Cambrian Class 61 - EM CHASSIS

00 chassis for the Cambrian Class 61 Locomotive.

 

IMPORTANT NOTE:  Both textual and scale drawings don't always seem to agree on what

wheelbase and diameter bogie wheels the Furness Railway K2 (21 Class) and the Cambrian

Railways Class 61's ran with.  For the Bogie wheel diameter many sources say 3' 6" but other

sources say 3' 0", similarly the

wheelbase is disputed between

5’ 6” + 6’ 6½” + 8’ 3”

5' 9" + 6'6" + 8'6"

&

5’ 9” + 6’ 8” + 8’ 6”


The Cambrian Class 61 available from SCC have been built and designed

with the top wheelbase  and is designed to take 3' 6" Bogies.

 

As all the Class 61 chassis and bodies are common to each other, any will fit in combination as they

are interchangable.

 

For more information on the discrepancies and to help you decide, you may look here for

more information...

http://www.rmweb.co.uk/community/index.php?/topic/106162-scc-sparkshot-custom-

creations/page-2#entry2146281

or here...

http://www.scalefour.org/forum/viewtopic.php?f=30&t=4577&start=25

 

As the frame is designed to take 3' 6" bogie wheels the top of the frames will be very thin and weak.  Neatly

cutting the frame here and glueing the front section that goes above the front bogie wheel

to the loco body may be a consideration and you may need to file a little extra clearence for the wheels, same for the optional  bogie splashers.  The real thing was a tight fit too.

 

Also prototype photo's sometimes showed the

optional bogie splashers removed (on the K2 at least), unless you have generous curve radii

these will likely have to be ommitted. 

 

On the EM and P4 versions these have been pulled

inwards by 0.7mm's.  As neither are to perfect width due to thickness and bogie movement, If you would like Optional Bogie Splashers pulled in or out to a

different degree please contact me and It'll be arranged.  The 00 ones are 5.7mm's width. 

 

Finally a more solid answer to the wheelbase issue between the Furness K2's and Cambrian Class 61's has been found with much thanks and credit to Mike Peascod of the Cumbrian Railways Association.  Here is His PDF he kindly compiled from a few sources to show the different wheelbases that existed as genuine variation...

 

http://www.scalefour.org/forum/download/file.php?id=10574

 

As a reminder, the Cambrian Class 61 bodies and the chassis are designed to fit the

5’ 6” + 6’ 6½” + 8’ 3”

wheelbase and will not fit the K2 chassis that has a wheelbase of 5’ 9” + 6’ 8” + 8’ 6”.

 

If you would like a Cambrian Class 61 with the same wheelbase as the K2 then please get in touch and will upload one as it is ready just in case.

 

-

 

The Bogey and Brake Gear is sprue joined to the top and sides, as are the optional Splashers (Wheel Arches) for the Bogey Wheels.  Unless you have very generous radius curves these likely will have to be omitted from the final build.  Some prototype photographs showed the locomotive without them though.  Cut these components off and keep them safe.  The chassis is printed square, however the rear frame spacer is sprued on the left side for you to add where you want depending on your gearbox choice.

 

1/8th / 3mm 'Top Hat' Bearings need to be glued into the axle holes for the 24mm / 6FT Driving Wheels and for the 3ft 6inch Bogey Wheels you can fit 2mm 'Straw Hat' Bearings once the holes have been reamed out to accomodate them.  Test builds show that, like the tenders it isn't really needed and they will roll nicely anyway, but the choice is yours.

 

The frames have a 10mm gap between the rear two axles for gearbox fitting.  The frames are thus 1mm thick.  Sprued to the insides are two x 1mm thick, thickening lengths that if fitted will make the frames 2mm's thick either side.  Your choice of gearbox will dictate if you use these or how much of them you use as you can cut them to size to thicken up most of the frames and leave a thinner area for a gearbox if needed.

 

For the Bogey to work there are two options:

A)  A thin 'cheesehead' bolt with a approximately a 1.5mm diametre thread (such as a 10 or 11BA) can pe pushed through the underside of the Bogey up into the bottom of the Loco Body under the smokebox and screwed in, this will allow the Bogey to turn in its arc and also provide lateral movement.  Adding a weak spring (like those in sprung coupling packs)  with a thin washer soldered to it providing a slide helps.

 

B)  Possibly the easier option, screw the chassis to the body with a 10 or 11BA bolt using the holes underneath the Smokebox, then using the optional Pivot Arm that was also sprue joined to the Bogey, screw this upwards into the rear chassis hole located in front of the front Driving Wheel, then at the other end screw a bolt downwards into it and through the Bogey, finally cap it with a nut and secure with a paint blob.  The clearence between the top of the bolt head and the bolt head that joines the chassis to the body is minimal.  If it conflicts a few gentle passes with a fine file will sort this easily.  The Pivot Arm is printed to the correct orientation so be sure to fit it the correct way!

 

The WSF and BSF Nylon the chassis is printed in will self tap.

 

For pick ups, crank pins, motors, gearboxes etc and the Coupling Rods (available on this site), the same methods used for conventional kit building need to be applied, and there are many options.

 

For the test builds the 'traditional' method of PCB strips and 0.45mm brass wire/rod was used to good effect.

 

On the 00 chassis only a tiny cube of about 1mm may need to be filed/cut off the insides of the frames at the front tops to slot around the inside of the buffer beam, two second job.

 

General note:  Once the chassis is built and working you may need to file/shave a small amount of material from under loco body for the coupling rods due to the running plate needing to be printed thicker than a scale reality.  On some models sometimes the inside edge of the splashers need a small amount shaving away too (moreso in P4).  A few passes with a brass brush in a mini drill makes this a 2 second job though.

 

Initial builds were done with Alan Gibson wheels that have a 14" 'throw' on the crankpins.  The Cambrians's had a throw of 12" and so this also explains some of the shaving of material needed if using 14" throw wheels.  Alan Gibson do currently do wheels with a throw of 13" so these will work even better needing less shaving.

 

Alan Gibson code =

4872V,   6' 0" / 24.0mm,  20 spoke,  LNER B13,  Class Plain,  PB,  13"  (or the S4 equivalent)

 

TIP:
To allow your model to be motorised without having to hack away at the underside of the firebox or boiler as is common with many of kits depending what parts you use,  a 'Roadrunner +' Gearbox from High Level will fit nicely, using a drive extender may make things easier too, especially if fitting a fly wheel.  These components were used in the research and development trial builds.

 

EDIT:  Future builds have shown that a London Road Models GB4 Single stage Motor Mount (Gearbox) fits better, is cheaper and quicker to build.  As with all loco kits the choice is entirely yours though.

http://traders.scalefour.org/LondonRoadModels/various/components/

 

For wheels, axles, crankpins etc
Alan Gibson is a great resource

www.alangibsonworkshop.com

...as is Markits
http://www.markits.com

For Motors and Gearboxes, High Level are recommended.
http://highlevelkits.co.uk/




For crank pins, hand rail rod/wire and pillars, washers, bearings and other small sundry items Mainly Trains is a good website to visit.
http://www.mainlytrains.co.uk/acatalog/index.html