Thursday, December 24, 2015

Happy Christmas!

Rail Cutting Jigs

So having given you a few days to think about the mystery 3D printed objects I'll put you all out of your misery. They are jigs to help cut rail at the correct angle for making Hudson Type 1 and Type 2 points in O14. While I have the KBscale jigs for actually soldering the rails together they rely on you cutting or filing the rail ends to either 15 or 9 degrees and I found doing this accurately was a bit of a nightmare and so a jig or two sounded like a good option.

The printed jigs are actually the third iteration of the basic idea which was to trap the rail in such a way that a razor saw could cut it at the given angle. The first attempt, which I've unfortunately thrown away so can't show you, used four pieces of 4mm square section styrene stuck to flat sheet, two on each side of the rail. The pieces on each side were offset so that you ran the saw across the rail resting it against the ends of the blocks. It worked well enough to produce the first crossing I made but it wasn't easy to hold the rail still while pushing the saw against the blocks.

The second jig used 12BA nuts and bolts to both clamp the rail and to help position the saw. The screw holes being carefully positioned so that they both allowed the nuts to grip the web of the rail, but also to act as the guide for the saw. While this was much better at keeping the rail in place it was still difficult to keep the saw in place against the upright screws, there was a danger of sawing into the nuts, and the cheesehead screws meant that the jig wasn't very stable on the worktop. It did, however, allow me to build two Type 2 point without requiring any extra filing of the rail ends.

The printed versions continue the idea but without relying on the screws to guide the saw. The two printed parts are used to clamp the rail in combination with grooves in both halves. The slightly bendy nature of the strong and flexible plastic is actually really useful here as it allows you to really tighten the jig so that the rail doesn't move at all. The saw then fits within in the guide formed between the top part and the block on the bottom half making it much easier to cut the rail.

I haven't had a chance to build a point using the new jigs but I have cut a couple of rails to check that they work and they appear to work very nicely which should make it easy to churn out more crossings in the future.

Tuesday, December 22, 2015

Christmas Mystery Objects Quiz

I seem to spend a lot of time over the Christmas period doing quizzes of one form or another. This year the GCHQ one is worth a go if you happen to like your quiz questions on the fiendish side. Anyway I had a Shapeways delivery this morning that contained a couple of test pieces that I thought I'd turn into a mini mystery object quiz. So without further waffle what are these?

Sunday, December 20, 2015

Driven By Him

So here we are, the last post on the build of this the third Clayton prototype (the second never got made up but allowed me to test the keeper plate). The driver is now in place which means the whole loco now weighs in at 34g. Possibly a little light for an O14 loco but there isn't much space to add extra weight.

Obviously it's not entirely finished as it needs painting and the name and works plates fitting but these will be left to David as my painting skills aren't up to producing a loco that would fit in well with the quality of Rhyd. It seems strange packing it up to send it off to it's new home as I've never built a model for anyone else before. Hopefully David will enjoy it and if you see Rhyd at an exhibition you might even see the Clayton working the quarry tramway. For everyone else here is one final video of the loco in action.

Starlight Express

One of the first comments I received when I announced I was working on a model of the Clayton was that the light mouldings really were crying out to be fitted with working lights, and who am I to refuse such a sensible suggestion. The problem is that while the mouldings are big in relation to the size of the model they still aren't very large. Fortunately LEDs are available that will fit but they are very very small.

The smallest surface mount components I've used before are the resistors in the Hudson-Hunslet, which come in a 1206 package. They are known as 1206 as that is the imperial measurements of the component, i.e. 0.126" by 0.063" or in metric just 3.2mm by 1.6mm. For the lights on this loco I've had to go for LEDs in a 0402 package which is 0.039" by 0.020" or an eye wateringly small 1.0mm by 0.5mm. Given that those dimensions are for the entire LED you can probably imagine just how small the two contacts are that you need to solder wires to. My eyesight for close work might be quite good and I have a brilliant magnifying lamp on my desk but I don't think I would have the patience or dexterity to wire these up. Fortunately you can buy them pre-wired on eBay! This helps but the wire itself (referred to as magnet wire) is also ridiculously thin so it's still a fun challenge wiring these up.

Of course there isn't just the LEDs to wire in, but a resistor to protect them from the full track voltage (2.2K Ohm in this case) and a capacitor to help reduce flickering all of which need to be connected together and then stuffed into the small space behind the motor.

As you can see there is quite a bit of stuff, even if some of those wires were trimmed back before I finished) to get into the body so there was a fair amount of careful stuffing involved. Once the body was on the result though is this.

I could probably have used a slightly bigger resistor to drop the brightness a little further but for a loco that originally worked in a long dark tunnel this seems okay, and a bigger value capacitor might have reduced the flickering a little further, but in general I'm really happy with the result.

Saturday, December 19, 2015

Powered Chassis Test

After a break of afew days due to visiting family I'm now back to building the Clayton loco and fortunately, given the little time remaining to post it on Monday, things seem to be going quite well, although the carpet monster did eat the small pulley although it then spat back two 1.5mm bearings! Anyway here is the current state of play.

The main job today is to fit and wire up the lights, and then I can add the final body details. Then tomorrow I need to finish the driver figure and to give the whole thing another good test run.

Tuesday, December 15, 2015

A Tiny Worker (Bee or Ant)

As you probably all gathered I really enjoyed building the Blacketty Water bridge model for this years Dave Brewer Memorial Challenge. Being given a set of constraints and a time limit helped me to focus and build something I'm really proud of as well as learning a whole new bunch of skills. I was expecting the challenge for 2016 to be announced sometime early next year, given that this years challenge was announced at the end of February, so I was a bit surprised when the announcement came at the end of November. There will be a blog post about the new challenge at some point as I do have an idea for it, but this post is about another challenge that I'm going to enter that was announced on the same day.

In general I'm not a forum person, the one exception to this is Narrow Gauge Railway Modelling Online (usually just abbreviated as NGRM) where I'm now a frequent visitor and poster. In the past they have held modelling challenges and they have decided it is time for another one, specifically to scratch build a locomotive. There is a full description and set of rules on the forum (you have to be a member to read them I'm afraid), but the motivation is

This challenge has been created to promote scratch building using various tools and materials. Over the years I have seen some very interesting locomotives scratch built using the very basic of hand tools in plastic, brass, and complete mix of other materials. You don't have to be a professional model maker to take part, all you need is patience and basic hand tools. Entrants are asked to respect the spirit of the competition when taking part.
To try and interest as many people as possible there are three different levels:

  • Level 1: scratch built body on a ready to run chassis.
  • Level 2: scratch built body on a modified ready to run chassis (e.g. Farish 08 with added cylinders, valve gear etc.)
  • Level 3: scratch built body and chassis.

I've never scratch built a loco before, and certainly never a chassis, but personally it wouldn't be a challenge if I didn't go all in at level 3! Having decided to enter though I had no idea quite what I was going to try and build but, not surprising given the locos I've been designing and building recently, I thought I'd look for something small and quirky.

Fortunately the UK has it's fair share of both small and quirky locos so I didn't have to look very hard to find something and here it is (photo from Wikipedia).

This is one of two locos (this one is Bee the other is Ant) that were built in 2004 for the Great Laxey Mine Railway on the Isle of Man. They are replicas of the original locos used at the mine which were unfortunately scrapped in the 1930s.

It should be clear from even just a quick glance at the photo, that this loco is both small and quirky. Having managed to find a set of drawings (thanks Rob) that appeared in the April 1991 issue of 009 News, I know just how small it is. According to the drawings it's just 4' 9" from rail to chimney top, but more interestingly the track gauge is just 19", which is really very narrow.

As yet I haven't decided what scale to build a model of this loco in. I had wondered about using a standard track gauge (9mm, 14mm, 16.5mm etc.) and then picking a scale to match, but if I want to be able to put the loco with any scenic stuff or figures etc. then using a standard scale and hand building track to match probably makes more sense. My current thinking is possibly to go up yet another scale from my usual modelling to 16mm to the foot scale, which will still give a tiny loco; just 76mm from rail to chimney top. I need to make a few more measurements before making a final decision though.

The Keeper Plate

One of the parts I had to redesign from the second prototype of the Clayton was the stainless keeper plate. If you remember I'd managed to design it 0.2mm too wide and reducing the width by hand was a nightmare due to the strength of the stainless steel. So I altered the design to remove 0.1mm on both sides, and opened out the screw holes slightly for an easier fit. The larger holes meant a change to the rebate for the head of the screw as well.

As you can see the changes worked well and everything fits together nicely. The two bolts are lightly glued into place just to make sure they don't come loose, and while the layshaft is now fixed in place (the two worms are fixed to the layshaft with Loctite which holds everything firmly in place) everything else is removable just by undoing the two retaining screws. Next job will be to strip it down again, and fit the pickups and associated electrical bits so that I can get it running up and down my test track.

Monday, December 14, 2015

The Bell

A quick update on another detail for the Clayton loco, this time it's the bell.

I don't think I mentioned this on the first prototype build but I've produced it in the same way by soldering a 4mm pinpoint bearing to an etched stand. Nice, simple, and fairly convincing from normal viewing distances.

Sunday, December 13, 2015

Some Assembly Required

After spending the day with friends I've done a little more on the Clayton build, specifically the rather fiddly brake leaver. This bit hasn't changed since I built one up for the first prototype so it still consists of eight tiny etched parts on a piece of 0.33mm nickel silver wire. Last time I found getting the front and back layers, which slot through the 3D printed body, aligned and straight very difficult, so the tool I included on the etch this time has two slots to make assembly easier.

So building the brake lever basically involves slowly laminating seven of the eight parts using the wire to help align them as well as keep them together. I pas the wire through a hole in piece of wood as well to help keep everything still while dabbing at it with a hot soldering iron. The eighth piece (the front support) is then threaded onto the wire with some solder paste on the wire and the whole thing then slotted into the etched tool to make sure the front and back supports are properly aligned. A quick touch of the soldering iron then fixes the front support in place and with the slots in the tool being the same as on the 3D printed body the completed brake just drops into place.

The tool also has a third use, in that the sticky out bit on the end can be used to make sure all the slots in the body are clear of wax support material so that the pickups, brake, and bell stand will all fit without being forced.

Tuesday, December 8, 2015

Phosphor Bronze Staples

If you've been following along for any reasonable length of time then you'll know that the main area that seems to trip me up building or designing model locomotives is getting the pickups to work properly. On the Clayton loco I think I've hit on a fairly good way of fitting the pickups where what looks like a staple of phosphor bronze strip is pushed through slots in the model from the inside with the ends then bent back at an angle against the outside of the body so that they rub on the rear of the metal wheels. The problem is accurately making the initial staple shape so that it fits perfectly as that helps with setting the tension of the pickups which if not right can affect the running of the model.

On the first prototype I folded up the staples by eye and while they were fairly good they weren't a perfect fit. With the addition of the keeper plate and retaining screws this is even more of an issue as I need to make sure the pickups are flat on the inside so they can't short against the screws. To help with this I designed an etched part to act as a forming tool (it actually has other uses so you'll see this part again).

The tool works well and as you can see the fitted pickup lays nice and flat against the inside of the body so it was well worth adding the tool to the etch. Hopefully it's other use will prove as successful but you'll have to wait a little to find out.

Monday, December 7, 2015

Weather Protection

With the base kit for the Hudson-Hunslet now out and selling well I've turned my attention back to producing a few cab varieties to help people customize their models. Today I got the test etches back for all three designs and have quickly put them together, not that there is actually much work involved.

So from left to right we have an open cab based on the one fitted to Macnamara at the Leighton Buzzard Railway. Then there is the half-open design which is inspired by the one on LCWW18 which is part of the Moseley Railway Trust collection. Finally we have the fully enclosed cab similar in design to the one fitted to Creepy which can also be found at Leighton Buzzard. If you fancy adding a cab to your model then All three cabs are available to buy from Narrow Planet.

Never Going Back Again

I've now made a start on building the third Clayton prototype. I'm still waiting on the etched parts to arrive (they've been posted so blame Royal Mail) so while I can't start on the body yet I can get to work on most of the mechanical aspects.

One of the main changes from both my approach to designing the Hudson-Hunslet and the first Clayton prototype was the decision to use a keeper plate and to assemble all the drive components outside the model. This means I can put together the layshaft and the wheelsets in comfort without having to try and fit everything together inside the body.

Compared with trying to fit gears inside a body this is so easy that I'm never going back to the old approach unless forced to do so for some reason.

Saturday, December 5, 2015

Turn to the Right

Having now recieved my order for more rail I've continued on with my O14 point building experiment. The first attempt was for a very tight Type 1 point which in retrospect was going to be a struggle even for short wheelbase locos so for my second attempt I've switched to the slightly less severe Type 2 point. Of course with more rail to hand I've gone a lot further than just building the central frog section, in fact I've built an entire point.

I've deviated from the suggested instructions in quite a few places though as I've built the point onto copperclad sleepers rather than the suggested plastic sleepers. This meant that I had to gap the rails to ensure that the polarity of the frog could switch when the points changed. I also simplified the tiebar slightly by not trying to fit nice looking plates and rivets but using a bit of wire instead. Of course photos on their own don't show you if any of this was successful or not so here is a video of me testing it.

So yes it does work, but I'm not entirely happy with it. Mostly I'm not happy with the hinges. Drilling the holes to make the two parts of the rail line up properly was a real pain. So having recently seen someone else build one without hinges where they relied on the rail flexing instead I'm going to have another go and see if that is a better approach. Still not bad for a first attempt.