Whatever happened to British Oak?

[2mmMark]

For the fourth edition of The Beginners Guide to 2mm Finescale Modelling, published in 2006, I built a small layout "British Oak" as a worked example of the techniques described in the book. Here's the description of the layout from the book:

 

British Oak is located in West Yorkshire, alongside the Calder & Hebble Navigation canal at the Eastern end of the Denby Grange colliery line.  Coal was transported from the pits to the canal, from where it was loaded into barges for onward transportation to Thornhill Power Station. It was a surprisingly long lived enterprise, lasting in service until the mid 1980s.  The scene is a highly compressed version of the scene in reality, but it contains the main elements from the overbridge to the canal drop. It makes a conveniently self-contained little diorama which can be operated by a single loco and a few wagons, either hoppers or bottom door mineral wagons. All the necessary items are available in N, ready to run or in kit form. The line was home to an ex-LMS “Jinty” sold by BR into industrial service which sported an unusual black, orange, blue & red livery.  Other plausible locomotives would be an Austerity (J94) saddle tank and for later years, a variety of small diesel shunters. The inspiration for this layout came from “Model Railway Planning and Design Handbook” published by Santona Publications in 2004 (ISBN 0 9538448 5 4) where it is featured in some detail, including scale drawings of the canal staithe.

 

The design was by Paul Lunn and I've been in correspondence with Paul, who's provided some useful additional information, including an NCB subsidence plan!

 

At the close of the book, the layout reached the stage below:

and was fully functional from an operating perspective.

One of the problems I had with progressing the layout beyond this was a lack of photos. I had a handful of pictures from various sources but a few more would have been welcome.  As is the nature of things with the Internet, pictures have a habit of turning up and most recently these series of images turned up on the Flickr photostream of "ee20213", so whoever you are, sir or madam, you have my thanks!

These images are dated 18th July 1973 and are very useful scenic references. Elsewhere in the photostream are views of the canal and surrounding landscape.
https://www.flickr.com/photos/58585785@N08/with/36173168172/

The loading staithe was rebuilt in the 1960s, replacing an earlier wooden structure. The new staithe was designed to accept bottom door wagons whereas the earlier one relied on tipping end-door wagons.

 

Anyway, back to the layout in question. A start was made on some scenery.  The staithe itself had already in constructed in a basic format as it was a necessary part of the layout. Plastic sheet and Evergreen I-beam sections were employed and the handrails came from a Peco turntable kit.

The next piece to be made was the overbridge forming the scenic break.  Girders were made from some I found in my bits box, I think they may be Peco but the packaging was long gone so I cannot be sure of this. The line running across the bridge will be modelled as the disused Barnsley branch. The foundations of the trackbed are a length of brass bar. An attempt was made to represent timber baulks going across the bridge using the old style cast chairpins but as will be seen later, this wasn't terribly successful so the track was subsequently relaid.  Nowadays, the Easitrac moulded chairs would be the automatic choice but British Oak predates this by some years.

The next step was to "block in" the scenic landforms using Dow Corning Floormate 25mm thick extruded polystyrene insulation. This was my first attempt at using this material. I had expected the 25mm material to be easy to work. Unfortunately that proved not to be the case. The major difficulty was persuading the blocks to adhere to each other. Previous experience with expanded polystyrene led me to believe that PVA glue would be OK. It was not, as the impervious structure of extruded polystyrene prevented the PVA from drying.  I changed over to a solvent free contruction adhesive and pinned each block together with cocktail sticks. The end result was not as neat as I'd hoped it to be. The following series of photos shows the process.

The end result wasn't too bad and is certainly strong. Hindsight shows that it would be better to shape the forms from larger blocks of the material.  I also tried to work too cleanly, using knifes and a hot wire cutter. Sawing and shaping with a Surform would have been a better, if messier, technique.

The polystyrene was covered with strips of heavy duty paper towel then painted with tinted Sandtex textured paint. This helped unify the whole landscape. I like using Sandtex, it provides a good base for subsequent scenery, it's strong and flexible so less susceptible to damage than filler based substrates. Unfortunately the lack of neatness in the shaping left the whole thing looking rather unsatisfactory and to be perfectly frank, was rather demotivating.

Something would have to be done. For some considerable time, British Oak languished inside its storage box while other projects occupied my attention.

 

Edited May 9, 2022 by 2mmMark
Images restored

[Mikkel]

Very neat and clearly quality work. An attractive subject too.

 

I like the look of the sector plate. Is it a standard design, i.e. pivots at one end and the supports slide on the baseboard?

[2mmMark]

3 hours ago, Mikkel said:

Very neat and clearly quality work. An attractive subject too.

 

I like the look of the sector plate. Is it a standard design, i.e. pivots at one end and the supports slide on the baseboard?

 

Thanks.  I thought it would make an unusual model and so it has proved.

I don't know about a standard design of sector plate, it's something I came up with to complete the other end of the run-round loop. Its not removable so it's not a cassette as such.  It pivots between the two roads and is kept in place at each end of travel by magnets, holding the sector plate against end stops.

 

Mark

Edited September 19, 2019 by 2mmMark

[JohnR]

It looks a lovely little layout! What are the dimensions?

[enginelane]

Very nice indeed. Sam from the Wakefield RMS built the same loading stage as part of the GMRC Series 1 Layout and an excellent job of it he made. The revised layout including the stage will be exhibited at the Wakefield Show Nov 2019 

[Gordon A]

A very neat layout.

I would have thought another layer of Sandtex paint followed by scenic material would disguise any imperfections in the scenery.

Keep at it.

 

Gordon A

[Ian Smith]

I remember seeing a "British Oak" or look-alike at one of the 2mm events a few years ago (unfortunately I can't remember which one or where).  I think it had a working coal drop.

Ian

[queensquare]

A cracking little layout. Mark brought it down to the Warminster show in 2017.

 

 

Jerry

[sir douglas]

the orange jinty is stored out of use at the midland centre, Butterley. and the 14 survives somewhere, i forget

 

https://www.flickr.com/photos/24041160@N02/3087665592

 

https://www.flickr.com/photos/dodger5450/8263017883

 

https://www.flickr.com/photos/62149471@N03/17073930376

 

https://www.flickr.com/photos/25747139@N05/3975210080

 

https://www.flickr.com/photos/24041160@N02/8200056936

 

https://www.rmweb.co.uk/community/index.php?/topic/28530-industrial-locomotives-in-the-late-80s-to-mid-90s/&do=findComment&comment=313675

 

https://www.youtube.com/watch?v=mTlhjUJoYzg

 

https://www.railscot.co.uk/locations/C/Calder_Grove/

 

these are not mine but i'm sorry i can't remember whose they are

 

 

 

 

Edited September 19, 2019 by sir douglas

[2mmMark]

10 hours ago, JohnR said:

It looks a lovely little layout! What are the dimensions?

 

30" by 8" overall and the visible section is 22" by 8".

 

9 hours ago, Ian Smith said:

I remember seeing a "British Oak" or look-alike at one of the 2mm events a few years ago (unfortunately I can't remember which one or where).  I think it had a working coal drop.

Ian

 

There is another British Oak model which also includes the loading screens as well as the canal staithe. It was at the 2016 Supermeet in Tutbury. The builder is Richard Caunt, I think. It rather upstages my model!

 

8 hours ago, sir douglas said:

the orange jinty is stored out of use at the midland centre, Butterley. and the 14 survives somewhere, i forget

 

https://www.flickr.com/photos/24041160@N02/3087665592

 

https://www.flickr.com/photos/dodger5450/8263017883

 

https://www.flickr.com/photos/62149471@N03/17073930376

 

https://www.flickr.com/photos/25747139@N05/3975210080

 

https://www.flickr.com/photos/24041160@N02/8200056936

 

https://www.rmweb.co.uk/community/index.php?/topic/28530-industrial-locomotives-in-the-late-80s-to-mid-90s/&do=findComment&comment=313675

 

https://www.youtube.com/watch?v=mTlhjUJoYzg

 

https://www.railscot.co.uk/locations/C/Calder_Grove/

 

these are not mine but i'm sorry i can't remember whose they are

 

Thanks for the photos, I've not seen some of those and the Youtube video is especially interesting.

 

Mark

 

[figworthy]

18 hours ago, 2mmMark said:

For the fourth edition of The Beginners Guide to 2mm Finescale Modelling, published in 2006, I built a small layout "British Oak" as a worked example of the techniques described in the book. Here's the description of the layout from the book:

 

British Oak is located in West Yorkshire, alongside the Calder & Hebble Navigation canal at the Eastern end of the Denby Grange colliery line.  Coal was transported from the pits to the canal, from where it was loaded into barges for onward transportation to Thornhill Power Station. It was a surprisingly long lived enterprise, lasting in service until the mid 1980s.  The scene is a highly compressed version of the scene in reality, but it contains the main elements from the overbridge to the canal drop. It makes a conveniently self-contained little diorama which can be operated by a single loco and a few wagons, either hoppers or bottom door mineral wagons. All the necessary items are available in N, ready to run or in kit form. The line was home to an ex-LMS “Jinty” sold by BR into industrial service which sported an unusual black, orange, blue & red livery.  Other plausible locomotives would be an Austerity (J94) saddle tank and for later years, a variety of small diesel shunters. The inspiration for this layout came from “Model Railway Planning and Design Handbook” published by Santona Publications in 2004 (ISBN 0 9538448 5 4) where it is featured in some detail, including scale drawings of the canal staithe.

 

The design was by Paul Lunn and I've been in correspondence with Paul, who's provided some useful additional information, including an NCB subsidence plan!

 

At the close of the book, the layout reached the stage below:

and was fully functional from an operating perspective.

One of the problems I had with progressing the layout beyond this was a lack of photos. I had a handful of pictures from various sources but a few more would have been welcome.  As is the nature of things with the Internet, pictures have a habit of turning up and most recently these series of images turned up on the Flickr photostream of "ee20213", so whoever you are, sir or madam, you have my thanks!

These images are dated 18th July 1973 and are very useful scenic references. Elsewhere in the photostream are views of the canal and surrounding landscape.
https://www.flickr.com/photos/58585785@N08/with/36173168172/

The loading staithe was rebuilt in the 1960s, replacing an earlier wooden structure. The new staithe was designed to accept bottom door wagons whereas the earlier one relied on tipping end-door wagons.

 

Anyway, back to the layout in question. A start was made on some scenery.  The staithe itself had already in constructed in a basic format as it was a necessary part of the layout. Plastic sheet and Evergreen I-beam sections were employed and the handrails came from a Peco turntable kit.

The next piece to be made was the overbridge forming the scenic break.  Girders were made from some I found in my bits box, I think they may be Peco but the packaging was long gone so I cannot be sure of this. The line running across the bridge will be modelled as the disused Barnsley branch. The foundations of the trackbed are a length of brass bar. An attempt was made to represent timber baulks going across the bridge using the old style cast chairpins but as will be seen later, this wasn't terribly successful so the track was subsequently relaid.  Nowadays, the Easitrac moulded chairs would be the automatic choice but British Oak predates this by some years.

The next step was to "block in" the scenic landforms using Dow Corning Floormate 25mm thick extruded polystyrene insulation. This was my first attempt at using this material. I had expected the 25mm material to be easy to work. Unfortunately that proved not to be the case. The major difficulty was persuading the blocks to adhere to each other. Previous experience with expanded polystyrene led me to believe that PVA glue would be OK. It was not, as the impervious structure of extruded polystyrene prevented the PVA from drying.  I changed over to a solvent free contruction adhesive and pinned each block together with cocktail sticks. The end result was not as neat as I'd hoped it to be. The following series of photos shows the process.

 

The end result wasn't too bad and is certainly strong. Hindsight shows that it would be better to shape the forms from larger blocks of the material.  I also tried to work too cleanly, using knifes and a hot wire cutter. Sawing and shaping with a Surform would have been a better, if messier, technique.

The polystyrene was covered with strips of heavy duty paper towel then painted with tinted Sandtex textured paint. This helped unify the whole landscape. I like using Sandtex, it provides a good base for subsequent scenery, it's strong and flexible so less susceptible to damage than filler based substrates. Unfortunately the lack of neatness in the shaping left the whole thing looking rather unsatisfactory and to be perfectly frank, was rather demotivating.

Something would have to be done. For some considerable time, British Oak languished inside its storage box while other projects occupied my attention.

 

 

Very nice.  I remember it working in its last year or so of operation.

 

Adrian

[nick_bastable]

excellent modelling but please tell me its not a ringer for the DJLC ?  

 

Nick

[2mmMark]

As Jerry has mentioned, I brought British Oak to the 2017 Warminster Show and thereby hangs another chapter in the saga.  Shortly before the show, I decided that the layout needed some smartening up, something I'd long planned to do. Unfortunately, I have a habit of putting all my roundtuits in a very safe place and then forgetting where I'd left them. By the time I'd remembered where the British Oak roundtuit was stored, it was pretty close to the show date, like the Wednesday before the show!

The first job was to cover over the point and uncoupler controls. I had originally left them open just in case of any problems but as they'd survived ten or so years without problem, it seemed reasonably safe to cover them in. The first step was to sheet over the area with some shaped cardboard, in this case the back of an MRJ subscription envelope. The card was glued in place with PVA and held in place by pins, then given a through coating of PVA. When this dried, it made a nice hard shell, thin and with a bit of resiliency.

 

Once the PVA had set reasonably hard but was still wet, I cut some strips from the front of the MRJ envelope and laid them over the cardboard again with PVA glue.
Please note, other finescale envelopes may be available...

 

After the strips were in place but while the PVA was still drying, I painted on a thickish layer of tinted Sandtex paint.

The reason for working with the PVA wet is that the whoe thing bonds together and forms a very robust shell for the scenery.  In fact it took a couple of coats to hide the paper strips but when it was done, it blended in quite well.

In fact I had used the same technique of paper strips and Sandtex to cover the polystyrene landforms. The Sandtex was tinted with artists acrylics. I have found subsequently that Indian Ink works just as well and possibly better as it seems to mix more throughly. Final colouring was done with washes of artists acrylics blended directly on the layout.

This took care of the top surface and covering in the ugly open areas massively improved the overall look of the scene.

Encouraged by this, the next move was to tidy up the front and back sides of the layout. I needed to keep the width within the confines of the storage box so a thin but strong sheet material was required. The solution was 1.5mm aeromodellers plywood. Some extra polystyrene blocks were inserted to provide some support and the front and back were skinned with the plywood. Cutting out was done using a Stanley knife. The following photo sequence shows the process.

 

The plywood skins were blended in with a thickened mix of tinted Sandtex and filler. There's a bit of theme here, still if it's good for ten or more years on the outside of your house, it ought to stand up well in this situation.  The final result was a much smarter looking layout and fortunately, everything dried out in time for the Warminster show, as can be seen from Jerry's earlier photo.

The next phase is to work up some more scenic detail and that is what is currently happening, ready for the layout's forthcoming appearance on the 2mm Scale Association's stand at Scaleforum.

 

 

Edited May 9, 2022 by 2mmMark
Images restored

[2mmMark]

7 minutes ago, nick_bastable said:

excellent modelling but please tell me its not a ringer for the DJLC ?  

 

Nick

It does fit within the size constraints but it would be very cheeky indeed to enter it.

 

Just like An Clár accidentally turned into a "cameo layout", Britsh Oak could be an accidental DJLC entry, but rest assured, it won't.

 

Mark

[2mmMark]

Progress update just before Scaleforum

 

Among the photos that Paul Lunn provided was this intriguing grounded van. It's obviously had a lick of paint during it's non-wheeled retirement and possibly has been re-roofed. I had already made a grounded van using the 2mm Association's Iron Mink kit but this one I feel has a lot more character. The colour is interesting, it makes you wonder if they simply found a job lot of cheap unfashionable paint and slapped it on to weatherproof the body. I can't imagine that a great deal of artistic "Farrow & Ball" judgement went into the job.

The first job was to make a concrete hardstanding, which I did using a section of printed concrete from the Scalescenes sampler kit for a warehouse.  The detail in these card kits is excellent. The only thing I felt was that the colour was a little too blue, so it got a wash of Pollyscale "Aged Concrete" paint.  Concrete is a very elusive thing to represent, I find.

The next job was to find a van body that was close enough to the one in the photo. A rummage in my box of part-made wagon kits revealed an LMS van body, made quite a long time ago from an 2mm Association kit. While not 100% accurate, it had the right look about it.  Some thin paper strips were attached to the roof and plastic strip sleeper sized bearers were glued to the floor.

The fun bit was the painting & weathering, which I did using Vallejo Modelcolor acrylics. The pea-green colour was mixed up to match the prototype. The roof used a flesh colour.

Various browns, red & greys were used to weather the van, aiming to match the weathering on the real thing.  A final wash of dark grey and a coat of matt varnish and the job's a good 'un.

 

Something which has been under consideration for a while is the treatment of the scenic break, which needs some sort of "endscene".  A search on the Internet for images of the Aire & Calder Navigation showed up a few possible images including this one from http://www.penninewaterways.co.uk/aire/acn34.htm

http://www.penninewaterways.co.uk/aire/acn516.jpg

My intention is to paint the details on the "endscene" as I'm not really a fan of photographic backscenes but this proved to be a useful image for trial purposes. The image was suitably cropped and resized to suit, printed on some thin card and placed into position.

 

I've been reading Mike Raithby's excellent guide to backscene painting in the June 2016 & August 2016 editions of the 2mm Magazine, the recommended paints have been ordered so the next step will be to attempt to replicate the scene.

 

 

Edited May 9, 2022 by 2mmMark
Images restored

[2mmMark]

British Oak seemed well received at Scaleforum this past weekend. We had significant interest in 2mm finescale, gaining one new member and selling a good quantity of 2mm books.

Even though the layout still has much to be done, smartening up the presentation was worthwhile.  The photo below shows the display arrangements.  The layout sits on its carrying case which usefully raises it above table top height and provides somewhere to attach the pole for the LED spotlight, which proved quite sufficient to illuminate the layout.  The hall lighting at the Stoke Mandeville venue is much improved.

 

 

Alongside the layout, I had my notebook PC showing photos and video of the real thing.  While I was away from the layout, I'm told that someone cheekily photographed the articles about British Oak contained in the Industrial Railway Record magazines in the picture. Tsk tsk whoever you were!

 

Throughout the weekend, I was using one of the amazingly cheap Chinese-made PWM controllers similar to this one:
https://www.ebay.co.uk/itm/1-8v-3v-5v-6v-7-2v-12v-2A-30W-DC-Motor-Speed-Controller-PWM-1803BK-Adjust-Y6F5/123841954827
fed a 12v dc supply from a plug-in transformer.  It gives very good slow speed control on a variety of mechanisms so I'm considering fixing one into the layout permanently. Incidentally, if anyone decides they'd like to do the same, look for controllers that have a 0% to 100% duty cycle, which means than when the control pot is set to minimum, no power is being provided. Some don't go down to 0% which allows locos with a low current demand to creep.

 

Overall, Scaleforum was its usual informative and enjoyable self, this year featuring several larger layouts. A personal highlight for me was meeting my former design & technology teacher, Denis Griffiths, again after about 45 years. Denis started working in P4 in the Studiolith era. I think Denis was pleased that at least some of what he taught me sank in. The school is now gone but at the time we had a superb set of very well equipped workshops for both wood and metal.

 

 

Edited April 1, 2022 by 2mmMark

[Dzine]

Looking fab Mark, love the grounded van...takes me back a long time,  pity the site's been completely cleared now. Kind regards Paul

[bcnPete]

So pleased you are sharing this Mark.

 

This layout has indeed inspired me on many occasions when reading the 2mm guides/handbooks.
 

All so well executed and each time I see the neatness of your handmade track I want to make a small layout with all PCB soldered track again 

 

Fantastic inspirational stuff

 

Pete

[5944]

On 30/09/2019 at 11:09, 2mmMark said:

Throughout the weekend, I was using one of the amazingly cheap Chinese-made PWM controllers similar to this one:
https://www.ebay.co.uk/itm/1-8v-3v-5v-6v-7-2v-12v-2A-30W-DC-Motor-Speed-Controller-PWM-1803BK-Adjust-Y6F5/123841954827
fed a 12v dc supply from a plug-in transformer.  It gives very good slow speed control on a variety of mechanisms so I'm considering fixing one into the layout permanently. Incidentally, if anyone decides they'd like to do the same, look for controllers that have a 0% to 100% duty cycle, which means than when the control pot is set to minimum, no power is being provided. Some don't go down to 0% which allows locos with a low current demand to creep.

They look useful. I'm planning a DJLC entry (whether it actual gets built or finished is another matter!) but I've ordered a couple of these to try anyway. They look small enough to attach in a convenient corner of the layout. 

[John57sharp]

4 hours ago, 5944 said:

They look useful. I'm planning a DJLC entry (whether it actual gets built or finished is another matter!) but I've ordered a couple of these to try anyway. They look small enough to attach in a convenient corner of the layout. 

I second this, thanks for showing them to us.

 

John

[2mmMark]

An important point to note about the controllers I mentioned.  They need a maximum 12v DC supply and do not come with a reversing switch. They are simply a speed controller.  For a power supply, I would recommend a stabilised plug-in transformer in the region of 1 amp. Some 12v power supplies need a load on them in order to supply 12v.  Off-load, they could be delivering a much higher voltage. It's also not possible to reverse the DC output by reversing the DC input. Do not on any account feed them an AC input.

 

I've got a plan in hand to revise British Oak's electrics to incorporate an on-board DC controller with the option to plug in alternatives if required.  It's just a pile of bits on the workbench at the moment but I will be writing it up.

[4109]

Superb little layout and really well presented. I've long had a soft spot for 2mm and would like to give it a try someday. For now I'm committed to 3mm with a new layout in the pipeline but I'll have more time come January when I take semi-retirement. This layout, Chapel Wharf and others make me reach for the 2mm starter wagon kit I purchased a few years ago.

Bob.

[2mmMark]

Sitting in a little plastic gloat box, I've had a Jinty conversion under way for far too long.  It's for the final Poole-era Jinty and predates the current model by a long way. For all its faults, it's still a reasonable model. Could do with a better dome and chimney but that's sorted with a couple of Nick Tilston's (N-Brass) excellent lost wax castings.

 

In a further attempt to make it even more of a Trigger's Broom, I've just got hold of a Tramfabriek 6mm coreless motor and the appropriate 0.8mm to 1.5mm shaft adapter. The plan is to replace the Farish armature with the 6mm motor, using the motor frame to support the motor.

A trial fit shows it's quite feasible

 

The next step will be to make a holder for the motor which will be fixed to the motor frame rather than the chassis, so if necessary, it can be dismantled.  I know people simply glue motors in place with perfectly good results but during this particular conversion process, the chassis block becomes significantly weaker in certain places, making any removal and replacement of the motor a risky business.

 

Here's a comparison of the armature and replacement motor

 

 

 

Mark

Edited May 10, 2022 by 2mmMark

[2mmMark]

Following on from the previous entry, I made a mount for the 6mm by 15mm motor using various bits of brass tube. A length of ¼" bore tube was sliced lengthways and closed up slightly so as to grip the motor body.  Then two layers of brass cut from successive size tubes were soldered on to match the curve of the original motor top frame. Finally the top of the motor mounting tube was tapped 14BA for a fixing screw. There were enough layers of brass to provide a usable thread without the screw biting into the body of the motor.

 

 

The worm was pushed onto the 0.8mm to 1.5mm converter shaft  and the shaft fixed to the motor using thread-locking liquid, as recommended by Sven at Tramfabriek.  A piece of cigarette paper was used to provide clearance and stop the liquid seeping in the motor bearing.

 

The motor frame was assembled ready for refitting to the chassis. A quick test run show that everything ran smoothly.

 

 

Unfortunately, when the motor frame was refitted to the chassis, I found the chassis ran superbly in one direction but was very rough in the other. I had several tries to fix this, moving the worm slightly in either direction, tweaking the mesh slightly and so on. Frustratingly nothing I tried worked.  I then replaced the worm with a longer one and removed the white front bearing. I don't quite know why but this solved the problem and a sweet running chassis was the result.  I made up some phosphor-bronze contact strips to connect the motor and frames, then tested the chassis on a rolling road which showed that it all worked OK.  Losing the front bearing doesn't seem to have caused any problems.

 

 

 

These coreless motors from Tramfabriek have a lot of potential for us in 2mm scale.  The 6mm size may be a little small for a mainline loco but in this case the Jinty will spend its life shuttling up and down 30" of track with a few coal hoppers, so it won't be over-exerting itself. The small size of the motor makes for a compact mechanism which will be helpful to those who use the Devil's Control Circuitry and need somewhere to keep their chips warm.

The question remains as to whether the whole conversion was easier than building a chassis from scratch. With what I've ended up with, I'd say probably not. Looking back, I think I started this conversion sometime in 2004. It is a classic example of the railway modeller delusion, that a "simple & quick" conversion will save time...!  

 

Mark

Edited May 10, 2022 by 2mmMark

[2mmMark]

One of the things I've been intending to do is provide an integral controller for British Oak.  For some time now, I've been trying out various small and inexpensive PWM speed controllers. There are a wide variety now available, sometimes also labelled as LED dimmers.  The most useful I've found are the type called "Mini DC Motor Speed Control Driver Board 3V-35V 5A PWM Controller / LED dimmer" or some variation thereof, usually costing between £3 & £4 from a UK seller on eBay, cheaper from overseas.

It's important that the controller has a PWM duty cycle of 0% to 100%, which means that at the lowest setting, no power is applied to the track. Some don't go right down to 0% which can leave a small voltage present causing some motors to creep.  If you're very interested in PWM, then a pretty good explanation can be found here
https://knowledge.ni.com/KnowledgeArticleDetails?id=kA00Z0000019OkFSAU
Suffice to say that the controllers I've used give a precise degree of control, very good slow running and don't cause any noticeable motor heating or noise, unlike the feedback controllers which rely on low voltage AC input to provide a waveform at 50 or 60Hz.  These controllers typically have a PWM frequency of 10KHz and require a DC feed. This means they can be used as battery controllers if necessary. For this application, the control pot usefully includes an off switch.  Ths photo below gives some idea of the size. Being a bare controller, a reversing switch is required.

 

For British Oak, I tapped into the 12vAC feed already provided for the plug-in controllers I use, like the Pentroller. The AC feed is taken to a small solid state bridge rectifier

(the black box at the bottom of the case) and from there, the rectified feed is fed in the controller, which has screw terminals to make the job easy. The output from the controller is taken into a DPDT reversing switch with a centre-off. This serves to isolate the controller when a plug-in unit is in operation. If this is not done, there is a strong possibility the two controllers will interact with each other.

 

Just to be on the safe side, I added some sleeving to the terminals of the rectifier. The controller also has screw terminals for the output.  The wiring follows my particular convention of red & black for track power, green for AC and in this case I used orange for the DC where the polarity is changed by the reversing switch.

 

It all fitted into a small project box which is screwed to a convenient location in the fiddle yard.

Incidentally, those who joined in the 2mm VAG Zoom conference the other day will have seen an unusually tidy workbench.  Below is much more typical, although there's actual bench still visible, not always the case...

 

 

 

Mark

Edited May 10, 2022 by 2mmMark