Thursday 26 November 2015

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.

Wednesday 18 November 2015

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.