Lumsdonia

[TimberSurf]

The dish clothes are a bit coarse, but capture the vast majority, hidden behind them is a Wilco cooker hood replacement filter (1/4 of £2 pack) that captures the smaller stuff.

[TimberSurf]

Been side tracked recently, all these Electronic ventures led me to buy some Chinese Buck converters, powered from my 10Amp PSU (destined to be the layout 12VDC lighting bus), they have been very useful, but once my PSU makes it to its home on the layout, I wont have a low volt supply!
I have dozens of wall plugs, but discerning what voltage and amperage each has and changing each time I need something different is a pain. I used to have a little bench PSU for just such occasions, but its disappeared (kids may have stolen it). So as I have copious quantities of electronic bits (a small Maplin outlet by most peoples standards!), I thought I would cobble one together (again)
Its based on an old CB radio PSU box (unfixable, but transformer is OK) and a L200, its a 2.7 to 35v variable voltage regulator, but you can also vary the max current through it! (0 to 2Amps) it will have fine and coarse voltage pots and 12 selectable max currents. Pictures to follow when its finished. Many other projects underway, twin road bridges over 7 tracks are at the metal panel weathering stage (salt method), developing bespoke Linka moulds for parapet and under arches. My white plastic tube holder is a great success, so am building it up to be longer, reorganised my shelves and workbench (much neater and more organized), wading through my electronics junk boxes and extracting the useful bits and storing in (findable) draw storage system.

[TimberSurf]

lab bench power supply now complete! Realy came in useful straight away for my investigations in to low ohm volt meter as the 5V reference supply!
Here is the tatty construction

Bench PSU rear.jpg (54.9 KiB) Viewed 2170 times

Bench PSU front.jpg (63.45 KiB) Viewed 2170 times

and complete

Bench PSU Before Legends.jpg (36.14 KiB) Viewed 2170 times

and with (I can read them, they they are good enough) legends

Bench PSU After Legends.jpg (33.35 KiB) Viewed 2170 times

Note it also has two separate regulated aux supplies of 12VDC/1.5A and 5VDC/2A

[TimberSurf]

My current project, is a new idea, taken on board from several layouts I have seen on NRM/exhibition/YouTube for a road bridge over the track at right angles, the width of the layout (currently 12ft x 2ft). I am also torn as to what the two long platforms are made from. So am going to make the bridge (at the end of the platforms) and tie the two together by using the same construction detail, so they look in keeping with each other. The road on the bridge will turn left and descend to the platform level down a ramp (this will come in a later stage [no board present at the moment]), but the side of it will form a back drop to the back of the far platform.

7 track bridge plan view.jpg (40.85 KiB) Viewed 2168 times

[TimberSurf]

I have considered brick paper and cardboard construction (Metcalfe do almost exactly what I am looking for), but I am dissolutioned with cardboard realism and feel I can do better. I considered plasticard (scratch build) and although I prefer the 3D effect over the cardboard "ready coloured", I realised that I could really get a bespoke look and take less time using Linka.
So I will try perfecting my Linka skills, and speed the process up by a mass manufacturing process.
What that means, is that I will create bespoke Linka type panels of my own, and make generic large panels that will cast in one, instead of building each from dozens of individual pieces.
First is a parapet piece of my own design, amalgamated as one piece from three (half height wall with recessed panel of brick) all joined together

Recessed panel mould casting.jpg (89.51 KiB) Viewed 2167 times

New mould being made with two new panels (green), when I have cast 3, I will join together and make a new mould so I can cast a triple panel in one

[TimberSurf]

Also going on is the steel bridge panel prep......
I have dozens of bridges in stock, so waded through them and selected two appropriate plastic kits (all bought second hand from eBay over many years, so don't actually know the makes!)
First stage, assemble (one), then slice that one in half!

Bridge 1 Before cut.jpg (26.02 KiB) Viewed 2140 times

Second stage, paint all over in rust (with airbrush in my ginormous spray booth)

Bridge 2 Rust coat.jpg (42.29 KiB) Viewed 2140 times

Third stage, dowse in water and IPA and scatter household salt and allow to dry (one side, then once dry second side repeat)
Fourth stage, paint in glorious green!

Bridge 3 Green coat still wet.jpg (40.37 KiB) Viewed 2140 times

Fifth stage, scrape all the salt off with a wooden lollipop stick and wash thoroughly

Bridge 4 Salt removed.jpg (67.48 KiB) Viewed 2140 times

Six stage, wash with "grimy" grey paint
Seventh stage, add (blue) repair panel and graffiti (may add more, just need some idea's)

[TimberSurf]

Finally think I have cracked the Linka joins. Not sure if its because of my old green moulds, my special mix ingredients or just Linka is rubbish!
Large piece casts are slightly bowed! The joins, after some filing leave some gaps. I tried several types and consistencies of mix to use as filler, followed the let nearly dry and brush off excess with toothbrush, etc, developed a "saw tool" to re-groove the brick mortar channels and all in all, left a mess! I have now decided to paint with a grey wash for the mortar (to be dry brushed on surface to get the red face) and once grey is dry fill the joins. As the painted surface does not hold the filler, its much easier to clean off and just leave the holes filled. More experimentation and time will tell! Linka building takes ssooooooooo loooooong! The triple parapet is coming along nicely, painted tonight, will make the mould at weekend. Ran out of brick, so made 15 moulds worth. So will have stock at weekend to keep building with. Any tips on concealing the finger joints and how to dry brush the faces, welcome.

[timbologist]

Hi TimberSurf

Large piece casts are slightly bowed!

One of the reasons for this is the expansion rate of plaster, it stretches the mould hence giving curved pieces. Different plasters have different rates of expansion, so depending on you blend how bad it will be.
Solution once the mould is filled, place a plastic film over the back of the mould and then sandwich between 2 pieces of a straight flat material, ( I use glass, or 3/4 melamine ) will give flat castings.

You must have patience to use the Linka system, not for the faint hearted. I have been using it now for about 4 years now and my joints are invisible, took a bit of time and effort to get it right.
Firstly I use a mix of 50/50 dentist and casting plaster for my tiles, has a relatively higher expansion factor but I use method above, I mix as more of a paste and have to work it into the moulds quickly. As it goes of very quick, and dryer mix is stronger and expands less.

Joining I use just casting plaster with a powdered pigment to see the join but very runny, give all areas to be joined a really good wetting so the mix does not dry to quick and stop proper butting up, while still green remove all excess plaster.

For filling if needed again use the casting plaster coloured, again wet and work into any holes with dentist tools, when still green remove excess, when hard finish clean-up and re-grooving, repeat if required.

Main thing is be patient.
Hope this helps

Cheers
Tony

[heda]

I like that method of adding rust as the rust is actually underneath the paint not on top. Much more realistic. I did a similar thing with a model car (post in the scenery forum).

Dave

[TimberSurf]

Heda
I did lots of research (including your car) before attempting it myself. I must say, I used a method that was the last one I saw on YouTube, and now regret it, as many like you, recommend sea salt and I used table salt. Were it amassed its fine, but the smaller particles are too small to scratch off! You live and learn, I never take advice verbatim and like to learn for myself, even at the cost of failure, I just NEED to know WHY things are wrong!

Timbologist

Like above, I am experimenting, yes takes patience! I think I may tweak my mix formula, I have been deliberating about a glass sandwich (so will try on next batch), already used glass as the base. I think your secret for dressing joints maybe the "green" element is pivotal! I will pay attention to timing next go.

[timbologist]

Hi TimberSurf

Experimenting is the best way, we learn by or mistake's, Forgot to mention in the mix for the actual joins I mix a bit of PVA about 5-10% making up for the wetter mix. When working the joints you need a gentle hand, or you over do it.

And with your weathering and rusting, for large area's I use latex, and another salt is rock salt.

If you want to look at some videos, or Magazines on the subject look for anything by Mig Jimenez, or his fellow modellers that build military models.
They are something else, I build Military models also so use these techniques on my trains, there is a magazine especially on rust.

It is worth a look
Tony

[End2end]

Are the rust basecoat and the green over-painting enamel paints?
Thanks
End2end

[TimberSurf]

Timbologist
I do look at military modellers during research, will find Mig and add to sub list. Rock salt is similar to sea salt (big lumps)
I always use PVA in my mix!
Latest batch of linka still bowed, I think its one mould! Trying glass sandwich this time.
E2E
Yes Humbrol enamels. I swear by 'em. Never even tried acrylic!

[TimberSurf]

Mig Jimenez, wow, that's what you call detail! That will take some time to absorb all he has on YouTube!
The Linka saga continues, another batch, more experimentation. Glass top seems to help the bow. Slowly perfecting the finger finish, but still some way to go! The new mould casting process has evolved, washing up liquid as my release agent destroys the master! Experimentation shows silicon direct on painted Linka, comes off clean. So casting some more pieces so make a new master for the triple parapet. Sloping embankment panel is complete and I have moulded it in silicon (tonight). Buttress is complete, will cast a mould of that next w/e. After a lot of finger joint rework, the nearest pier of 7 track bridge is nearly complete. Started constructing the wood sub frame and measuring up for the middle pier.

How do you like my weathering? Green slime, grass, mineral stains and knackered old brickwork.

Bridge near pier 951.jpg (157.72 KiB) Viewed 2007 times

[End2end]

Thanks Timbersurf. I know a bridge like this I see quite regularly and you've given me the idea to take a good closer look at it!
Thanks
End2end