Terrier Chassis - Episode 5

Still making progress, and still making mistakes. The etched chassis does not include any provision for mounting the motor, but I spoke with Jerry Clifford at the Didcot exhibition who said he fits a piece of plastic onto the centre frame spacer, files a curved saddle into it and glues the motor to that.

I always want to be a bit different, so I thought a blob of Milliput might form a saddle without the need for filing. My first attempt started well, but as the Milliput took a long time to harden, the weight of the motor, and possibly the attraction of the magnet to the steel tyres, meant the motor ended up not quite parallel to the chassis, and the worm sat right down on the worm gear too tightly meshed. I pulled it all apart and tried again. This time I added a piece of thin paper onto the worm gear, forcing it down into the teeth with a fingernail, so that the worm should end up at the correct meshing distance.

I took some video of the chassis in action before the Milliput had set on the first attempt, which looks encouraging:

And a photo of the second attempt with the paper spacer on the worm gear:

Preparations for adding the Dapol footplate and body are underway. Two pieces of the footplate have been removed to make room for the motor, but still leaving the fixing holes for the lugs on the body. I had to remove the smokebox door (which is a push-in to the boiler end) in order to push out the weight. The slot in the weight is not big enough to take to new worm and will have to be enlarged. Once that is done, the body should fit without further fettling. Indeed, there should be room in the side tanks to fit extra weights. I have not decided where to put the DCC chip yet.

Still to do is fit crankpin washers and see if everything will fit between the steps of the footplate. Then there is the brake gear to put together.

Terrier Chassis - Episode 4

Having produced a free running chassis at the end of the last session, I had to disassemble it in order to add the 'Simpson Spring Pickups'. These are pieces of fine phosphor bronze wire, acquired by straightening out some unwanted N gauge coupler springs. They are soldered at one end into holes in the chassis and pass behind each bearing so they will rub gently on the axles with the absolute minimum frictional force. The axle muffs need to be shortened to make room, and must have smooth ends so as not to catch the wires.

Once the six pickups were fitted, the chassis was cleaned in an ultrasonic bath. Small balls of White-Tac were pushed onto each side of each bearing and the chassis was then sprayed with Halfords matt black. Once dry, the White-Tac was removed.

The wheels, gears and con-rods were fitted again. After tweaking the quartering for a while, the chassis was once again free running.

Sorry the photo is confusing, the gears are driving the front axle of the locomotive, but I did not think about it when setting up the photo.

The next job should be to fit the motor, but instead, I wanted to see how much work will be required to fit the Dapol footplate. Having dismantled the Dapol Terrier, and removed the motor and its cage from the footplate, it was obvious that not much work is required. I had to remove some plastic from the rear of the front sandboxes, and file a little of the front spacer PCB on the chassis for the plastic clip to fit, and then the footplate went onto the chassis. The gears were catching on the footplate, so a little filing was needed there. Unfortunately, it looks like the footsteps will have to be removed to make room for the con rods and crank pins, and remaking them may be a bit tricky. Also, more of the footplate will need to be removed to fit the motor, but on the whole, it looks promising.

Terrier Chassis - Episode 3

More slow progress this week, and a sense of achievement. To put this into perspective, I have to admit that in the 25 years that I have been a member of the 2mm Scale Association, I have attempted to build a number of chassis for a variety of locomotives, using several different techniques, none of which were completed. I had at least 5 tries at making a chassis for an S15, using phosphor bronze strip for frames, as was recommended in those days. I just could not drill and ream holes without them drifting away from where they should be, resulting in gears that just would not mesh. A similar chassis for an E4 had similar problems. Switching to etched nickel-silver chassis should have improved things, but a 3F Jinty and an 09 diesel shunter build both stalled with gear meshing problems from what appeared to be eccentric gears. The Terrier chassis build has benefitted from using turned axle muffs, which appear to result in gears that run true and concentric with the axle.

At the end of the previous episode, I had the worm gear on its idler axle, with an intermediate gear meshing perfectly with the final gear on the rear axle. This week, I added the crank pins to the wheels, fixed with a touch of solder on the rear. I reamed out the axle holes and muffs for a good fit for the wheels. I folded up and soldered the con-rods, and reamed out the holes for a good fit on the crank pins, and put them together and quartered the wheels, mostly by trial and error. After assembling, dismantling, gentle reaming, and assembling again countless times, I eventually produced a free running chassis, with almost no slop, and no wobble anywhere. Indeed, it is so free running, it can be pushed gently on a rubber cutting mat and the wheels turn under its own, featherlight weight. This is a first for me.

 A video of it running on a 'push test'.

For the next episode, I will probably mess it all up as I add 'Simpson pickup springs' and paint the chassis, ready for mounting a motor.

Terrier Progress - some gears

I have now received a new set of wheels of the correct diameter (8mm) and I have given them a quick spray of primer (one set black for my second Terrier and this set grey for painting green and black for my Southern livery Terrier).

The next job on the chassis was to drill out the 0.3mm holes for fitting the brakes and the 'Simpson Spring' axle pickup wipers. Two of the brake support holes require drilling into the side of a glass fibre PCB spacer. Typically, my drill bit broke doing the last hole. I had to unsolder the spacer, remove the broken drill bit, put the chassis back into the jig and resolder the spacer. Then I had to redrill the holes with a fresh drill bit.

Now I was ready to start fitting the gears to the accurately turned 'muffs' and fit them in the chassis temporarily with some long pieces of axle steel. The muffs needed a little triming to length, and drilling and reaming to give a tight push fit on the axle steel. I also drilled across the centres of the muffs to let air escape and to insert superglue if required when the wheels are finally fitted. The gears were deburred with some fine emery paper and then fitted to the chassis. They would not turn. The main worm gear was fouling the axle muff. I took the axle muff, inserted a length of axle steel and mounted it in the jaws of a mini-drill. I then used a good small file to reprofile the muff to give room for the worm gear to rotate. Once refitted, everything turned freely. The turned muffs do appear to be better than the old ones. I might return to the '09 Diesel Shunter' I started building previously that suffered from non-concentric gears, to see if they improve things.

Well, that was it for the evening, the broken drill bit and gear-muff interference problems meant I did not have time to fit any wheels. Hopefully next time ...

Fiddling with the Fiddle Yard

Not much progress to report on my Freshwater layout itself, as various projects have stalled for one reason or another. However, with some exhibition bookings a couple of months away, I had to make some progress somewhere. I turned to the fiddle yard.

Originally, in the rush to complete the layout for the 2mm Scale Association Golden Jubilee Challenge, I just roughly laid a few 60 foot track panels on double sided sticky tape across the fiddle yard and joined them up electrically. This single line has sufficed so far, but it did mean a passenger train had to be taken off or put back on again when required.

Five years later, and the sticky tape is not as sticky as it once was. Track panels started coming loose. I decided to take the opportunity to add a point while I was relaying the track. This would pretty much double the capacity of the fiddle yard, although slightly reducing the train length. So I built my very first EasiTrac point, with a 1:6 crossing so it would be as short as practical. The point, and track panels, were glued down with EasiTrac glue this time.

I laid the plain track straight, at the diverging angle from the crossing, for several reasons:

1. There was room to do so
2. it is easier to put stock on straight track than on curved track
3. it is easier to put stock on when another track is not too close to it

I decided on a low-tech approach to point operation, similar to that used on my previous layout 'Brunswick', in complete contrast with the Merg CBus controlled servos and under-baseboard tie-bars used on the layout itself.

A piece of glass fibre PCB is used as a tie-bar, and an electrical toggle switch, mounted on a bracket from the DIY superstore, provides both the mechanical movement and the electrical switching of the frog. The switch is connected to the tie-bar with some Plastruct pieces (the outer tube section being glued to the baseboard with a smaller rod section free to move back and forth inside) and some pieces of wire guitar string.

A Terrier for Freshwater

As anyone who has seen my layout at exhibitions can tell you, so far some very unlikely motive power has been operating the Freshwater line of the Isle of Wight. I do intend to rectify this, but getting the layout operating smoothly, and scenery added were higher priority. I have acquired some Dapol A1X Terriers (one at least with the correct extended bunker) ready to be converted to 2mm finescale. Many months ago I started work on modifying the original chassis, as per an article in the 2mm Scale Association magazine. I even 3D printed some replacement gears incorporating axle muffs, to replace one of the originals that I ruined while reaming the centre hole. The hole had drifted off-centre. Just a couple of weeks ago, I had the chassis running, although its starting speed was about 40mph. I even got as far as connecting a small DCC decoder, and this actually improved it, with much better starting and stopping. However, electrical pickup was still a bit hit and miss.

Then, the long awaited replacement chassis etches appeared on the 2mm shop lists (3-661). A couple were ordered. There are no specific instructions for the Terrier chassis, just the generic build instructions, plus a couple of drawings hidden away in the 2mm VAG files area. After a couple of emails to Chris Higgs,I put together a parts list:

• 6x crankpins and washers (3-107 & 3-109)
• 1x 30:1 worm and gear (3-364)
• 2x gear muffs (3-102b)
• 2x axle muffs (3-100)
• 1x 14 tooth M0.3 gear (3-390)
• 1x 22 tooth M0.3 gear (3-394)
• 6x 8mm driving wheel (3-005)
• 8x frame bushes (3-113)
• PCB strip (3-156)
• Nigel Lawton 8mm dia x 16mm Midi Motor

The Terrier chassis etch has some differences from the other chassis etches:

• There is no fold up gearbox for the worm assembly
• There are frame reinforcers to be 'sweated' to the insides of the main frames to strengthen them.

So, for my first evening working on the chassis, I started by folding up and soldering the chassis building jig. With luck it will survive long enough to be used for the second chassis.

Then I started on the chassis frames. Unfortunately, the reinforcers are not arranged on the etch as a 'fold and align' arrangement like the coupling rods and bosses are, but need to be cut out separately before attaching to the main frames. Where the idler gear axle bush cutout is on the frame reinforcer, it dissects the top edge leaving a very thin piece of metal keeping the two ends of the reinforcer together, so must be handled with care. It might be possible to use some fine rod in the brake gear holes to align the reinforcer and the frame when soldering them together, but the rod would probably get soldered into the holes at the same time. I therefore aligned them by eye. Alignment needs to be accurate, or the frame bushes will not locate properly into the frames.after sweating them together, I inserted the frame bushes into their holes and soldered them in. The holes needed to be reamed a little to get them to fit. This requires a slightly larger reamer than found in the usual, cheap reamer sets.

The PCB tabs were then folded at right angles. The tabs with holes in, I folded along the wrong fold lines, so I will have to rectify this later. The frames were then fitted into the jig, and axle rod inserted, as shown. This completed the evening's work. Next time, the PCB spacers need to be added, then I can try it with wheels and gears, and add the coupling rods. Then I have to ponder fitting the motor and worm.

On show at Portsmouth

Someone asked for more photos of the water tower, so here are some I took during the exhibition