Priory Road - North East Essex in BR days

[Izzy]

Thanks John, ha yes, I thought the magic smoke had escaped when the tantalum went pop, it poured out, masses of it. Luckily I had a window open and was out the rest of the day because the acrid smell hung around a very long time. It’s a shame CT’s are so hard/ expensive to get now. Zimo’s are just as good of course, perhaps better in many respects, but nothing can touch CT for size.

 

Bob

[Izzy]

A Hunslet 05 in 2mm – pt 8

 

Having got back to testing the loco on Priory road I wasn’t at all happy with it’s performance. Okay-ish at best. Not smooth through the lower speed range and better faster than slow. Just not right at all, not what I expect, or will accept. So I went back over the chassis re-checking everything, gear meshing, quartering and so forth, until I got to the coupling rods. After a lot of study here I found the problem. Somehow they just didn’t quite match the wheelbase despite the checks carried out during their construction.

 

 

It took me a while to see they weren’t right, which of course explains why I had to open the crankpin holes up to 0.75mm to get things to run in the first place, which really should have been a warning sign. What also puzzled me was that the error was identical on both rods, The front two holes being out by the same amount. I can’t really explain it as the etches were measured before construction and were exact to the drawing and totally correct. It's obviously something I've done wrong, I just can't figure out what.

 

Anyway, whatever the cause they needed replacing, but to make absolutely certain they were the issue, it wasn’t just faulty eyesight on my part and something else was the problem I decided to make some temporary rods up using some spare scrap etch. Just a single 10thou layer.

 

 

Please don’t laugh at the size, it’s just what was to hand and done in the quickest possible way with the least effort. With these the loco finally ran as I had been expecting right at the start when first fitting the original rods. So it seemed ‘Plan B’ would happen after all. Oh well.

 

Now the 05 is a small loco even compared to the 03/04’s and I’d felt the tiny exact scale rods fitted it’s size nicely. Looking through my spare coupling rod etches I came upon the two sets I’d originally bought for the Jinty and 4F, the too-fine ones I couldn’t then cope with. One set made up, one not. Could I use these? Cut up of course. Had my skills improved enough? I thought I’d give it a try, nothing to lose really.

 

 

I have written previously about making replacement ‘cut & shut’ coupling rods from two layer etches. Usually I just use a simple hand drawing to set the correct size. Given the problems I had encountered with the rods I thought that perhaps this time I aught to make a jig to set the coupling rods on and also check them after making. This I made from a strip of single sided PCB. I drilled it using the temporary rods as a jig, drilling to take the standard 2mm association 0.5mm crankpins. These I soldered into place using the reverse/plain side to mount the rods. I held the temporary rods in place with some magic tape while drilling the pcb.

 

 

 

 

 

Cutting up a rod etch for a six-coupled loco is fairly simple. For an eight-coupled it’s a bit more complicated because of the need for two knuckle joints each side so two sets of six-coupled rods need cutting up. This wasn’t the case with the 03/04 I did as they didn’t have two knuckle joints, rather an overlap joint to the flycrank, so only (!) a four-coupled and six-coupled were needed.

 

Added into this complication was my desire to try and make these coupling rods as strong as possible by reversing how they went together. The etches consist of a half etch layer for plain rods and another layer for fluted rods soldered together and depending on which way around they were used. I only needed plain rods so wanted to place this half etch layer onto the fluted side to give more solder between them and thus hopefully more strength. This wasn’t difficult as such, just required a bit more thinking about as regards cutting and matching the various layers up.

 

 

 

 

 

 

I got there in the end. Slowly. Three part soldered ‘pairs’ could be made using the jig to set the crankpin distance which then needed joining together around the crankpins, so in exactly the same manner as I’d assembled the original etch coupling rods.

 

 

I’ve done this quite a few times over the years, and which can only be accomplished by hand. No jig can be used. Getting them straight as well as at the correct distance is slow patient work. Once they had been checked, double checked on the jig, that they fitted, I enlarged the holes in stages to 0.7mm. So they were an easy fit over the jig. There is I have found over time, a world of difference between coupling rods that are a sloppy fit on crankpins and have correct centres matching the wheelbase, and ones that don’t. If they don’t, as illustrated here with this build, it doesn’t matter how much slop there is, the loco will never run properly. You’ll see there is some difference in size with the original rods, but they are not nearly as big as the standard size coupling rods I use.

 

 

At this stage I have now made and fitted the Simpson springs. Okay they are really about current collection, but will as in this case also act as springing if needed/wanted/desired. The wire I use is very fine hard phosphor-bronze. Around 36-38swg.

 

 

I drill a 0.3mm hole in the chassis spacers 10mm from the axle centre-line and solder them in place. A 15mm length with about 2.5mm bent over to go in the hole gives sufficient to stretch past the axle and press on it. It can then be bent to adjust the tension

 

 

I don’t fit them to the geared axle as there is usually not enough room.

 

 

With these fitted the loco was given another outing on Priory Road. It now runs as I originally expected it to, thankfully. A bit ‘springy’ with the Simpsons but they won’t be finally adjusted until all weight is added and it’s about to go through the paint shop.

 

 

 

There is still the brake gear and sandboxes, guard irons etc. to add. This will be left until the body is finished and clearance is established behind the footsteps for the fly-cranks and coupling rods.

 

Bob

 

Edited October 10, 2022 by Izzy

[sb67]

That is some proper miniature engineering Izzy, great work! 

Glad it's all coming along, I'll look forward to seeing it after the paint shop visit 🙂

[Nigelcliffe]

Hi Bob,

 

couple of things to mention: 

 

Surface mount components for the resistor, diode, and zener are a fraction of the size of wired components.   See the very old photos of my class 02 

http://nigelcliffe.blogspot.com/2013/07/stay-alive-capacitors-in-2mm-scale.html
(Ignore the ceramic capacitors, we've all discovered that tantalums are a lot better.  Technical explanation available on request). 

 

And I strongly suspect that CT (Tran) are no more.  They're website has been dead for some months, and I know from other sources that emails to the business are no longer answered.  

 

Really small decoder options are now either Zimo or D&H.   

 

- Nigel

[Izzy]

 

Thanks Nigel, that's a real shame about CT but given the recent experiences perhaps not surprising.  Bet the NGS are glad they finally got their shunter sorted, I believe CT did the onboard decoder for it.

 

I have used SMD reisistors alongside the mini-MELF's and thought that if the 25v tantalums pan out won't need a zener in the mix, so a bit swings and roundabouts with pack size. I don't envisage needing many/any more really, I've got more than enough locos now (although never say never!), it will just be refining the stay-alive packs should further issues rear their heads.

 

Bob

[Izzy]

 

A Hunslet 05 in 2mm – pt 9

 

Now that the loco runs okay I have completed the body. Weight will be added last once the mating of body and chassis is deemed okay so it can be adjusted to suit the space available.

 

This last stage I find usually takes the longest amount of time and as this is just an etch there are some details that need to be fabricated from scratch. With 2mm I do find that care is needed in what actual details to fit, in some cases leaving them off being less obvious than adding ones too over-scale, and simplified details to scale standing a better chance of fitting in. It’s all a bit trial and error really but the time spent is well worth it in my opinion, and especially with locos such as this where I feel the details can change the basic appearance of the loco beyond recognition. As always using and studying photos and drawings are key, and especially the former when basing the loco on an actual prototype as here. I find it reminds me of bits still to add that might not be mentioned if there are any instructions and crucial if there aren’t.

 

I started off with the radiator. This is three layer with alternatives.

 

 

It's suggested you align them and just solder around the outside to prevent solder bleed filling the detail in. I tried this but then felt tinning all the bits first would work better, make the radiator fins firmer if they were all soldered in place, so this is what I did. Then sweated them together without any more solder except at the edges. It worked much better. Fitting it into the engine casing I hit a problem I should have spotted much earlier. The front is curved, so it won’t seat properly with the half etched rebate all around, the top and bottom ones need removing. The top can easily be filed away, but the body retaining nut stops the same being done with the bottom and I should have done this modification at a much earlier stage. So I had to file away as much as I could, and then slowly cut the middle bit with a scalpel until it broke away. I could then solder the radiator in place from the inside, top and sides anyway, and it remained flat and upright.

 

The steps locate into half etch slots. This strengthens them considerably over a plain soldered joint I discovered. I did at first think no extra strengthening would be needed, I usually add ‘L’ shaped straps at the rear on most steps, to keep them upright against handling etc. However these steps have half-etched rebates for location of the treads and the middle ones meant they kept getting bent here as I worked on the body, so I had to eventually add thin plain straps cut from 5 thou brass shim at the rear to offset this occurrence.

 

I also fitted the DG’s into the bufferbeam slot. I cut the rear protrusions short but still found I had to file them shorter still to get the chassis in. I had reduced the chassis length a bit front and back, perhaps by 0.3mm each end, to allow clearance for electrical isolation purposes. I’d also set the ends of the chassis spacers back a bit from this as well.

 

With shunters and tank locos with enclosed cabs I prefer to make the roof plug-in. This helps not only with adding interior bits if desired but with painting and adding crew post paint. I did this by soldering small strips of n/s upright along the inside rear of the cab and at the front sides. Usually I just fit them front and back but the front windows reach almost up to the roof and space needed to be allowed for glazing. These strips are set so after painting the roof will be a fairly firm fit. Well, that’s the plan. There’s considerable overhang front & back but hardly any sideways so getting these strips in the right place was a bit of trial and error even after marking out.

 

 

The first parts that needed fabricating were the air reservoir cylinders under the front footplate on both sides, the small vacuum one under the middle left side, and the sandbox fillers on top of the footplate at the front steps. I tackled the last named first because I couldn’t see a way to add them after the air cylinders were in place. All of these parts I made from metal, not only so they were more robust but added weight as well. It might not be much but it’s sometimes surprising how much can be generated from lots of small parts and every gram helps in the running and haulage stakes.

 

These sand fillers were not present on the drawing so the size was approximated from photos. As they sat at an angle, roughly 45degrees I estimated, I made them from tube and wire plus a crankpin retainer. The tube was Albion alloy 1mm x 0.5mm as it appeared to be about the right size. I filed the 45 degree angle before cutting them off to size. Then inserted a length of 0.45mm brass wire, and added the etched retainer as the lip.

 

 

 

There is a large hole in the footplate for them. I guess mouldings/castings are provided in the 4mm Judith Edge kit along with the air cylinders etc.

 

 

This hole assists being able to slant them at the correct angle while soldering from underneath to fix them in place. I just held my finger on the (top) end of the wire while doing this, and is why I left it long, to get them all square and not burn my finger! I trimmed them to size afterwards and filed it all away underneath to provide room for the air cylinders.

 

 

 

 

Producing these air cylinders needed a jig making. With a lot of these cylinders the straps holding them are all under the footplate but in this case they are attached on the outside of the footplate valance. So the straps need to separate from the cylinder at some point and thus can’t be produced by a simple turning. The cylinders were made from 3/32” brass tube with 1/16” rod soldered in as I didn’t have any 3/32” solid rod. The straps were cut from brass shim. I made a simple jig from scrap etch to trap the straps around the tube while I soldered them in place. I could then solder the straps to the footplate and cut off any surplus. A layer of masking tape was used to prevent the cylinders attaching to the jig.

 

 

 

 

 

I should add that at this juncture I had changed the soldering iron tip to the biggest for the remaining work although the iron itself was still my 15w Antex. With the mass of metal that the body now consisted of contrary to earlier the heat absorption was quite high and all the work required a quick ‘in-and-out’ technique to allow the solder to run in just a limited area.

 

My original intention had been to use 9thou guitar wire for all handrails. It’s what I normally use and stays nice and straight. But it is hard to cut and to file back. I was thinking particularly of the engine casing doors with all the handles, where after soldering into place they would have to be trimmed right back inside to allow the lead sheet to be squeezed in between the casing and motor. I couldn’t afford to lose any more space than had happened with the decoder place change. So as an alternative I used the same 36swg hard PB wire used for the Simpson springs. It’s about 7 thou/0.2mm so fits easily through a 0.3mm hole. Hard is a relative term, it’s stiff within reason, but compared to the guitar wire is soft.

 

I made them as a square U shape inserted from behind, soldered into place, then bent and trimmed to size with a little jig. Another piece of scrap etch, actually frame spacer with a slot cut with a razor saw. And marked so I could cut off to the correct size with a scalpel after bending at right angles. The 10thou thickness of the jig being the distance from the body.

 

 

I chose the PB wire to be able to do it this way, easily bend and cut it. This would not have been possible with the guitar wire. The downside being it’s a bit too easy to bend/kink so care is needed with handling.

 

 

 

It was quite tricky fitting the vertical handrails above the sandbox fillers. The top of them fits in-between two engine door handles and there is precious little room. I also used the PB wire to make and fit all the other cab handrails, using in the normal fashion a piece of card to space them out from the body. Again as the PB wire is fairly soft I could cut off the surplus inside after soldering with the scalpel.

 

 

The two handles on top of the engine casing and above and below the rear right-hand cab window I had trouble getting completely square because of their very small size relative to the wire diameter.

 

 

The two long horizontal handrails on the top angled sides of the engine casing I made using 0.33mm brass rod because they looked in photos to be slightly thicker. I think now this might be too thick but can’t change them without a lot of work undoing and re-making, so they’ll stay. The stanchions are individual strands of wire stripped out of electrical cable, twisted around the brass rod and then soldered into place. Again the inside surplus could be removed with a scalpel.

 

 

 

 

Finally deciding to produce D2554 I had a bit of trouble working out the two manhole covers, that they didn’t appear identical with the fitments on top of them. It was extremely difficult, impossible actually, to locate any top views of these locos to assist. I found the odd view of models others had made along with those of the Heljan 05, the later, larger version. It isn’t really good practice to copy others work as such, since they might have been in the same position and just ‘winged’ it, as indeed it seemed I would have to do, but I felt that perhaps as they all appeared pretty much the same I would at least be in good company.

 

Oh, the exhaust pipe. Many 05’s didn’t have one, at least at first, but as with D2554 quite a few seemed to gain them later. Just small thin vertical ones mostly although I’ve seen one example stretching as far as the cab before going up! Talking of the cab the horn was filed up by hand from some 1mm brass rod. It will mostly be hidden under the large roof overhang.

 

The vacuum brake pipes were made from enamelled wire (stripped from an old solenoid point motor) wound around 0.3mm brass wire. As luck would have it their position is clear of the DG’s as I only have the latch on loco’s.

 

 

Perhaps the trickiest job has been the making of the marker lights/lamp irons. These I made from 1.5mm brass rod filed square and cut into 1.2mm lengths, drilled 0.3mm to take brass wire then filed down to just leave a ‘bump’ representing the light, soldered to a length of N/S strip bent and filed to shape and finally soldered to yet more 36swg PB wire as the wiring pipe runs. These were fixed in place with cryno. Trying to solder them in place risked the whole assembly falling apart.

 

 

 

 

 

 

 

 

 

 

The body was repeatedly cleaned/washed with Cif during all this work to get rid of the phosphoric acid flux residue so that when it came to the final stage of fixing the marker lights no further cleaning was needed as it wouldn’t be possible past that. I have found that trying to clean/degrease bodies after using cryno usually results in the bond failing due I presume to chemical reaction, so I don’t do it.

 

Now that the body is done, well apart from windscreen wipers which will only be added after painting and glazing, I will return to finishing the chassis.

 

Bob

 

[Argos]

A fantastic master class there Bob. Lots of very useful tips. I learnt a lot. Thanks for taking the time to document and post the detail. 

[Argos]

Duplicate post

Edited October 19, 2022 by Argos

[John57sharp]

1 hour ago, Argos said:

A fantastic master class there Bob. Lots of very useful tips. I learnt a lot. Thanks for taking the time to document and post the detail. 

Completely agree with Argos, thanks Bob

 

[jonas]

Massively informative, thanks for taking the time to document your build - it’s going to make a stunning little loco.

[Izzy]

 

A Hunslet 05 in 2mm – pt 9 – some additions!

 

Firstly, many thanks to all those who have left comments etc. it’s much appreciated.

 

Now an apology. I did say the body was finished didn't I. Whoops, wrong…..

 

When I went back to the chassis I thought I should add the guard irons. These seemed to be added after delivery and were shaped angle iron. But I then discovered I couldn’t really add them to the chassis as it was too narrow plus I couldn’t quite figure out how to add them at the rear anyway and leave room for the brake gear parts, the pivot rod being right at the extreme back of it. So I fixed them onto the bufferbeams where the rivet detail was that represented their fixing so they were in the right place track-wise.

 

 

 

 

Then as I studied the photos to get this right I saw a small detail on the right hand front side of the engine casing. I had noticed this several times and meant to get around to it, but had then overlooked it. I’m not entirely sure what it is, a small pipe or something that emerges and rises vertically for a short distance. I have a feeling it might be a sight glass/indicator for either the radiator or perhaps the fuel tank. Not sure because only some locos had them and it seemed to be a later fitting. And D2554 was one that did. So that’s been added as well.

 

 

So now, hopefully, it is back to the chassis…..

 

Bob

[queensquare]

An excellent series Bob, many thanks for taking the time.

 

Jerry

[Izzy]

 

 

A Hunslet 05 in 2mm – pt 10

 

Getting back to the chassis I found there wasn’t much more to add, but as usual it proved to be quite time consuming. You might notice that a lot/most of the work is done with the wheels out of the chassis. This is why I prefer the drop-in-wheel/keeper-plate system. I really can’t figure out how people cope with doing all this work with the wheels fixed in the chassis and I wouldn’t even want to try doing it that way.

 

The easiest job was just adding the balance weights to the wheels, using cryno.

 

 

The brakes are two-layer and composed of the hangers with shoes that are soldered into place on top, a common design. The issue I hit was the hangers were minimal where the holes for the pivots were and even putting a 0.3mm drill through broke some of the top ones.

 

 

This made soldering them into place tricky. Fitting brakes to 2mm locos with split frame chassis isn’t easy in the first place since you can’t just string wire rod from side-to-side as it would cause a short, and with using drop-in wheels wouldn’t allow them to be fitted/removed either. In larger scales having it all pivoting out of the way is a technique I’ve used in the past, but the split-frame chassis adds too much complication for me.

 

So I’ve used a design where both top and bottom wires are soldered to the chassis on each side. I’ve also left off the pull rods. This is the compromise I’ve had to accept as being the best I could come up with in terms of strength of the visible parts coupled with still allowing the wheels to be removed etc.

 

There are holes for the wires in the chassis.

 

 

For the wire I went back to using 9thou guitar string to get the strength. Here I had a bit of luck, the holes were just below the frame spacer. So L shaped bits were hooked though and then bent forward at an angle. Why? Because the wheels being oversize the brakes would otherwise be too close to the wheel treads, tight on them actually.

 

 

 

 

 

 

I used more of these L shaped bits for the bottom rods, snipped off to size after soldering, and again soldered to the inside of the chassis. I hope the shots make all of this understandable. The end result is nice and strong.

 

 

 

 

 

There was an air-brake cylinder at the rear on one side, for the loco brakes. Vacuum brake was provided for any fitted stock the loco might haul. At first I wondered whether to leave this cylinder off, after all it was situated half-hidden behind the rear steps and space was limited what with the wheels, sandboxes and especially flycranks. But it’s not really in my nature if it can be avoided despite what I said earlier about leaving details off.

 

So I made it up from a slice of tube, some brass sheet, a couple of sizes of Albion small bore tube and a bit of 0.3mm wire.

 

 

 

 

In the end I had to file a flat on the back of it to get space for it behind the steps and also cut away the rear of the buffer stock. This last proved quite tricky. I soldered it to the chassis. Connecting it up to the brake rod was another challenge. This cross-rod was visible below the bufferbeam so I the end I used some Slaters plastic rod. I found there was only – just – enough room between the guard irons for electrical isolation when the chassis was popped into the body.

 

 

The last items were the sandboxes and pipes. To prevent any electrical issues here, them touching the body and particularly the front air reservoir cylinders I used plasticard, 0.5mm three layers thick and drilled 0.3mm to take more 9 thou wire. All cryno’ed into place. It all looks a bit crude at magnification and the room between the pipes and flycranks is pretty much non-existent. I’m hoping it will all run alright when I get it back together, time will tell…….otherwise some fun might ensue.

 

 

 

Having got there I have started painting the chassis parts. All done simply with a small brush and thinned enamel paint, no primer. I’m not taken with most present day paint, it’s more carrier than pigment, and while the thickness might not be too bad in the larger scales it’s problematic in 2mm I find at times. But these parts aren’t going to get subjected to hard wear and tear anyway so a single coat of thin enamel is enough for me. Matt black for the chassis and wheels and red for the coupling rods and flycranks. I made a simple resting jig from plasticard on which to sit and paint the rods.

 

 

Now it’s waiting for it all to dry off and harden properly.

 

Bob

[Flying Pig]

3 hours ago, Izzy said:

So I’ve used a design where both top and bottom wires are soldered to the chassis on each side. I’ve also left off the pull rods. This is the compromise I’ve had to accept as being the best I could come up with in terms of strength of the visible parts coupled with still allowing the wheels to be removed etc.

 

 

I struggle to see the pull rods on photos of the prototype taken at track level, so I doubt the proverbial man on a horse will be offended.  There have to be limits on a working model - finescale is pushing them, but they're still there.

[Izzy]

 

 

A Hunslet 05 in 2mm – pt 11 – Some incidents

 

Yesterday I suffered two near disasters, which I’ve often heard referred to as ‘spanners in the works’, one of which has brought everything to a halt now until I can solve the problem.

 

The first was after letting the paint fully harden when I went to get the coupling rods to assemble the chassis and give it a run only to find one rod had broken. This had happened at a joint where only the half etch section is across the join, and obviously wasn’t strong enough to cope with the amount of handling they have received. Soldered joints can be strong, but also a point where fractures can occur under pressure.

 

 

So, what to do. Normally I manage to use two layer etches where both layers are full thickness. Making new one-piece ones from scratch seemed at first the only real solution until I hit on the idea of using the scrap etch ones I had made as temporary test ones as the base layer, and adding the full thickness parts from the broken ones as the second. This would give a better outside face than I could probably file up, and would also mean less filing as well. So I de-soldered the made up ones, salvaged said thick layer bits, and soldered them on top.

 

 

 

 

Filing the second layer down took about 30-45mins a rod but produced a nice strong result. What was better still the loco ran nicely once they were fitted, and they were then painted. So, back to square one.

 

After letting the paint fully harden off again I fitted the wheels and gave the loco a test before adding the coupling rods. It didn’t seem to want to respond at first and then ran for a while and all seemed well. Then it stopped and the CT DCX76 decoder just fried itself.

 

 

I’ve never had a CT let go on me before although I understand quite a few others have found them less than totally reliable. The only idea I have is that somehow one of the drivers touched the motor outputs on the PCB I fitted to provide connections, so I’ve removed it for now. However I had removed it from the maroon 309 and replaced it with a Zimo MX617 so there must have been a reason I can’t remember now. Perhaps it was already ‘iffy’.

 

Whatever the reason this has left me in a bit of a pickle because although I have quite a few spare decoders none of them are of a size that can fit. Indeed I think I have said previously I felt lucky to have the CT as it was the only one that could and give an acceptable performance. Just to make sure I got out my Sprog, fired up JMRI/Decoder Pro, and tried them all. A usual the only ones to give an acceptable performance were Zimo MX600’s and a Zimo MX622, but all far too big to fit. There are a couple of Digitrax Dz126’s, but they are as big as the inside of the cab, and don’t give a good enough performance to bother about anyway.

 

 

The same really goes for a couple of Lenz silver minis which are also 6-pin. The problem is there are few decoders that it appears would fit, only really the newish Zimo MX615 which @Bryn used in his industrial but that is around £40 - if you can find one. This would only be in the cab, there just isn’t the headroom in the engine compartment.

 

So I may fiddle around with one of the Lenz silver minis as a stop-gap measure, I’ve nothing to loose. It’s almost the same size as the CT DCX76 although much thicker, 2.7mm v 1.7mm.

 

 

 

 

I could take the pins off and fit wires.

 

 

It’s motor control performance is somewhat less than Zimo/CT but perhaps better than most others. I’m talking here about inertia from rest. Once past a certain speed they are all pretty much the same but for BLT’s and shunting type layouts this aspect is pretty crucial. It would have to fit in the cab, indeed no decoders will fit where the CT was placed, they are all too thick. And there are solder pads for stay-alive. We’ll see.

 

 

Bob

 

 

[Izzy]

 

A Hunslet 05 in 2mm – pt 12

 

I spent today sorting out the PCB on which the decoder connections are, modifying it and fitting it the other way up on the chassis, and then fiddling around with the Lenz silver mini. I’ve had some success.

 

Feeling that perhaps the PCB was the cause of the CT decoder going pop I have altered it so two pins go down through it and are soldered to the chassis. This provides the track connections as well as fixing it in place. So the electrical connections are now on top instead of underneath. Perhaps a wiser design which I should have produced in the beginning but a lot of modelling is learning from mistakes as with the rest of life.

 

 

I’ve now also altered the Lenz Silver mini, removing the pins and adding wires for track and motor along with those for positive(+) and ground (-) for the stay-alive.

 

 

 

 

 

I found that the decoder was just about the same size as the stay-alive pack and could sit on top of it. This does mean it comes above the side window line but this is unavoidable as things stand. The advantage is this now gives more space in the engine compartment for lead weight to be added. Indeed things seem to have come full circle as this was the original plan, to sit the CT decoder on top of the tantalum pack.

 

 

I’ve also managed to adjust the decoder to give a better a performance with the coreless motor. Not quite up to CT/Zimo standards, but close enough to do for the moment. If I cannot live with it in the longer term then getting a Zimo MX615 and replacing it won’t be such a major change. But using it at least for the present will allow me to finish the loco.

 

Now I can proceed to fit weight and then paint it. The basic body and chassis weighed in at 13gms. Now all the other bits have been added this has risen to 17gms. It will be interesting to see how much higher this figure this can be pushed.

 

Bob

[Clive Mortimore]

Hi Bob

 

I am going to give up modelling. Your 2mm model makes my scratchbuilt 4mm ones look total (please use your own non RMweb four letter word for rubbish).

 

Yours work is amazing.

[Izzy]

7 hours ago, Clive Mortimore said:

Hi Bob

 

I am going to give up modelling. Your 2mm model makes my scratchbuilt 4mm ones look total (please use your own non RMweb four letter word for rubbish).

 

Yours work is amazing.

Thank’s Clive, that’s very kind of you to say, but please don’t, it was the encouragement I have gained from seeing your models that gave me the courage to try making my own, my class 15 and the 309’s. Without it I doubt I would have started. 
 

Bob

[Izzy]

 

A Hunslet 05 in 2mm – pt 13

 

Well, lets start with the good news (!). I’ve managed to add quite a bit of weight to the body. This was all cut from a small sheet of lead I have which is about 1.5mm thick. A slab under the roof, double thickness at the back of the cab beneath window level, and the engine compartment lined with it, sides, top, and front.

 

 

 

 

All up with the chassis it now weighs in at 33gms. Quite respectable given it’s size and slightly more than my blue Farish 04 with the association chassis at 30gms. I’m pleased. It’s all I need in the haulage stakes.

 

So, now comes the downside.  I am going to have to make a new chassis from scratch. This has come about from several related problems which appeared when I tried to finally mate the running chassis and body. I have of course trial fitted the chassis but not run it together because it wasn’t possible with the crankpins at full length due to the two sets of steps, the rear in front of the fly-cranks, the front ones over the leading wheels. Having decided the chassis was as finished as it was ever going to be I fitted the rods, soldered the retaining washers in place, cropped and filed the excess away, and checked the overall size to establish the amount of clearance behind those steps.

 

There wasn’t any. The over-crankpin size was 14mm. I’d made this as small as I could but this was exactly the same as the between-steps measurement. Oh....bother…. It’s all my fault really because having built a few locos I should have checked this aspect at a much earlier stage given how small & narrow the loco is compared to others. Most of my 2mm locos have over-crankpin figures of between 14 -15mm and easily clear steps etc. so I didn’t pay the attention to it I should have.

 

Study of the supplied drawing showed there were a few minor discrepancies that had occurred as the between-steps figure should have been 14.5mm. Not massive but in this scale every 0.1mm makes a difference. So I decided that the only option was to remove the steps and sit them further out. I wasn’t sure about this because it might make things look wrong but I didn’t seem to have many options. So I very carefully unsoldered them not wishing other body parts to start coming off after all the work carried out on it.

 

At this point I decided to fit the chassis and test the complete loco before working out exactly where to place the steps. It just stuttered along the track, not running at all well. Investigations revealed the chassis was being warped by being screwed to the body, and to add to that woe it had developed a ‘kink/twist/hump’ where there is no chassis spacer, where the double reduction gear train is situated. This probably acounts for the problems I have had getting decent running even thought I have regularly checked for squareness etc. Here's the sorry state after stripping it down.

 

 

These are of course some of the downsides of using very thin chassis frames, these being just 10thou, which of course is the etch thickness and just right for the body. You certainly wouldn’t have wanted it any thicker. I thought with it being a very small loco I could get away with it. Seems not with my obviously heavy handling somewhere at some stage.

 

I took a step back and tried to work out what it was best to do although in reality I knew what this was. Build a chassis from scratch using thicker frames, and re-build the wheels with different crankpins to help reduce the width a bit more so I didn’t have to move the steps out by a silly amount. I’d used the ‘flanged’ crankpins and thought that perhaps the plain ones allowing the rods closer to the wheels might be possible, the ‘every little helps’ principle being used here. If it didn’t work out there wasn’t much loss involved, just time and effort, which is what a lot of modelling is about isn’t it, the challenge of overcoming difficulties. Frustrating when you can’t, rewarding when you can.

 

In truth I’m pleased with how the body has turned out so whatever it takes to get a decent working chassis will be undertaken as I think it deserves it. I will of course keep updating as things progress. Hopefully I can make a slightly better job of it this time.

 

Bob

 

Edited November 1, 2022 by Izzy

[Caley Jim]

Bob, I've trawled back through the build to check and I think I'm correct in saying that you have two screws attaching the body to the chassis.  If I'm correct, then this may be what was causing the distortion of the chassis, especially if there is the slightest mis-match between the two.  I was warned against this very early in my 2FS modelling by, IIRC, Stewart Hine and I have always only used one, usually at the front of locos and rear of tenders.

 

Jim

 

[Izzy]

Yes Jim, you are correct, one each back and front. All my 2mm chassis ones are like this and I’ve not suffered from this before but there’s always a first time isn’t there. I’ve read before of problems like this. Easy fix on it’s own but in this case it just really highlighted the fact the chassis was distorted to start with which left me feeling uneasy. I thought it better to start again just in case issues arose further down the line which dictated a re-build when the body had been painted and finished and might cause damage. 
 

Bob
 

[Nigelcliffe]

If remaking the chassis, then there's scope for more weight.  When I've done small diesels, I've added a lot of weight in the chassis from 1/4inch square brass bar between the frames, with slots cut to clear the axles (etc.).  Insulated from the actual live frames with thin paper.  

 

- Nigel

[Izzy]

Yes Nigel, thanks. I have dug out some 1/4” square brass and had a look. It along with 1/32” strip would work well width-wise I think. As I’ve managed to get enough weight for what a I need at present I’ve decided to take the easier route and use 1/64” strip. I’d say the bar will form chassis mk3 but I don’t want to tempt fate……..

 

Bob

[Richard Hall]

Finicky little things, these 2mm mechanisms.  I just repositioned the motor on my Pannier chassis, corrected the height on the compensating beam, and now it runs like a three-legged donkey and I can't see why. Bob, I feel your pain.  

 

Couple of pages back you mentioned problems fitting crankpins to wheels.  I ran into the same problem: my nice Mitutoyo digital caliper measured the crankpins at 0.53mm diameter... Association Yearbook tells me the answer is a No. 75 drill bit but being a crude bodger and not having a set of numbered drill bits I just put each crankpin in a pin vise and filed the inner end down a bit.  One day I'll actually remember I have a lathe which does stuff like this.  Good luck with chassis number two: this is much too lovely a body not to have an equally good chassis under it.

 

Richard

[Izzy]

On 02/11/2022 at 21:49, Richard Hall said:

Finicky little things, these 2mm mechanisms.  I just repositioned the motor on my Pannier chassis, corrected the height on the compensating beam, and now it runs like a three-legged donkey and I can't see why. Bob, I feel your pain.  

 

Couple of pages back you mentioned problems fitting crankpins to wheels.  I ran into the same problem: my nice Mitutoyo digital caliper measured the crankpins at 0.53mm diameter... Association Yearbook tells me the answer is a No. 75 drill bit but being a crude bodger and not having a set of numbered drill bits I just put each crankpin in a pin vise and filed the inner end down a bit.  One day I'll actually remember I have a lathe which does stuff like this.  Good luck with chassis number two: this is much too lovely a body not to have an equally good chassis under it.

 

Richard

Sorry not to have replied before, been a bit occupied as you can probably imagine. Hope to post the results soon….

Ha, yes. Just a thought Richard, have you tried oiling the chassis. I use one of those pin oilers from Expo tools, the yellow coloured one. The difference it can make to a ‘dry’ and newly fiddled with chassis can sometimes be stark, like night & day. I oil everything, bearings, gears, motor shaft etc. even the crankpins with the temporary sleeves.

 

Talking of which I’ve just encountered the crankpin size difference myself, this time going the other way, too loose now after opening up the holes for the previous ones. It’s all good fun!
 

Bob