An international forum for garden railway modellers in all scales and gauges. It is free to join and is funded through voluntary contributions by its members. Many thanks to all those who keep it going.
Well, I've finally got a cooling fan to try out, but first I thought I'd better fit the front grille. I didn't want to solder it directly in so had to cut out a steel retaining piece which sandwiches the mesh and is held in place with screws. Two days of sawing, filing, drilling and tapping.
Last edited by dewintondave on Sun Feb 09, 2020 4:48 am, edited 1 time in total.
dewintondave:108517 wrote: Two days of sawing, filing, drilling and tapping.
'Fess up, you enjoy that sort of thing or you wouldn't be building a live DM.........
It's looking good, but the engine doors do look a bit plain. Queensland cane tram style mesh openings might be worth considering as an alternative to louvres.
Coincidentally, your countryman Paul Berntsen has an article in the current issue of Narrow Gauge Downunder, showing how he built a 16mm scale Fowler PM. As is his way, he made a punch for forming louvres in the engine doors.
The project was slowed up by a slow delivery from Germany. I ended up fitting a centrifugal type blower fan to blow air across the cylinder fins. In all fairness the fan from Germany is excellent and almost silent (but I'm not using it after all, it's an axial type). Though having thought about it, silence isn't important in a live diesel set-up.
To help expel hot air from under the bonnet and through the mesh, I have installed two small fans at the top of the grille.
I need to sort out the electrics now. The fans are all 12V dc types
Last edited by dewintondave on Sun Feb 09, 2020 4:53 am, edited 2 times in total.
It's only a small issue, but I accidentally blew the 2.5V bulb in the headlamp by applying 6V to it. When I went to replace it, the new bulb was a good 1mm longer. It turns out that the original bulb was malformed and too short. I based the whole headlamp around that bulb, so I had to make an extender cap to fit over the rear cover. I've shifted to using 5.4 V bulbs from eBay now...
I've got a neat PWM controller from eBay to dim the headlight. I've been unsoldering the potentiometer from the PCB to remote mount it behind the headlight, I need the PCB to be horizontal.
Last edited by dewintondave on Sun Feb 09, 2020 5:58 am, edited 1 time in total.
Finally, I have something to show. The cooling arrangements have been wired-up and connected.
As soon as the bonnet is fully slid onto the loco the blue micro switch powers-up all the electrics. The electrical connector provides power for the loco mounted blower. There are 4 AA cells in the battery holder. The toy-like smooth exterior has been preserved with no through bonnet fixings for all the bits and pieces.
Last edited by dewintondave on Sun Feb 09, 2020 6:03 am, edited 1 time in total.
At last we had a break from the rain and I was able to test the cooling fans for the first time in use. The fans appear to be effective. After the run, (the tankful was consumed after 17 minutes) fans were left running for a while, and the cylinder head was just warm. The bonnet / hood rattled at times. From analysis after the run, I found that the motor was running 30% too fast, and the loco was doing about 6.5 scale MPH.
Last edited by dewintondave on Sun Feb 09, 2020 6:15 am, edited 1 time in total.
A while ago I bought a small LED torch/Flashlight on eBay. I thought I'd use it for the headlight, but it was rather small. I've just finished converting it to use as the rear light for shunting and reverse running.
Here's what I bought:
I'm just using the LED, reflector, and bezel. This was a single AA cell torch. Interestingly there is a small PCBA that steps up the voltage to 3.7 V. I'm not going to use it as I'll be using the blowers 12 V supply with a step-down module.
This light is very bright, and a cold white. But it responds well to the PWM dimmer. The wiring still needs arranging.
Last edited by dewintondave on Sun Feb 09, 2020 6:20 am, edited 1 time in total.
Finally, I have started painting. I bought a benchtop convection oven, on special offer, to bake the paint after initial drying. The setting I'm using is 90 deg C for one hour. The paint is coming out nice and hard.
Because I'm not using an undercoat, the red is coming out quite a nice dark shade
Last edited by dewintondave on Sun Feb 09, 2020 6:22 am, edited 1 time in total.