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More Like the Real Thing

Pugsley

By Pugsley,
in Kitbuilding & Scratchbuilding

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Pugsley

Pugsley

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Although I've started this thread, it's mostly a pointer towards my blog where I'm building my first 7mm kit! It's early days yet, but here's a photo to whet your appetite:

 

 

gallery_6668_11_402.jpg

 

Progress to date (and any updates) can be found here:

http://www.rmweb.co.uk/community/index.php/blog/8-pugsleys-workbench/

 

Part 1: http://www.rmweb.co.uk/community/index.php/blog/8/entry-2227-unleashing-the-genie/

 

Part 2: http://www.rmweb.co.uk/community/index.php/blog/8/entry-2295-what-do-you-do-in-the-bath/

 

Part 3: http://www.rmweb.co.uk/community/index.php/blog/8/entry-2350-giving-my-chopper-a-good-workout/

 

Thought I'd put a topic in this area as well, as I know not everyone looks at the blogs these days.

 

It'll be in 1991 condition, in InterCity Mainline livery, a bit like this:

http://rugbytown.fotopic.net/p717525.html

 

built to S7 standards, which is going to require a bit of ingenuity bogie-wise, but more of that nearer the time ;)

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Ressaldar

Ressaldar

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Hi Martin,

 

the 37 is coming on a treat. Will you fit the bulkheads and windows before or after painting? I left those on the 40 until after and could see no reason why they had to go in first. It seems strange that there are hardly any conduits on the bulkheads. These new? gel pens with the fine tip are great for 'painting' the conduits and other bits on the bulkhead and control panels and are available in a number of 'correct' colours.

 

I also like your signage - I keep meaning to have a go at it using your method - maybe soon.

 

Will be interested to see your S7 solution in future postings.

 

regards

 

Mike

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James Hilton

James Hilton

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Chaps - I'd direct these questions on Martin's blog - where I expect he'll keep more of a close eye. As he says - this thread is more of a teaser to get you over to visit it! Don't be afraid - adding blog comments is exactly like placing a reply in a thread like this! :)

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Pugsley

Pugsley

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To be honest, I don't mind if questions/comments are put here or on the blog - I'll be keeping an eye on both sections. There seems little point in duplicating posts word for word, so I just link to the blog, which will always be the part I update.

 

looking great Pugs.

 

I really like the decals.

 

Not a big fan of the toothpaste livery on a 37 but Itll be one impressive model thats for sure.

 

btw Posts are better than blogs :)

 

 

Mike

Thanks Mike. I think we'll have to disagree on the latter point ;)

 

The 37 is coming on a treat. Will you fit the bulkheads and windows before or after painting? I left those on the 40 until after and could see no reason why they had to go in first. It seems strange that there are hardly any conduits on the bulkheads. These new? gel pens with the fine tip are great for 'painting' the conduits and other bits on the bulkhead and control panels and are available in a number of 'correct' colours.

 

I also like your signage - I keep meaning to have a go at it using your method - maybe soon.

 

Will be interested to see your S7 solution in future postings.

Thanks Mike - I'll be fitting the windows and bulkheads before painting, but only because I'm adding some details which will make the windscreens tricky to fit afterwards. The 37 bulkheads are quite free of clutter - I could have added some smaller pipes around the AWS gear, but decided it wasn't worth it as it wouldn't really be visible.

 

Yes, the S7 solution is certainly interesting :D

 

 

Another convert! I really like the signs, how did you create them?

Thanks Tony, if you read the blog posting you'd see how I did them ;) They were drawn up in CorelDraw, working from prototype photos.

 

Dan - Cheers B)

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craigwelsh

craigwelsh

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Chaps - I'd direct these questions on Martin's blog - where I expect he'll keep more of a close eye. As he says - this thread is more of a teaser to get you over to visit it! Don't be afraid - adding blog comments is exactly like placing a reply in a thread like this! :)

Its not actually as you have no idea if they were replied to compared to a thread unless you remember to go back and look. I responded to Rich (Fatadder) in a couple of his blog posts and its a nightmare keeping all the conversations going.

 

Considering the 4mm 59 im very much keeping an eye on this Puds, not disappointing so far :).

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Pugsley

Pugsley

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Considering the 4mm 59 im very much keeping an eye on this Puds, not disappointing so far :).

Erm, it's Pugs ;) There's not actually much scope for detailing with this on the outside, everything is pretty much catered for in the kit! I'm sure I'll find a few little things to add though :D

 

More progress:

gallery_6668_11_29793.jpg

 

More details here:

http://www.rmweb.co.uk/community/index.php/blog/8/entry-2602-interior-design/

 

Edit - replacement photo.

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Pugsley

Pugsley

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A change of focus from blogging to posting for the next phase of the project, as this is a little out of the ordinary and opening it up to easier discussion seems like a good idea, advice will most likely be needed as I'm a little out of my depth here...

 

From the beginning, I've intended this to be a very special model, to the extent that I wanted to make it almost completely different. It started after reading MRJ188 and Chris Pendleton's inspirational article on the construction of fully sprung bogies for his 4mm Deltic. Having read it, my thoughts turned to 7mm scale (there's no way I'm good enough to try it in 4mm scale yet!) and the possibility of combining fully working springing with individual traction motors to each axle. Whilst the ABC traction motor units are most likely very good, they are too big to have more than two per bogie, and are also frighteningly expensive, I've decided to make my own.

 

This is the initial proving diagram, which I've used to check clearances etc. The original copy is to exact scale size, the diagram below is enlarged for clarity.

 

gallery_6668_11_14410.jpg

 

The dark blue bits at the top of the image are the chassis rails, on the floor moulding, that project downwards. The red box around the bogie is the maximum height allowable to ensure that the buffer centres are a scale 3' 5.5" above rail level (24.21mm), although I could allow myself an extra mm or two if required, there's variation in the real thing, after all :)

 

The hornblocks are from Slaters, and the inner frames will be etched from either 0.70mm brass or nickel silver, I haven't decided yet. One thing to note, the wheels haven't come out very well in that picture, the larger floating green things you can see are the axle mounted gears, with the grey rectangle underneath being the rail. I'll upload a better diagram at some point.

 

Now that I'm satsfied that the concept works, and I've found the right parts for the job, next job will be to finalise the motor and gear positioning before deciding on the design for the frames and motor mounts. What I learned when designing my class 455 etchy bits is going to come in handy here!

 

The best part is, now that it's public, I'll have to get on with it and make it work! :D

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Pugsley

Pugsley

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Thanks for the vote of confidence JB B) , I do hope it's not misplaced. It should be OK though, I'm not really doing anything here that hasn't been done before, it's just not something I've done before! I've been putting a lot of thought into the design, so it should work out as planned...

 

I also need to pull my finger out, it's supposed to be finished by June :lol:

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eldavo

eldavo

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That sounds like something of a challenge! Have you had any thoughts about what electrical wizzardry you will need to keep 6 separate motors operating together? I know we commonly use 2 motors on O gauge diesels just wired in parallel but with a motor per axle I get the feeling you would need more control gear.

 

Cheers

Dave

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Pugsley

Pugsley

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Already I'm convinced of the benefits of having this part of the build in the traditional format as there's been a couple of things raised that I haven't given much thought to!

 

JB - Shouldn't deadlines always be realistic ;) :lol:

 

Ian - I've no idea, TBH. I know that the stall current for the 6 motors is 2.4 Amps, so power consumption isn't going to be significantly different to fitting two larger motors. If it matches more conventional drive systems in terms of power, I'll be happy. It'll never be taxed that much, as the eventual layout will only be a long-ish shunting plank, so it'll only ever have to move itself and a few wagons about.

 

Dave - It'll be a challenge alright! The biggest challenge for me will be working precisely, I'm a bodger at heart but for this to work properly it's going to require precision in terms of design and assembly. I haven't given the electrical side of it much thought, it'll be DCC controlled and my initial thoughts were to wire each bogie in series and connect the two in parallel.

 

Any thoughts or advice on the electrical parts of the bogies would be appreciated.

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richard_t

richard_t

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Hello

 

I've pretty much had the same ideas for traction motors as you have, although in my case I've chickened out and gone for a Bo-Bo bogie for my prototype. I've designed mine around inner frames with Hobby Holiday ball bearing hornblocks. A couple of things I found was that I couldn't get the gear reduction I wanted in one stage, so I needed to have a two stage "gearbox".

 

The other is that although I too model Scale 7, there still isn't a lot of width to play with between the frames, and the range of motors that could be accommodated was quite small - although I've limited myself to coreless examples. Perhaps you've squeezed more width with the Slaters hornblocks? If you're a member of MIGO+1 I dropped a database/spreadsheet of motors for just this type of operation.

 

With a Bo-Bo I'm going to be using two 6-volt motors in series, and then each bogie wired in parallel - well unless someone here knows any better.

 

My drawings are awaiting access to some engineering equipment before becoming reality.

 

BTW your 37 is inspirational stuff sir!

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Pugsley

Pugsley

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Thanks Richard B)

 

I can't get quite the gear ratio I wanted either - I calculated a ratio of 15:1 in order for the top speed of the model to be a scale 90mph - the closest I can get is just over 12:1, so top end will be a little higher than desired. The model will spend most of it's time at low speed though, which is where the DCC control will come in handy.

 

I liked the idea of using roller bearings in the construction of this too, but I think that clearances are so tight for what I have in mind, there's no way I would get them to fit. Again, the Hobby Holidays product is supposed to be very good, but are frighteningly expensive. I figured that making my own would be a step to far at this stage - this is already the most complex miniature engineering project I've ever tackled and I didn't want to run before I could walk!

 

The original plan to leave enough space between the frames was to use the Slaters hornblocks as outside bearings - as in the real thing, leaving the space between the wheels completely free for the motors and associated gears. This would be acheived by using actual coil springs in the place of the moulded ones, between the frame and the equalising beams, in the same vein as the Pendleton Deltic, with the hornblocks running in the bogies axlebox guides, with cosmetic bearing covers. The secondary springs will also be functional.

 

This, however, has lead to some head scratching in terms of coming up with a solution that will fit after additional exploratory work last night - I stongly believe that it's still feasible, but it is going to require a rethink in terms of how I'm going to do it.

 

Extending the axles is going to be the first job - this will require drilling out the Slaters wheels and reaming to a sliding fit on to the extended 3/16" axles. The challenge is fitting the hornblocks into the space available outside of the wheels, I've only got 38.90mm to play with inside of the moulded frames, without moving them outwards, which I'm loathe to do. If it comes to the worst, I could mill 1mm from the backs of the moulded bogie frames. I guess I could go down the inner frame route if I can't make this work, but I'm fairly sure I can - it just requires more thought, I guess! :)

 

I've got a couple of ideas knocking around my head, which I'll put up later on once I can take a few more measurements and draw up a diagram or two.

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