Kerr Stuart diesel

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Old Man Aaron
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Re: Kerr Stuart diesel

Post by Old Man Aaron » Sat Jun 25, 2022 5:33 am

Very interesting! I hear that clear plastic can be hard to cut, looking forward to seeing how you get on. :study:
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Re: Kerr Stuart diesel

Post by ge_rik » Sat Jun 25, 2022 9:34 am

Glad you figured out a solution. Looking forward to seeing how it progresses.

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Re: Kerr Stuart diesel

Post by Andrew » Sun Jun 26, 2022 7:12 pm

Old Man Aaron wrote: Sat Jun 25, 2022 5:33 am Very interesting! I hear that clear plastic can be hard to cut, looking forward to seeing how you get on. :study:
Hello!

Yes, that's what I'm finding! As per advice elsewhere, a knife was pretty useless. A razor saw did better, but I found it hard to stop it skittering off the line I'd drawn. I've ended up using a cutting disc in my Dremel, which cuts cleanly but is hard to keep accurate - I'll just be using a lot of filler! I did try to cut the cab down a little to change the cab:bonnet proportions slightly, but I gave up because I didn't feel confident I could end up with a clean edge. The bonnet will have to be cut, of course, but it will be easier to hide any mistakes.

Here's where I got up to this afternoon:

KS 3.jpg
KS 3.jpg (123.72 KiB) Viewed 6332 times

The footplate is cut from 2mm plasticard, and is a fairly snug fit around all the RH gubbins. The side "skirts" are from the kit, shortened to fit by taking a slice out of the middle. The bufferbeams should have been the original acrylic ones, but I drilled the holes for the couplings in the wrong place, so I had to replace them...

Next up will be the cab, pretty much as per the instructions but with the spectacle plate hacked about to fit around the chassis.

Cheers,

Andrew.

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Re: Kerr Stuart diesel

Post by GTB » Mon Jun 27, 2022 1:11 am

Andrew wrote: Sun Jun 26, 2022 7:12 pm As per advice elsewhere, a knife was pretty useless. A razor saw did better, but I found it hard to stop it skittering off the line I'd drawn.
I'd be very wary of using a Dremel on acrylic, there's too high a risk of the plastic melting, shattering the disc and possibly the part.

How were you holding the part to saw it? If the part was flat on the bench and the razor saw was held horizontally, I'd imagine it would skid around. Making up a small bench hook from bits of wood and using that while making the cuts would be better.

I've been trying to remember how I used to cut small perspex parts when building HO passenger cars in the '70s, but it eludes me. Possibly a piercing saw, as I had one by then.

Nowadays I usually rough the sheet down on my little Proxxon bench saw and make the more complex cuts with a piercing saw. However you do it, I think the cut needs to be made with the part held flat and the saw blade vertical. It would also help, if using a razor or piercing saw, to file a little nick in the edge of the part to help keep the blade located as you start the cut.

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Re: Kerr Stuart diesel

Post by ge_rik » Mon Jun 27, 2022 8:24 am

I'll echo Graeme's point about a Dremel disc melting the plastic. On the few occasions when I've tried cutting perspex or acrylic sheet, I found scoring and snapping to work. But, of course, that only works with long edge to edge straight cuts and the scoring needs to be on both sides (easy to see the opposite score with clear sheet). Fiddly little cuts and cut-outs are much more tricky.

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Re: Kerr Stuart diesel

Post by Andrew » Mon Jun 27, 2022 10:22 am

Thanks for the advice chaps. Most of the skills I possess are fairly self-taught, so I appreciate all the help I can get!

The cab's now on too, still some filling and sanding to do though. The Plastic Weld recommended over on Phil's railway thread is great stuff, the whole thing seems really strong and rigid. I ought to have said too that the kit is great, really well designed and all the parts seem to fit together nicely, I'd definitely recommend. It's only because I'm messing around with it (essentially shortening it by around 6cm and modifying to fit a RH chassis) that I'm running into problems!

All the best,

Andrew.

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Re: Kerr Stuart diesel

Post by Phil.P » Mon Jun 27, 2022 10:32 am

Talking of plastic weld / MEK, etc.

How do people apply it? - Does a fine-brush go solid, and useless?

I would like a bottle with a fine, long nozzle, but they are all plastic, and I am pretty sure these solvent adhesives will melt them.. :dontknow:

Phil Partridge.

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Re: Kerr Stuart diesel

Post by Andrew » Mon Jun 27, 2022 10:52 am

Phil.P wrote: Mon Jun 27, 2022 10:32 am Talking of plastic weld / MEK, etc.

How do people apply it? - Does a fine-brush go solid, and useless?

I would like a bottle with a fine, long nozzle, but they are all plastic, and I am pretty sure these solvent adhesives will melt them.. :dontknow:

Phil Partridge.
I have been using a brush, and it has indeed gone solid and useless but it softens again when you dip it back in the Plastic Weld. So it remains good for that, just not for anything else!

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Re: Kerr Stuart diesel

Post by philipy » Mon Jun 27, 2022 11:47 am

Always use a brush. Squirting from a nozzles can't really be controlled and you risk squirting it everywhere and/or applying far to much..
I use a signwriters brush, kept exclusively for this purpose, which has long soft bristles and is what Slaters sell at a vastly inflated price as a Mekpak brush. Mine has bristles about 23mm long and says "Handover Series No.3 Kalinsky Sable" on the side and came from an online art shop called "Jacksons".
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Re: Kerr Stuart diesel

Post by Phil.P » Mon Jun 27, 2022 5:19 pm

Thank you Gentlemen.. Brush it is, the.
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Re: Kerr Stuart diesel

Post by Andrew » Mon Jun 27, 2022 7:29 pm

Good evening!

Here's the cab in place...

KS 4.jpg
KS 4.jpg (103.81 KiB) Viewed 4595 times
KS 5.jpg
KS 5.jpg (96.31 KiB) Viewed 4595 times

The roof trusses are only resting there temporarily for now while I work out what to do inside the cab. The radiator will have to be further back than the original (and central too, rather than offset), so it'll be harder to hide the fact that there's not a great big engine behind it. Or in front of it, I suppose, given that the radiator's at the back. Modelling the louvred shutters in the closed position should help...

Cheers,

Andrew.

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Re: Kerr Stuart diesel

Post by philipy » Mon Jun 27, 2022 7:47 pm

Full marks for effort Andrew and I'm sure the finished item will look superb. Can't help thinking that a blank sheet of styrene, a pencil and a ruler would have been easier though!
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Re: Kerr Stuart diesel

Post by Andrew » Tue Jun 28, 2022 8:41 am

philipy wrote: Mon Jun 27, 2022 7:47 pm Full marks for effort Andrew and I'm sure the finished item will look superb. Can't help thinking that a blank sheet of styrene, a pencil and a ruler would have been easier though!
You might well be right, and that was the original plan. It still is for an parts that I mess up!

What I like about the approach I'm taking is that a lot of the thinking (in terms of design) and much of the work of creating the main parts has already been done. That's speeding the process along (maintaining a momemtum that should actually see the project finished) while also leaving me enough of a challenge (including working with a new material) to make it feel like an achievement.

I think the finished thing will look better too. The parts are much more squarely and cleanly cut than I generally manage, and while I think a bit of wonkiness can add to the charm of a slightly dilapdated carriage or wagon, on a loco it just looks wrong.

Time to tackle the bonnet next, but this week's looking busy, so I'm not sure when that's going to happen. Hopefully I'll have a few hours spare at the weekend...

Cheers,

Andrew.

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Re: Kerr Stuart diesel

Post by Andrew » Sat Jul 02, 2022 5:26 pm

Afternoon!

Just a little more progress to report, with the construction of the bonnet this morning. A sheet of plasticard will actually cover the whole front/top, but I liked it that you could still see inside, so I took the photo before it was finished:

KS 6.jpg
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Once the bonnet's complete I'll attach it to the rest of the body, fill and sand as necessary and then pause for a think. I want to get a coat of primer on so I can see where further work's required, but first I need to consider how the cab detail's going to work...

Still a long way to go, but I like the shape that's emerging...

Cheers,

Andrew.

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Re: Kerr Stuart diesel

Post by Old Man Aaron » Sun Jul 03, 2022 10:40 am

Gorgeous little thing already.
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Re: Kerr Stuart diesel

Post by ge_rik » Sun Jul 03, 2022 7:21 pm

Old Man Aaron wrote: Sun Jul 03, 2022 10:40 am Gorgeous little thing already.
Iconic!

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Re: Kerr Stuart diesel

Post by Phil.P » Mon Jul 04, 2022 1:07 pm

"Iconic" Sounds like a good name, for a distinctive loco..
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Re: Kerr Stuart diesel

Post by Andrew » Mon Jul 04, 2022 1:21 pm

Or "Ironic" if the rest of the build goes badly...

It did last night, when I underestimated the power of my daughter's hairdryer which I was using to bend the front of the bonnet. It buckled horribly, so it's off to the model shop for another sheet of plasticard...

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Re: Kerr Stuart diesel

Post by GTB » Mon Jul 04, 2022 4:27 pm

Andrew wrote: Mon Jun 27, 2022 7:29 pm The radiator will have to be further back than the original (and central too, rather than offset), so it'll be harder to hide the fact that there's not a great big engine behind it. Or in front of it, I suppose, given that the radiator's at the back. Modelling the louvred shutters in the closed position should help...
The attached builders photo is I think the second K-S 60HP diesel, b/no. 4418, which was sold to a railway in the Sudan, hence :shock: the open cab. More importantly, it has an engine cover between the radiator and the front plate of the cab. I've never seen a clear enough photo to tell either way with 4415, but it was a prototype, so may not have had the cover. I don't think this pic was taken in Sudan either......... :roll:

https://topstastic.blogspot.com/2021/07 ... -4415.html

Those perforated metal doors would be interesting to model, not.... :shock: The louvred doors on modern diesels are bad enough.


Welcome to the lottery of heat forming polystyrene sheet. It's a very fine line between softening the stuff enough to form it and releasing the internal stresses so that it shrinks and turns into something resembling a potato chip. Acrylic is much easier to heat form as it turns rubbery, but doesn't shrink appreciably, when heated.

If all else fails, I've been known to 'plank' sharp bends and use filler and sandpaper to form a smooth curve in polystyrene.

Graeme

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Re: Kerr Stuart diesel

Post by Andrew » Tue Jul 05, 2022 9:13 am

That's a great photo of the Sudanese Kerr Stuart, thank you! Very good news about the engine cover - I think 4415 mnay have had some mesh, but this will be lots easier! The bell's a tempting addition too...

I'm very pleased to see one in lined works grey as well. It's a long way off, but if the build goes well I've been thinking that I maygo for that as a livery. The idea of my model is that KS also tried out a prototype of the 30HP loco on the WHR/FR, and that, in my parallel universe, the railway could afford to buy it, unlike 4415. If that had happened, I reckon it would have ended up green, like the Ffestiniog's other "tractors", but it's so much more recognisable in grey. Lined photographic grey would tick that box while being a little different too, fit the "trial" thing, and - hopefully - look nice! I didn't know there was a prototype though, unti I saw your photo!

I'm grateful for your "Plan B" re the bonnet too - I imagine I may well end up needing to use it! It's a shame about my first attempt - it went pretty well apart from a couple of wrinkles at one edge, which I just couldn't get rid of...

All the best,

Andrew.

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