Adding false frames and outside cranks to an N gauge chassis

[tedp]

Since many modellers struggle with the idea of inside frames on a loco that should have outside frames, I decided to publish an idea that might help many of you. Perhaps this is a murky photo, but it shows how easy it is to convert a RTR N gauge chassis to outside frames. In this case an Arnold 0-6-0 with the centre wheels dropped out, bushes and plastic cranks glued on to the wheel faces and false frames added. All glue and plastic construction, and the loco still runs OK 30 years after the conversion.

The main requirement is that you have a gear driven chassis with little play between the first and last wheelset. A conversion like this can be done inside one evening, with simple tools. The crankpins are tiny brass nails, by the way, and the rods were made up of wire folded around a pin and soldered together. One end of the coupling rod ends in a fork to even out any irregularities in crank throw and quartering, after all this is a 'belt and braces' approach.  ;)





EDIT - if you want to see how it looks in action, try this video.

[tedp]

Perhaps it isn't for everyone to do such a modification, but it is far easier than building an outside frame chassis, and the advantage is you have a mass produced chassis that can be replaced if it wears out. The basic steps are as follows, but allow some deviation for each type of chassis:

• remove the cylinders and motion from the N gauge chassis. Cut the cylinders from the block.
  make up false frames from styrene sheet and cut the apertures for the crank bushes. Leave at least 1mm space for them to turn.
  
• glue the false frames to the chassis block using styrene spacers. These can be seen in the Darjeeling loco photo. I used 1mm styrene sheet to cut spacers from. The false frames can be 0.5mm but 1mm is stronger although overscale.
  
• glue crank bushes to the wheel faces. I used neoprene glue for the initial 'fetch', then some CA glue to make the final bond. This also works for the frame spacers on the chassis.
  
• cut the cranks from 1mm styrene and glue them to the crank bushes. Make sure they are 'quartered' - fiddle the wheels so you have a feeling for the amount of slack in the gearing.
  
• drill tiny holes for the crankpins - tiny nails will do the trick.
  
• reassemble the motion and fit the cylinders to the outside of the false frames. You may have to allow for more slack in the crankpin holes.
  
• trial run the chassis during assembly of the motion. Solve any binding issues by increasing the slack in the crankpin holes, or even by altering the angle on a crank that causes binding.
  

A neater conversion was done on my Lawley which uses a Roco 0-6-0 chassis, larger wheels fitted but still a gear coupled chassis block. The motor is in the tender by the way. Here I glued cut down roofing felt nails to the wheel faces, and lost wax cranks to them. Otherwise the principle is similar:

[tedp]

Re-using the rods that the original chassis came with is best, although you must be prepared to ream out the crankpin holes in the rods, as fitting crank extenders isn't a very accurate process.

I made a few close-ups of the Lawley, showing the running gear. The chassis is unpowered and the metal crank extenders (roofing felt nails) and brass cranks were an improvement on the previous plastic ones which I made from Airfix Pug buffers and rods! The chassis is pushed by the tender and one wheel has a traction tyre to aid the turning action. I have known the chassis to have a bit of rolling resistance due to the gears, so it was pushed with wheels slipping a little. A funny sight. Since I cleaned off all the oil and ony used graphite for lubrication, it runs very freely...

[Otty]

As a newcomer to OO9, I've been reading a fair number of posts on various forums re: chassis & it appears that the KATO chassis is a cheap & reliable chassis. I've a few, just a shame there's no valve gear.

I'm sure I've missed something but does anybody think that there is a way of adding false frames and outside cranks to said chassis (? a 3D "print").

[rod335]

Sorry, this is a total non-starter. From what I recall the Kato (presumably 'tram') chassis to which you refer has outside frames and the axles are a push fit into pin-point bearings. To fit flycranks, the axles would have to be extended, thereby losing the pin-point bearings and necessitating an fundamental redesign of the chassis.

Rod

[Graeme Dunbar]

I'm not sure if anyone has managed it yet, but the Bandai B-train shorty chassis has been mentioned as a possible candidate for a freelance double Farilie:
http://www.ebay.co.uk/itm/B-Train-Powered-Motorized-Chassis-4-Bandai-N-scale-/360636833322?pt=Model_RR_Trains&hash=item53f7a15e2a

[Otty]

Sorry, this is a total non-starter. From what I recall the Kato (presumably 'tram') chassis to which you refer has outside frames and the axles are a push fit into pin-point bearings. To fit flycranks, the axles would have to be extended, thereby losing the pin-point bearings and necessitating an fundamental redesign of the chassis.

Rod

Thanks Rod, guess that'll teach me to look at things more closely :-[

[scratchbuilt]

hi

do u think u could help me do my darjeeling cuz im a big fan of the darjeelings...

plss i would like to have one of my own...

[rod335]

Otty

I hope you didn't think my reply was too curt. It was not meant to be a put down!

Rod

[Otty]

Otty

I hope you didn't think my reply was too curt. It was not meant to be a put down!

Rod

Hi Rod,

Not at all, really pleased you replied - would have messed up a chassis without you pointing me in the right direction so thank you  :)

As I said, I'm new to OO9 (although have modelled OO, O-16.5 & 'G' amongst others) so no real knowledge re: N gauge chassis.

[Frank]

Rod, Otty,

Just to check, were you talking about the 0-4-0 tram chassis or the Bo-Bo illustrated?

Thanks

Frank

[rod335]

I was talking about the now ubiquitous tram chassis. I think the Badai chassis is built similarly.

Rod

[tedp]

hi

do u think u could help me do my darjeeling cuz im a big fan of the darjeelings...

plss i would like to have one of my own...

You'd have to start building a Langley Darjeeling kit on an Arnold chassis without the false frames. These then can be added. If you need any guidance, drop me a line.

[Graeme Dunbar]

I was talking about the now ubiquitous tram chassis. I think the Badai chassis is built similarly.

Rod

I don't have a Bandai 4 wheel tram chassis (just the Kato equivalent), but I believe this is a photo of the Bandai one which suggests you are right:


If the link doesn't work try here towards the bottom:
http://flickrhivemind.net/Tags/nspoor/Interesting

If there is any mileage in adding frames to a Bandai Bo-Bo chassis then the Tomix ones are constructed in a similar way and are available in various lengths:
http://onlineshop.modellbahnunion.com/Modelrailways/Modelrailways-N-gauge/Tomix-accessories-spare-parts/Tomix-Tomytec-motorized-chassis.htm?shop=union_e&SessionId=&a=catalog&t=34&c=1253&p=1253

[David Prime]

This message is posted well after the last post but I'm hoping to see if Ted will read this. You mention Ted the bushes glued onto the wheels , in the case of the Darjeeling locomotive . Can I ask what you used for bushes or did you buy? The rest of the  explanation I think is quite clear.
Hope you a) read this and if you do b) can help me out.
Thanks Dave P.