Drawing the Etched Panels

Emboldened by my success in drawing the artwork to etch a set of replacement rods for Canopus I moved quickly on to something a lot more complex; the etched parts to complete the Hudson-Hunslet diesel locomotive.

In retrospect the connecting rods were easy to draw. Not only are they a fairly simple shape, but they are also the same on both sides, so the artwork for the back is the same as for the front. Also all four are obviously the same so you only need to draw one. The parts for the Hudson-Hunslet are a number of magnitudes more complex. Not only are some of the parts quite complex shapes (i.e. not a simple combination of rectangles and circles) but every single part needs different artwork for the front and back of the etch, plus some of the parts fold. The flat parts took a while but by far the most complex was the single piece that wraps right over the loco to provide the body panels at the drivers end.

I took a similar approach to designing this part as I have done metal pieces for previous models. I started by drawing out a part that I thought would work, then printed it out, stuck it to some brass, cut out and folded the part and then checked to see if it would fit. On the third attempt I ended up with this.

Designing this folded part was especially complex, as what I had was measurements for the inside of the part, but it is much easier to draw the part if you know the outside dimensions. It's fair to say that it was very frustrating trying to get this right. It seems to be a good fit, but I'll only know for certain when I try and fit the etched version. The final artwork measures out at 62.56mm by 35.02mm yet contains 15 different parts (some are spares and some are variations) so some of the parts are going to be devilishly small.

There will now be a bit of a pause in posts on this locomotive while I await the etched parts and the next set of prototype 3D printed parts.

Canopus: Replacement Connecting Rods

So it's been almost three months since I last did any work on Canopus. If you can remember back that far then you'll know that I hit a bit of a problem as some of the parts that come with the kit aren't the right size. Specifically the slide bars are two close in to the wheels and the connecting rods are a touch too short. It should be fairly easy to move the slide bars out slightly but there is now way to stretch the connecting rods to make them longer. The solution was to get a new set of rods etched.

A few days ago the new rods arrived in the post having been etched for me by Narrow Planet. On it's own that might not be worth a blog post, but what you are looking at is the first set of etched components for which I've drawn the artwork! Okay, so Steve did tweak them slightly but I did the majority of the work.

I actually only need two rods but these are etched onto 0.25mm nickel silver whereas the kit uses 0.5mm, although it seems to measure out nearer to 0.4mm, so I'll probably have to laminate two rods together to get the right thickness and strength, although it's tempting to see if I one rod is strong enough as this will improve the tight clearances involved.

Now I know roughly what I'm doing I've moved on to drawing up the artwork for the body panels for the tiny Hudson-Hunslet but that can wait until the next post.

A.G.W.I. Oil Refinery Wagons

This isn't going to turn into a 1970's comedy show but it's time [and] now for something completely different..........

I was recently rather worried by the fact that Parkside Dundas were listing their 5.1mm narrow gauge wheels as both out of stock and out of production. This was seriously worrying as I use these wheels in most of the 3D printed narrow gauge wagons I've designed and without the wheels the wagons wouldn't be much good. I sent a rather panicked e-mail asking if they were ever intending to have more stock and received a prompt answer saying that more stock was on order. The site hasn't been updated yet but hopefully I'll be able to order some more soon.

A few days later I saw a posting over on NGRM by Jam describing his new layout, which you can also read about on his blog. He'd been asked about the rolling stock he intended to use on his layout which is going to be based on the narrow gauge railway that used to serve the A.G.W.I Oil Refinery at Fawley in Hampshire. He mentioned that he'd seen some flat wagons he wanted to use but that the Parkside Dundas wheels were currently unavailable. I replied to let him know that they should be available again soon only to discover that the wagons he'd been looking at where the freelance wagons I designed back when I started modelling narrow gauge railways! A quick look at a the few available photographs of the wagons used on the line and I could see why my flat wagons had appealed but I decided that it would be fairly easy to update the 3D model to more accurately represent the wagons from the refinery.

Unfortunately neither Jam or I have been able to find any scale drawings of the wagons, so I've had to work from just four photographs which appear in the book "The Calshot and Fawley Narroe Gauge Railways" by Frederick W. Cooper. Fortunately one of the photos includes the end of a wagon end on to the camera so given that we know the line was 2' gauge I could easily determine the total width of the wagon as well as some of the details. Jam had already decided to use the PECO model scene oil drums to represent the asphalt barrels and amazingly the width I came up with was an almost perfect match for three barrels as shown in the photos.

With the width worked out and knowing that the wagons were long enough to hold four barrels (photos show them holding 15 barrels, three across and five along the length of the wagon, but the fifth one is always about to fall off the end) I could then work out the length of the wagon and the remaining details. With the rough model posed to match the photos it looks like I've got the basic geometry correct at least.

This render shows that I still needed to add final details (bolts etc.) but most of that will have to be from guesswork as I can see almost no bolts on any of the photos (the quality is just too low), but there are some places where bolts would be needed to hold everything together so I'll at least add those before I order a set of prototype prints.

At Long Last

As long time readers of this and my other blogs will know I've been trying to catch a steam engine passing along the line at the bottom of my garden since 2009. The first time I just saw smoke, the second time the train was delayed until after it was dark and again I just saw smoke. On the third occasion, I managed a couple of pictures of it crossing the viaduct on it's way out of Penistone having seen smoke as it passed the bottom of the garden. This time, however, I was ready in time and it wasn't delayed. So finally I give you video evidence of not one, but two steam trains going across the bottom of our garden.

Now With Two Working Axles!

This will probably be the last post for a while on the tiny Hudson-Hunslet locomotive I've been building but before I show you the current state of affairs I thought a quick recap was in order, especially for anyone who has joined us part way through.

In the break between Christmas and New Year I came across a set of scale drawings for the small 24HP diesel locomotive produced by the Hunslet Engine Company and distributed by Robert Hudson Ltd. As the Robert Hudson works at Gildersome were probably the closest narrow gauge tracks to have existed to where I grew up I thought having a go at building a locomotive they sold seemed like a good idea. While I was able to fairly easily turn the drawings for the body into a 3D model and to produce some nice looking renders I didn't initially know how I was going to be able to power the model.

Given that it has a tiny wheelbase (2' 10" on the prototype so just 11.33mm on an OO9 gauge model) and I wanted to produce a cabless version I couldn't find a suitably sized motor bogie I could use, so I decided to try and print the chassis as well as the body. I printed the body using the FUD material from Shapeways and this turned out nicely. The first attempt at a chassis I printed in the hard wearing nylon material (black strong and flexible) that Shapeways also offer. Unfortunately while the dimensions etc. of the printed chassis seemed right, I was unable to actually get it to work.

While the first chassis didn't work I did learn a lot and received a lot of helpful feedback. Most of the feedback suggested that I alter the chassis so that I could fit brass bearings to support the moving parts. While this sounds like sensible advice I didn't want to sacrifice the shape of the chassis I'd designed (it would need to be bulkier to have room for bearings) as this would compromise the final look of the model. The solution I settled on was to have the chassis 3D printed in brass.

After a few initial teething problems I managed to get the printed brass chassis up and working, albeit directly connected to a power source. By the time I'd wired the chassis up so that it would collect power from the track one of the worm gears had come loose and so the front axle wouldn't turn, although the power from the rear axle was enough to make it move very slowly along the track. And that brings everyone up to date.

While the current version is still just a prototype and the next version will be improved, mostly to make assembly easier, I still wanted to see if I could make this version work properly. So yesterday I completely stripped down the chassis and re-built it. To avoid getting glue into the bearing surfaces (like I did the first time) I took a razor saw to both worms to cut between the teeth until a small hole appeared through into the central shaft hole. I then reassembled the chassis without using any loctite on the worms, which meant I didn't get any into the bearings. Once everything was in position I then added loctite through the small holes I'd cut which fixed the worms in place. Unfortunately I managed to somehow destroy the motor I was using (I'm not sure how, maybe I pulled too hard on one of the wires and broke something inside) so had to swap it for a spare, but after re-assembly I ended up with..... two working axles.

So there we have it, I've managed to design, have printed, and assemble a complete and working locomotive! It is still a prototype though so next I'm going to tweak the chassis to make it easier to assemble, make a few minor changes to the body, and I need to draw up the artwork for etching the remaining body panels. All this will take some time, hence there probably won't be a post on this topic for a while, but I've proved that the idea works and I've already had a number of requests to turn it into a kit!

Now on Sale in an Actual Shop

If you cast your mind back to just before Christmas I announced the availability of 3D printed chimneys and finials based on those found on the Woody Bay station of the Lynton and Barnstaple Railway. In January I even showed you the first batch packaged and ready to send out to people who had ordered them from Narrow Planet. Well now I can go one better and show you them on sale in an actual shop!

The shop at the Ffestiniog and Welsh Highland Railways Harbour Station in Porthmadog ordered ten sets and John (aka Lord Stoner) was kind enough to take a photo for me after he'd put them on display. There is something extremely satisfying about seeing them on sale next to other products in an actual shop.

Going Wireless

So having got the chassis for the Hudson-Hunslet diesel to work the next stage was to fit the pickups so that it could collect power from the track. As the chassis is brass and will conduct electricity this process is simplified slightly as I only need to add pickups to the insulated wheels the other wire from the motor is then soldered directly to the chassis. The process is complicated though by the need to include a resistor to protect the 6V motor from the full 12V that can be supplied through the track.

As you can see there isn't exactly lots of space to add the pickups and resistor. The pickups are obvious, and they are soldered to one end of a little black rectangle which is the surface mount resistor. This is soldered to a tiny bit of copper clad board which is stuck to the chassis. The board is pretty much the same size as the resistor so you can't really see it. The black wire from the motor then feeds down through the inside of the chassis and is soldered to the other end of the resistor (the blob of solder at the bottom of the resistor in this picture). As you can probably imagine this is kind of fiddly to fit, although I amazed myself by getting it on the first attempt. I think the trick was to not use electrical solder from a roll, but to use the solder paste I've been using for kit building. As well as being easy to accurately position using the syringe it helps to hold things in place and then just a quick touch of the soldering iron creates a nice small joint. Of course the real test would be if it actually worked when placed on some powered track.

As you can see the answer is partially. The problem is that the worm nearest the pulley is now completely loose (I mentioned in the previous post that it seemed loose) and so the front wheels aren't turning. I've been given a suggestion of how to fix this without completely stripping the chassis down but I haven't had the chance to try it out yet. Either way I'm really happy now that it's picking up power from the track and moving, albeit slowly. Yes there are things to adjust to make assembly easier and I need to find places to add extra weight but I think that I've more than proved that the idea works.

To give you an idea of just how small this locomotive is here are a couple of photos of it with my other two completed OO9 locomotives, neither of which is very big.

Yes it really is tiny. In fact the body measures just 15mm by 30mm and is just 20mm tall. Not quite watch-making level of tiny but not far off!

It's Alive!

Monday saw the arrival of the latest set of printed prototype parts from Shapeways which means I've been able to have another go at building a chassis for the tiny Hudson-Hunslet diesel I've been working on. If you remember from last time while the parts all seemed to fit together I couldn't actually get it to work. Of course, since then I've bought the right tools for the job so should have no problems with clearances this time.

While I still think I could make the chassis work using the cheap 3D printed nylon material, a lot of the feedback I got to the first design was that I really should be using brass bearings. The problem is that because of the size of the chassis and my wish to have clean air between the wheels, there really isn't room to print a big enough hole to take a bearing. Of course that doesn't mean I can't have brass bearing surfaces as Shapeways offers brass as one of it's materials. Technically it's not 3D printed brass as they actually print a 3D wax and then use that for traditional brass casting. The end result though is that I can have the chassis made from brass.

On first impressions it seems to have come out really well and seems to be dimensionally accurate and a nice fit inside the 3D printed body. Of course I still need to ream out the holes and in the first photo you can see I've only done the right hand set, while the left hand set are as printed. In the second photo I've finished reaming out all the bearing holes using the 1.55mm reamer you can see hiding at the back.

Once all the holes had been reamed out I set to assembling it starting with the layshaft and worms. It took me three attempts to get the thing assembled as on the first two goes I managed to glue everything solid. I'm using Loctite 243 for this, which is designed as a thread locker but works well on none threaded parts as well. Unfortunately in this case it works too well. The problem is that I had to put the Loctite into the holes in the two worms and then push the layshaft through them. As you slide the shaft through it gets covered in Loctite which of course then gets onto the bearing surfaces and everything locks solid. On the third attempt I used a lot less and then oiled the bearings as best I could before applying power and after a little initial prodding this was the result.

I'm amazed how quite it is when run like this, but I'm also rather impressed that I got a stage further than last time and that the motor turns the layshaft without issue. I left it to run for about an hour to make sure the oil worked into all the bearings nicely and to make sure there was no remaining Loctite that could cause problems.

With the layshaft working I turned my attention to the wheels. Each axle also needs a gear adding as you fit it, and again these should probably be glued in place, but for now they are just a loose friction fit as I didn't want to waste them if it didn't work, and unlike the layshaft I'm not sure if I'll be able to get the requisite purchase to remove the wheels once fixed in place. Anyway even with just a friction fit the result is this:

Amazingly it all works nicely. This also shows just how small the chassis is as it is too small to sit properly on the rolling rod for testing. Getting this far has highlighted one problem though in that the worm nearest the pulley seems a little loose on the layshaft. I'm guessing this is because it has almost all the layshaft pushed through it so will lose more Loctite than the other worm during fitting and I used the smallest amount I could to avoid gluing everything solid again. In hindsight this was a bit of a design flaw so I'm going to tweak the design to make assembly easier, probably by dropping the central layshaft supports which will allow the worms to be fitted and then secured in place.

As you can imagine I'm seriously happy with how well it's gone so far. I need to figure out a set of pickups for the insulated wheels next and wire in a resistor so it can be used with a normal 12V DC supply (the motor is rated for 6V and I've been using a 5V supply for testing) but it certainly looks as if the approach will work even if it needs a little refinement.

Is There a Point in All This?

So having built the track for my Hudon's Pizza layout and bought a baseboard I've now come to a bit of a halt while I decide what to do with the extra space available. If you remember back to when I first introduced the idea for this layout I showed both a map and an aerial photo of the test track.

Both of these seem to show that the test track is completely isolated from track anywhere else in the works. Given that Hudson's did deal in portable railway systems I'm guessing they were use to having to manhandle rolling stock, but it does seem kind of odd that at their works they wouldn't have made access to the test track easier. I also have a thread over on NGRM about the layout (you have to sign up to be able to read that link unfortunately) and on there someone suggested that maybe there was a point on the test track with rail leading off to the top left. As hard as I looked I couldn’t see anything though.

You'd think, given how much railway equipment Hudson's produced, that it wouldn't be too difficult to find photos of their main works which would clear up the issues regarding how the test track was used. Unfortunately the only other photo that has turned up is this one, which appeared in NG&IRM issue 36.

Certainly from an initial glance this photo of a 'Ganges' class 0-6-0WT doing laps of the test track doesn't exactly show a lot of detail. Upon taking a closer look though I started to notice that what looked like rails to the top left of the locomotive wouldn't match up with the rails just in front of it. To see what I mean here are two cropped and zoomed versions of the loco and on the right hand one I've drawn red lines over anything I think is rail.

So, if everything I coloured red is definitely rail then there is no way they join up in a complete circle, which leads me to the conclusion that I'm looking at a point leading off the test track. Given that my layout was always going to be inspired by rather than a reproduction of the works I now have to decide what I want to do. On the one hand I have a circle of track built and ready, but on the other hand I've got space for a little more track, and if I can avoid having to resort to the "hand of God" to change stock on the circle of track that would be nice. The problem of course is that I've no idea if I'm capable of building a working point. Plain track I think I've mastered well enough for it to work reliably but a point is a whole different game, made more so by the very tight radius of the circle it has to fit into. I'm not going to make any decisions yet, but I think I am going to have a go at building a working point (will be useful to know for future layouts if I can build one) and then see where that leads me. It does of course mean that there is unlikely to be any scenic work on the new layout for quite some time.

It's Bigger Than I Thought

So Hudson's Pizza has taken a small step forward today as I popped out and bought the baseboard; as I did for Jerusalem I've gone with 9mm MDF (68cm by 53cm). As I'm not planning to mount anything under the baseboard this works well. It's fairly light but gives a strong foundation and doesn't take up too much of the depth of the storage box I'm intending to use to keep the layout in.

The main issue that has arisen is that I've actually got more space to play with than I thought I had. I built the track to match the prototype (see this previous post) and then sized the board based on the storage box. In my head they were a lot closer in size than they have turned out to be. I'm still trying to work out exactly what I want to do with the extra space but I'm thinking some extra track in amongst some builds to add a little more movement to the layout. Building mockups will be next which should help me decide exactly what to add in the space.

Just Like Pulling Teeth

Six days before I got married I was sat in a dentists chair being treated by a trainee dentist. I'd managed to break a tooth and the remaining stump had to be removed. After half an hour of pulling on the stump he gave up and let the supervising dentist take over. She had the tooth out within about 10 seconds.

It turns out that removing gears and wheels from an axle is a bit like pulling teeth. Experience and the right tools and it can be a quick and (fairly) painless process. Use the wrong tools and it can be a slow and frustrating process.

When I built the first test chassis for the Hudson-Hunslet diesel I found getting the wheels off the axle exceptionally difficult. It's supposed to be possible using a set of pliers and a hard surface, but that didn't work well for me and in the end I destroyed one insulating plastic part and bent an axle. Now the wheels aren't two expensive (£1.25 per axle) but I wouldn't have to ruin too many before it got costly.

The solution of course is to buy a tool designed for the job, specifically a small gear puller. A number of people made suggestions but in the end I went with the NEEWER W010 gear puller. According to the box this seems to be designed for people building remote control helicopters but it seems perfectly suitable for railway modelling as well. It comes with five different size pins to allow for different sized shafts. There are no measurements given but three are completely round and measure (according to my callipers) 0.8mm, 1.58mm, and 1.85mm. There are also two pins that are mostly round but have a flat side, the round part of these measure 1.70mm and 2.7mm.

So far I've tested it by removing a wheel from an axle and pulling a worm from a layshaft both of which it did without any effort at all. If you are tempted by one be careful where you shop though. I bought mine from Amazon and paid £11.95 although the price does seem to fluctuate a little. If you look on eBay though they seem to be on sale for around £112! I think someone got the decimal point in the wrong place but amazingly the page suggests that they've sold at least 17 at that price. Some people really do have more money than sense.

Having the Right Tool for the Job

Work has been keeping me very busy recently so I've not had much time for modelling. Plus I'm still waiting on the next round of prototype parts for the small Hudson-Hunslet diesel I'm trying to build. This slight lull in modelling has at least allowed me to collect together a number of new tools that should increase the chances that the second prototype locomotive will work a lot better than the first. Given the lull I'm going to spread these out across a number of posts and today we start with a 1.51mm straight chucking reamer.

One thing I wanted to avoid when designing the chassis for the locomotive was too much space for the axle and layshafts to move around as that would seriously affect the running. To try and ensure a sensible fit I designed all the holes to be the exact same size as the part that would fit through them. In fact all the holes are designed to be 1.5mm in diameter as both the layshaft and axles are 1.5mm. My plan was to then ream out the holes until I got a nice sliding fit. In fact my first attempt failed probably because I didn't ream out the holes far enough. Part of the problem was that I was opening out the holes using tapered reamers.

I own a cheap set of tapered reamers which allow me to easily open up a hole, but they don't give any control over the size of the resultant hole. Also it is often difficult to ream out a perfect cylinder given that the reamer is tapered and you can't always access both sides of a hole. I'd always assumed this was something we just had to live with until Jeff (in a comment on NGRM) introduced me to the concept of a straight chucking reamer which are apparently the tool for reaming out bearings. Given the wonderful chassis Jeff has produced I wasn't going to argue with him.

As you can see this reamer isn't tapered (it has a very slight taper at the point to help start the hole) and looks more like a drill bit. This allows you to ream out a perfectly sized hole, which as Jeff pointed out, is exactly what you want for a bearing. As both the axle and the layshaft are 1.5mm in diameter the suggestion was that I should buy a 1.51mm reamer. Unfortunately it turns out that while the wheels I was using are advertised as having a 1.5mm axle they actually measure out at just under 1.54mm so I was rather annoyed to find that they wouldn't fit through my perfectly reamed out hole. The layshaft fitted very nicely though. My annoyance was exacerbated by the cost of the reamer.

I have a set of 20 mini drill bits that cost me around £10 and a set of 5 tapered reamers that I think were about the same price so I was rather shocked to discover that the cheapest 1.51mm straight chucking reamer I could find (part number A01510BAM from Toolex) would set me back £25! Now you can see why I was annoyed to find the axles were larger than advertised. My initial plan was to use the reamer for the layshaft holes and then open up the other holes in the second prototype using the tapered, but less exact, reamer. Since then, however, I've tweaked the chassis design and it would now be very difficult to ream sensible bearings using a tapered reamer due to the size of the bearing holes and access to both sides of the holes, so I've now invested in a 1.55mm reamer as well (part number A01550BAM) and on a quick test with some scrap this produces a perfect hole for the axles.

So two new tiny tools for almost the cost of a small locomotive kit, but hopefully they'll allow me to produce a number of my own models, which might in turn become kits and cover the cost. Not sure how successful this will be, but I can guarantee you'll get to read about the journey.