Jump to content

Izzy

Members
  • Posts

    2,356
  • Joined

  • Last visited

Everything posted by Izzy

  1. Of as big a concern for me as these ads is that in recent times RMweb has reduced to a crawl for much of the time, or just completely inaccessible. I don’t know if the ads are connected to this problem but I’m sure things will resolve themselves in one way or another sooner or later.
  2. Forgive me for I know nothing of SR EMU’s but Worsley Works do a couple of Bullied sets it seems and wondered if they might be a better proposition.
  3. Yes, that might account for it. It is a quite early shot so perhaps it was a problem at the time for either the fellow on the left footplate is very heavily bearded or has a scarf/mask on. I did think he was a time traveller from the present for a moment (!). Looks like the tunnel behind had been shaped for the chimney………Given the number hitching a ride you have to wonder if it was an inaugural run considering the dress of most.
  4. Gosh, those large tanks and very tall chimney really stand out don’t they. I understand the need for the former but not the latter.
  5. Chemical etching of course started off as a one sided affair, and how many printing plates are/were originally made. Both sided through etching requires some extra care with regard to accurate registration so things line up ( why ‘registration’ makes are often seen on un-trimmed one sided multi-plate - 4-colour - printed stuff) along with correct bath/dipping time to ensure the etches aren’t given too long, producing undercut edges, or not enough, and large ‘cusp’. These days it’s down to a fine art from the etchings I’ve handled compared with the distant past while digital files will overcome the stretching problems that can occur with both prints and negs when multiple reductions are required for a given repro size. This is where poor/wrongly sized uneven etchings can come from. Localised stretching or over the whole sheet in just one or both directions. The copy camera I used to play with, (along with stuff like step& repeat cameras etc.) was the size of the average small car - like an SLR upended onto it’s lens so you stood on a high platform - and used up to 16”x20” sheet negative taped to it’s ground glass screen although it might be as small as just an inch square, with a 3x enlargement/reduction capacity. You can imagine the size of the darkroom it was in, one of two I had. Those were the days…….(!). Know this is a bit OT but might be of interest to some.
  6. I believe what is generally referred to as the ‘etch tool’ is the final negatives, which used to be lithographic sheet when I did all this for a living in the distant past as a technical photographer, but how it’s done in these digital days I have no idea. Only needs one set of drawings, the ‘tools’ being reproduced at the final size/scale required.
  7. Izzy

    DG Magnet Uncoupler

    I have used these in the past without issue with DG's in 2mm; https://www.gaugemasterretail.com/magento/seep-gmc-em1.html A strong field and don't overheat if left on for any length of time like the Peco, which I found useless, no strength at all.
  8. Quite apart from the wheel size/type, and the Gibson's mentioned do seem the only real option unless you re-worked the wheels that come with the loco as I probably would, the main concern I have is keying the drive gear on the axle - not sure if it's just a push fit or a splined axle, the CAD doesn't show if it is, and the cast motion. Not sure what the castings are, mazak I guess, but unusual and thick, as with the crossheads, so clearance is going to be an issue I feel. Looks like it's tight as it is in 16.5mm with the motion braket etc into the bargain. Nice little challenge though......
  9. Brass wire can tend to 'temper' over time so tends to lose it's spring a bit. If you can find small enough gauge piano wire for the spring rate needed this would be better. It's meant not to get a 'memory' and no matter how long held at very tight curvature will always return to the straight when allowed so the springiness remains constant. K&S do fine stuff, and John Dutfields do/did stock a wide range of it in long lengths, 36" etc. 10thou/33swg or finer is probably around what you need.
  10. Izzy

    Oxford N7

    Just posted about the above conversion here for anyone interested;
  11. An N7/4 for All Saints East. The Oxford Rail N7’s first arrived quite some time ago. When the BR livery versions appeared I thought about getting one for a while but question marks over the coreless motors being used and whether conversion to P4 was feasible meant it went no further at the time. More recently I obtained one secondhand at a reasonable price having learnt in the meantime that conversion to P4 appeared possible. As with my Hornby J15 the idea was to see if it could be done simply by machining the wheels to run on track to P4 standards, with the backstop that should this not work out then purchase of suitable wheels from Gibson would be possible. There is no doubt that it is a nice looking loco and the body finish is to a good standard as with most present day RTR. I had hoped not to have to alter the body save to add screw couplings to ensure no damage was caused to the nice BR mixed traffic lined livery but some grinding away to gain enough clearance for the wheels and coupling rods has proved necessary. Thankfully no damage to the finish occurred, a cradle in 5mm foamcore being made to hold the body firmly and safely upside down to assist with this work. I don’t think I have seen a complete chassis strip-down of one of these online, if there has been I’ve missed it, so I’ll start off by doing just that. The chassis is held in place by three screws. One at the front underneath the coupling pocket, and two towards the rear one each side. The body is a mix of a cast footplate and internal sections mated to a plastic outer shell. The chassis is a single casting with a two layer plastic keeper plate incorporating the pickups. The motor is held in place with a plastic cover. There is another cover for the gear train. Both held in position by screws. The motor is a small double shafted coreless just 10mm x 23mm in size and fitted with a flywheel that couples to the worm in the gearbox via a U/J. The worm also has brass bearings on it’s shaft. It’s all nicely done, the use of the U/J removing any end thrust pressure on the motor. This is advisable with many coreless motors since most are not designed to cope with and absorb it in their construction. A major difference is that the chassis has the leading driven axle and the rear carry wheels sprung using centrally placed coil springs bearing on the axles. But not just downwards, they have movement above the median as well. I have to say I am not particularly keen on such a design arrangement as it can lead to the ‘nodding donkey’ syndrome. Luckily the wheels run true and weight distribution appears such that enough is over the middle and rear driving wheels to prevent this happening. Again as with the J15 the gearing was stuffed with lubricating grease. This had dripped down into the keeper plate which contains the phosphor bronze pick-up strips which bear on the back of the wheels. The multi-stage gearing produces a 50-1 reduction by my reckoning, which gives reasonable slow running and is pretty essential I feel with such a small motor being used for the weight of the body. Wiper pickups are used on the driven wheels as stated. The carry wheel is dead. The drive is to the rear axle. There is a pcb at the rear with an 8-pin socket. The DCC blank fitted has a largish capacitor, presumebly to smooth current going to the motor on DC. There are brass sprung plungers that connect this pcb with the keeper plate. I cut most of this off, just leaving the plunger connection. Later I soldered the plungers to the pcb to improve electrical reliability. I did find it possible to machine the wheels in a similar fashion to the J15. Less thinning of the fronts were required so the moulded centres were not touched which made things much easier. However longer replacement axles were required. The originals were 2mm splined so after running through with a 2mm reamer plain 2mm rod was not a tight fit and roughing them and using loctite was required to get the wheels to key firmly on them. The final drive gear was drilled through at an angle on the axle and a pin fitted, some 0.7mm brass rod, to lock it in place on the axle with again some loctite. I also fittted brass tube spacers between the wheels and bearings to reduce excess sideplay. However initially decent and reliable running proved elusive due to a combination of excessive slop in the coupling rods along with intermittent current collection. The coupling rods had very oversized holes for the crankpins. What was even worse the leading and centre ones were slotted lengthwise. I could not get decent smooth consistent running until I sweated 10thou N/S sections behind the bosses and re-drilled to get a much closer fit on the crankpins. The crankpins are turnings fitted in from the rear of the wheels and these were shortened before refitting. This involved drilling right through and running a 12ba tap in to give a decent thread length for the hexagonal headed crankpins. I may make replacement items as with the J15 at some point. The current collection issue was traced to the springs in the chassis. These seemed to have been stretched, making them too strong and lifting the middle sets of drivers up off the rail and thus loosing electrical contact. So these were squeezed down using pliers until they were more compact, reducing their strength and allowing better rail contact and current collection. However the phosphor bronze sheet wipers still didn’t seem to work that well, so were eventually cut off and replacements in 0.45mm brass wire made and fitted. The difference was quite noticeable, but complete reliability was not obtained until a stay-alive pack was added. Luckily I use DCC, and also fitted sound, which I will describe later. The chassis is very narrow, just 11mm, perhaps to help allow sufficient play for the loco to get around tight curves in OO. I decided to add false frames to make it look a bit better. 3 layers of black plasticard I had to hand each side and giving a width of 15mm overall. The section behind the carry wheels is narrower. Again three layers of the black plasticard were shaped and fitted into the circular recces to keep the narrower than the main frame relationship. These parts were all attached to the main chassis sides with d/s tape as glue of any kind would not keep them in place and only served to cause them to warp and pull away. It can now get smoothly through a A5 crossover without too much throw of the rear. I had not thought that any grinding away of the body to provide clearance for the wheels at the wider P4 measurements would be needed. I was wrong. While the front and middle splasher internal distance is 23mm the rear one is too tight at about 22mm. A set of wheels will just fit but allows no room for error. So I ended up using a diamond cutting disc in a mini-drill to widen these. I then found yet more grinding away was required to clear the coupling rod bosses at the wider gauge setting as well as reducing the bosses in size to help with this. Once decent running under DC had been obtained I fitted sound. The sound project used was a YouChoos N7 immersive drive on a Zimo MX648. It was fitted with a small stay-alive. These were both located in the bunker. There is not enough room to use the larger MX645 with it’s on-board stay-alive circuits. It seems most sound installs also fit the speaker in the bunker. However there is a lot of empty space under the motor and so I placed a 15mm x 11mm planar speaker in a custom box – black plasticard cut to size and shape – in the rear half inside the tanks. This sounded better than in the bunker. Tamiya masking tape was used to seal and insulate everything, giving it a matt black coat of paint where necessary. With a driver & fireman added into the cab the job was finished. Oh, and some coal glued into the bunker, this perhaps being the weakest part of the loco looks wise, the moulded finish. It now runs well and looks and sounds good, so I am pleased I eventually got one. Izzy
  12. Izzy

    Oxford N7

    Found a BR version s/h recently so finally got around to converting one to P4. I've also added sound from YouChoos, putting a speaker in the rear void under the motor rather than in the bunker where the Zimo MX648 and stay-alive pack are. I ditched the pcb. Now runs well and sounds good so worth the time and effort involved and I'm glad I got it.
  13. Most probably an issue with the wires and connection between the loco & tender I would think. A wire broken etc.
  14. I think perhaps a pertinent aspect to consider is whether odd complete track panels would normally be left at the side of track. Lengths of rail for replacing worn out ones, individual sleepers and chairs, but not full panels unless a long length was being replaced/upgraded.
  15. Izzy

    Bute Road,

    Does not the DCC bus feed to the layout, or at least a good length of track either side of the flap go through it? Otherwise there is danger of plummeting stock if it’s not down. If taking the bus feed at least 5amp would be safer. I assume it’s just a non- latching push button, which aren’t often rated for continuous current flow.
  16. I believe the basic problem for home printing decals of the small sizes most modellers want using ordinary laser/inkjet is twofold. One is the native resolution of the printer in terms of the droplet size laid down, and the second that the actual software allows for a white base in the mix for the correct tonal reproduction. So printing onto a clear base just won’t work.
  17. There is more ‘give’ in P4 than is generally believed. As with any other standard the crucial bits are the same. BTB’s and checkrail measurements with no under-gauging. The rest is moot. I am sure Wayne could do it without issue. As is said, is there the demand to cover all the effort involved. Really not sure at all but very much doubt it.
  18. I don’t believe it would need anything other than the gauge widening and the flangeways narrowing. The manufacturing standards would I presume be the same. But there lay the issue, new castings for all the crossings whereas I think the OO-FS and EM use the same ones to help, so a lot more work. Wayne does seem to have his hands full at the moment……….
  19. The previous 2mm Guv kit by Chris Higgs Masterclass models had an etched roof template for the vent positions to go with the nice resin roofs they had. I have managed to find and scan this etch which is below and should I hope be the right size when copied and printed out. The end slots are of course the centre line. Bob
  20. I have used Eckon ones in the past, and they formed the basis of my current searchlight ones. But as a brand they also seem to have disappeared now. N BRASS do kits of 2/3/4 aspect, with it seems metal heads, but I’ve not tried them.
  21. Since the contact pressure of the wheel on the rail is, probably, a key factor here I have to say that while I have not yet found the need for SA’s in the larger scales such as 7mm, or as Nigel says in smaller scales with stock having multiple wheel current collection and plenty of weight, I have found them to be a distinct advantage in many cases with 4mm, and most particularly with 2mm. The difference is, in some cases, like night and day if you value decent and reliable running, which I always have. I seem to recall having such current collection problems well before commercial SA’s appeared, before DCC existed even, all my modelling life of over 50 years really, yet I don’t think I am too lax in my track construction, loco building, or cleaning regime. You don’t have to use them, the choice is yours, but home produced ones, which is all I use, are fairly easy and cheap to make, so why not? Nothing to loose, plenty to gain.
  22. To discover which is the neg/pos legs/leads on a LED simply use a 3v coin battery. No danger of overload, and it will show if the LED is okay. As a basic rule-of-thumb a 1k resistor is often used as standard for a 12v supply.
  23. Hand drawn and hand built is I think the basic answer. Done in what would be considered perhaps the old way now Templot is here, but normal to many such as myself. I know that sounds obvious, but that the planing angles of the blades and the V’s didn’t follow any set size makes a big difference I would suggest. Draw out the plain tracks and overlay with curves where the points are needed. All very much ‘old school’ now. Look at the way the lower slip blades pivot and are shaped. Clever and practical but might be frowned upon today by some as not looking or following real life practice. Following prototype practice, as Peter Denny did with almost everything I think, but not constrained by it. That had what has always drawn me to the Buckingham branch and his layouts. That they looked real.
  24. Look like the wheel centre before the actual tyre is added. Whoops. Oh CAD……
  25. Generally I have found that because of the way they are moulded, face down into the mould IIRC, the the rear often has a bit of flash or the bore is tighter at the lip. In one sense this is good at it provides decent grip, but is also a pain as axles are inserted from the rear and not the front. One solution is to ‘break’ the lip edge with a countersink drill or a very much larger one than the bore size. Then also twist the axles as they are pushed in. This helps keep them concentric.
×
×
  • Create New...