Ian M's 7mm workbench - Back to the MACAW B.

[mike hughes]

I used HMRS pressfix but believe

 

Michael,

 

Thanks for the warning. I have just looked through all of your wagon photos, I can only hope mine will turn out half as well. The Slater's kits have no lettering transfers supplied. What did you use? I am trying to avoid Pressfix type because they and I don't get on with each other. 

 

I am thinking about making replacement brake levers, rack, safety loops out of brass sheet. Then again I may just use those supplied in the kit. Makes me sound very fickle I am afraid!

 

Ian Major.

I used HMRS pressfix/methfix transfers but believe that Modelmaster do waterslide transfers for the vans. I forgot to say that pretty certain needed to add a strip of 10x60 strip to each end of floor as it wasn't long enough, built a fair few to learn that

 

Michael

[Ian Major]

Michael, again, thank you very much. I will keep that it mind for when I get around to painting the wagon - though painting and me don't keep happy company.

 

Progress...

 

I started by preparing the buffer housings. The castings still have the plaster cores in place. I used a 1mm drill bit to clean out the base end. I intended to use a 1.7mm drill bit to clean the main part out but I found there were ridges of brass inside the bore. So I used smaller bits and broaches to niggle the ridges out before finally cleaning the main bore with the 1.7mm bit whilst avoiding drilling straight out the other side! 

 

The photo shows two of them test assembled.

 

 

Two things became apparent. 

 

First, the nuts were not biting on the base with the springs under light compression when wound to the full extent of the thread. The lower buffer in the thread shows this well. It means the buffer rams slop back and forth a bit.

 

I have no info on BR buffers, but I have a dimensioned diagram of similar buffers in my GW books. This shows the buffers as being 18" over all with the housing being 13". As the lower buffer shows, with the slack taken up they are 18" long. So the answer will eventually be to solder some brass packing on to the base.

 

The other point is that the lip(?) where the ram enters the body looks very thin. The Parkside buffer housings have a separate ring moulding that is glued on. I will try producing some brass rings for this purpose which will bring the housings up to a scale 13" long.

 

Turning to the plastic components, the first move is to drill the holes in the ends, sides and solebars. The holes for the buffer housings I slightly countersunk so that castings would sit down nicely. 

 

An issue that I hit was the chalk plates(?) to be fitted on the ends have 4 moulded pins, but the instructions only call for two holes. Also one of the moulded pins is distinctly fat. 

 

 

I decided to cut three of the four pins off then use the remaining one to get the position correct and to get the horizontal positioning by eye. When attached the plate didn't sit square so I put small cubes of 10thou Plastikard under 3 of the corners. 

 

The photo shows this in place along with the coupling reinforcing plate on one end. The brass parts are test fitted.

 

I am still using my open wagons to hold parts awaiting fitting!

 

 

 

 

Edited March 31, 2022 by Ian Major

[brossard]

Hi Ian.  Thre is no substitute for having copious prototype information.  Paul's collection is one source.  The wagoins pictured are generally at end of life but do provide insight into mechanical details. 

 

I also have been collecting books and magazine articles.  Most of my library is LMS so I too sometimes have issues finding BR data. 

 

Every question that I have had has been answered by the helpful and knowledgable members here.  Creating a thread is a great way to generate interest and get the answers you need.

 

As for transfers, Slaters seem to be hit and miss in this respect.  Some kits have them, others don't.  I like Fox transfers.  There's a vast range to suit most vehicles. 

 

John

[Ian Major]

John,

 

 

Thanks for your input.

 

 

 

I have continued assembling parts on to the ends and sides whilst in the flat. The instructions say to drill the holes for side vents 0.75mm. However the locating pins on the vent castings are fatter than that and actually required the holes to be opened out to 1mm. They were still a tight fit.

 

 

 

I then turned back to completing the buffers so that I can permanently fix them to the ends.

 

 

 

My original idea was to put packing on the rear of the buffer housing to take up the slack. Rather than do this I decided to put a packing piece inside the housing to push the ram fully forward. This consisted of 1mm lengths of 1.6mm O/D brass tube. The centre of tube was reamed out to 1.2mm so that it would clear the thread and the narrower part of the ram. The buffer was assembled with the tube slipped on to the ram first, followed by the spring, this was put in to the body and the nut spun on. Result. The nut just bites on to the body as the spring comes under a compression.

 

 

 

The photo shows the assembly sequence.

 

 

 

The photo also shows the part of the castings that represent the plates that bolt on to the headstocks are not at 90 degrees to the centre line. I will have to make sure the buffers are not at a queer angle when I finally fix them.

 

 

 

 

 

 

 

Next was to address the half starved lip around the outer end of the buffer body. For this I made up brass rings made from 1mm rod annealed and formed around a 2mm drill bit. I rubbed the two faces of the rings on emery paper to flatten them down slightly. These were then soldered on.

 

 

 

The photo shows the first one completed compared to an unmodified one. Well I think it looks better!

 

 

 

 

 

 

 

Edited March 31, 2022 by Ian Major

[dibateg]

Almost like prototype practice! I think they welded rings on buffer housing to extend them in the past...

 

Wire wound round various sizes of drill comes in useful for all sorts of jobs.

 

Regards

Tony

[brossard]

Just a quick note, and you may already be aware, I use Loctite Thread Locker to secure the nuts in place.  This can easily be overcome if the nut has to be removed.  I took over the build of a van from a friend.  He used CA to secure the nuts and the buffer broke when I tried to remove the nut.

 

John

[Ian Major]

John,

 

I agree with you about the use of superglue. I normally use nail varnish if I have no Thread Lock to hand. I have found (accidentally) that paint can hold small nuts almost a securely as superglue!

 

Tony,

 

I have used wire wrapped around formers a lot to make chains with links down to about 1mm. If I need advice on such matters I talk to my youngest son who trained as a blacksmith. This is him wielding the hammer not the one supporting the wall.

 

 

He was making a billet of pattern steel, which is layers of tool steel alternating with layers of mild steel fire welded together, folded over and fire welded again, then folded again and so on. The billet is very hot to allow the fire welding to take place. He used the billet to make a variety of things including a bottle opener for me and this pendant for unknown:-

 

 

What has this to do with rings? He also studied the creation of chain-mail and related jewellery for which he produced large quantities of rings:-

 

 

Sadly, there is little call for blacksmiths in the UK so he became a copper in Essex instead (I tend not to argue with him these days!). But I can still still pick his brains on the subject of metal handling techniques from time to time.

 

Well back at the fruit van....

 

I have finished preparing the buffer assemblies and have now turned to the chassis members. The instructions recommend installing the buffers and couplings in to the headstocks before assembling the chassis. I prefer not to do so before painting - I struggle enough with the painting as it is. The photo shows why this is recommended.

 

 

The coupling hooks are rather nice brass castings. The springs are retained by split pins. As things stand it would not be possible to fit the split pins on to a fully assembled chassis. It is also a tight fit between the chassis members requiring the split pin to be bend right over and clipped short. I prefer to just splay the split pins slightly so that they can be removed it required eg to fit certain types autocouplers.

 

I decided to cut slots in the ends of the centre members which will allow (I hope) the split pins to be fitted/removed and allow them to move back and forth against the springs. The chassis moulding will be strengthened when it is attached to the van floor. It is also only "L" sectioned at the moment and will have Plastikard strips added to make the channel section. This will reinforce the lower edges.

 

The next photo illustrates this. It also shows that the link twixt hook and instanter might be a bit tight so may need some easing.

 

 

I cleaned up the solebars ready for assembly and have been passing a jaundiced eye over the protrusions on the lower edges, two each side. These represent the stops above the axleboxes. I have marked one of these with an arrow in the photo.

 

 

I would expect them to be more like the one in the next photo, which is a Parkside version.

 

 

I have looked at a variety of photo sources but can't find any wagons with solid lumps like this. I suppose it is possible that some BR wagons had India rubber stops(!?). Anybody got any thoughts? Else I will look at fabricating the inverted bridge rail type. Fun, fun, fun.

 

Edited March 31, 2022 by Ian Major

[Hal Nail]

Interesting interlude about metal work and a cracking “copper” pun. Of course you could have added he forged a new career etc!

 

I bought a part built slaters wagon where the springs had been cut from the solebars at one end and fixed to a plasticard rocking unit leaving a small gap. Initially I intended to undo this but I must admit it works and once it’s all black and part of a full rake, you don’t notice. So you could probably get away with ignoring those “stops” but it’s nice to get the details right.

[Nickey Line]

Probably a bit late for this wagon, but to deal with sloppy buffer heads I find it easiest to just stretch the springs slightly...

 

You're right about the bump stops. I'd built a few other Slater's kits before deciding they weren't good enough and replaced them  with tiny bits of plasticard strip on later builds. Decidedly fiddly... must think of an easier way.

[Ian Major]

Welcome to Cock-Up Corner. Or the art of thinking everything is going swimmingly when in fact there something not quite right.

 

But before I go there, my thanks to Hal Nail and Nickey Line for their input. I did consider the idea of stretching the springs but the engineer in me recoils at the thought! I am of a very sensitive nature.    

 

The instructions give some excellent isometric exploded diagrams for each stage but not necessarily the order in which to assemble the parts.So I started by assembling the solebars on to the main under-frame molding. This was done on a plate of glass to keep everything flat and with frequent checks with engineers squares and straight edge to ensure there was no banana shape developing. 

 

 

Next up I fitted the ends. I did not glue the floor to the under-frame before fitting the ends. The rear of the headstocks have pockets in them in to which the (very flexible) ends of the under-frame fit. My concern was that if I fixed the floor first then I might have difficulty in getting the ends to sit properly on the under-frame. So I glued the ends to the under-frame then placed the floor in position with my squares in place to make sure the ends were vertical.

 

As Mike Hughes indicated in entry #26 the floor was a bit short.

 

 

When the end joints were hardened I fitted the sides. Again without the floor. I have had floors that were too wide in kits before so I reasoned that with the ends and sides in place I could trim the floor to fit if needs be. The sides were fitting nicely - or so I thought.

 

 

I then glued the floor in place. As can be seen from the last photo there is no need to drill holes in the floor to let the solvent vapour out, the ventilators in the ends are open.  

 

The lower end of the side vertical strapping (4 per side) have one or two pieces that project inwards towards and attach to the solebars. These, it transpired, were a little bit long. There was no flash or sprue remains to cause this. The result was that where these parts lined up with the under-frame cross pieces, the sides would not seat properly on the floor, and where the solebar was not supported from behind (where the "W-irons" will fit) was pushed out of shape.

 

I hadn't noticed this until the following day by which time everything had hardened up.

 

 

To rectify this I decided to chop off these horizontal parts. I softened the joints between the solebars and the bottom of the sides and the floor. With a bit of heaving with a piece of wood I managed to improve things though still not perfect. I will replace these with small parts of 20thou plastikard later.

 

I think if I do another of these kits I will do the same actions up to fixing the ends, then attach the floor. The underside of the floor has a raised locating area which aligns with the centre of the chassis molding so getting it centralized is straightforward. Checking the fit of the sides would then be easier.

 

On the back of the headstocks there are shoulders on which the solebars are located. The distance over these shoulders is 43.8mm and the distance over the under-frame molding is 43.3mm. This doesn't sound much but it does result in the ends of the solebars splaying out as can be seen in the next photo.

 

I have fitted the plastikard strip along the bottom of the under-frame to complete the channel and added the square gussets. I did a trial fitting of the triangular gussets around a buffer. I think I see why Slater's recommend fitting the buffers (complete) early in construction. The nut on the back of the buffer would be awkward, though not impossible, to get at.

 

 

So I made a 12ba box spanner. Quite easy. I cut a 8mm length of thick walled brass tube with an O/D of 3.2mm and an I/D of 1.6mm. The latter clears a 12ba thread. I drilled one end to a depth of 2mm with a No42 bit. I held a 2.3mm allen key in a vice with a small part of it pointing upwards from the jaws. I then placed the drilled end of the tube on to the key and hammered it on which gave the bore of the tube a hex shape. A quick tidy up with a file then soldered a handle on to the non drilled end using 220 degree solder. The result was this.

 

 

To use it I put a 12ba nut on the bench and push the box spanner on to it.

 

 

The spanner is fed in to the rear of the headstock and the buffer ram pushed in to the housing. The whole lot was tightened by turning the buffer ram. Job done.

 

It also worked well removing the buffer. The only change I would make is reducing the tube length from 8mm to 6mm. Not perfect but it works.

 

 

Now its time to think some more about the lumps on the bottom of the solebars.

 

[Ian Major]

My first entry following the RMWeb upgrade. I might be doing a few post publication edits until I get used to the changes! I like the single step drag and drop to add images, rather than the old 3 step approach. 

 

Whilst giving some thought on how I am going to replace the "protrusions" I started on the brackets that fit under floor. These are brass castings that instructions show being fitted towards the end of construction. It occurred to me that it would be much easier to fit them before the rest of the chassis and wheels. There are two brackets each side and one central larger bracket that also represents the hole that the door locking latch would engage, though nothing on the model will actually do any engaging.

 

I fitted the central brackets first. Then I added the first of the smaller brackets to the left end of the sole-bar. The following photo shows a couple of problems.

 

The first is that the bracket is positioned between molded representations of the maker number plate and the shipment label clip. It is too wide to fit in the gap. The second is the horizontal part of the bracket butts up against the top flange of the sole-bar which pushes the whole lot outwards. The result is that neither end of the bracket beds down to the face of the sole-bar or the underside of the body. In fact the small brackets would have ended up proud of the body sides, which would have looked silly.

 

 

 

To tackle this I reduced the width of the bracket slightly and cut a little of the number plate molding away. I also cut off the horizontal part of the bracket. It now fits very well. There are two spare small brackets supplied with the kit so any minor disasters are covered.

 

I have also reinstated the horizontal parts of the body strapping using 20thou plastikard strip left over from creating the chassis channel. In the photo it can be seen that the one reinstated part doesn't look right. It is fitted as per the original kit part. Checking various prototype photos the part should be in contact with the sole-bar flange, so I changed it. 

 

 

 

I found the body sides tended to bow inwards so I added a couple of 40thou partitions. These are slightly lower than sides to avoid fouling the roof.

 

 

 

 

Some 1mm plastic rod is supplied with the kit to represent the vacuum pipe. The ends of the pipes are represent by brass castings which have a pipe diameter of 1.5mm. I didn't think I could get this lot to stick together securely so I used 1.5mm brass rod instead of the plastic.

I used 1mm lengths 2mm O/D brass tube to represent the securing clamps, lined up with the cross members of the chassis. 1.5mm lengths of the tube were used to join the castings to the end of the brass rod.

 

 

 

The instructions are not consistent regarding the routing of the vacuum pipe. Fig 4 shows the pipe routed along the underside of the longitudinal chassis members. However Fig 3 gives measurements to drill the holes to locate the end castings. This aligns the pipe to the side of and parallel to the chassis members. 

I found a photo of the upside down remains of a fitted BR mineral wagon in Paul Bartlett's collection (https://paulbartlett.zenfolio.com/brmineralclaspvb). This shows the pipe to the side of the chassis members so I drilled the holes as per Fig 3 and did a test fitting.

 

 

Before finally fitting the pipe I started on the vacuum cylinder.

 

 

 

The lid molding looks distinctly eccentric and also short of detail. I think I might have a crack at making a master and casting it in whitemetal.

 

Nothing ventured nothing gained!

 

 

Edited February 3, 2019 by Ian Major
Remove a couple of extraneous images. They were the original too large files which I had meant to delete. Experimenting with resized images. using the same size as before now look too big in the new format.

[Ian Major]

Progress is a bit slow due to other activities taking up a lot of time. So a quick update.

 

I debated with myself about the "protuberances". In the topic "JLTRT van kit underframe", Brian Daniels' entry <here> shows photos of his JLTRT BR banana van underframe it shows the same style stops as the Slaters fruit van. There is also a photo of a prototype van in his entry which shows the same style.

 

However, in Paul Bartlett's collection, are photos of Dia 1/233 number KDB875760 at Cambridge and another one of B875800 at Kidderminster. (https://paulbartlett.zenfolio.com/brfruitvan) These show the open "U" shaped stops. So that is what I went for.

 

I milled a set of dies out of steel bar and used these to press the parts out of 1.5 x 0.5mm brass strip. I drilled holes in one of the dies to allow alignment pins to be used, but I didn't need these. The slot in the other is about 0.2mm too wide so the parts came out slightly rounded. I annealed the brass then pressed the lot in my vice. The following shows the results. The parts may be the wrong size, they may be the wrong shape but at least they are all same wrong size and shape!

 

 

I fitted the first one and checked it. Its size looks OK against a diagram of a GWR wagon that I have and also compared it to my Parkside open. I can live with that.

 

 

All 4 stops are now fitted.

 

 

Now, about that vacuum cylinder... Time to look for some decent photos of a BR one, if I can find them.

 

Edited February 7, 2019 by Ian Major
Correcting tryping errors.

[Nickey Line]

I very much like your bump stop solution. Far easier than fiddling with bits of plasticard...

Having said that, Geoff Kent would do it that way, and in 4mm too!

[georgeT]

Some very interesting stuff going on here lan watching from now on...my thread is on here somewhere its a while since l made any kits georgeT's 7mm workbench...

Edited February 8, 2019 by georgeT
error

[Nickey Line]

On 07/02/2019 at 20:27, Nickey Line said:

I very much like your bump stop solution. Far easier than fiddling with bits of plasticard...

Having said that, Geoff Kent would do it that way, and in 4mm too!

 

Just to illustrate the point;

a Slater's 13T steel open I'm working on at present...

 

 

Five squares of 55x20 thou microstrip... definitely not something to try in 4mm if you value your sanity.

[Hal Nail]

Seeing your partitions has reminded me you might want to think about filling it with bubble wrap or similar inside before fixing the roof to deaden the amplified hollow sound these make when running. I often use old sprues for bracing at the top and sometimes as reinforcement glued into corners or across the sides.

 

Also think about weighting - I use plasticine sausages pressed along either side/floor join usually - easy to break everything when doing this so care is needed!

[Ian Major]

My thanks for the input from Nickey Line, George T, and Hal Nail. It gives me some ideas to work at.  I have been rather tied up recently so I apologise for my tardy reply.

 

Next up was making some masters so that I could cast replacement vacuum cylinders.

I started by turning a cap to make the dome of the cylinder. This I made from some wooden dowel. It would have been better in brass but I had no stock big enough. The shape of the top of the dome was copied from a cross sectional diagram that I found on line. The dimensions were taken from the Slater's original. 

I parted this off leaving a disc in the centre for location purposes.

 

 

I turned the body from the same dowel and bored out the centre to be a tight fit for the dome top. 

 

 

I cross drilled the body 1mm right across. The dome top was permanently fitted and the body parted off.

 

 

To make the base end I glued two pieces of 60thou plastikard together, and stuck them to the end of the dowel. The base was turned to shape including 
using a cross slide to give the indentation towards the centre. It was detailed with 10thou plastikard strip 1.5mm wide and 0.5 plastic rod.

This was parted off again living a disc in the centre for location purposes.

 

 

The base was glued to the body and a pivot was created using a length of 1mm brass rod, with reinforcement strips made from the 1.5mm strip. I painted the wood red to seal it. I also painted the plastic base but that was a mistake so I cleaned the paint off.

The following photos show the finished cylinder alongside the Slater's version, plus the first trunion.

 

 

 

I tried the new cylinder in place. The trunions needed to be shortened a little. The cylinder is about 0.2mm greater diameter than the Slater's one, but after the casting process I believe (hope) the shrinkage will take care of that. I have since the photo was taken sanded the paint surface with fine wet and dry paper to get rid of the small bumps in the surface.

 

 

 

The Slater's cylinder sat alongside the new version (the Slater's one occupying the correct position). The trunion lengths have been corrected.

 

 

I failed to mention that this is the third iteration of the cylinder, the other two went in to the bin.

 

So now to make molds from the masters. I have done whitemetal casting before but this will be my first attempt at making the molds.

If this fails I can use the master on the wagon - and if all else fails I can revert to the Slater's version - or take up flower arranging.

 

Ian.

Edited March 3, 2019 by Ian Major

[Ian Major]

Well here I go making the moulds. 

 

As guidance I used an article written by Robert Chenery for the 12th October 2007 edition of Model Engineer. It was about that time that Tiranti started advertising their moulding products in that magazine so I guess he was something to do with them or at least an "evangelist".  The content therefore should be trustworthy.

 

The materials I bought as a "get you going" set included modelling clay to make the bed. The surrounding wall I made from Lego bricks. This wall has to be big enough to give a minimum of 10mm of mould material around the patterns. I built the walls two bricks high then made the clay bed up to be level with the top of the wall.

 

I carved indentations in the clay to allow the patterns (including the ingate) to be half submerged, then dressed the clay up to the parts to leave no gaps. Four holes were bodged in the corners with a pen to create the alignment posts and the wall completed up to four bricks high.

 

 

Actually in the photo I had made a ridge of clay between the ingate and the cylinder to create the passage for the molten metal. It was a bit naff so I cut it out and replaced it with a short length of dowel. I will cut the passages for the trunions with a lino cutter later.

 

Now to pour in the first lot of silicone rubber. In the article it suggests filling the brick wall with water from a measuring jug to work out how much rubber mix to make up. Apparently any residual dampness will not adversely affect the curing process though I did have water leaking out of the gaps between the bricks for the next couple of hours.

 

I used a stiff brush to work some of the mix in to the detail then poured the rest within the wall. The next photo shows the result. The red bricks are in there to show the orientation to me.

 

 

The mix took much longer to cure than I expected which puzzled me. I had measured the rubber in to a plastic tumbler, weighed it, then added the appropriate amount of catalyst. Later I realized I hadn't shaken the catalyst bottle so it was probably weak. Doh.

 

Eventually it did cure and I dismantled the lower half of the wall and removed the clay bed.

 

 

I hit a few problems:-

 

1) Some clay stuck to the detail which was quite difficult to remove. There was also clay embedded between the rubber and the pattern which I picked out. I must have left a slight upward lip when dressing the clay up to the pattern. Something I must watch out for in future.

 

The author of the article used Scopas wax for the bed. I looked this up on the Web but only found references to a mountain in the Middle East and some Jewish religious articles. Very interesting but not helpful in this case. I only found references to Soya wax flakes and cheaper Paraffin wax. I will look in to these next time to see if it is better than the clay. 

 

2) Another problem was air in the holes for the locating pegs. Next time I will use the brush to force some mix in to the holes to avoid this.

 

3) I did the mixing of the rubber in a plastic tumbler. When I poured the rubber from its tin it was like thick cream. Once it started to flow it wouldn't stop, so too much came out. Bit of a mess. For the second mix I used an old spoon to ladle it out.
 
After a clean up (both me and the patterns) I smeared the cured surface with Vaseline to avoid the two blocks of rubber from sticking together. I rebuilt the lower half of the wall and poured in the next rubber mix.

 

At this point I wondered if I would ever see the patterns again, or were they now entombed in a block of rubber for ever?

 

After an anxious 24 hour wait I demolished the Lego walls and the two halves of the mould split apart with no problem. Phew.

 

 

From the photo it can be seen the clay has left some deposits. It also shows that I didn't get a flat surface to the clay base so the mating surface looks like a 3D map of the moon. This shouldn't be a problem but I would probably get better results with wax. 

 

I have still to cut the channels to feed the trunions and to clear those for the cylinder. The author of the article says that a lino cutter should be used since a scalpel or similar risk splitting the mould.

The instructions say that the fresh moulds should be allowed to mature for 3 to 4 days before the first cast which means it will be week before I try it.

 

I will turn my attention to other jobs for few days.

[georgeT]

Hello lan, Could do with a couple of those tanks for my seacow, very nice, sorry couldn't make the club on Friday hope to catch up next time....

[Ian Major]

George,

If they come out OK you are welcome to some all for the price of some advice on how to make a shunting plank!

 

Ian.

 

[Ian Major]

Casting.

I have changed the title of this thread to reflect what I am doing at the moment - probably should have called it "Reinventing the wheel".   

Here is my casting set up..

 

 

If you are wondering what the object is in the bottom right corner it is a stone hot water bottle that is older than me.

 

I am using metal ingots from Prince August - I have no connection other than as a satisfied customer. There are three types of metal alloy from them:

 

1) "Model Metal" which is 11% Tin/35% Bismuth/54% Lead Alloy. Its melting point is 138 C (280 F) and it has a casting temperature  range of 300-320 C (572-608 F). This currently costs about £0.04 per gram (double this to include postage). 

 

2) "Standard Metal" which is 33% Tin/2% Antimony/65% Lead Alloy. Melting point 210 C (410 F), cast at 320-340 C (608-644 F). Cost £0.03 per gram.

 

3) "5 Star Metal" which is 94.5% Tin/3% Zinc/2.5% Antimony Alloy (Pewter). Melting point 230 C (446 F), cast at 320-340 C (608-644 F). Cost £0.09 per gram.

 

I have stock of the Standard and Model metal. I decided to try the standard metal which is more difficult to cast but its higher melting point means soldering is a practical proposition. It is also the cheapest metal.

 

Before casting, I noticed the pattern for the cylinder had a joint that was opening up. This was where it had been exposed to water when I was measuring how much silicone rubber to use. The pattern being wood obviously objected to the water. This had left a thin piece on the mould which would have left a grove in the final cast. So I trimmed this off.

 

For the final casts I will probably use a piece of brass rod to make the pivots, but for testing I will leave this out. The result of the first test casts were mixed. The cylinder came out fine but the trunions did not come out at all. Before I did the next test cast I cut some vents for the air to escape and increased the metal temperature a little. My melting pot temperature range is 450 F to 900 F. It is an American thing though it looks like the sort of gadget that I saw in the shops when I worked in Moscow in the early '70s! It has a rotary knob to vary the temperature but no indication what the temperature is.

 

 

The photo shows there is some flash. This is where I didn't get the clay bed quite right. Better next time....?

 

I tidied up one of the cylinders and tried it in situ on the wagon using the trunion patterns. It fits OK. Cleaning the flash was a bit of a challenge. It doesn't look too bad. Some of the marks showing up in the photo are where the clean metal is showing through the tarnish. There was some shrinkage due to the casting process. The cylinder pattern is 13.9mm diameter and the casting is 13.7mm,  which is about 1.5% shrinkage.

 

 

Also a side view. This shows up some marks I left from my filing. Needs a bit of emery paper around it.

 

 

Another problem was revealed. There was a ring of blow holes where the sprue was attached to the dome. This is due to my using a short length of dowel to make this channel in the mould and having issues with the clay bed around it. I will be making another mould in which I won't use a dowel for this but I will cut the channel.

 

You can just see the holes in this photo. The yellow bloom is the reflection of my angle poise light.

 

 

I tried increasing the size of the channels to the trunions and cut some vents to allow the air out. I did three further castings. The result of the final one was a bit better. One trunion came out fine - with a bit of flash, the other was only partially formed. However, more importantly, there are signs that the moulds are deteriorating. I have done five castings, they should be good for a hundred. I am obviously over stressing the moulds with the higher temperatures.

 

<phot 049>

 

It looks like I will have to revert to the lower melting point "model metal" after I have made some fresh moulds.

 

I am off to Cambridge for a week so they will have to wait on my return. I will probably be off line for that time as well.

 

[mike hughes]

They shouldn’t deteriorate that quick, I believe I’m using RTV 101 for my red rubber moulds using Tiranti number 3 white metal and some moulds I’ve easily had 100 plus from them. 

What you have done looks good

 

michael 

[whiteknight024]

It’s lovely to read your posts Ian I have a ruck of wagon kits that I need to build so your postings have given me much food for thought. I also love Georges layout postings also. I will miss this Friday at High Lane as I will be in Cornwall but I have much to do to meet your standards.

 

Kind regards

 

Iain 

[Ian Major]

Many thanks for all the likes. 

 

Michael, 

I would be very interested in more on your experiences with mould making.  I looked up the Tiranti spec and its RTV 101 appears to have roughly the same temperature tolerance as the Hobbytime RTV/HB that I am using. The Tiranti number 3 metal that you use has a similar melting point to the Prince August "Standard" metal. So my experiences should be similar to yours. I suspect I am getting the metal too hot. I am not impressed with the melting pot that I have. I decided to get a small electric ring and heat the ladles directly which I have done before.

 

I let George T have three castings for his walrus. He liked the detail but felt that the dome was too shallow. The dome on the pattern is OK. The problem seems to be that the feed going on to the top of the dome makes it difficult to clean it up without flattening it. So I am making fresh moulds with a pair of feeds straddling the peak of the dome. I will need more domes for other vehicles that are in the pipeline.

 

Iain,

 

Good to hear from you. I was at High Lane on Friday for all but the last hour. Progress, not a single electrical fault (well at least whilst I was there). We had some good DCC running.       

 

I am struggling to get my feet back on to the ground after riding the "The Bard of Avon" steam special. It took me around lines that I was familiar with in my youth. I am a dyed in the wool GWR loco fan but have to admit that Tornado is an amazing machine. On the return via Shrewsbury we were routed in to the Cosford goods loop for an unscheduled stop to allow a service train to pass. This meant we ended up 20 minutes down. Setting off from Shrewsbury we negotiated the sharp curve on to the Crewe line nice and steadily and then the driver opened up. It was an exciting run to Crewe where we arrived 5 minutes early. Brilliant.
  
Well I have made steady progress on the fruit van. The dome of the vacuum cylinder is hidden on this wagon so I was happy to use one of the castings. The kit supplies 0.5mm plastic rod for the connection to the train pipe. This was to be in the form of a simple "U" shape. I decided to use brass wire.

 

To make a representation of the relief valve I drilled a hole 2mm from the end of some 1mm brass tube. In this hole I soldered a length of 0.5mm wire (to fit in to the cylinder). I rounded the end of the tube then sawed off the tube near to the 0.5mm rod. Some more 0.5mm rod was soldered in to the tube and the first 0.5mm rod was cut back to 3mm long.

 

The next photo shows the completed item along with the castings of the trunions and cylinder (which is not as rough as it looks!).

 

 

I glued the trunions in place, pivoting the cylinder between them. I shortened and shaped the long tail on the relief valve and soldered it to the train pipe. The short brass rod on the
relief valve was glued in to the hole in the cylinder.

 

I soldered the supplied etched actuating rod to the cross shaft. I replaced the supplied plastic "T" actuating rod with one made from 1mm brass rod.

 

The photo shows these in place. The train pipe is now permanently fitted but the "T" piece and cross beam will remain loose until the brake push rods are fitted. The cylinder rocks on the trunions in a most satisfying way.

 

 

Time to fit some wheels methinks.
 

[Ian Major]

The kit supplied "W" irons, springs and axle boxes are separate parts. There is a choice of axleboxes. I was under the impression that BR designed/constructed wagons in the '50s tended to have boxes with a plain rectangular front cover. Non of the supplied axleboxes looked like this. So I fitted the split front type which matches those on the later photos of these wagons.

 

I have dry fitted one set of brake gear to see how it looks. I was debating whether to make my own, but I will use these. The brake shoe support needs shortening a little to make the shoes concentric with the wheels.

 

I am pleased with the decision to replace the brake cylinder. The bolt detail is very visible. Also since the cylinder rocks in its trunions it sits at a slight angle as per the prototype. Kit supplied cylinders tend to be perfectly vertical.

 

As Mike Hughes noted earlier in this thread certain of the underframe parts are very delicate. At least one of the brake safety loops cracked and I had to put a spot of solvent to do a repair. I am thinking of replacing these along with the brake racks with suitable strip brass. I don't have any at the moment so I will get some from the Leigh exhibition. That's in 4 weeks so this van may  go on hold until then. There are plenty of other things awaiting my attention.

 

 

Tried the roof for fit. It is starting to look like a van now rather than a grounded body!