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#1 Pixie

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Posted 07 June 2011 - 13:42

Hello all,

There seems to be an ever increasing interest in 2mm finescale and as a result there is the possibility of questions that some people may think are too obvious or silly and be afraid to ask. Well, this is the place for them, absolutley anything to do with 2mm finescale modelling is invited and I'm sure with the knowledge base that this forum has that a complete answer can be provided. One suggestion I would make is for new comers to 2mm to have a read through this page - http://2mm.org.uk/ar...rted/index.html - for an excellent overview of the scale. Full credit must go to Bryn for the idea of this thread.

As long as people think it's a good idea, I shall make this a sticky post and as questions arise I will add an index to this post.

So, please, fire away. :)

Pix

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#2 The Nth Degree

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Posted 08 June 2011 - 14:31

Ah, this is handy, I'll have loads of questions!

I'll start with this: I'm planning to build 3 scratch-built 0-6-0 Fox Walker steam locos. I've got some photos to work with and they are all very similar designs (http://www.steampict...find=fox walker) so a common chassis would work for two of them, with the third being slightly larger. The question is how do I go about building a chassis for each of them? Is there a standard width of the axle box part or, is there an off-the-shelf 0-6-0 chassis? Where can I get wheels and motions from? Is there a common way of electrical pickup or are there options? How do you isolate the supply from the chassis? What about motors and gearboxes - is there a source of tiny motors and gearboxes (the engines only averaged 16mph over the branch I have in mind).

Well, this should set you off nicely!

Cheers in advance,
Steve

#3 Kris

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Posted 08 June 2011 - 14:53

These are the suggested standards for 2mm loco chassis construction, Steve.
Bob Jones of Fencehouse models does a 0-6-0 chassis but whether the wheel spacings are correct for this I don't know. The other option might be one of the chassis kits that are being released to fit the farish pannier, again comments on wheel spacing apply.
This article will give you some information on one method of chassis construction. If you are a member of the 2mm association then there is a booklet on building a 0-6-0 that can be downloaded from the members only area.

Some lengths of motion are available from shop 3, if these don't work out to be the right length then you'll be making your own.
Wheels come from shop 3 as do a selection of small motors and gears.
Pick up is frequently done via the Simpson spring method where a sprung wire brushes against the live section of the axles.
Isolation is generally done via gapped PCB.

#4 Gingerbread

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Posted 08 June 2011 - 16:30

Get hold of the Association booklet (slightly illogically it comes from shop 1 which deals with track):P-103An Introduction to Split-Frame Chassis Design£5.00

I think the wheelbases on the two chassis options suggested by Kris would be rather too large, judging by the photographs. Similarly I suspect the coupling rods available from the Association shops would probably be too long (shortest one I can see is 14 + 15.5 mm).

The wheels from the Association are designed for a split-frame chassis, with pickup directly from all wheels to the frames through bearings, without any need for further contacts. Simpson springing is an option which should help ensure all wheels make contact with the track.

Apart from the gapped PCB method for insulating the frames, I have seen the following possibilities recommended:
  • Blocks of tufnol between the frames, with the frames screwed (or glued) to the blocks (which I think is recommended in the locomotive building book on the Members section of the site) - though you would probably want something heavier with such small locomotives.
  • An alternative form of this uses brass blocks between the frames, with insulating layer (eg cigarette paper) between frames and the blocks, then holes drilled in the block and filled with epoxy, and re-drilled for screws to hold the frames.
  • Small pieces of PCB as insulators between frames and crosspieces - so you solder one side of the PCB to the frame and the other side to the crosspiece.
I would suggest Nigel Lawton for motors - small and cheap:
http://www.nigellawt...icroMotors.html

Gearboxes are generally scratchbuilt, or acquired from a variety of other sources - see for example post 64 on http://www.rmweb.co....ms/page__st__50 for one (together with a photo of the small Nigel Lawton motor).

Good luck with your project

David

#5 richbrummitt

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Posted 09 June 2011 - 09:28

Ah, this is handy, I'll have loads of questions!


The book on build an 0-6-0 (that is already suggested above) will answer many of them. It follows one persons build. There are some things that I would disagree on, like the keeper plate method for the wheels.

There is a second book on split frame chassis construction. Also available from the 2mm SA Shop 1, or if you are not already a member (why not :P ) it is available from any exhibition that the 2mm SA association stand attends. This is possibly better than the above book because it gives the principles, reasons and ideas for this method of construction.

I'll start with this: I'm planning to build 3 scratch-built 0-6-0 Fox Walker steam locos. I've got some photos to work with and they are all very similar designs (http://www.steampict...find=fox+walker) so a common chassis would work for two of them, with the third being slightly larger. The question is how do I go about building a chassis for each of them? Is there a standard width of the axle box part or, is there an off-the-shelf 0-6-0 chassis? Where can I get wheels and motions from? Is there a common way of electrical pickup or are there options?


Other replies have answered most of these questions. N Brass Locos also offer 0-6-0 chassis (think frames and connecting rods) which I believe are based on a SECR C class, but there's every chance I am wrong.

How do you isolate the supply from the chassis? What about motors and gearboxes - is there a source of tiny motors and gearboxes (the engines only averaged 16mph over the branch I have in mind).


The supply is not isolated from the chassis. You have to make sure that the frames are isolated from each other. This is explained by the principles of split frame chassis construction.

Gearboxes are usually built into the frame to make the most of the small space available between the frames (usually 6-7mm depending on the material used for the frames). Thus when planning the frames you will also plan additional holes to site the shafts for the gears to sit on. (These are also split and joined by an insulating sleeve, like the locomotive wheels)

#6 The Nth Degree

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Posted 09 June 2011 - 22:04

Thanks for the insight, links and suggestions chaps. I hadn't considered PCB as a chassis tub, I thought I'd had to origami a sheet of brass.

Thinking logically, I'd better sort my gearbox and ratios and find a motor. My thinking is to work backwards by finding the bits then designing the chassis around them rather than producing a scale proto chassis and scouring the universe to find bits that fit.

I'm waiting for one more book to arrive (hopefully tomorrow) then I can start tech drawings. One question though; how do you join PCB pieces? Solder? Glue?

Cheers,
Steve

#7 Bryn

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Posted 09 June 2011 - 22:08

I think this might be worth reading:

http://www.2mm.org.uk/articles/dy1/

An article about how Nigel Cliffe constructed an 0-4-0 diesel shunter chassis, using PCB side frames.

#8 Kris

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Posted 10 June 2011 - 06:52

One question though; how do you join PCB pieces? Solder? Glue?



Solder



#9 The Nth Degree

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Posted 11 June 2011 - 21:24

Kris, as always, thanks. Interestingly, on Nigel Lawton's site a chap has made 2mm scale tram chassis' from perspex. A really interesting (and non-solder) way to produce them. With my non-existent soldering skills I may look in to this method.

#10 backofanenvelope

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Posted 12 June 2011 - 14:45

Ok so my first question, I brought a back to back gauge at 2mm Expo and had this little dodger in the packet I have no clue what it is for, can any kind person put me out of my misery?

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#11 2mm Andy

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Posted 12 June 2011 - 14:59

Ok so my first question, I brought a back to back gauge at 2mm Expo and had this little dodger in the packet I have no clue what it is for, can any kind person put me out of my misery?


Tom,

It's a vacuum cylinder. The short stubby bit at the top locates in the hole in the chassis, and the long thin spindly bit goes downwards (where it should meet an actuating arm which is usually included on a chassis etch for fitted wagons).

Hope this helps!

Andy

#12 backofanenvelope

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Posted 12 June 2011 - 15:03

Thx Andy, but was it meant to be there? as it seems a bit strange to be in a back to back packet?:unsure::lol:
Tom

#13 Kris

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Posted 12 June 2011 - 15:07

Nope it should not have been there, never mind, it would cost you more to send it back that it's worth (20p).

#14 2mm Andy

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Posted 12 June 2011 - 15:20

It certainly doesn't have any use to do with a back to back gauge, so I imagine it was packaged-up by mistake when the central shop was being stocked-up before the Expo. It's amazing where these little 2mm bits sometimes end-up!

Andy



#15 backofanenvelope

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Posted 12 June 2011 - 16:20

Thx Gents mystery over, I will hand back next time I see the travelling shop! ;)
Tom

#16 Gingerbread

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Posted 14 June 2011 - 17:21

Perhaps the biggest question for anybody starting in 2mm is: "How to make points?".

I know Geoff Jones is gathering together various views to include in a definitive (?) handbook, but it would probably be useful to outline some of the alternatives here:
  • Solder - this is the most widespread method. Details vary, but generally it's a case of cutting/filing/soldering rails to sleepers made from printed circuit board. Templates, jigs, sleepers, rails, and optionally chairs, are available from the 2mm shop. For those with good soldering skills it's probably the way to go.
  • Easitrac - attractive for those with limited soldering skills. Milled plastic bases, plastic chairs, rails and jigs are available from the 2mm shop. The disadvantage is that it's much more difficult to "fix" if you have glued the chairs in the wrong place, rather than soldered. Preliminary sections of the Geoff Jones guide are available at http://www.2mm.org.u...ac_Turnouts.pdf
  • Subcontract - there are a few kind individuals who will build points to your requirements.
Having built your points, the next problem is how to operate them, and again there are multiple options available, with no clear preference as far as I can tell. Basic concept is to firmly attach the two switch blades to a sliding bar, then allow the operator to move the bar either manually through a wire-in-tube system or by connecting it to an electromagnet. There is a "turnout operating unit" available from the shop, with a sketch (and video) of how it fits together at http://www.2mm.org.u.../TOU/index.html

Comments, clarifications, corrections, contrary views, etc all welcome...

David

#17 The Nth Degree

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Posted 17 June 2011 - 21:28

Following on from the points post above, where do you start and stop building the point section? Do you build it so it's the 2mm equivalent of a set-track point, or can you include a decent length of straight on all entrances/exits?

Also, when building track, is it best to build in scale 60ft lengths or just nick the track at 60ft intervals (for sound effects)?

An obscure question (I think) but, what are the electrical losses across track joins? Actually, how do you join track sections?

#18 Bryn

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Posted 17 June 2011 - 22:12

Following on from the points post above, where do you start and stop building the point section? Do you build it so it's the 2mm equivalent of a set-track point, or can you include a decent length of straight on all entrances/exits?


That's the beauty of hand built track, you can do it any way that suits you, or more importantly what suits the project at hand. If you are building the track on the baseboard, the length is unlimited. I normally build my points on a sheet of glass away from the layout and fix them down after, these usually have short pieces of track (an inch or so) coming off each road.

Also, when building track, is it best to build in scale 60ft lengths or just nick the track at 60ft intervals (for sound effects)?


I built sections as long as possible, otherwise you will struggle to get flowing curves and will have to have loads of separate electrical feeds to cater for.

An obscure question (I think) but, what are the electrical losses across track joins? Actually, how do you join track sections?


We don't use fish plates, just line the rail end up and fix the track in place. Each separate piece of track has it's own electrical supply.

#19 Ian Smeeton

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Posted 18 June 2011 - 00:34

As a recently lapsed 2fs member, with loads of intentions, but no get up & go, for those who are just starting out in 2fs trackbuilding, would it be an idea to have a "starter pack" or starter list, of what is needed to get somone like me started on the right track?

Pun Intended, Jacket on, exiting stage left.

Regards

Ian

#20 -missy-

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Posted 18 June 2011 - 05:20

Hello Ian.

There are quite a few 'beginners packs' available ranging from small packs of track to more substantial selections of books and wagon kits but as far as I am aware (and I could be wrong) these are only available at shows where the 2mm 'roadshow' is attending and not through the 2mm shop but non-members (and lapsed ones!) can purchase them.

There is of course the 'Beginners Guide' which is a very useful and comprehensive guide to modelling in 2mm finescale and obviously covers trackwork to some detail and if you wait a little longer there is also a booklet being produced purely about 2mm finescale trackwork. Booklets like these are usually available at the roadshows as well as the 2mm shops.

Of course in reality nothing beats actually getting on an having a go! Are you planning on rejoining the 2mm Association?

Missy :yes:

#21 nick_bastable

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Posted 18 June 2011 - 07:09

South Kent Canterbury area group will be doing a points building evening at its next meeting if you can come along

#22 2mm Andy

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Posted 18 June 2011 - 10:34

As a recently lapsed 2fs member, with loads of intentions, but no get up & go, for those who are just starting out in 2fs trackbuilding, would it be an idea to have a "starter pack" or starter list, of what is needed to get somone like me started on the right track?

Pun Intended, Jacket on, exiting stage left.

Regards

Ian


Hi Ian,

As Missy has said, there are beginners packs available for three different types of plain track and a wagon/track pack (and a wagon/track/beginners guide pack). The beginners guide is being updated to illustrate the use of Easitrac and the replacement wheels for Farish diesels, but the previous edition is still available. There is also quite a lot of information on the 2mm website on trackwork, including two fairly new sets of notes on Easitrac (which are extracts from the forthcoming trackwork handbook) but which are also useful for soldered track construction.

All are available from the 2mm roadshow, which goes to quite a few shows around the country - I think the next ones are Railex NE, The International N Gauge Show and Shipley. I will check to see if the packs are available by post.

Andy

#23 backofanenvelope

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Posted 18 June 2011 - 10:56

Ian,

Personally I don't think you can go far wrong with some bullhead or flat bottomed rail and 3 packets of sleeper timbers, that's of course if you want to build soldered points. I think its a case of just get in there and have a play with it.. I started with absolutely no knowledge/skills of building a point and am now after about 5 points comfortable building them.. slips etc I haven't tried yet.. but..

All this is irrelevant if you are Easitrac building.. :)

Regards
Tom

#24 richbrummitt

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Posted 19 June 2011 - 19:24

Ian,
All this is irrelevant if you are Easitrac building.. :)

Regards
Tom


I disagree. You are trying to do almost exactly the same thing, but you have glue for the plastic bits instead of solder for metal ones. The prototype is no different.




#25 backofanenvelope

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Posted 19 June 2011 - 21:53

Hi Richard

I meant the soldering bit would be irrelevant although looking at some articles on Easitrac I might be wrong on that too! Will sit in corner quietly for a while.. :)
Tom






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