First go at Loco Design..

[Caley Jim]

I wonder what 'elf and softy would say about that shaft spinning around between the driver and fireman?    

 

Jim

[Graham Hughes]

It makes you wonder why S W Johnson designed them with the drive shaft up there.

 

[garygfletcher]

I got somewhat bored last night and decided to have a go at checking the scale by 3d printing the boiler and cab to check scale on a low resolution FDM printer - note this is not a method I plan to use in the construction.

 

It came out surprisingly well. Today I am putting together a shopping list of wheels and gears and later I will finish the chassis.

 

[garygfletcher]

I thought I'd post a bit of an update. I had an awesome time last week at the Midland Study Centre copying the original spinner plans and having a look over an number of the amazing historical documents they have there.

 

I've now decided to CNC some parts out to try soldering and assembly. I may still send these off for etching but am frankly amazed with the quality that came direct from the machine.

 

It's certainly an amazing prototyping tool.

 

I also had a go at turning the chimney on the lathe and am quite happy with the first attempt.

 

Appreciate any feedback or soldering tips - I do a lot of electronics, but now this is in my hand looks immensely challenging - I may add some groves and tabs in the next version.

[Donw]

That looks very good to me.  I think the only advantage of etching would be the ability to add surface detail. but that can produce rather flimsy parts.

 

Don

[CF MRC]

You will certainly save some broken piercing saw blades with the CNC set up Gary.

 

Don't forget that the chimney has to accommodate the curve of the smoke box at its base and will flow into this over a bigger diameter than indicated from your drawing. I only use drawings to give the overall dimensions for boiler fittings. After that, it comes down to interpreting the prototype with a British standard eyeball, using photographs. As an example, the lip on Edwardian chimneys is often slightly re-curved under the rim to make it a bit finer than is obvious from drawings. I normally turn boiler fittings using a hand held graver, similar to wood turning. The tricky bit is to then make the flare very thin so that it emerges almost imperceptibly from the boiler/smoke box.

 

Soldering in scratchbuilding is very different to electrical soldering. It is really tin smithing. I am a great believer in using liquid acid flux. Much of the challenge is in how you hold the components when soldering.

 

You are not that far from me, I would be happy to show you some techniques.

 

Tim

[garygfletcher]

Thanks Don and Tim

 

I'll reply more tomorrow with some particular issues I'm having with the dome and wheels (basically I am struggling to find a file thin enough for tooling), but just thought I'd post my first attempt at turning the tyres for the drive wheel.

 

I went through a few methods this was certainly the nicest seat on the track but a bit of a way to go to meet the handbook standard. I also found the EN01 mild steel a little too soft to finish nicely. It also didn't seem to match the association wheels?

[Graham Hughes]

You will certainly save some broken piercing saw blades with the CNC set up Gary.

 

 

But what of the simple pleasures of sitting down at the bench and spending a morning or an afternoon with the piercing saw and some sheets of metal? I think that is my favourite bit of building models.

 

Interesting comments about the flare on the chimney. How do you form these? I have always shaped the base of the chimney to fit the smokebox and then filed it down at the sides to the correct(ish) profile. From your comments I get the impression you do it a different way?

[John lewsey]

Wow very impressed

[CF MRC]

Interesting comments about the flare on the chimney. How do you form these? I have always shaped the base of the chimney to fit the smokebox and then filed it down at the sides to the correct(ish) profile. From your comments I get the impression you do it a different way?

Graham

I turn a deep base that is the diameter of the front to back dimension. This is milled out to the diameter of the smoke box and then the sides of the flare are ground away using burs, stones and abrasive rubber points. Probably much the same as yourself, but I do thin out the base from the underside a bit to make it easier to settle it into the smokebox. I've never been a fan of the thin it down and swage it over the smokebox technique.

 

Tim

[2mmMark]

Graham

I turn a deep base that is the diameter of the front to back dimension. This is milled out to the diameter of the smoke box and then the sides of the flare are ground away using burs, stones and abrasive rubber points. Probably much the same as yourself, but I do thin out the base from the underside a bit to make it easier to settle it into the smokebox. I've never been a fan of the thin it down and swage it over the smokebox technique.

 

Tim

 

Not sure I've ever had a smokebox strong enough for that...!

 

Oh, you're supposed to use a bit of solid rod instead?

 

Impressed wth your progress Gary.  The CNC machine looks fascinating.

 

Mark

[Graham Hughes]

Graham diameter 

I turn a deep base that is the diameter of the front to back dimension. This is milled out to the diameter of the smoke box and then the sides of the flare are ground away using burs, stones and abrasive rubber points. Probably much the same as yourself, but I do thin out the base from the underside a bit to make it easier to settle it into the smokebox. I've never been a fan of the thin it down and swage it over the smokebox technique.

 

Tim

That sounds just the same as the way I do them, even including hollowing out the base very slightly, except I never got on with the burrs, stones and other stuff and just use a round needle file. 

[CF MRC]

There might be.a reason why I get on with the 'burrs, stones and other stuff'....

 

Tim

[JohnBS]

There might be.a reason why I get on with the 'burrs, stones and other stuff'....

Tim

Tim,

Do you inject the smokebox with novocaine?

John

[CF MRC]

Tim,

Do you inject the smokebox with novocaine?

John

No John, but the (unused) needles make jolly good handrails.

 

Tim

[Caley Jim]

No John, but the (unused) needles make jolly good handrails.

 

Tim

Memo to self:  don't touch any of Tim's loco's handrails - there's no saying what you might catch!

 

Jim (who also gets on well with burs, stones etc. for some reason!)

[garygfletcher]

You are not that far from me, I would be happy to show you some techniques.

 

Hi Tim

 

I am actually surprised how effective the CNC has been and how accurate it mills these very small parts, it would certainly help make a few Spinners to eventually run up and down St Pancras!

 

My mill was out of service so I was unable to make a curve for the smoke box, but this gave me an opportunity to try using some hand tools as you described to me and I was quite happy with the first result. 

 

This week progress has been slow, but hopefully I can pick up a bit over the bank holiday weekend.

 

I must admit I was fairly confident in my attempt at soldering the cab but failed miserably. I cut some edges into some balsa wood to hold it square and the flux and temperature and tip must have been a million miles out because it looked a horrid mess after.

 

I would therefore really appreciate it if we could meet up for some tips, as I say I am no stranger to electronic soldering at a finite level so I am sure I will pick it up quickly, but as usual knowing a valid technique and being shown the ropes is key here I think.

 

Thanks

 

Gary

[justin1985]

Hi Gary,

 

I'd really start by soldering a few wagon kits together to get the hang of soldering the kinds of joins you'll need. I'm sure one of us will be happy to bring some kits and tools along to the MRC and go through it together as you say. I only really "got it" myself by spending a day a good few years ago with David Eveleigh, Nigel Cliffe and some other members of the Darkest Essex group - a picture might tell a thousand words, but watching someone's technique for real is invaluable. I'm not free Sunday but could do next Thursday, if no one else is free sooner.

 

Otherwise, there was a "group build" thread on here a year or two ago on building the entirely etched Stephen Harris BR mineral wagon, which went through all the stages and techniques in considerable detail, which might help.

 

Justin

 

EDIT - The thread I had in mind http://www.rmweb.co.uk/community/index.php?/topic/46368-2fs-etched-16t-mineral-group-build/

[2mmMark]

Hi Tim

 

I am actually surprised how effective the CNC has been and how accurate it mills these very small parts, it would certainly help make a few Spinners to eventually run up and down St Pancras!

 

My mill was out of service so I was unable to make a curve for the smoke box, but this gave me an opportunity to try using some hand tools as you described to me and I was quite happy with the first result. 

 

This week progress has been slow, but hopefully I can pick up a bit over the bank holiday weekend.

 

I must admit I was fairly confident in my attempt at soldering the cab but failed miserably. I cut some edges into some balsa wood to hold it square and the flux and temperature and tip must have been a million miles out because it looked a horrid mess after.

 

I would therefore really appreciate it if we could meet up for some tips, as I say I am no stranger to electronic soldering at a finite level so I am sure I will pick it up quickly, but as usual knowing a valid technique and being shown the ropes is key here I think.

 

Thanks

 

Gary

 

My main setup for soldering is a temperature controlled iron, such as ebay item 351299946763 fitted with a small chisel tip (mine came from Maplin), thin gauge 188 resin cored tin/lead  60/40 solder about 0.5mm dia and dilute phosporic acid flux.  This seems to get most things done acceptably.  The particular soldering station I use has a knob to control temperature and it's easy to tweak up and down.  For most jobs, I have the temperature set between 240 to 270 degrees centigrade. Go hotter and the tip seems to get dirtier through corrosion.  I don't use a wet soldering sponge as a tip cleaner, instead I use what looks like a brass pan scourer in a small tin (like ebay item 121064358019).

 

I do have 145 degree solder, solder paint and paste flux but I find fewer uses for those but they do come in handy from time to time.

 

Always use lead based solders, these flow very nicely at lower temps than lead free. I briefly tried lead free solder to see if I could manage with it. It was OK but not as easy to use as 60/40 tin-lead solders.

 

I was taught to solder properly by one of the technicians where I worked back in the late 1970s/early 80s when I was building a Heathkit strobe gun in my tea & lunch breaks in their workshop.  I was then able to translate electronic soldering to 2mm work.

 

In fact I still do soldered trackwork as if it were PCB assembly (which really it is) just using clean rail, clean sleepers and resin cored solder, most of the time without additional flux, as this aids formation of a better chair-shaped blob.

 

Flux is essential for soldering up etchings and loco platework as you want the solder to flow down the seam nicely.

 

You may find some blocks of Tufnol better than balsa wood.

 

Nickel-silver is nicer to solder than brass as the heat transference isn't so quick but brass is easier to form and roll. It's easier to learn soldering using a nickel-silver kit, so Justin's recommendation to try some 2mm wagon bits is a good one.

 

For a novice solderer, brass can be tricky as fast heat transfer means bits come unsoldered which your soldering more bits on. This is where you need to learn to be quick with the iron and ignore the pain in your fingertips!

 

Mark

[Graham Hughes]

If you are used to soldering electronics I am guessing you are using the same solder for modelling. Electrical solder is very good for making nice neat blobs on circuit boards but for building models in 2mm you ideally want something that has better wetting properties and "runs" better. The electrical stuff of similar has its uses if you want to fill gaps such as the corners of tender flares you often find in kits which are made up of little "fingers" that you then fill with solder, but for general work it will leave an untidy joint that needs a lot of cleaning up. My preferred choice is generally Carr's 188 degree. Mostly I use the paste.

 

Iron is an Antex TC50 bought for the 50watts of power not the temperature control. It hasn't been turned down from the full power since I bought it getting on for thirty years ago. The bit is a 5mm one and the only time I use a different one is if the 5mm one is physically too big to get into where it is needed. The aim is to get the parts set up so they can't move, with the solder paste in the joint and then a quick application of the hot iron to make the joint before the heat starts to dissipate into the rest of the model and causes bits to fall off elsewhere. For cleaning the tip I use the little tins of tip cleaner and tinner and then a quick wipe on the sponge in the stand to get off any excess. 

I endorse Mark's comments above about nickel silver being preferable to brass and on lead free solder. Maybe it needs different techniques or something to get the best out of it but I found it terrible to use.

One other thing I would stress is when a joint doesn't go right don't keep trying to adjust it with the iron. That is when heat builds up in the model and other joints come apart. If it doesn't go right first time separate the parts, get everything cleaned up and cold and then try again. 

[Caley Jim]

One other thing I would stress is when a joint doesn't go right don't keep trying to adjust it with the iron. That is when heat builds up in the model and other joints come apart. If it doesn't go right first time separate the parts, get everything cleaned up and cold and then try again. 

I would endorse that, as well as Mark's comments on N/S and lead free solder.  It is also a good idea to just make tack joints when making longish joints, such as joining van/carriage sides and ends.  Just make a tack joint with the minimum of solder at the top corner, then ensure that everything is properly aligned before sealing the whole joint.  If the parts are not in their proper relationship, you only have the 'tack' to un-solder and then start again.  Likewise soldering roofs to vans or coaches, tack the middle at one end, then check that the overhangs are even before proceeding.

[garygfletcher]

Little bit of experimenting again tonight, checking position of the chasis and wheel alignments as well as guaging how suitable the laser cutter is in this role (it's worth noting I am trying to use easily repeatable techniques to make a few of these Spinners). This was 8mm acrylic, I think I'll work on refining this technique with 5mm acrylic and then cnc the outside edge with the 2mm association phosphor bronze strip and bushes.

 

I have a rough design for the bogie I may put into practice tomorrow too as well as a first look at gears and driving.

[Valentin]

[...] and then cnc the outside edge with the 2mm association phosphor bronze strip and bushes.[...]

 

You don't need bushes if you use the 0.5 mm P/B strips as chassis frames.

[Chris Higgs]

Little bit of experimenting again tonight, checking position of the chasis and wheel alignments as well as guaging how suitable the laser cutter is in this role (it's worth noting I am trying to use easily repeatable techniques to make a few of these Spinners). This was 8mm acrylic, I think I'll work on refining this technique with 5mm acrylic and then cnc the outside edge with the 2mm association phosphor bronze strip and bushes.

 

I have a rough design for the bogie I may put into practice tomorrow too as well as a first look at gears and driving.

 

It looks really great, but ... do you intend this to be way you do it for the real loco. It's just, at least on the loco, the acrylic is filling valuable space both in the loco and that should contain something heavier, to add weight for adhesion. And for a Spinner, you are going to need that adhesion.

 

Chris

[Hawk]

You will certainly save some broken piercing saw blades with the CNC set up Gary.

Well, I would guess that the number of broken/dulled milling bits at least cancel outs the savings.

 

Would love to hear more on your experiences with CNC milling, Gary. Feeds & speeds and cutter types are something I am struggeling quite a bit with...