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DLT's SR Locos - Another Z-Class, DMR Kit


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On 20/05/2020 at 23:11, Portchullin Tatty said:

Interesting you say blackening and then painting - do you chemically black the whole thing and then paint it?

 

19 hours ago, Jack P said:

 

Having started re-reading this thread from the beginning (for the umpteenth time!), It seems that Dave will chemically blacken everything possible and then paint over, the reason for this, is in case the paintwork takes a knock or a scratch, you don't get bright metal shining through.

 

I wonder if blackening helps with adhesion? 

 

Yes, that just about covers it.  Additionally, all bare metal areas (motion, wheels etc) are all blackened and not painted.  Sometimes I don't even paint the chassis.

Cheers, Dave.

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On 22/05/2020 at 10:03, tender said:

I've never had much success with blackening, can you give us some tips as to how you go about it.

Ray.

 

Righto Ray.

Like other techniques, its vital that the metal is clean.  If its greasy it won't work, also if its a fresh sheet of brass so shiny you see your face in it it won't work.   In either case the solution will "bead" on the surface and not fully wet it.  I rub surfaces with a fine abrasive Garryflex block (the finest you can find) to achieve this. Make sure you get into the flange root, and don't forget the front face as well. 

How you then apply the solution depends on the object, in this case a Markits driving wheel.  I use a large brush-full working it quickly to cover the whole surface.  After a few seconds, wipe it off with tissue and Hey-Presto!  If there's a bit that didn't blacken I abrade it again and apply again.

As an alternative to the brush, you can pour a little in to a small container and submerge the whole wheel in it.  You can then rinse it in water, which stops the reaction and washes it off.

 

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For rods the method is the same but the execution different.  I abrade them with a fibreglass brush and/or a wire brush, in order to get right down into the recesses.  Then rather than trying to brush the solution on, I suspend them in the bottle from a length of brass wire.  )Bend the ends over so that it can't fall in!)  Or immerse them in a small container.  Then again, dunk it in water to rinse or wipe with a tissue.  Or both.

The metal only needs to be in the solution for a few seconds, but like any technique, practice makes perfect.

 

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For larger parts, like whole locomotives, we need to go a bit bigger!  The component sub-assembly parts of the loco body are shown:  front bogie, footplate & cab, cylinder block, boiler, chassis, and motion-plate.  Method to follow.

Hope this helps, Dave.

 

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Posted (edited)

Fantastic blow by blow Dave.

 

I don't think it can be understated just how much the blackening of motion/wheels makes a difference.

 

While you're taking requests (!!) I'd love to know how you solder so neatly! Edit: or how/what you use to clean up.

Edited by Jack P
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Also shows the confidence of the builder with no plug in the sink ! 

Nicely done Dave.

 

G

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I've never done a full loco body, but use the technique a lot on small parts, which can allow you to get away without a primer painting coat if they just need a touch of black to finish. Blackening brass wire is especially useful prior to use in making handrails etc.

 

Dave's insistance on cleanliness in preparation is spot on in my experience, the fluid simply won't take if there is any residual muck or grease.

 

Worth also mentioning that "blackening" isn't quite the outcome, you don't get a deep black sheen, but rather a dullish dark grey brownish cover - as Dave's photos of the body show.

 

Very tempted having seen this excellent outcome to try a "full monty" on my next kit!

 

John.

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Posted (edited)
1 hour ago, tender said:

Many thanks for the 'step by step' Dave. I'll have to give it another try.

Ray.

 

Keep at it Ray, its worth persevering.  It may seem a bit of a long-winded process, but its well worth doing.

 

1 hour ago, John Tomlinson said:

I've never done a full loco body, but use the technique a lot on small parts, which can allow you to get away without a primer painting coat if they just need a touch of black to finish. Blackening brass wire is especially useful prior to use in making handrails etc.

Dave's insistance on cleanliness in preparation is spot on in my experience, the fluid simply won't take if there is any residual muck or grease.

Worth also mentioning that "blackening" isn't quite the outcome, you don't get a deep black sheen, but rather a dullish dark grey brownish cover - as Dave's photos of the body show.

Very tempted having seen this excellent outcome to try a "full monty" on my next kit!

John.

 

I blackened handrails and other small parts etc, before I tried it on a whole loco body.  You're right about the colour, its great on wheels, motion etc, as the finish has the look of dull or oily steel.  Additionally if there are parts in materials that don't blacken, a coat of Humbrol Metalcote Gunmetal paint is a really good match.

 

If you are REALLY clever (which I'm not) you can control the depth of the blacking by reducing the time in the solution.  Martyn Welch once showed me a highly detailed 0-Gauge boiler backhead in all sorts of varying shades, that he had done with careful blackening.

Edited by DLT
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Dave,

 

Whilst looking through the garage last week I came across some of Carrs Metal Black for Nickel Silver. Prior to using this I have tended to use Gun Blue but as I had a spare Slaters O Gauge wheel the thought occurred about trying the Carrs product on them as a test piece.

The steel rims were given a good clean prior to administering the N/S liquid and I was pleasantly surprised at the result, being somewhat better than the Gun Blue.

I'm certainly not into alchemy but after treating and giving it an extremely light oiling then buffing up I am really pleased with the results. No ill effects to date and when tested with my meter no loss of current.

 

G

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6 minutes ago, bgman said:

Dave,

 

Whilst looking through the garage last week I came across some of Carrs Metal Black for Nickel Silver. Prior to using this I have tended to use Gun Blue but as I had a spare Slaters O Gauge wheel the thought occurred about trying the Carrs product on them as a test piece.

The steel rims were given a good clean prior to administering the N/S liquid and I was pleasantly surprised at the result, being somewhat better than the Gun Blue.

I'm certainly not into alchemy but after treating and giving it an extremely light oiling then buffing up I am really pleased with the results. No ill effects to date and when tested with my meter no loss of current.

 

G

The issue of conductivity on whel tyres is someting that has always bothered me.

 

When Heljan started their 4mm diesel range the wheels were subject to some form of blackening which looked fine and realistic. Unfortunately it appeared to carry on reacting so that if you didn't use the loco for a while and then tried it, it wouldn't go without a lot of wheel cleaning!

 

Interesting to read of your experience with Slaters wheels as I've been doing some modelling in 7mm. I used blackening fluid on some driving wheels as otherwise they seem prone to corrosion, having read somewhere that it shouldn't affect conductivity, and your experience is further proof.

 

John.

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These questions come up regularly!  The blacking process changes the colour of the surface of the metal, and doesn't affect conductivity.  It can leave a powdery deposit that you need to clean off.

You still have to keep the wheels clean though, and after time and regular cleaning you may need to re-blacken.

 

As for the type of blackening solution, I'm reliably told that Carrs is actually Birchwood Casey in a different bottle.  Also, I've only got the Brass solution, but it works just as well on nickel-silver and steel.

 

Cheers, Dave.

 

PS  I've edited another photo into the procedure above.

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16 minutes ago, DLT said:

These questions come up regularly!  The blacking process changes the colour of the surface of the metal, and doesn't affect conductivity.  It can leave a powdery deposit that you need to clean off.

You still have to keep the wheels clean though, and after time and regular cleaning you may need to re-blacken.

 

As for the type of blackening solution, I'm reliably told that Carrs is actually Birchwood Casey in a different bottle.  Also, I've only got the Brass solution, but it works just as well on nickel-silver and steel.

 

Cheers, Dave.

 

PS  I've edited another photo into the procedure above.

Many thanks for your very illuminating and helpful posts.

 

I've only ever used the Birchwood Casey products, so interesting to read your last comment!

 

John.

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4 hours ago, mike morley said:

If all the process does is change the colour of the surface then, presumably, it can still be soldered?

No, not at all - or at least not in my experience. I tried blackening a few years ago after reading Dave's thread, but what I didn't like about it was that it resists solder (that's why it's useful as a coating for parts that you don't want to gum up with solder - one side of valve gear components, for example). This means that if you'e making ropy 90s kits as I often am - and by the looks of it, Dave is too - and the primer reveals a problem, it's a major PITA to un-solder or re-solder anything; the blackening solution makes a horrible mess when heated. I suppose a counter argument is that it's just as hard to un-solder or de-solder things once they've been etching primed, which is true, but there was just something really nasty about the goo that resulted from heated blackening solution. I've never gone back to it.

 

Apart from that issue, I found that it simply wasn't effective: edges treated with blackening solution were just as likely to scuff as those without - though admittedly I could have been doing something wrong. But then on the other hand, I don't know of a professional painter that recommends blackening as part of the preparation of a model for painting. Are there any? 

 

One last thing: if no blackening is happening, don't be tempted to leave things in for longer and longer - I had a cab roof end up with rivulets etched into it... 

 

 

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On 16/04/2019 at 01:40, DLT said:

Two bridging wires fitteds, linking the two pickup plates together.  One is visible in this picture, also the plasticard washers under the fixing screw and nut.

 

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To hold the motor in position I've added another small frome spacer, on which is pressed a small blob of Blue-Tack that holds the motor down comfortably.

 

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Cheers, Dave.

 

Hi, 

 

Which High Level Gearbox was used with the Mashima motor?
 

Thank you

 

Cheers and Stay Safe

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21 minutes ago, Jack Benson said:

Hi, 

Which High Level Gearbox was used with the Mashima motor?

Thank you

Cheers and Stay Safe

 

Hi Jack,

I didnt built the loco, but I'm pretty sure its one of the RoadRunners.  Jack.P built the kit; https://www.rmweb.co.uk/community/index.php?/topic/120327-southern-railway-modelling-southern-steam-on-shed/

My job was pickups, cylinders and valvegear.

Cheers, Dave.

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Yep - I'm pretty sure from memory it was a Roadrunner +

 

Dave did an absolutely amazing job (thanks again Dave!) - the loco really needs to be finished, it's been in construction for over 2 years!!

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Hi Dave,

I find this is all very interesting, your quite the expert. I've not tried blackening but I think I'll give it a try. Tell me, what do you use in the ultrasonic cleaner? Is it a regular household cleaner in water?

Phil.

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Hi Phil,

I just use warm water, I know there are various solutions on the market, but I've not tried them.  I suppose it depends whether you are trying to de-grease at the same time.

Cheers, Dave.

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