Roxey Mouldings ICI hopper part 2 - bogies.

The bogies are made up from an etched frame, to which whitemetal sideframes are attached. Here's the etch in the flat;

Note the angled strengthening ribs.
The holes for the bearings are etched to 1.3mm. I opened them out with a 5 sided broach and a 2mm reamer, holding the frames in a Hold & Fold, being carefull because there's very little material between the hole and the side of the frame. The bearing holes could also be opened out whilst the frames are still on the etch.
Then the sides can be folded down, noting that there's actually no need to deepen the etched fold lines for a change. Then the outer edge of the ribs need to be filed shorter, otherwise folding the ribs down splays the sides out! On the frame below one rib has been shortened (arrowed);

It would have been far better if the centre section was straight rather than angled, then the strengthening ribs could have been made full-width, saving me a job later...

Bearings, waisted in this case, can be soldered in place once the ribs are folded down and all folds strengthened with a fillet of solder. However, the frames are a little too wide so on one side of the frame a washer is soldered behind the bearing to stop the wheels rattling around. I couldn't find any washers (I usually have a packet or two of Gibson 2mm washers laying around) so I just drilled a series of 2mm dia. holes in scrap etch then roughly cut around them to make my own. At this point I realised that waisted bearings vary from manufactorer to manufactorer. There needs to be a 2mm dia. parallel section long enough to pass through the washer and still locate in the frame sides. I had two packs of bearings in stock, 51L and Kean-Maygib, on both sets the parallel section was too short. So I ordered some Gibson bearings (G4M63W) which have a 2mm section long enough to pass through the washer and still locate the bearing central in the frame. Normal 'top hat' bearings would of course be a better option, but there's not enough metal in the cast frame sides to accomodate them without breaking through the casting when drilling clearance holes for the bearings to sit in.

My own wagon will be fitted with 3 link couplings, but Jon uses tension locks. There's no provision for mounting, so I made up mounting bars from .5mm x 5mm brass strip. The coupling itself is drilled 1.3mm, and the bar has two 1.3mm holes drilled in it 2mm apart. A 12BA nut and bolt holds the coupling in place, the outer hole allowing the coupling to be fitted the 'standard' distance from the wagon end (as taken from a Bachmann RTR wagon) whilst the inner is for closer coupling. A 1mm pin (brass rod) is soldered under the bar and sits between the tails of the coupling to prevent it rotating;

I also made up a strengthening plate from an offcut of etch to sit on top of the stretcher, this can be seen on the left hand bogie on the photo above.

There are a pair of cut-outs in the etched sides which should line up with a matching pair of cut-outs in the cast sideframes. But they don't. The solution is to enlarge the cut-outs in the etches with a square needle file to suit the castings. This weakens the bogies sides so is best done after the etches are folded and soldered and the bogies are ready to have the wheels fitted and the cast frames (which will strengthen the sides) glued in place. In the photo below the bogie in the middle has a cast frame placed over an unmodified etch, the etch is blackened with a marker pen to highlight the excess material. Above and below are an unmodified frame (top) and one where the cut-outs have been enlarged (bottom). Click to enlarge;

The castings are for bogies fitted with roller bearings, which according to Paul Harrison's book were fitted in the late 1970s, fine for Jon's wagon which will be finished (by him) in late 1990s condition. My wagon will be modelled in earlier condition so I've carved out some axlebox covers from .015" x .156" Evergreen strip (117), with bolt detail from cubes of thin styrene.
Here's the finished bogies ready for primer (hence the masked off tyres);

I'm not entirely convinced by the frame shape, the curve on the outer ends doesn't seem large enough.
Frames next.

Paul.