Jim's 7mm workbench: Acorn BR Standard 3 Tank

[doilum]

I may have the answer to my own question.

On google images there is a good rear view of 82005.

The lamp brackets are all curved to the left, even those centrally mounted.

[jim.snowdon]

Having got the new cylinders fabricated and set in place, the next task (problem?) is assembling the slidebars and working out how to attach the motion bracket.

 

Unlike some better organised kits, the slidebars and cylinder rear covers come as separate castings, with very little by way of positive location for the former. The motion bracket casting, apart from being a rather simplified version of the original (if indeed it was ever actually designed for this kit) has no means for positive location either so the whole assembly is little more than a bag of bits.

 

The slidebars are, thankfully, T section, so although they neede a little of straightening, it was a practical proposition to clean then up and reduce their width to fit the crosshead in the mill. (those without milling machines will need to look away and resort to filing by hand). That gets four nice clean and straight slidebars, but does nothing to help with betting them attached to the cylinder cover. A technique I have used in the past when faced with this problem is to use the crosshead casting itself as a jig to hold the bars at the correct spacing, but it is still a bit of juggling act to get them attached square in both axes.

 

For this build, now that I have the vertical mill, I machined a block of Tufnol to a fat T section that could sit between the slidebars and hold them parallel and at the correct spacing, then fitted a small screw clamp to hold the bars, as per -

 

 

The end of the block is machined square as it turned out that the part ofthe end cover casting that represents the piston rod gland is both flat and level with the end of the brackets that take the slidebars. That meant that if the slidebars were set to stand proud by the depth of the brackets, the end of the block could sit on the face of the gland, which would thus set them square to the cover whilst they were soldered in place.

 

 

So far, so good, making the next task locating the motion bracket on the other end of the slidebars. It too is provided with pockets into which the slidebars will locate, except that they are at marginally wider vertical centres than the bars (no surprise there), Since the slidebars are tapered right to the end, technically an error, but a useful one, the motion bracket will sit on the bars, just, but sufficiently tightly to stay put whilst the first joint is soldered - delicately.

 

The result - a complete slidebar / motion bracket assembly -

 

 

The last task is to work how to attach this.The motion bracket casting has, thankfully, a hefty great mounting foot. Unthankfully, most of it stands above the top edge of the frame, which makes any method of securing it with screws interesting.

 

 

The solution was to make up a pair of frame extensions, however that is not as simple as it sounds, as they need to be fitted to the inside faces of the frames yet present an outside face that is flush with the outside of the frames so as to provide a flat mounting surface for the motion bracket. Back to the milling machine to cut a rebate into a piece of 1mm scrap nickel silver left over from another project.

 

Holding small pieces of plate in the mill requires a little more ingenuity than simply nipping it up in the machine vice, especially when it is the top face that is going to be worked on. The solution is to clamp it to a parallel, setting it square using a square, and then nipping that up in the vice, with two parallels underneath to set the height and level.

 

 

The results, once cut out of the plate -

 

 

These are soldered to inside of the frames in the appropriate place, using the completed slidebar assembly as a reference to mark the frames.

 

The mounting on the motion plate casting having been previously drilled for the mounting screws, the assembly in then clamped in place so that the first hole can be spotted through, then drilled and tapped 12BA for the screw. With the first screw in place, the procedure is repeated for the second screw, as per -

 

 

 

At this stage, the screws are temporary and will get replaced by proper short brass ones for neatness, whilst the whole assembly will end up attached to the cylinder block using epoxy. Before that happens the brackets for the expansion link need to be attached to the motion bracket, a task that is going to be easier with the sub-assembly of fthe frames.

 

Jim

 

[doilum]

Love the clamp idea.

Help please.

Can anyone point me at a photo of the cab interior, especially the firebox back plate. I have the RCTS vol3, which has a schematic layout of standard control layout, but would prefer a photo of the real thing.

[3 link]

Hi Jim,

 

Just a quick note to say I'm enjoying the build and one question if I may. You say your going to attach the cylinder block using epoxy, so you obviously have faith in the stuff. I have had mixed results over the years with epoxy, so can you tell me which type and make you are happy with.

 

Regards,

 

Martyn.

[pwr]

I may be lucky. The scorpio kit uses parts from a brass etching leaving the ones on the nickel silver frame etch unused. Is this a correction?

Yes I just looked at my instructions and they suggest the original nickle silver etchings are not used.

 

Does anyone know where I can get a 7mm GA drawing

 

 

Paul R

[PAD]

Hi Jim,

Is this an original Transport Age kit,

or is is from Scorpio?

Cheers,

Peter

[doilum]

There are GA diagrams and critical dimensions in both Brian Haresnaps "Ivatt and Riddles locomotives" and the RTCS vol3 which covers the standard tank engine classes.

Both will need rescaling. The Haresnap drawing is slightly larger and clearer, but the RTCS one has more detail and has a head on view.

Both books have excellent photos of everything bar the cab interior!

[pwr]

There are GA diagrams and critical dimensions in both Brian Haresnaps "Ivatt and Riddles locomotives" and the RTCS vol3 which covers the standard tank engine classes.

Both will need rescaling. The Haresnap drawing is slightly larger and clearer, but the RTCS one has more detail and has a head on view.

Both books have excellent photos of everything bar the cab interior!

I looked in the Davis and Charles Standard Steam in Close Up albums and there is nothing there.

 

Regards

 

Paul R

[doilum]

Picked up both books on amazon for less than 15 quid.

[Dave Holt]

There are GA diagrams and critical dimensions in both Brian Haresnaps "Ivatt and Riddles locomotives" and the RTCS vol3 which covers the standard tank engine classes.

Both will need rescaling. The Haresnap drawing is slightly larger and clearer, but the RTCS one has more detail and has a head on view.

Both books have excellent photos of everything bar the cab interior!

The drawings in these books are weight diagrams rather than GA drawings. Being diagrams, they are not necessarily accurate or to scale. Better than nothing, but you need to be wary.

Dave.

[Sandy Harper]

Mode

 

Yes I just looked at my instructions and they suggest the original nickle silver etchings are not used.

Does anyone know where I can get a 7mm GA drawing


Paul R

Try Modelling Railways Illustrated Vol 1 No3

 

Regards

SAndy

[doilum]

Agreed better than nothing. Both have all the critical dimensions in writing to check the model as it is assembled. For anyone who hasnt seen it, the RTCS book has a lot of the individual loco history and modification. Not quite as good as a volume of Yeadons register but still useful.

[doilum]

A good couple of hours in the workshop.

Front footplate section now soldered to the main superstructure. I took a few minutes to knock up a plywood platform to keep everything straight and level. Time now to trial fit the firebox. I had followed the scorpio instruction to remove a millimetre from each of the tank tops, another had to be removed in situ. I am more than happy with the result and inner tank sides will not be needed. If you dont have a dremel, time now to try and borrow one. This is not the kit for off grid modellers!

[jim.snowdon]

Hi Jim,

Is this an original Transport Age kit,

or is is from Scorpio?

Cheers,

Peter

the one I am building is badged as a Transport Age kit, "brought to you by Acorn", which to me indicates its origins as being Jim Harris. But, it has been got at somewhere along the way, as there is clear evidence of the chassis etches being CAD drawn rather than the usual Harris freehand (for which the usual giveaway was the hand drawn nature of the tabs keeping everything in the fret).

 

A good couple of hours in the workshop.

Front footplate section now soldered to the main superstructure. I took a few minutes to knock up a plywood platform to keep everything straight and level. Time now to trial fit the firebox. I had followed the scorpio instruction to remove a millimetre from each of the tank tops, another had to be removed in situ. I am more than happy with the result and inner tank sides will not be needed. If you dont have a dremel, time now to try and borrow one. This is not the kit for off grid modellers!

Thank you - I shall keep this in mind when I get to starting on the body. I always like to get the chassis together before tackling the body, as if there are mismatches that emerge it is usually easier to tweak the latter. At the moment, the next stage is to assemble the motion, then I will get back to the rest of the chassis.

 

Jim

[3 link]

Hi Jim,

 

Just a quick note to say I'm enjoying the build and one question if I may. You say your going to attach the cylinder block using epoxy, so you obviously have faith in the stuff. I have had mixed results over the years with epoxy, so can you tell me which type and make you are happy with.

 

Regards,

 

Martyn.

[jim.snowdon]

Martyn,

 

I have used a number of epoxy adhesives over the years, none of them with any problems. At the moment I'm using some rapid Araldite from RS, before that it was some 12 minute epoxy that I had got via a trader at ExpoNG a good while back. The only one I didn't really like, I think because it was a bit too runny, was some Devcon, many years ago. They've all been pretty tolerant of less than accurate mixing ratios, and short of not mixing the two parts thoroughly, it's difficult to see what could go wrong.

 

Jim

[3 link]

Hi Jim,

 

Regarding what could go wrong has made me realise that maybe the Araldite does not cope well with low temperatures, the Araldite I had was stored in a unheated workshop when I was living in the centre of France. One winter in particular we had temperatures down to -22, so looking back now this possibly did not help the hardening process.

 

Martyn.

[doilum]

Just a bit on the firebox.

I am pleased with the way this has gone together. The white metal washout plugs went in the bin and I scratch built replacements before finding a set of turned brass ones that had been hiding in a drawer for twenty years. The kit doesnt give a lot of help in fixing the firebox. Photos clearly show the line of washout plugs just above the level of the tank. The "boiler" bands were trimmed back to set the level of the fire box and the boiler and smoke box sections trial fitted. Happy days?

I think I will delay final assembly until the chassis is up and running. I have also part cut incisions in the back of the firebox and cab front in case that extra couple of millimetres are needed for the intended ABC gearbox.

[doilum]

Another good hour this morning. I have been looking at the smokebox front. I had already soldered up the wrapper and added handrail knobs. The instruction to "add smokebox door" and the parts provided, a white metal disc and a rather chunky door casting leave a bit of room for " metalworking skills and knowledge of the prototype"

I have a large colour photo as inspiration on the bench and this reveals the challenge. The door is set almost, but not quite flush into a front plate, which in turn is almost flush into the smokebox wrapper. A close look a a good photo shows this clearly. Having considered severeral options I settled for fettelling the whitemetal disc until it was a perfect tight fit and tapping it down to create a recess deep enough to take the depth of the smoke box door.

A ring of brass was cut from brass sheet. Lacking any clever equipment, the job was marked out with dividers, the centre drilled 1 mm and then taken to the pillar drill and opened out with a 25mm wood bit. This old bit didnt cut cleanly creating a rough dome shape. The dome was removed with the dremel cutting disc and amazingly left a concentric hole that could be gently opened up to take the smokebox door. The outer material was removed with scissors and then trimmed with the dremel until a perfect fit in the wrapper. This was then soldered in leaving the edge of the wrapper showing. The door was then slimmed down slightly on 40 grade emery cloth. Must confess I am "well pleased", just hope I havent exhausted this months allocation of luck!

[Sandy Harper]

Another good hour this morning. I have been looking at the smokebox front. I had already soldered up the wrapper and added handrail knobs. The instruction to "add smokebox door" and the parts provided, a white metal disc and a rather chunky door casting leave a bit of room for " metalworking skills and knowledge of the prototype"

I have a large colour photo as inspiration on the bench and this reveals the challenge. The door is set almost, but not quite flush into a front plate, which in turn is almost flush into the smokebox wrapper. A close look a a good photo shows this clearly. Having considered severeral options I settled for fettelling the whitemetal disc until it was a perfect tight fit and tapping it down to create a recess deep enough to take the depth of the smoke box door.

A ring of brass was cut from brass sheet. Lacking any clever equipment, the job was marked out with dividers, the centre drilled 1 mm and then taken to the pillar drill and opened out with a 25mm wood bit. This old bit didnt cut cleanly creating a rough dome shape. The dome was removed with the dremel cutting disc and amazingly left a concentric hole that could be gently opened up to take the smokebox door. The outer material was removed with scissors and then trimmed with the dremel until a perfect fit in the wrapper. This was then soldered in leaving the edge of the wrapper showing. The door was then slimmed down slightly on 40 grade emery cloth. Must confess I am "well pleased", just hope I havent exhausted this months allocation of luck!

Ok, I'm now getting confused! Not difficult really but, what are we reading about here? Jim Snowdon's build of a Standard class 3, illustrated with pictures, or 'doilum's' musings about something he is building? Can we please revert back to the original poster (jim) describing  his build and could 'doilum' please start his own post on his own build?

Regards

Sandy

[jim.snowdon]

No offence to Doilum, but I think Sandy has a point. I will get to the upperworks in due course, at which time his observations will be considered, as they may well be useful (the "may" is there only because I have a suspicion we are building different kits for the same locomotive).

 

Jim

[JeffP]

I have to admit to being confused too, even as to beginning to wonder if doilum was Jim's pseudonym?

[doilum]

Me culpa.

I am new to this method of storytelling. Perhaps when I get my head round the technology needed to upload photographs I can start a new thread.

[JeffP]

Yes, please do.

 

Photos are easy, first click on the light blue "Reply with attachments" box at lower right when you have clicked reply.

Then attach your photos, remembering that there is a size limit, 1 MB I think.

 

Once uploaded, click attach in the relevant part of your text, and away it goes.

[pwr]

Mode

 

 

Try Modelling Railways Illustrated Vol 1 No3

 

Regards

SAndy

Yes I think I have that somewhere. They did do an Ivatt class 2 GA also which I know I have