And the Next Project please - Impetus Big Bagnall

[5050]

Having finished the Fowler and the Planet I've raided the now slowly depleting kit stock and decided on my remaining Impetus kit, the 'Big Bagnall' 0-6-0.  The construction of one of these has already been covered by Adam on his thread -

 

http://www.rmweb.co.uk/community/index.php?/topic/30496-preston-docks-bagnalls-impetus-kit-and-prototype/page-2

 

but I will possibly tackle some of the elements slightly differently and it will be P4 rather than EM.  I'm not following any specific prototype such as 'Florence No 2' but will use the bits I like!  I might even move away from the 'Corporate Blue' colour scheme that all my diesels use, possibly some fetching shade of Green?

 

First of all - the chassis.  In my version of the kit there were both a brass or nickel silver versions of the chassis and rod etch.  I think Robin must have realised that nickel silver is a far better option for these items and I have preferred them to the brass ones. 

 

To construct chassis I have a set of 'jigs' that I made some time ago using half inch brass bar, drilled 1/8" and separated into 3 sections per 'jig'.  The larger is the required internal width of the frames and the 2 outer ones are tapped 3mm approx and screws inserted to secure them to a 'false axle'.  Where top-hat bushes are required the internal section is bored out each end to clear the larger diameter and still allow the faces to be flush with the inside of the frames.  If the chassis is going to be compensated or sprung then assembly should be done before any hornguide slots are cut, using the original etched axle holes.

 

The Impetus chassis is etched to facilitate suspension on the middle and front axles, drive being to the rear axle.  There is a beam provided which is an elongated 'U' shape so as to clear an etched hole in the frame exactly where the pivot point would be on a 'plain' frame.

 

 

 

This shows the principle of the 'jigs' in use.  The boring out of the centre sections to clear bushes can also be seen.

 

 

The rear driven axle will also be made removable but 'fixed' so the axle hole has been extended downwards and keeper wires will be added to hold it in place.  The black patches are felt pen used as 'blue' to mark out the wheel diameters prior to drilling for Alan Gibson plunger pickups.  I am reliably informed that these have been improved with softer springs, brass plungers etc. so I thought I would give them a try.  Initially their positions have been pilot drilled approx.0.5mm, ultimately this will be opened out to the required 2.5mm. 

 

 

I have not yet fitted the centre frame spacer as I am waiting to see where the High Level gearbox ends up being positioned relative to it.  I will also need to take account of the 'tails' of the plungers and their wiring.  Forward thinking is a definite requirement when building loco kits!

 

Next post - some bodywork!

[rope runner]

Rather nice these Impetus kits, does anyone know if they're still...Oh wait no, we've been over this before. 

 

Lovely prototype, though I think on balance I prefer the rounder saddle tank of the wartime variant - like Cranford No.2 etc. 

 

5050, if your brass chassis and rod etch needs a home, I'd be happy to give it one in exchange for some funds to speed the build along...?

 

Paul A. 

[5050]

The chassis is as far as I can get without the plunger pickups which are on their way so I decided to start on the body.  The footplate has 2 valance strips to solder into a half etched groove each side and the buffer beams are two layers sweated together and attached flush with the footplate top along with the coupler 'pockets'.  As is usual with my loco builds I want to make the superstructure in separate pieces for ease of painting and future disassembly.  These will be Cab, Footplate and Boiler/Tank/Smokebox. 

 

The cab front and back tab into location slots in the footplate which will help in assembly.  Attachment to the footplate will be with four 10BA screws into soldered nuts on the cab floor underside.  As this is raised above footplate level they will fit neatly into the space.  The footplate is attached to the chassis by an 8BA screw and captive nut under the cab and a similar method at the front inside the smokebox.  This screw/soldered nut will also be the attachment for the boiler/tank/smokebox assembly.  Three large pins through the cab front will locate into holes in the tank rear plate to locate tank and cab together.

 

Here you can see the cab floor and the footplate with pilot holes for the attaching screws drilled prior to assembly.  These will be drilled to correct size for 10BA clearance.

 

 

The 10BA nuts are being attached to the underside of the cab floor using a cocktail stick to hold them in position for soldering.  A 10BA tap was run through after to clear the threads.

 

 

This shows the cab front and the tank rear with the location holes drilled ready to accept shortened brass pins soldered into the cab front in due course.

 

 

The cab soldered up.  This uses butt joints - and singed fingers!  Adam mentioned making a new bunker back and I must admit I was a bit perplexed myself initially as when I measured the one provided it was narrower than the cab back - which was itself narrower than the cab front!  Only a very small amount admittedly but this can make a difference when soldering.  I made both cab elements the same width as the bunker back with some careful filing and my vernier calipers.  Shaping the bunker back was 'interesting' ( a term you will come across with increasing regularity I'm certain!) as it has to be curved/bent into an 'S' shape to fit the shape of the bunker sides.

 

 

 

Note that I have several wood blocks to provide soldering/holding/filing supports.  The fact that they also raise the work closer to my failing eyes is a bonus!

[5050]

Rather nice these Impetus kits, does anyone know if they're still...Oh wait no, we've been over this before. 

 

Lovely prototype, though I think on balance I prefer the rounder saddle tank of the wartime variant - like Cranford No.2 etc. 

 

5050, if your brass chassis and rod etch needs a home, I'd be happy to give it one in exchange for some funds to speed the build along...?

 

Paul A. 

I might have potential future use for them myself I'm afraid.  I have a couple of old odd bodies around that I may decide to do something with eventually.

 

But don't hold your breath...........................

[Turin 60]

Hi, with regard to your removable rear axle and its bearings, how are you stopping the bearings from rotating?

 

John.

[5050]

Hi, with regard to your removable rear axle and its bearings, how are you stopping the bearings from rotating?

 

John.

Some fine bore brass/copper tube is soldered across the bearing and the frame, cut each side of the bearing and a length of wire inserted. On the 'moving' bearings, the tube across the bearing is omitted to leave room for compensation movement.  I'll photo all this when I come to it.

 

You can see a similar installation on my Fowler Diesel chassis on this thread -

 

http://www.rmweb.co.uk/community/index.php?/topic/28335-impetus-fowler-diesels-different-ways-to-build-a-collectible/page-2

Edited May 28, 2015 by 5050

[Turin 60]

Some fine bore brass/copper tube is soldered across the bearing and the frame, cut each side of the bearing and a length of wire inserted. On the 'moving' bearings, the tube across the bearing is omitted to leave room for compensation movement.  I'll photo all this when I come to it.

 

You can see a similar installation on my Fowler Diesel chassis on this thread -

 

http://www.rmweb.co.uk/community/index.php?/topic/28335-impetus-fowler-diesels-different-ways-to-build-a-collectible/page-2

Ah yes, I think I can see what you mean. A neat solution to the otherwise"fixed" axle.

 

Thanks John.

[5050]

After a bit of a 'hiatus' I'm now getting back to it and these photos show progress.

 

The cab door beading is added.  This was a flat strip with a half-etched groove along its length to locate it on the edge of the opening.  As usual, an 'interesting' exercise in soldering using a selection of round objects to push the strip into the bends as soldering progressed.  Cab handrails are also now fitted.  The main body of the smokebox is built up.  This attaches to the footplate with a captive nut and once the boiler and tank are finally attached, this will be the front securing location for this element of the body.  Rear spectacle plates are sweated in position.

 

 

 

The tank has been 'formed'.  This was an EXTREMELY interesting task.  The kit part has lots of narrowly spaced half-etched grooves along the places where the main bends are - plus some half-etched marks along the centre of the top of the tank as location points for the formers.  Of course, as soon as I started to form the 'initial bend' (as the kit instructions state - whatever the' initial bend' is!) the tank creases along the line of these marks.  There are also 3 formers provided.  The 2 end ones weren't TO bad to fit as it was possible to use a 90 degree jig to hold the parts but the middle one??  Absolutely no method of location apart from the etched marks and, of course, all 3 have to be exactly in line.  After several struggles and a liberal use of industrial strength language (which didn't help at all!) i decided to omit the middle former and continue trying to 'roll' the tank around the formers.  At one point I actually dismantled my pitiful efforts and made use of the gas cooker to try and anneal it for ease of rolling but it didn't seem to have much effect!  However, all of a sudden it started to bend and follow the profile of the formers but it still took a lot of 'tweeking' to get it into an acceptable shape.  The crease along the top was reduced by rubbing along the inside with the rounded end of a scalpel handle.  If anyone says anything I'll tell them it was dropped as a baby.

 

As an aside, as Adam stated in his build, the tank does seem a bit short.  It should prototypically stop slightly short of the smokebox but I reckon the kit is slightly wrong and the gap is a tad to wide.  I've made up a 30 thou plasticard spacer to fit between the tank and the cab to reduce it but until I get a bit further with the build I can't yet say if it is correct.

 

The tank, smokebox and boiler are still separate as I will be making some alterations to the boiler to ease assembly.  Watch this space!

 

 

 

At this point I decided to re-visit the chassis and built up the coupling rods.  These are laminated to pivot over the centre axle and, as the wheelbase is symmetrical, are all the same length.  First, the holes were reamed out to 1.5mm to fit crankpins.  A 1.5mm drill was inserted into some wood and the rod sections dropped on the ensure alignment and then sweated together.  The chassis has had the hornguide cutouts removed ready for the attachment of the compensated ones which will be solderd in place using the Perseverance jigs and the completed rods.

 

 

 

Stand by for more on the chassis!

 

 

 

 

[5050]

And here we go with today's second gripping instalment.

 

First, the chassis.  Here you can see the hornguides soldered in position with the bearings fitted, individually tailored to fit their own slot and marked.  Short lengths of brass channel have been added to the sides of the hornguides to act as stops to prevent the bearings from rotating in use.  The bearings are filed along one 'side' to bear against them and also at right angles at the 'bottom' to fit against the 'keeper' wire so that there is sufficient movement to allow compensation rocking.   Note that the length of wire soldered across the chassis is a temporary 'spacer' to prevent the sides from bowing in during handling.  It uses the holes for the compensation beam bearing and will be removed in due course.

 

 

Here the 'keeper' wires can be seen in position fitting through the short lengths of brass tubing which allow the bearings to be removed during assembly.  On final assembly they will be cut to a shorter length.  Note that the tube under the fixed bearings still needs to be cut to allow removal of the bearings during assembly.  I suppose I could have used some thinner wire (this is 1mm diam.) but this size is reasonably substantial to resist the occasional bit of heavy-handidness!

 

 

The gearbox has been assembled and this is a test fit to assess its relationship with the cab front and the height of the boiler etc. It will just clear the cab front and will be a sliding fit into the boiler.  The flywheel is one I have turned to fit into the boiler tube and still needs to be reamed to an exact fit on the motor shaft.  To allow easier fitting and removal during assembly I have slightly altered the shape of the top of the gearbox to a lower profile to clear the end of the boiler tube.

 

 

The smokebox wrapper has been fitted around the basic shape but, like Adam, I found it to be a slightly poor fit.   However, I think I've made the best of it and a coat of paint might help to disguise the faults!  The firebox etch is now attached and I have removed the centre portion (ie - the front) to allow it to slip over the motor during assembly.  If the lack of a 'front' becomes noticeable when complete I can try to fit a 'dummy' one somehow.

 

 

I have modified the boiler tube by making cutouts in the top and rear underside.  The smaller rear underside one is required to clear the motor/gearbox inside the firebox as standard but I thought I would add another larger one on the top so that the motor/gearbox/flywheel can be 'got at' more readily, both during assembly and afterwards for maintenance.  To ensure the flywheel clears the bottom of the tube I added a small piece of the redundant tubing to the inside to act as a spacer.  This cutout should also make it more easy to attach the leads etc. to the motor as i will have the space inside the tank.  However, I do anticipate adding some layers of thin lead sheet inside the tank as the loco will be quite light.

 

 

 

 

Here you can see the boiler in position along with the motor/gearbox/flywheel.  It is a snug fit!  The flywheel can just be seen.  In use it will be much closer to the motor.

 

 

Note that the boiler/smokebox/tank etc. are all still separate parts and probably won't be attached together until I know the loco actually works!

 

Now - what to do next!?

[Kenton]

Almost looks like the gerbox and motor were designed just for this kit. Makes you appreciate why these great little kits still get bid up over all expectations on ebay.

[wagonbasher]

This is obviously a long running build that you have just chosen to post over a couple of weeks judging how that block of wood has aged !!

 

Andy

[5050]

This is obviously a long running build that you have just chosen to post over a couple of weeks judging how that block of wood has aged !!

 

Andy

The way things are currently panning out it will definitely be a long build!  It seems that everytime I do something another complication arises.  Serves me right for trying to be clever and not build it as Robin intended!

 

I have a 'selection' of blocks.  In due course I expect them all to age.

 

Hopefully as gracefully as me............................................

[5050]

I'm back on this again - but not taken any photos.  Yet.  The High Level gearbox and wheels are fitted and all runs very smoothly with very little fettling.  The main current 'challenge' is fitting the cylinders, slide bars and connecting rods.  As it is P4 then clearances behind the slide bars will be tight so I will probably turn up a couple of threaded crankpin bushed to be inserted from the 'front' and countersunk into the connecting rod.  The cylinders supplied are a chunk of solid turned brass and have proved to be difficult to solder on the etched 'ends'.  I anticipate the same will be the case for the etched slide bars which are supposed to be soldered to the face of the cylinder.  Not an easy prospect.  I have therefore filed up 2 sets of slidebars from 2mm x 1mm nickel strip, filed a 1mm 'round' at one end which will fit into a 1mm hole drilled into the cylinder.    Hopefully a more secure and permanent fix.  Crossheads are to be assembled from etched components - something I'm not particularly looking forward to!

 

Try and get some photos tomorrow.

[5050]

Only a month further on (!) and I've now done quite a bit more, especially with the chassis and cylinders.  The latter were the more awkward element of the build as, with it being P4, there ain't a lot of room behind the crossheads to clear the front crankpins.  The kit instructions say to solder in a length of thick wire into holes in the cylinder sides which in turn go through holes in the frames and are the soldered when the cylinders are at the right spacing.  I thought this was a bit hit-and-miss, especially with the close clearances I would be experiencing, so elected to solder in some short lengths of 8BA studding (left over from previously shortened long bolts) with some matching 8BA nuts soldered inside the chassis holes.  This meant I could screw the cylinders onto the frames and give myself some more finite adjustment.  However, this turned out to be a bit of a 'dead end' and I amended this in the light of experience - see later!

 

The kit slide bars are etched NS which I thought a bit 'thin' so I filed replacements up from 2 x 1mm NS strip.  These were filed at the cylinder end to round sections which were Araldited into holes lathe drilled above and below the cylinder rod hole in the solid brass turned kit cylinders.  I also had to Araldite the cylinder end plates in position as, as expected, the solid brass proved difficult to solder to.

 

Crossheads were fabricated from the kit etch although I substituted some NS etch scrap of a suitable width for the bearing surfaces to match the new slidebars.  The cross head pin is a brass 'pin' sourced from Mrs 5050's beading fittings.  They have a large flat round head and a 0.7mm shank which is larger than the 16BA screws the kit suggests for the cross head pin (and didn't provide!).  When fitting they were soldered to the outside of the crosshead only and nipped off flush at the rear.

 

When trying to fit the cylinders with wheels, rods etc. in place it became apparent that the adjustment provided by the 'screw-in cylinders' was just not fine enough so I drilled out the inside nut threads to a tight fit on the cylinder 8BA studding and fitted a thin 8BA nut between the cylinder and the frame.  This can be adjusted back and forth to achieve just the minimum amount of crankpin/crosshead clearance for good running.  The 8BA studs will then be soldered to the inside of the frames.

 

To achieve clearance on the front crankpin I 'rebated' the front crankpin hole and utilised a pair of Gibson crankpin nuts to retain the rod.  One was screwed 'right way on' hard against the face of the wheel and the other was reversed with the 'top hat' section fitting inside the rod hole with a couple of 'flats' filed for gripping in small pliers.  This diameter of this section is larger than the 'normal' 1.5mm crankpin bush size so some gentle reaming was necessary to get a good fit.  However, it was found that a lot of the Gibson Crank Pin Nuts do not have the threaded hole drilled centrally resulting in an eccentric action inside the hole leading to everything seizing up!  Careful scrutiny is required to find suitable nuts.

 

Here is the chassis/frames virtually finished -

 

 

And with the cylinders -

 

 

The underside view showing the retaining nuts.  The drilled and threaded spacers are for the pick-up 'plate' which will also act as a keeper plate for the compensated wheelsets -

 

 

Frames with cylinders temporarily attached.  The 'adjusting' nut can be seen between the cylinder and the frame -

 

 

The wheels, rods and gearbox -

 

 

Closeup of the rebated front crankpin nuts -

 

Edited December 8, 2015 by 5050

[5050]

Chassis now painted and wheels fitted with pickups - and it works!

 

A couple of photos of it while I was testing/running in this morning.

 

 

 

The drill running across the frames is temporary, it will be a length of 0.9mm rod in use.  This fits into short lengths of brass tube soldered to the top of the frames and the rear of the gearbox sides to prevent the motor torque rotating the gearbox in use.

 

Crankpins and nuts secured with a dab of nail varnish.  In this case, the Red as used on the sides of the gearbox to hold the cross shafts in place.

 

Cylinders yet to be painted - once I decide on the body colour!

 

Just realised - balance weights need fitting!

Edited December 11, 2015 by 5050

[Gordon A]

Hi Paul,

 

What sort of pick ups are you using.

 

Gordon A

Bristol

[5050]

Hi Paul,

 

What sort of pick ups are you using.

 

Gordon A

Bristol

NS wire (0.3mm) scrapers mounted on the copperclad 'keeper plate'.  I was going to use AG sprung plungers as per Dave Franks but the amount of sideplay needed in the centre set of wheels decided me otherwise.  I'll post a photo.

 

Soon.......

[wagonbasher]

I know that its P4 but are there any flanges on those wheels?

 

Andy

[5050]

I know that its P4 but are there any flanges on those wheels?

 

Andy

I'm experimenting with no flanges and just relying on the 120 degree cant of the rails in the chairs and the coning of the wheel tyres.  This seems to work on a length of plain track.  However, I have found that the optimum length of track can be no more than 2" - the best length is 1.883".

[5050]

Good Lord, a year and 9 days since I last posted on this topic.  Doesn't time fly etc. etc.

 

Well, I decided that after abandoning my 'Drybrook Road' project I had better get on with something so as to hopefully keep my Mojo ticking over.  I decided - at last - to get the Bagnall out and get it finished.  To a level that I am happy with anyway.  Some people might wish to keep on adding 'things' but if it ever appears in public it will be working for its living so ultra-close inspection will be out.

 

The chassis was painted anyway so the body was given a thin coat from an old tin of Humbrol Chromate Primer, thinned with cellulose thinners 'cos I discovered that Humbrol thinners made it curdle, and then brush painted with original Humbrol acrylic (in the plastic pots) Green - a fair bit darker than has come out in the photos - giving it several thin coats.  Doing this was made easier by the body being in several parts.  The cab firebox door plate casting was slightly detailed and painted as well - but I know from Adam's thread that the design is not really correct for this loco but once a driver is positioned and the cab roof fitted it will hardly be seen.  A Judith Edge reversing lever is also fitted.

 

Once fully dry a thin coat of Kleer was applied as a further protective layer, weathering is yet to be applied which should tone down the apparent brightness of the Green and (shiny in places!) Black.

 

On test, it runs very nicely with a small flywheel added that just fits inside the boiler.  Name plates yet to be fitted which will again be along my 'Blackadder' theme.  Wait and see who it will be!

 

 

Now, where can I get some Bagnall works plates from?

Edited December 22, 2016 by 5050

[pete_mcfarlane]

Narrow Planet do custom Bagnall works plates, along with plates for pretty much every other builder.

 

https://narrowplanet.myshopify.com/collections/works-plate-styles

[5050]

Narrow Planet do custom Bagnall works plates, along with plates for pretty much every other builder.

 

https://narrowplanet.myshopify.com/collections/works-plate-styles

Thanks for this.  I've already checked their website and seen them but I was hoping to get a 'generic' set off the shelf rather than have to order something special - particularly as the loco doesn't represent an actual loco with a specific build number.  Perhaps just an oval of plain brass heavily weathered might do.

[decauville1126]

Thanks for this.  I've already checked their website and seen them but I was hoping to get a 'generic' set off the shelf rather than have to order something special - particularly as the loco doesn't represent an actual loco with a specific build number.  Perhaps just an oval of plain brass heavily weathered might do.

You just might be pleasantly surprised if you ask Narrow Planet for a custom price ........

[Ruston]

I know you wanted to look in the cab of Florence when we went to Foxfield but it was in pieces. Did you just make the interor up in the end?

[5050]

I know you wanted to look in the cab of Florence when we went to Foxfield but it was in pieces. Did you just make the interor up in the end?

Yup!  Doubt if it's anything like - but it's my Bagnall.