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A Diesel for the BVLC - Part 1

Hi all,

Following the completion of my 2-6-2 saddle tank, there's only one empty spot left around my layout's turntable. Given that it's 1948 in my On30 slice of Oregon, I decided that this last locomotive would be a diesel. I didn't want to do a small 'critter', as I'd tried one before. I hadn't been able to get it to perform the way I wanted. As well as this, quite a few of the On30 diesels I've seen are critters, and I wanted to do something a bit different. With this in mind, I decided that BVLC No. 10 would be a narrow-gauge road switcher.

Since I started modeling in On30, I've attempted 6 conversions of HO scale models to On30, only 3 of which have worked out. All three of the working ones used older mechanisms, all of which had metal chassis' and robust drive trains. As such, I decided this diesel project would use an Athearn Blue Box mechanism. Via Ebay, I was able to obtain a Blue Box GP40-2 in new condition.

After checking to see how it fit on the turntable, I tested the mechanism and stall current. It ran smoothly, and the stall current of 0.66A meant that I'd be able to reuse the TSU-750 decoder I had in the aforementioned critter. With this sorted, I started designing the new diesel.

My plan was to 3D-print the body, then add details as needed. After an evening with the calipers and the GP40-2, I was able to put an outline of the mechanism in Blender. As usual, I colour-coded the components. Red is the metal chassis, and the yellow is the space taken up by the drive train. I also imported the pilot and coupler box I'd modeled for the 2-6-2T, in order to get the size and positioning for them. I also added shapes for the decoder and speaker, after this render was taken.

I've always liked the look of the early Alco road switchers, particularly the RS-1. That became the inspiration for my design. After doing the basic body shell, I realised that it was using quite a bit of material. So I uploaded it to Shapeways to get an idea of how much it would cost. I was going to get the shell printed in 'White Strong and Flexible' plastic, but as designed it was a lot more than I'd budgeted for.

As such, I cut back on the amount of material needed. Instead of having a slight curve along the top and down the front, I decided to make the top and sides flat. This could be done using the 1mm thick styrene sheet I already have. After removing most of the material used in the hood, I created lips around the edges to hold the styrene.

However, this was still a little pricey. Further to this, the 'White Strong and Flexible' plastic has a grainy finish when printed, and needs to be sanded smooth. Given that I haven't done this before, I was a little concerned about ruining the curve of the rounded parts. As such, I came up with a third option. Instead of rounded edges for the hood, I would have a 45-degree angle on each of the corners. No support was needed for the top panel, as it would be resting on the supports, front and side panels. I also did a variation with the curved edges, to see if the reduction in height and removal of some additional material (e.g. the cab steps) would reduce the cost to something a bit more friendly on the wallet. I also added drill starter holes for the coupler lift brackets, and four screw holes to mount the footplate to the chassis.

As well as the body shell, I also modeled several detail parts, which I coloured green for clarity. These will be 3D printed in 'Frosted Ultra Detail' plastic, which has a smoother finish and higher resolution than that used for the body shell. Using the steam loco pilot as a guide, I created a coupler box at the front. After measuring a 3mm LED and re-creating it in Blender, I created two headlights. The rear one is designed to be glued onto a vertical side, and the one at the front was designed to go onto a horizontal hood. I also designed a radiator, and some side doors for the long hood.

With that done, I separated the cab from the body for printing. Locating tabs were added to the underside of the cab, and corresponding slots in the footplate. I also added holes along the sides for the handrails. I'll be making these out of wire when the time comes. With that done, I uploaded the body and details to Shapeways.

Unfortunately, there were some issues with both the body and the details. On the walkway, the walls between the handrail holes and the edges were too narrow, as were the walls between the lengthwise slot for the cab and the edge. The sharp corner on the corner posts was also too thin. After correcting these, I sorted out the detail parts. The only problem there was the hood top headlight. In order to fit the LED into it, some of the walls had to be made thinner than the minimum tolerances for the Frosted Ultra Detail plastic. Increasing them would have made the headlight too large, and so I decided that both the front and rear headlight would be mounted on the vertical end panels. As such, I printed two of the rear ones.

With that sorted out, I ordered the body and parts through Shapeways. I expect I'll have my next update in a month or so, once they arrive.

#On30 #3D printing #Shapeways #narrow-gauge #diesel locomotive

Szegedi Fehér-tó

#fish #fishery #railway #work railway #narrow-gauge railway #narrow-gauge #train #freight train #szeged #szatymaz #fehér-tó

Képeim Bulgáriából

My photos from Bulgaria

#railway #train #locomotive #bulgaria #bdzh #bdz #henschel #septemvri #velingrad #Dobrinishte #autumn #colours #landscape #mountains #rodope #rodopebahn #narrow-gauge #narrow-gauge railway #kisvasút #mocanita #balkans

Limestone train waiting at a passing loop on the CFI Govora, Valcea county, Romania. The line has closed last week. Click here to see full report or the link above for high resolution photo.