Jynn: a 7 1/4" gauge wren

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Nomis
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Jynn: a 7 1/4" gauge wren

Post by Nomis » Sat Jul 04, 2020 10:48 am

Having recently put together a thread on my new garden line elsewhere on the forum, https://gardenrails.org/forum/viewtopic.php?t=12858
It seems people are interested in my steam loco...

Jynn is a scale model of a kerr stuart wren class, running on 7 1/4" gauge:
ImageDSC_0201_1589044108855 by simon mace, on Flickr

I will go through some of her history on this thread, along with teething troubles and pictures from running at home and when visiting other railways.

Please feel free to ask questions / make suggestions.

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Re: Jynn: a 7 1/4" gauge wren

Post by Nomis » Sat Jul 04, 2020 10:58 am

There is a very good history of the prototype from the IRS archives on line (although I am sure most of you have seen a full-sized wren at some point)
https://www.irsociety.co.uk/Archives/5+6/KS_Wren.htm

A picture of jennie from the amerton railway (which I believe is also a modern "new build" loco):

Image35028161470_cc5949c66d_b by simon mace, on Flickr

There are a few similar designs available in the "ride-on" scales, the most common being from maxitrak, although these are quite small - being built to an "undersized" scale.

Jynn is an example of the design originally created by Ken Swan (a prolific designer and builder of engines). The story goes that an american customer saw a wren in the old manchester museum (I think this loco may have been Lorna Doone), and commissioned drawing to be prepared for 7 1/2" gauge, as is common in the US.

The model is therefore built to a scale of 3 3/4" to the foot (just under 1/3 full sized).

This makes for quite a chunky engine, that is still light enough to be transported in a small van or estate car. The finished loco stands 30" tall, is just under 4' long, and weighs around 150kg (so ramps are essential, but trailers and winches can be avoided).
Last edited by Nomis on Sat Jul 04, 2020 11:05 am, edited 1 time in total.

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Re: Jynn: a 7 1/4" gauge wren

Post by Nomis » Sat Jul 04, 2020 11:03 am

My engine was one of a pair started together long ago by a local model engineer.

While one engine got finished and saw quite a lot of use, the other (my one) never got beyond a bare frame, boiler, and some part finished castings.

Ultimatley when the "finished" engine bacame due for some rebuilding, the owner chose to have this done professionally by south west steam, who took the part-built twin as payment.

Jumping ahead a bit, the story has a happy ending as both engines have now steamed together:

ImageFB_IMG_1577640769167 by simon mace, on Flickr

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Re: Jynn: a 7 1/4" gauge wren

Post by Nomis » Sat Jul 04, 2020 11:14 am

I purchased the pile of parts late in 2018, under the agreement that south west steam would do all of the machining / fabricating / assembly work (at an hourly rate) while I would do all of the painting.

This saved a bit of cash, and allowed me to take my time fussing with paintwork.

The work was undertaken gradually, with a set budget agreed each month to match what I could afford. This way the cost was spread out, and there were no suprises.

(I am not going to go into details of costs too much here, but I did keep tabs of the spend, and the total was about equal to 2.5 roundhouse double fairlies - which I don't think is too bad considering I plan to only ever have one or two live steam locos of this size....)

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Re: Jynn: a 7 1/4" gauge wren

Post by tom_tom_go » Sat Jul 04, 2020 11:16 am

I would like a complete run through with how you went about preparing and painting her.

I am done using Halfords rattle cans and want to move on using to brushes and durable paints that can withstand real world use.

Brands, where you purchased items from - more details the better please!

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Re: Jynn: a 7 1/4" gauge wren

Post by Nomis » Sat Jul 04, 2020 11:23 am

The frames as bought;

Image20180225_175348 by simon mace, on Flickr

Image20180225_174951 by simon mace, on Flickr

You can see the level of detail in these pictures. The model really does have every nut, bolt, and rivet of the prototype. Also, even though this is a relatively "modern" engine, there are still quite a few castings involved.

I cleaned up the frames, welded up a few unwanted holes, and drilled new ones for couplings of my choice (a typical multi-height industrial type on the front, and a simple link & pin type for the rear - both of these were bought as sets of laser cut parts via specialist suplliers on eBay).

After a coat of paint, things look a lot better:

Image20180307_190504 by simon mace, on Flickr

I like to use Rusoleum brand paints, mostly brush applied.

For the chassis, I used satin black and gloss red, applied straight from the tin. This paint takes quite a long time to dry fully, but goes on well and seems quite tough.

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Re: Jynn: a 7 1/4" gauge wren

Post by tom_tom_go » Sat Jul 04, 2020 11:35 am

What type of brushes are you using and what cleaning products to prepare for painting?

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Re: Jynn: a 7 1/4" gauge wren

Post by Nomis » Sat Jul 04, 2020 11:37 am

Prep was simply a flap wheel in the grinder, clean off with white spirit on a rag, leave to dry, then brush the paint on.

I like to leave it a full week between coats, but two coats is usually more than enough when used "neat".

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Re: Jynn: a 7 1/4" gauge wren

Post by Lonsdaler » Sat Jul 04, 2020 11:43 am

Nomis wrote: Sat Jul 04, 2020 11:37 am Prep was simply a flap wheel in the grinder, clean off with white spirit on a rag, leave to dry, then brush the paint on.

I like to leave it a full week between coats, but two coats is usually more than enough when used "neat".
I would have thought some type of etch primer would improve paint adhesion, maybe acid etch #8 or similar?
Phil

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My Line - https://gardenrails.org/forum/viewtopic ... 41&t=11077

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Re: Jynn: a 7 1/4" gauge wren

Post by tom_tom_go » Sat Jul 04, 2020 11:45 am

Nomis wrote: Sat Jul 04, 2020 11:37 am Prep was simply a flap wheel in the grinder, clean off with white spirit on a rag, leave to dry, then brush the paint on.

I like to leave it a full week between coats, but two coats is usually more than enough when used "neat".
That's the process I followed with my tender but I used a primer and then Halfords acrylic spray and I don't think it is durable enough as despite leaving it to harden off it has scuffed easily.

I also think white spirit is leaving residue on the metalwork possibly? Did you not use a primer?

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Re: Jynn: a 7 1/4" gauge wren

Post by Nomis » Sat Jul 04, 2020 12:18 pm

Nope, no primer.

The Rustoleum is intended for application directly to a roughened surface (hence the name).

I have found that a course flap wheel gives a good amount of surface "bite".

I have used the same brand with good results on my van, there are people (with more patience than me) who habe achieved amazing high finishes with a roller application and plenty of polishing - have a search on YouTube for rustoleum car painting....

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Re: Jynn: a 7 1/4" gauge wren

Post by Nomis » Sat Jul 04, 2020 12:22 pm


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Re: Jynn: a 7 1/4" gauge wren

Post by Nomis » Sat Jul 04, 2020 12:37 pm

A bit of a thread drift, but this is how the van turned out:

Image2019-04-07_12-11-06 by simon mace, on Flickr

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Re: Jynn: a 7 1/4" gauge wren

Post by Nomis » Sat Jul 04, 2020 1:31 pm

A good bonus of this paint brand is that a very wide range of RAL colour codes are available.

I particularly wanted the maroon as used by the modern day ffestiniog for thier new build locos. A bit of digging on line revealed that thos was RAL 3004.

I then ordered a tin via a supplier on eBay. Had to buy quite a large quantity (2.5L) to get this particular colour, but that provided enough to paint the loco, it's transport trolley, a large battery diesel (and tender), with about a pint left over for future touch-ups....

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Re: Jynn: a 7 1/4" gauge wren

Post by bambuko » Sat Jul 04, 2020 2:14 pm

I know that "Rustoleum" seem to be in common use on interweb and everybody seems to know what you are talking about :D ...
but looking at all the Rustoleum products available (see: http://www.rustoleumdirect.co.uk/products.php) I remain confused :scratch:
Can you, please clarify which one of these you have used :?:

I am guessing, this one? :
https://www.rustoleum.com/product-catal ... yd-enamel/

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Re: Jynn: a 7 1/4" gauge wren

Post by tom_tom_go » Sat Jul 04, 2020 3:40 pm

Thanks for all the info.

What about paint brushes, do you buy anything specialist or just use once and throw away?

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Re: Jynn: a 7 1/4" gauge wren

Post by Nomis » Sat Jul 04, 2020 5:03 pm

Sorry, i should have been more clear.

I have been using their "combi colour" brand for the most part:

https://www.ebay.co.uk/itm/313062262218

(Check out the range of colours!)

I have also used their "painters touch" range for the smaller quantities of common colours (the red & black parts mostly).

The "painters touch" is available in both brush and spray cans - i have had no issues of reactions between the types.

No special brushes used, I just buy a decent named brand for the more visible parts to avoid lost bristles.

Thinning with relatively small amounts of white spirit makes a big difference to how it goes on, and reduces drying time. I generally work by pouring a rough quantity of paint into a disposable plastic cup, then adding small amounts of spirit (and mixing) until it is about the consistency of full fat milk.

The red parts took about 4 coats to get a density of colour I was happy with, but that would probably depend on the colour you are using (i think red is notoriously "thin" on pigment).

If you have large flat areas to cover, I would highly recommend using a small (4") foam roller to apply - much quicker & easier.

That is how I painted the van, and my O&K diesel:

Image20190317_120037 by simon mace, on Flickr

(This picture was taken a few years after painting & after some pretty rough use)

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Re: Jynn: a 7 1/4" gauge wren

Post by bambuko » Sat Jul 04, 2020 5:32 pm

Thank you for the clarification Nomis :thumbright:
looks like I wasn't far wrong when suggesting you might have used 7400 :thumbup:
...CombiColor Metal 7300/7400 coating is primer and topcoat in one, based on a urethane modified alkyd...
Good range of colours indeed!
BTW I have just discovered that they also do heat resistant (600 deg C) coating - that must be useful for the steam locos... :mrgreen:
(it is called Hard HaT 1078 for black and 1015 for aluminium colour).

The only question in my mind is - how appropriate is this paint for our smaller models?
It sure is OK for your big gauge stuff, but how will it perform on 16mm stuff??
I guess it would be a case of thinning it sufficiently?

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Re: Jynn: a 7 1/4" gauge wren

Post by Nomis » Sat Jul 04, 2020 5:54 pm

Don't know really - but I cant see a reason it wouldn't work.

Having to buy a large quantity might be the problem. Although a single 2.5L tin would do a whole fleet of 16mm locos....

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Re: Jynn: a 7 1/4" gauge wren

Post by Nomis » Sat Jul 04, 2020 6:08 pm

The next parts to come home for painting were the smokebox & chimney assembly:

Image20180330_165801 by simon mace, on Flickr

As these would be subjected to pretty high temperatures I used a spray on barbeque paint. This has a pleasing semi -matt finish, but is quite easily damaged until it has been heat cured.

This was a problem as I knew it would be a long time yet until the first steaming, and uncured paint would be very likley to get damaged during the construction process....

So I improvised with a gas camping cooker:

Image20180328_195253 by simon mace, on Flickr

The whole assembly got "cooked" on all sides over a couple of evenings.

BTW, the bare metal smokebox fittings are all stainless steel so should stay looking good.

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