Saturday, February 28, 2015

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.

Wednesday, February 25, 2015

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.

Friday, February 20, 2015

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.

Sunday, February 15, 2015

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.

Saturday, February 14, 2015

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.

Friday, February 13, 2015

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!