7mm Mickoo's Commercial Workbench

Michael Hall

Western Thunderer
Finally! Inside motion all fitted to the 4F.

It needs a lot of running in and there is a little tight spot that needs chasing down, plus the right hand valve rod has a little kick as the pin in the expansion link is a little loose....read cast expansion link slot too large, a poke with some suitable implements will solve that.

It's a real mish mash of parts, none (other than the new motion etched bits) is designed for this engine, it'd make any East end chop shop boys proud :p

I do need to rejig the cylinder block, no matter how it was cut and shut the narrow frames really hampered the internals, along with castings just too fat to fit in there, consequently the valve linkages and alignment is slightly out, each needs moving onward by 0.75 mm to line up with the motion.

I had to loose the inner lifting links, there just isn't room in there and the expansion link is the wrong type for this engine with only one link pivot point, there should be two, one each side.

Apologies for the shaky video, it actually runs better on the track, something I find with most engines actually.

New motion bracket and valve linkages.

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All fitted up.

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It's quite simply modelling of the highest order. awesome.
 

mickoo

Western Thunderer
Very neat Mick.
Is the slidebar assembly removable? I normally make the valve gear so that it can be split at the expansion links. The J6 is very similar, except that the the rocker arms are split across a shaft because the valves are wider apart. I've not worked out a way of splitting it, so I'm making it so that it will come apart... It's all very tight and I'll have to scratch up some of it I think.

Cheers
Tony
Tony, it is at the moment, mainly so I can slide it back to release the cylinder block for upgrading.

Once that's done it'll all get fitted permanently, I don't really want to and the painter will curse me but re-assembly will be impossible once painted without causing extensive damage.

That's the problem making part A match part B, then add part C to which the sum has to be fitted to part D which is no where near suitable, in short if another crosses this desk I'm just going to junk the whole chassis and etch up a new one with associated valve gear.

The LG valve gear is designed for engines with under slung slide valves with very close centres, the crank is designed scale width so they all have to be skimmed down, the rest of the linkages are not class specific. You have to trim them all to fit your designated pivot centres, the connecting rods are fine as you just shorten the small end and drill a hole for the pin, the eccentric rods are a lapped joint and I've no idea what this material is but it does not solder well.

A future engine would take bits and pieces from here and there, I'd keep the cast connecting rods and crossheads, replace the piston rod with nickel silver rod; the cranks I'd commission to have milled and make up myself. The slidebar assembly is salvageable but needs a lot of work to clean up and make square. The cast eccentrics I'd bin, they're just not round and use Finney7 turned ones. Eccentric rods would be new laminate etch ones, same for the expansion link.

It's a lot of work but you have a green field site and it'd be significantly faster, the engine and tender took just over five weeks to build. The inside motion hacking and rebuild has taken just over three weeks so far. By comparison, the 47xx inside motion (yes it's simpler and only for the valves) took two days to fabricate, paint and fit.
 

cmax

Western Thunderer
Mick,

As usual, fantastic modelling, always interesting to hear how you navigate round the various problems that crop up, nice touch with the video.

Gary
 

mickoo

Western Thunderer
A possible alternative starting point? 'Mini' kits & parts packs with the option for building it with the frames in the right place. :rolleyes:
Cheers, that is a very good alternative.

But, me being me would have to change the cylinder block, ashpan and stay, I can't see any expansion links so it looks like it would need modifying for inside motion, which means the motion bracket may also need adapting.

The crux is that you really need everything or nothing, trying to mix and match different products is (as I am fully conversant with) rather difficult.

I now need to turn to the backhead, the actual backhead is no problem, a 3D print will fill that need, it's all the fittings that are the issue.

The kit has none to speak of, most/all being cast integral into the kits white metal lump. Thus I need to trawl the 3rd party sites, LG does several LMS/MR packs but like the inside motion pack, only suitable for earlier engines, those with only one sight glass and injector feed valve; in short you need to buy two packs and throw away a large amount of surplus items, especially as the other items do not appear to fit the 4F.
 

dibateg

Western Thunderer
As you have the skills to design an etch for inside motion that would be the way to go, as you say, it's probably quicker in the long run than trying to adapt cast parts , that are designed for something else and spending time scratching your head, trying to work out how it could fit.. An etch would certainly be crisper than some of these castings, which are a little 'rounded'.

Cheers
Tony
 

mickoo

Western Thunderer
Thanks for all the feedback, greatly appreciated.

The last component for the Connoisseur 4F is the backhead, the kit is supplied with a one piece all in inclusive white metal jobbie, I'd post a picture but can't seem to find it anymore. As one of my kids used to say "it's mysterpiered".

I wanted something with a little more relief and accuracy so whizzed up a new 3D base. The brass components are in the post and some of the fixing holes might need tweaking.

This is only a test to see if it fits trial, there's a few more lumps and bumps I want to add and tweak some other aspects before I'm totally happy. The etched bits are just temporarily stuffed in the holes for the photos.

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mickoo

Western Thunderer
Time to head back to the Garrett for a few days before starting a new project next week.

It's a slow burner as it requires quite a few tweaks, in this case the cab. The kit cab is clearly hand drawn, good for it's day, but I didn't find two windows that matched in size or position, plus the rivet positions were all wrong and simply representational.

The upshot was new cab side etches, doors and new roof. The dome is a first pass print and needs a tweak to get it to sit perfectly on the boiler and the smokebox door will be fully secured shortly.

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mickoo

Western Thunderer
Small update on the Garrett.

The kit engine bed pipework is frugal and incorrect in some aspects.

As supplied there is a common smokebox manifold for both the rear engine live steam and Vacuum exhaust ejector pipework, they should be separated.

In addition I needed to find a way of fixing the smokebox to the bed plate somehow, the kit only supplies the sides for the smokebox saddle so new front and rears were fitted. I could have then placed a floor each side with a nut on the upper side, to which screws on the underside would secure too.....but I had other plans below.

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The manifold is supposed to be fixed directly to the base of the smokebox, if you do that then you cannot make it irremovable for paint, I will need to do that, as well as for other work.

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The result was a new plate fixed to the engine bed, this covered the ugly holes in the smokebox wrapper and allows the manifold to fixed to the engine bed.

The front end fixing was simply a small piece of wire that pokes into the smokebox front, you can just see it near the new platework, the rear end is secured by the cab with four corner screws.

The external exhaust pipework from the rear engine is incorrect, it's split in the wrong place for the ejector/injector, can never get them the right way around.....it should be where the tooth pick is. There are other issues with the elbows and there's no support bracket.

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Moving on to the beginnings of the revised manifold, a new 3D print replicates the area better, I've worked up a best guess spin off look alike from the SAR GF class which is very close in many aspects. It's probably not authentic but what I had before was so dire, any upgrade here is beneficial.

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The new manifold needs three ports, ejector, front and rear engine exhausts, the big hole in the bottom is for the front engine exhaust (a print of that fitting is in progress) and the ejector is plumbed in; the angled port is for the rear engine. The pipe will run to the side frame, pass through and then run down the outside of the frame to the rear of the cab before cutting back in.

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I've just posed the bearing pedestal casting, it needs a little notch cut and cover to hide the pin holding the front end of the smokebox in. It's not a good print, a basic size and form fit before the final renders are fitted.

The rear engine live steam pipe is now diverted to one side and into a new elbow (recovered from the now redundant side pipe), the black dot is where the live steam fitting for the front engine will eventually be secured.

Whats throwing me at the moment is the surplus of exhaust steam pipes, I have two going to the rear ? I know the side pipe is the main exhaust pipe as all of that layout matches the GF almost part for part, what's throwing me is where on earth is the lower one that runs through the ash pan from the ejector pipework going.

The exhaust ejector pipe comes from the centre of the manifold to the transverse barrel and then kicks out and around the ashpan to the ejector, but why the extra pipe going rearward ?
 

Dave Holt

Western Thunderer
Mick,
Presumably, there is a live steam feed to, and an exhaust steam from, both power units and the exhaust steam supply pipe from the blast pipe to the exhaust steam injector (not ejector). So, five pipes in all?
Lovely modelling, as always. The 3D printed detailing parts look superb.
Dave.
 

mickoo

Western Thunderer
The pipework, I've annotated the relevant pipes, the one in question is the one running rearward from the transverse barrel near the brake brackets.

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The green pipe is not fitted yet but is the main exhaust from the rear engine, it also has part of the injector fitted to it as does the lower white metal pipe already fitted.

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In the cold light of dawn, it could be that the side pipe is not the exhaust from the rear engine, it may well be the water balance pipe between the two engine tanks, in which case I'll have to revise the smokebox manifold and remove the 45° pipe fitting.
 
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mickoo

Western Thunderer
Last update on the Garratt for a while, not quite as far as I wanted in the last three days but far enough to see a way forward with other parts required, which I will pick off as and when.

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The smokebox manifold has been corrected to only have the two exhaust pipes, the third (alongside the outside of the frames) is not exhaust from the rear engine as I originally thought, it's the water balancing pipe and will need plumbing accordingly.

The front engine pipes are just placed in there, the live steam covers the pivot point, in reality this will cut back to the spherical coupling and appear to dive into the engine bearing casting that will hide the pivot screw.

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The front exhaust pipe is a conundrum, I think it passes below the rear driver axle so cannot be fixed to the boiler bed plate, unless I can slide the front engine in and down onto the pivot. I'll probably have to come back to this once the front engine is near complete and work up a model spherical bearing to allow the pipe to flex between the two.

The alternative is that it passes above the axle just below the live steam pipe and likewise enters the engine bearing casting in a spherical bearing.

The water balance pipe is fitted to the outside of the bed plate with the pick up fitting for the vacuum injector, that'll come later and fit to the lower white metal pipe. The pipe bracket isn't secured to the frame yet and I need to blend in the joint on the pipe just ahead of it....or get a bigger printer.

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I may also replace the white metal elbow for the rear engine live steam, it's kind of looking a bit out of place with the other 3D parts. I also need to add all the clamps to the brass tubes, the printed parts have them included.
 

mickoo

Western Thunderer
New project underway this week, I was struggling to visualize the brake rigging and realised others probably would too during construction, out with the crayons and a few scribbles later I've worked up some CAD renders.

To these I can now add the part numbers to help (hopefully) assemble it all, lots of fiddly bits, not for the faint hearted :cool:

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