16mm Andrew Barclay Darent

[hobbyhorse]

With the Nelson build coming along nicely and nearing completion,  I’ve started thinking about the next project.

 

Some time ago I started a scratch build on another forum of a pair of 16mm scale Andrew Barclay 2 foot gauge gas works locos. (Apologies if you’ve already seen the first part of the build)

 

The reason for the interest was that I owned a quarter share of this Loco and wanted to build a pair of models of her, in as first restored condition without cab and as running today with enclosed cab. 

 

​Darent on the Bredgar railway with enclosed cab and tail chimney.

 

 

16mm as a scale offers a lot of possibilities especially with fine scale electric models, this scale is mostly garden type with live steam and robust track work but has seen a lot of interest lately in fine scale models.

 

A group of us run a small garden railway in 16mm live steam, and its from this that the initial inspiration to go 16mm fine scale sprang from.

 

These are  going to be as close to a true scratch build, as other than the motors, gearboxes and bearings I will make all the parts myself.

I enjoy the whole process of scratch building more so than kit building as it give you complete freedom to build as you wish, and at some point the pair will be used on a 16mm layout.

 

I won’t be doing much on this build until the Nelsons are completed, but will drip feed in all the material that I have to date, plus some of the work involved restoring the full size Darent as the models will follow the full size one in construction as closely as possible. 

 

The full size Darent has now been sold to the Kempton Water Works railway.

 

Simon

 

 

 

Edited October 27, 2018 by hobbyhorse

[KCR]

Should be good to watch this come together.

 

Something that stands out on the small chimney photo is the line around the base that suggests a plate has been put in between the chimney and smoke box wrapper, as a former part owner of the loco can you say with any authority if this is the case and if so why this was like this? it's not something I've seen before.

[N15class]

Looks an interesting project, I do like the larger scales. I have often thought of trying something larger.

[hobbyhorse]

The chimney in it's short form is a one piece casting with on plate between it and the smokebox, and I think it's a trick of the light that shows a line. It was an amazing casting which to extend the chimney we had to cut the top off, and in the best tradition of recycling the parallel tube section is from a street lamppost and the cap from one of the other members.

 

Simon

[hobbyhorse]

A couple of photos showing the kit of parts before any work commenced, it certainly isn’t a MOK kit!

 

The starting point for this project was to produce a drawing on clear drawing film, this material is more stable than tracing paper. The photo shows the setup for the saddle and cab on film with some white paper behind the film, photos of the film on it’s own doesn’t photograph well, but it gives the idea.

As a lot of the parts are cut out on my profile engraver, this dictates how the drawings are produced. And yes I could draw it on CAD but I still like the drawing board.

The basic GA drawing is drawn twice model size at 32 mm/ft, on different layers so that each part can be checked and this ensures that the drawing doesn’t get to cluttered, the film make this very easy.

From this GA other parts are drawn to a larger scale, these can range from 3:1 upto 20:1.

Once each section of the drawing is completed it’s checked again and the plastic patterns are marked out by pricking through the film into the plastic sheeting. This gives the outline on the sheet, which is then drawn again using the pin marks. The pattern is then cut from 40 thou and backed on to 60 thou, which is robust enough for the small run of parts needed for the build.

This shows the wheel pattern.

 

The starting point on the build is the wheels which are solid casting on the real thing with bolted on tyres.

The photo shows me cleaning up the edges of the tyres.

 

The model ones are cut from cast iron bar blanks and set up on a rotary table on the engraver to machine the details of the centres, and finished on the lathe just the same as the AGH type, I won’t go into detail about turning these as I’ve already covered that in depth on the Nelson build. 

But the machining of the front face contours involves some interesting machining which wasn’t without disaster on a couple of blanks, but I did cut more than needed. The leading and rear wheels are the same other than the driven wheel has the balance weights cast in, this is shown on the pattern with the balance section removed. So the machining of the two is very similar using two verities of slot drills, plain long series and bull nose types. the plain ones used in cutting the various levels and holes with the bull noise for the radiuses around the lower level peripheries on the crank web and outer rims. Some cleaning up was required mostly with some wet and dry to remove the cutter marks other than two small wings of metal that couldn’t be reached, a small home made chisel made from old files soon removed them.

 

Completed wheel.

The down side of cutting cast iron on the engraver is the vast amount of dust it creates, the wheel patterns show the dirt on it. It’s not good for the rest of the machines in the work shop, which all needed covering.

 

 

Sorry about the quality of some of the photos as some are scanned, with others taken on a very early basic digital camera.

 

Simon

[hobbyhorse]

With the basic wheels completed the next stage will be the frames.

Working up the drawing for the frames involved the hornblocks, motor/gearboxes and inside valve gear.

As I want the eccentrics to operate clearance is at a premium with the motor mounted on the same axle, the photo of the full size gives the idea.

 

Giving the models descent bearings with limited width moved me towards roller bearings, this I thought would be straight forward, but with most of the market flooded with cheap china imports that have a very lumpy fill when rotating, my research paid off finding bearings made in Japan which have a press fit on the axles removing any play, although not cheap a well made product.

With the bearings sourced the rest of the eccentrics could be draw, although these have to be set closer to the bearings which is a compromise.

The bearing are encapsulated in three pieces of brass to give a slot to fit into the frames.

 

From the drawing the patterns for the frames, buffer plate and hornblocks are produced and cut out.

 

The frames and buffer plates from .9mm Nickel Silver and the hornblocks from .9mm and .4mm brass.

 

Rivet templates

 

Both the frames and buffer plate have rivet details which can't be pressed into .9mm material without distorting the plate work, to over come this the position of the rivet has to be pre drilled to a depth of .7mm leaving .2mm which will form easily. All the rivet positions are drawn on the master drawing, and from this some templates for drilling are made into patterns and cut out at the same time as the frames.

 

Drilling the rivet positions in the buffer beam marked in red, the other holes are for bolts.

 

 

Riveting after pre-drilling.

 

Rivet detail showing on the top of the frames, bearings test fitted with the keeps.

 

 

Simon

[scots region]

I shall keep an eye on this, Darent could be a future Bertie conversion.

 

SCR

[hobbyhorse]

With the layout for the Darent models now under development, which I'm one of the group.

To keep the layout thread clear of the rolling stock, this thread will detail the construction of all the stock needed for FSIJ.

And as its all scratch built its going to be an interesting journey. 

One of the common items is the couplers used on the locos at Bredgar, so this week a start was made on the patterns.

 

As most of the group also runs a garden railway,  I'm going to modify one of the coupling head patterns so that it can pivot.

This will allow for the tighter radiuses used outside, these fixed heads will be fine on FSIJ as all coupling operations will be done on straight sections of track.

Simon

Edited May 2, 2015 by hobbyhorse

[hobbyhorse]

Most of last week was spent completing the coupling patterns.

The opportunity was also taken to make a coupling head that swivels for use on our garden rail stock, as the fixed headed one will be fine on FSIJ but we need some flexibility with the tighter radius curves.

 

Thinking ahead a bit with the Barclay Diesels that will be needed for FSIJ, which one do we model, or do we do them all?

 

Simon

[hobbyhorse]

Having the Slaters kit of the MOD D class bogie wagon in stock for some time and a bit of time on hand before the track work takes over the workshop, I've spent a pleasant few hour assembling this kit.

As the kit goes it's very well detailed, mostly injection moulded plastic with a few brass castings.

The bogies go together well with only three areas that need a little work, firstly the bogie sides need the top edge squaring off to enable then to sit in the inner frame work at 90 degrees,  secondly the wheel bearings need not be pushed completely in the housing as this gives far to much side play on the wheels, and lastly the the brass hand brake column has only a small contact area between the plastic upright, so with a small brass angle soldered to the underside of the hand wheel this strengthens the joint. 

Before

Not the best photo, but the top edge squared off.

I've not used the coupling supplied as we have developed one that is the same as used on the Bredgar railway, and as this wagon will initially be used to test the new layout before correct stock is built. These fit in the same housing without any modifications.

The body goes together without any problems, but needs care ensuring the fit is good with the sides to the ends. The photo shows the body weighted down while the glue sets, this keeps the body flat as the two body sides have only as small contact area between the joint in the middle of the sides.

Once set this is adequate and no movement is evident on the sides.

Next is some cleaning up and adding a few additional details such as chains that run between the bogies and the underside of the body, other than that just a coat of paint.

Wagon coupled to a garden rail loco fitted with the Bredgar couplings. 

The height of the coupling on the wagon is correct for the Bredgar stock, the the loco is the height for Accucraft. In light of this difference our garden rail group will fit the coupling to the Bredgar height.

​It looks like these couplings are going to be popular for garden use, so to make shunting easier I've made some test pins with loops to help coupling and shunting. if successful will cast them.

 

Simon

[hobbyhorse]

One of the requirements with the layout is that the couplings are automatic, and can be controlled via the DCC system.

Modifying them to fit this is work in progress, and so far we do have a working coupling which will need some refinement.

The bar fitted is counterbalance on the rear of the coupling, so that the bar is always in the closed position.

 

 

The first drive system didn't work as the small motor couldn't lift the arm, the idea was good as with a small motor this would fit easily into all the rolling stock, and driven via the function out put on a small sound chip.

 

This one with a servo does work, as this clip shows,  

This is driven via a Locsound XL chip which is a bit large, so we are looking at some sort of interface to drive the servo via a function output on a smaller chip.

 

Simon

Edited September 18, 2015 by hobbyhorse

[hobbyhorse]

With a bit of a deadline looming its time to get on with the two locos, our FSIJ group are attending ExpoNG at Swanley on the 31st October with a Demo. If you do attend the show drop by and have a look at what we are doing.

 

Building the boiler/saddle and smokebox assembly follows the same techniques used by most kit manufactures, this allows a rigid frame to fit the boiler and saddle skins.

Quite a lot of time was spent at the drawing board with these parts, time well spent when all the alignment holes line up.

 

 

 

The frames have been profile milled from 1.25 mm brass, and are held together with 8ba studding which is removed once the skins have been soldered on. The saddle, boiler and smokebox skins are from 10 thou nickel silver, which has been rolled without any heat treatment to the metal.

 

The design allows for the lower boiler section to be removed from the saddle, this will allow access to the sound chip and the associated wiring and will also make painting a lot easier.

 

With the smokebox fitted, it's beginning to look like loco.

 

 

With the saddle skin formed that’s the next job to fit.

 

Simon

[M Wright]

Hi, nice to see some top quality modelmaking on this forum.  So nice to see the engraving machine being used to make the parts for a small batch and to develop masters for casting.  I find the engraver linked to  etching when necessary the way to make masters. I am too old to learn the new ways of rapid prototyping the masters in wax or plastic that completely burns out.   With the cab and tall chimney what a pretty loco you owned.  How did you ever let her go?  Although I think I saw that you have a 12" to the foot line in one of your photos.  I have a 101/4" chassis and Bagnall boiler waiting for me to find time to bash into something.  Looking forward to following this construction and hope to see the progress at Expo NG. Regards, Workwright.

[hobbyhorse]

Owning a full size loco, even a small narrow gauge one can be quite expensive. Having restored Darent and run her for quite a few years we had a lot of fun, but like all good things it doesn't last forever. A couple of the photos shows the loco at her home line which was located near Severnoaks in Kent, plus she was run at the Bredgar railway.

Making these models from scratch is something that I enjoy, and using machines like the engraver adds a crispness that stands out.

Although I do own a small CNC mill I much prefer the manual way of doing things in the work shop.

Do come and have a chat with us at Swanley.

 

Simon

[M Wright]

Hi, we are attending EXPOng as traders (Wrightscale) I look forward to putting a face to a name. It is good to see the scale being exploited along one of its original paths. That of using the scale to build accurate scale models, rather than impressions of the real thing. If you are interested in WD I am trying to get a model maker to make some figures (as kits) that are up to the standards of Slaters products.  SInce that is rather a gap at the moment on the 16mm scene. Regards, Workwright.

[hobbyhorse]

Looking forward to meeting you, and one of the things we are looking at is figures as well.

 

Simon

[hobbyhorse]

With the EXPONG only a couple of weeks away, last week good progress has been made on the loco.

The weight shaft has been test fitted with the eccentrics, as after the show I'll be working on the rest of the valve gear.

 

With the saddle skin formed and on its beginning to look like Darent. The smokebox has also been fitted and the saddle/smokebox test fitted on the frames.

 

 

The running plates either sides of the loco are supported by two intermediate brackets, one with a strengthening plate and the other an L shape.

 

 

The full size Darent early on in its restoration showing the footplate brackets.

 

 

The running and foot plates have been cut out, on the foot plate in slot in the middle shows the shape of the boiler backplate and an access hole for the blowdown valve which is operated from the foot plate.

The motor when fitted will sit vertically inside the firebox, and as I'm still waiting for the motor gearboxes to arrive I've not cutout the footplate to accept it as I want to minimise the hole size around the motor.

 

Running plates fitted.

 

End view showing the fit of the brackets.

 

 

Under side view.

 

 

At EXPONG we are on stand 64 which is located in the small hall, we will have Demo about our layout "First Sunday In June" If your attending the show come and have a chat, we will have our concept models, track work, couplings, Darent locos and some  other 16mm rolling stock.

 

Simon.

[hobbyhorse]

The spec for the layout (First Sunday In June) calls for the locos and rolling stock to be fitted with auto couplings operated via the DCC system. I've already developed the Bredgar couplings which work with a small servo, this is great as the ESU XL chips which will fit into the larger locos have function outputs for the servos. The problem with these models is the XL chip won't fit into the Darent models, so the standard V4 chip which will fit can't drive the servo on its own, so with the help of Duncan Mcree at Tam Valley Depot the Singlet ll servo motor driver can be linked to the chips. The Singlet range is designed for servo point operation and is only 1.25" square. I can operate both couplings from a single servo but as sometimes double heading is required, independent control will be needed so two Singlets will be needed. The function output from the chip is a Logic one which needs the wire soldered on, and with the help of the programer its just a case of mapping the function and assigning it to an unused F key.

 

This link shows it working.

 

I did try operating the couplings with a small coreless motor which is shown in an earlier post, this one didn't work as the motor didn't have enough power but the idea is sound as it can be operated from a function output on any chip, I've not given up as I'm about to try with a slightly larger motor.

Zimo also do small sound and function chips that can operate servos which I'm also looking at, these can drive the servos without the driver boards but need some additional external circuitry, but my preference at the moment is to stick with the ESU range as I have the programmer.

 

I've now received some smaller servos which are the ideal size, but use a lower voltage so we just need to alter this.

 

If you've not heard of Tam Valley Depot, well neither had l until l was introduced to Model Rail Radio which is a Pod cast based in the states, it's recorded live monthly and you can call in to talk about your modelling, but importantly a lot of manufactures from around the world also take part. I listen to it in the workshop and it's amazing what you pick up.

 

This is the link.

http://www.modelrailradio.com

 

Simon

[hobbyhorse]

Not much to report this week other than getting ready for EXPONG this Saturday and making up a display board for the coupling which will be on the demo at the show.

 

If you don't already know our FSIJ group are part of the Bredgar railway, and the Sunday after the show is our end of year gala. 

 

http://www.bwlr.co.uk

 

Simon

[hobbyhorse]

Our attendance at EXPONG was very successful, with a lot of interest in the Bredgar couplings.

 

Before the Darent build could continue I needed to fit a voltage regulator to reduce the voltage to the servo from 5 to 3.3 volts, this is because the small servo would only take a maximum 3.7 volt.

 

 

 

 

 

 

 

With the arrival of the boards one was wired into the converter lead, I didn't use the plug type connector but wired to the bottom of the connector as I need to save space. Once the board was tested the plug terminals are snipped off.

 

 

Darent's couplings don't use the self contained bodies like the Bredgar ones, as the springing is located behind buffer plate with a coupling pocket on the outside of plate. The pockets have been profile milled, the reason for six is four for the locos and two for patterns to cast.

 

Using the design from the test couplings the coupling head was modified for the coupling bar and fitted to the buffer beam with a spring and washer, this allows the coupling to extend and also a small amount of sideways movement.

 

The servo fitting differed from the test one as its smaller and is encapsulated in a brass box which has the mounting bracket soldered on, the reason for this is the plastic fixing points on the servo would protrude outside the the frames making it visible. The brass box was machined to fit the servo from square section.

 

With the successful fit of the coupling and servo the other model can have it fitted as well, although we have quite a lot of electrical components it's certainly been an interesting journey getting to this stage.

 

Simon

[hobbyhorse]

It's been a while since I did any work on the Darent models, so on with the build.

First job was to complete the wrapper on the second tank, which is a bit time consuming but with a bit of careful work fits well.

I've been putting the next stage off for some time as it's the most detailed bits of the locos, the firebox and backplate. Quite a lot of time was spent pondering the best way of producing the parts before the drawing and cutting the templates ready for the panto engraver.

As both parts aren't clothed the rivets are very prominent, and I just happened to have some brass ones of the correct size. The wrapper will be in .45 nickel silver and the back plate 3.70 brass machined to the correct thickness.

With the templates made next stage is to start cutting.

 

Simon

 

 

[hobbyhorse]

With the basic firebox/backplate test fitted its starting to look like Darent.

Cutting the backplate was a bit time consuming with a multitude of different holes sizes required for regulator, gauge frames, washout plugs, rivets etc, from 2mm down to .7mm. Those above 1mm used the cutting tools on the engraver, but the .7mm for the rivets used a slightly different approach. Firstly the location is spotted then drilled to size on the drill press.

The frame for the firebox uses two endplates and three spacers, with access holes to enable fixing to the saddle and boiler. The backplate is fixed to the endplate using 12ba screws located in the recess that is the fire hole, and two other points that are stays with hex headed fixings. The fire hole fixings will be hidden by the doors.

The wrapper uses the same rivets as the back plate, so with a lot of holes to drill in thin nickel silver a drilling template in brass was made first. Rolling the wrapper did cause a bit of distortion because of the holes, but was easily removed with some emery cloth.

Next will be profiling the radius on the back plate, I've made a template to help with that.

Simon

 

 

 

 

 

 

 

 

 

[doilum]

Rude question. How will it behave with such a long overhang at the rear? On my shelf there is a never finished loco built around an old Hornby clockwork unit. The idea was to have something to play with whilst my Roundhouse Kayti was cooling down.  Whilst pushing was not a problem, it struggled to pull stock around the 42" curves.

[hobbyhorse]

The front end of the loco will be heavily weighted, and as it'll only be hauling a couple of coaches it shouldn't be a problem. On the full size one you had to be very careful when running chimney first as it could lift at the front end, it was OK when coupled to some coaches.

 

Simon

[hobbyhorse]

Before applying the rivets to the backplate the small additional thickening plate that allows the blowdown valve to be fixed to the bottom was made. The rivets required two different methods of fixing, those on the wrapper are soldered in, and the backplate ones glued in from the rear. A little bit of cleaning up is needed with solder around rivets, bit other than that I'm well pleased with the result.

Next was the firehole doors, runners and tray. These have to operate to cover the fixing screws in the door recesses.

Simon