2mmMark

A little white ago, we left the chassis soap opera with this cliff-hanger "Coming in part 3, mounting the motor and meshing the worm & wormwheel". Well, it's here at last!. The chassis block and frames have been trimmed up thus This chassis is a particularly unfancy set of ironmongery, referring back to the prototype photograph in part 1 http://www.rmweb.co.uk/community/index.php?/blog/1345/entry-14132-peckett-y-class-framed-part-1/ Note the lack of anything resembling guard irons. They've either been knocked off or deleted by a cost-conscious accountant. I suspect the latter. Anyway, it's jolly convenient for a lazy person like myself. The ends of the chassis have been given a recess where the buffer beam will sit, in order to avoid a short circuit across the split frames. Next on the agenda is how to power the locomotive. I chose to use the flat sided can motor available from the 2mm Scale Association. This is a compact powerful and smooth-running unit. It has a pair of mounting holes in one end which accept an M1.0 thread (12BA can also be used). Here's the motor and worm. The worm & wormwheel are Association products from several years ago but are none the worse for that. I needed to use the motor in an upright configuration which meant there was not a flat surface allowing the motor to be glued in position. To be perfectly honest, I'm not a fan of glueing motors in place. It's a perfectly sound practice and with the right adhesive, will give no problems. It's just that I prefer a slightly more engineered solution. What was needed was a strong right-angled section to mate up with the chassis block and hold the motor rigidly in place. I chose to use a section of 12mm aluminium angle of the type available from DIY stores. This has the hard work done as a slice of it will give an accurate 90 degree angle. It was drilled and shaped using my Proxxon MF70 mill and finished off with files. A mill isn't necessary, it's just a quick way of achieving the end result. Hopefully the photos will show the small amount of shaping and drilling needed. The base was tapped 12BA for the mounting screw. The large countersink is to accomodate the bearing boss of the motor, so it sits flush against the mount. With the motor attached, it should now be clear it's held in place. The front face of the mount has a small recess to allow the mount to be as close to the wormwheel as possible. To fine-tune the mesh of the worm and wormwheel, the base is carefully sanded on some wet & dry paper glued to MDF. Working slowly using a circular motion, it's possible to reduce the dimension quite precisely. The fixing screw is placed in the chassis then the mounting is screwed in place. It is just a fraction narrower than the central chassis block thus electically isolated from the frames. A single mounting screw has proved quite sufficient to hold the mount in place as there's quite a bit of friction between the mounting and the chassis block. If it becomes necessary, a small shear-pin can be inserted to lock everything in position. The worm is slipped onto the motor shaft and as can be seen, the meshing is just about right. There are a number of ways to get the worm/wormwheel mesh correct. For every combination, there is a specific dimension of axle centres but as these are at right angles, I personally don't find it easy to use. Originally, I started off using either a "Rizla" cigarette paper or a sliver of aluminium kitchen foil to set the meshing clearance. Nowadays, I tend to eyeball it and work by feel, knowing from experience how much backlash there needs to be on the wormwheel. The photo below shows the result Using a steel worm on the motor shaft, there is a way to check the mesh is a happy one. The worm is reamed out so it easily rotates on the motor shaft but has no perceptible clearance. This allows the worm to be spun on the shaft by fingertip to ensure there are no tight spots and it all rotates freely. A fingertip is a surprisingly sensitive measuring device! Once everything is confirmed OK, the worm will be secured with a drop of Loctite. Now we can try the chassis against the body. The unused end of the motor shaft needs some trimming to fit. This is marked with a felt tip permanent marker and will be cut off using a carborundum disc in a mini-drill as the motor shaft is hardened steel. The shaft won't be completely cut back as I want to try mounting a small flywheel, simply to see what effect it might have. This brings the progress on this loco up to date. The next instalment will hopefully cover the fitting of the coupling rods, flywheel and wires to the motor. Oh yes, I fibbed about the "small recess allowing room for the wormwheel". I made a mistake with the position of the mounting hole and had to relieve some of the mounting to allow the wormwheel to rotate because I did not particularly want to make another mounting...!

The kit doesn't include anything like that. I have some 0.3mm square nickel-silver wire which I'm thinking of soldering in to represent the panel joins but looking at the photos, the joints are not that prominent and the rivets are very small in 2mm scale. It might be as well to simply fill in the lines and use Archer rivet decals if they do one fine enough.

Well, it's certainly been sometime since I last updated this blog! In the intervening time, it seems that Pecketts have become very fashionable. The Hornby version is indeed a superb model and has deservedly been a runaway success. This has prompted me to get a move on with my model, which has been languishing for a while. In an effort to get motivated, I've put some boiler fittings on, to make it look more like a loco. The fittings have all come from the N-Brass range and are lost-wax brass castings, which makes them easy to solder in place. The castings used are: - Chimney - Stanier 8F, part no. 2042 - Dome - LNWR Coal Tank Safety Valve, part no. 2027 - Tank filler - LNER Pacific Tender Filler, part no. 2098 - Smokebox door - GCR ROD Smokebox Door, part no. 2113. Bit of a mix and match but they fit the bill. The etched saddle tank comes with holes to locate the fittings. These needed just a little easing out to ensure the chimney & dome were centralised. The tank filler needed slightly different treatment as the casting is quite tall and it needed to be recessed into the tank. Comparison of the two photos below shoe the adjustments. The chimney did need to come backwards slightly, hence the oval hole. The smokebox door had its casting spigot removed and it was then thinned by rubbing on some wet & dry paper glued to a piece of MDF. The beauty of it being lost wax is that it's much more robust than a white metal equivalent. The door darts remained intact. The secret of doing this kind of work is to work slowly and steadily in a circular motion, and to dampen, not soak, the wet & dry paper. Here's the result of the initial soldering Everything is firmly fixed but in need of a bit more solder fillet in places. Showing an improvement but still some more work needed. In fact there are a few gaps which will need filling. I'll be using solder for this, sanding, filing and scraping back where necessary. I make small sanding sticks by cutting pieces from emery boards. It's a good way to get into small areas and corners to remove solder. There's no need to worry about clogging a file. One final task was to grind away the excess of each casting on the inside, to allow room for the motor. So, the Peckett is now looking a bit more complete. Some more work to do on the cab with strapping and beading to be added. I've also left off finer details like handrails and whistle as these can be a bit vulnerable. There's been some developments on the chassis which I'll write about in the next instalment. As an aside, most of the photos for this entry have been taken using my smartphone, an LG G3. It's got a pretty acceptable camera, which is one of the reasons I chose it.

I think you've caught the Trump disease of repeating oneself. Caught the Trump disease of repeating oneself. Together, we'll make RMWeb great again.

What was the condition of the worm? Looks like that Nylatron is pretty stern stuff. On some of the Z gauge mechs that have come through my hands, the wear has always been on the worm, the gears have been fine (the whole gear train is steel and suffers if run unlubricated). Mark

You may find that code 40 flatbottom on PCB will look rather "mainline". As an alternative, I'd suggest code 40 bullhead laid upside down, so the heavier railhead section is at the bottom with the lighter foot at the top. It fools the eye quite nicely when sweated down onto PCB (so there are no "chairblobs"). There is also the code 30 strip rail which would look very spindly laid to standard gauge. Mark

The tooling to produce the sleepers is basically a power guillotine with indexing. 0.8mm thick FR2 paxolin board cuts cleanly this way, particularly if warmed. FR4 does not and also ruins the cutting edge of the blades. FR2 can be worked down to quite a narrow width, 1.3mm wide sleepers for 2mm narrow gauge are produced. Importantly, guillotining is a clean process and does not produce much, if any, waste or dust. A big consideration when working in a home workshop environment. Due to lead free solders and their higher working temperature, FR2 in alternative thicknesses to 1.5mm is now hard, almost impossible, to find. We need 0.8mm as it's conveniently a scale depth for 2mm sleepers. Back in early 2013 I spent quite a bit of time searching for alternatives. FR4 0.8mm is available but cutting it into narrow strips is problematic. Sawing requires a carbide blade, produces a nasty dust and uses up considerable raw material in the saw cut. I was offered water-cutting for FR4 but that worked out quite expensive. I was told laser cutting isn't possible for FR4. It looked like producing PCB sleepers in FR4 was likely to prove uneconomic. The issue was that sleepers require lots of cuts to a high standard of accuracy, it's far different from simply produciing a board for etching into a circuit and when you're working on a price per cut basis, packs of a few hundred sleepers get pretty costly. Fortunately, I was offered the opportunity to piggyback on a larger commercial order for FR2 and the Association was able to purchase enough 0.8mm FR2 sheet for many years supply. Bill Blackburn, who produced the sleepers (and designed & built the tooling!) said to me "It'll certainly see me out" which sadly proved to be the case. Production of sleepers was resumed until Bill's ill health curtailed his activities. FR2 makes very strong trackwork that lasts for years. Overheating the copper can break the bond but once the knack of making the solder joint is achieved, it's not a problem. In any case, with 100% PCB track, there are plenty of other joints to keep the rail in place. Track made from FR4 will be at least equally as strong, if not stronger so I would not worry about it. As Jerry says, FR4 is good for tie bars. With the advent of Easitrack, I have looked at other methods of making turnouts, one of which was milling 1.5mm FR2 so as to leave raised copper clad sections as point sleepers. This works very well but doesn't give the flexibility for flowing pointwork that individual sleepering offers. Easitrack reduces the need for plain track sleepers for standard gauge but there is still a demand for PCB sleepers. There are some, like me, who like soldered track construction. Mark

Almost certainly not as the 0.8mm SRBP (FR2 grade) PCB we use is very hard to find. We had the opportunity to have a significant batch of the basic PCB sheet made back in 2013 and there is still plenty left. Sadly, the Association member who made the sleepers died shortly before Christmas after a period of illness. The tooling to produce the sleepers is expected to pass to the Association but that has not yet happened. There is likely to be some sleepers and sleeper strip stashed away in people's gloat boxes so an appeal to the membership via the VAG or the newsletter might produce results. Mark

"Is it safe?"

That's interesting. Given me some ideas for the pony trucks on my A-W diesel. Talking to Alan Smith a few days ago, sometimes there are stresses within the wheel castings which can get released in a drilling or machining process. You might have dodged a bullet here! Mark

I heard E F Carter described as someone entirely unencumbered by any practical experience. That might be a touch unfair but I've got his 000 book and it's an interesting curio, recommending stud contact as a suitable system for 2mm. Mark

No different to an ordinary turnout, really. If you study the photo, the only additional rail is at the toe. Where it gets tricky is when both gauges carry through the turnout in all routes. Then you end up with 3 crossings and not much room to move. Mark

Hot finger time! Here's a few bits of trackwork for a micro-layout I have in mind, to try out some ideas buzzing around in my batty belfry before committing to a larger layout. From top to bottom, the wagon turntable is a disc of 1.5mm PCB turned in the lathe with a brass tube pivot. It's going to be live and only has to rotate through about 15 to 20 degrees, so it'll have one side wired to the pivot and the other to a wire running up through the tube. In the middle is a straightforward A6 turnout made using the Association soldering jig & template system. At the bottom is a mixed gauge (9.42mm & 6.5mm) turnout. I used the soldering jig to keep the sleepers in place but pretty much laid it by eye, putting the straight stock rail, crossing and diverging stock rail in place then setting out the other rails to gauge from there. The PCB strip is some old 1.1mm thick material I've had in stock for ages. Here's a closer view of the mixed gauge turnout. In theory, it could have been done without a moving point blade but that would require a pretty sharp divergence of the narrow gauge side. As it is the radius of the 6.5mm gauge is about 9". Stock runs through smoothly enough. You'll notice I'm using plain strip rail. That's because the narrow gauge section will have the code 30 strip rail and I felt it best to have a consistent style of rail throughout. It's also very easy to use when shaping crossing vees and point blades Some of the non-dual gauge track will be using plastic moulded sleepers produced by Denys Brownlee. These are a little bit thicker than the current Association standard, hence the thicker point PCB strip. Dual gauge track will be soldered. Still to be made is a 6.5mm turnout, which will be probably be completely conventional although it might be fun to try a stub turnout. Mark

I'm missing the Llangullo blog too. Geoff's excellent photography and explanation of his thought process behind the layout's development were very absorbing. Thanking my lucky stars that I managed to read a good portion of it before it was caused to be removed by what I'd describe as pond life, and I think that's being charitable towards them. I hope some of the content will reappear, even if it has to be much less interactive than before.

I definitely agree with the rearward motor and tanks full of weight. My J69 is arranged like this and pulls well.

If you're looking for a way to accomodate a small discrepancy in height between the motor shaft and worm shaft, flexible silicon rubber tubing could be the way to go. It's available from fishing suppliers as "rigging tubing" in a range of useful internal diameters like 1mm & 1.5mm. I've got some 1mm bore tubing that grips a 1mm motor shaft and stretches easily to fit a 1.5mm shaft. Readily found on eBay. Mark

I'll have to go through some my boxes of photos. I did take a few at various shows. The positioning of the proscenium arch is interesting, due to the way the layout was lit.. I well recall those somewhat fragile display lights we used. James grew up with the layout, didn't he? A very good operator, as I recall. He came with us to Dortmund. Mark

I'm always in awe of John's work, which all seems to emanate from barely two square feet of a scruffy portable workbench. There's a lesson in this for all of us - forget all the theorising and just get on and do it. Mark

What's been amply illustrated to me in the past few months of building work is the difference between "DIY" materials and tools, and what the professionals choose to use. DIY products are deliberately made easier/simpler to use but there's a trade off in strength and convenience. Glues and fillers definitely show up the variation. Mark

Some photos of Copenhagen Fields at the CMRA Exhibition last Saturday, 14th January. The Layout was awarded the Denis Moore trophy for best scenic layout. First is a view from the North End operators position. A view not many will have seen. Here are a series of views of the layout from left (south) to right (north) Mark

Puns like that will get you free entry into the carp ark.

Recently off my workbench are a couple of turnouts for the fiddleyard on Copenhagen Fields. Most people will know that brass and nickel strip is used and the challenge was to make something comparably robust. I used the plain strip rail on a sheet of PCB. Check rails are extended to aid reliable running through the crossing and the tiebar has a wider throw than normal to avoid any possibility of wheels catching on the blades. The rails on the diverging road are left loose to enable final alignment when installed and they are simply tack soldered together for protection. I found this to be a good way of making turnouts for fiddleyards. I used 0.8mm PCB sheet so it would match normal 2mm soldered trackwork. The rail is soldered all the way along as I felt that tack soldering might give rise to expansion and contraction problems. Electrical gapping was simply a matter of scraping suitable gaps in the copper and a single sawcut to isolate the crossing. Mark

1968 to 1969. I think our Viva was registered in 1968. It was my Grandad's car originally and replaced his much loved Austin A40. My grandad had a terrible sense of direction so it probably did more miles getting lost than getting to a destination. The registration year ran from 1st August to 31st July. The first year ran from January to July, which is why there were always relatively few A reg vehicles around. Remember the midnight rush to collect new cars on 00:01 on 1st August? I also remember pop-riveted wheel arch extensions to cover the wider wheels. Flared cars & flared trousers. What fun we had!

I was delighted to find this while out and about on Saturday. As mentioned previously, I passed my test in a G reg HB Viva. This is the GT model! It's a very elegant little car I think. Obviously competing with the Ford Escort at the time. Mark

I think it did. There's a consultation going on about whether the MOT exemption should also be a rolling 40 years. I'm in two minds about this. It would good to be rid of one more burden of bureaucracy but an MOT is a good second pair of eyes and despite people's dread of it, it's only a basic safety test. Most classic vehicle owners take the roadworthiness of their pride and joy very seriously but it would only take a newsworthy accident and tabloid headlines to provoke demands from a rentaquote backbencher that "something must be done". The problem comes in finding a test centre that has some knowledge of older cars and can approach the test with some sympathy. Mark