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philipy:107658 wrote:That looks good.
TBH I've been thinking the bonnet looked very plain and "un-diesel-like"! So aside from the technical requirement IMO it improves the aesthetics as well.
Yes, it's supposed to have louvered doors on the sides, but I'm too chicken / lazy. It was a bit of a mission cutting the cut-out, and laziness took it's toll again. There's going to be a fan above the flywheel / clutch blowing air over the engine and out from where the radiator would be. Air can be entrained from the new ventilation opening and from underneath - between the frames. I'm not a serious modeller, I quite like a toy like appearance. This project has been going on for far too long now, it's into the 3rd year now
Last edited by dewintondave on Sun Feb 09, 2020 4:40 am, edited 1 time in total.
As I'm waiting for the cooling fan. I decided to add a headlight to the loco. This light was made from the lens, reflector, and bulb assembly of a small torch (flashlight). I'm fond of brass, so I'm thinking of keeping it polished. The back plate is steel, and that can be painted.
It's surprising how long it took to make. The outer shell is 0.5mm brass sheet and had to be annealed and rolled around a former. Then it had to be wired closed and then silver brazed. The 1.2mm brass end pieces had to be cut-out, then they were soft soldered to a chucking piece, then turned to size to fit the outer shell. They were then silver brazed one at a time into the shell and turned on the lathe. The ends were drilled and bored for the reflector and lens.
This is a large light. It officially fell off a much larger NZR locomotive, and was pressed into service.
Last edited by dewintondave on Sun Feb 09, 2020 4:43 am, edited 1 time in total.
I have only contributed to this thread once before and can only repeat what I said then.... this has been one incredible project and I have no ability to emulate your skills with metal or IC power.
Your understanding of the materials, process and manufacture have been second to none, even the descriptions have been outstanding.
My congratulations on (almost) completion of the model. Please show the loco in its final painted state before you close.
The best things in life are free.... so why am I doing this?
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.
Here's a small video of the bonnet/hood in operation. The two small axial fans on the front take about 50 seconds to reach top speed, it must be a feature of their brushless controllers.
Last edited by dewintondave on Sun Feb 09, 2020 6:06 am, edited 1 time in total.
