just the running plate on). Anyway I get great pleasure in breathing life into these old kits. Before I get too far I will devise an alternative arrangement for the bogie that I can install without too much surgery if needs be. I attached the rubbing plate/packing piece only with 100 degree solder in case it had to come off.

I will post about the brakes in due course but I am yet to embark on the joys of keeper plates.

I've missed any discussions on gearbox restraint recently but was under the impression that it was not an issue with a fixed axle. The motor/gearbox assembly sits on a spacer and is restrained in the other direction by the pickup wire but would welcome more advise.

I do strive for perfection but I am still building everything on the same piece of wood I used in my bedsit in London back in the 70's with pretty much the same hand tools.

Peter

[Will L]

...I've missed any discussions on gearbox restraint recently but was under the impression that it was not an issue with a fixed axle...

That's right,its only an issue when the driven axle is free to move up and down on some form of suspension.

[davebradwell]

I was drawn into commenting to warn of perceived flaws on the high bogie slide. As there isn't one in the photo, and can't be with the suspension arrangements in use, I've climbed back into my pram and will leave you compensation folk to your ways as, apart from a few early efforts, I've never built such a model and have no experience of them. As you say, it's much easier to go with these old kits rather than attempt an update and I can't see what else you could have done without making new frames. As long as the front bit can twist a little and move up and down with respect to the rear it should be fine but if you can get even a small amount of rotation for the bogie it will help it take up its own alignment. Given a clean slate there can be no reason to copy the arrangement.

Now you say there is a slide but this will only work with a sprung bogie - if there is one I suggest you make the top plate as wide as possible, the inside of the valences can serve as stops, in order to minimise tendency to tip and dig-in.

Brakes are a good example of an accepted method which sometimes failed to survive the challenges I've thrown at it and I hope you find my suggestions interesting in beefing these up and my locos no longer go round with sparks down below or shorting on curves after being handled. Some sort of assembly screwed under a chassis is, you'll find, very useful for attaching things like pick-ups, sandpipes, brakes, etc and they all come off in one chunk.

Finally the requirements for a gearbox torque restraint are exactly the same for a fixed as a sprung axle. It should only restrain in one direction - rotation - and should not influence the side to side movement as this is defined elsewhere. You are, however, spared any worries about having a vertical component to the reaction as there's no suspension to influence so there is more flexibility in position.

DaveB

[petermeyer]

Re the brakes: I would think there is a strong case here for the shoes to be of plastic or paxolin, although it's not clear whether you have done this already?

Philip

The brake hangers with the kit are half etched. For some reason they have a hole in the centre but none at either end. Some had already fallen apart in the box and others broken through. Drilling into these was futile as they just disintegrated.

IMG_0874.jpg

So I replaced them with hangers from a LRM Coal Engine in Nickel silver. I removed the brake shoes on these and I did indeed sandwich between some plastic shoes. The result is quite thick so there is danger on them fouling on the rods. The other issue is the arrangement shorting out on the wheel ahead as there is very little room. So a lot of fettling required. Luckily I made them removable. I plan to insulate with epoxy before painting.

Another great frustration is that as you can seen from the photo of the etch of the chassis fret, the items on the fret are all numbered. And these numbers are cross referenced in the instructions. Great apart from the fact that this is not repeated on the two body frets which have no numbers. As the kit is for both the Experiment and Prince of Wales, when it gets to the finer details this is becoming a problem.

Also on the last but one page, the instructions state " ...reference to enclosed G/A drawings...". No G/A drawing is enclosed (and neither are any instructions for the tender; lucky I do have these in the Precursor kit)

[petermeyer]

Update. Firstly, can I say that those currently involved with Brassmasters were unlikely to have been around when this kit was introduced and are probably not responsible for its quirkyness.

IMG_0876.jpg

IMG_0878.jpg

This is the current status. I have built the upperworks on a piece of mdf and, as suggested in the instructions, I have routed this jig out to allow for the valances. This just about keeps it all flat. The boiler supplied was a piece of 22mm copper pipe. I rolled my own boiler to replace this. Splashers made and installed. Frame extensions, tank tops and tank top beading all installed. And the roof is on all along with all its ribs.

Next step are boiler bands and washout plugs. Neither mentioned in the instructions. But this build is now likely to stall as have many in the past due to unidentified or missing parts. For example, there is no combined lamp bracket and handrail knob for the top of the smokebox front. Also, in common with LNWR locos, there is a pipe that comes out of the front of the spectacle plate and runs down onto the splasher; not in the kit. Neither is the blower valve. To be fair other kits have had similar items missing and have stalled for the same reason. Over time I have acquired the missing parts, from suppliers, at shows or on ebay. But in the meantime I have moved onto other builds and those half-finished have been put on the back burner. It is highly likely that I have some of the missing components on the sprues I already have. But to be fair to the other 4 LNWR locos that are sitting unfinished in the cabinet of shame (one for almost 9 years!), I really need to get on and finish those and see what missing elements I can find in the leftovers for the Experiment.

[Will L]

...Next step are boiler bands...

Quite a lot of folks only apply boiler bands as part of the painting process, often as transfers, as scale thickness ones are vanishingly thin.

Will

[petermeyer]

...on the subject of leftovers, when a build reaches this stage you have some things left in the box. On this kit there are the obvious, such as the parts for the later belpaire firebox version and parts exclusive to the Prince of Wales superheated loco. However, I have what must be parts "10a Ashpan profiles" which are listed in the List of Parts but not mentioned in the instructions. It's my fault, I should have realised I needed an ashpan and for other kits I have scratchbuilt these but memory let me down. So can I retro fit these? The firebox/ashpan in an LNWR Experiment had a very untypical shallow grate which was the bane of firemen. This drawing is a cutdown:

boiler002.jpg

As can be seen, the middle axle ran through the firebox/ashpan. On my chassis there are hornblocks and other things around this area so I'm going to have to conduct some surgery on the "Ashpan profiles" to accommodate them. Luckily the brakes and rear pair of driving axles are removable. Should I bother?

And then onto the castings which are not listed in the Experiment instructions at all:

IMG_0879.jpg

In all five bags and very little means to identify the contents of them. For example there are a total of 7 chimneys! I thought I might have mingled the castings with the Brassmaster Precursor kit, which is a much later model, however, on inspecting the Precursor kit there is the same issue. But the Precursor has a helpful list of the whitemetal castings and states "3 bags included in all LNWR kits". So I have castings exlcusive to the G1/G2, POW/Experiment, 19" Goods, Precursor/George V and multiples of castings common to all. I won't bother listing them all but for example between the 2 kits I have enough tender axleboxes and springs for 6 tenders! And then on top in the Precursor kit there is a set of nice lost wax chimney, dome and safety valve making the whitemetal redundant.

To be fair this kit was part of the scratchbuilder range and has since been withdrawn but is is a challenge trying to identify everything.