Bill Bedford's New O4/5 Conversion Arrives

[Atlantic 3279]

I may well have covered this in bits and pieces about 18 months ago when showing parts of my DIY O4/8 and O1 conversions, but here's how the Bachmann O4 comes apart.

There's a body-chassis screw at the rear, hidden by the spaghetti. You don't need to unplug any of the through-wiring to the tender DCC socket or uncouple the tender to get at this screw. A slim screwdriver fed through the wires will undo the screw fully, and unless you are plain unlucky, or you feel that you must remove the screw entirely for safe-keeping, then the wiring will generally keep the free screw in place in the hole, ready for re-fitting of the body. This eliminated the task of persuading the screw to go back into the hole through that wiring.......

There's another body-chassis screw at the front. If you haven't fitted the cylinder draincocks then there's no need to detach the pony truck and spring to get at this screw, just push the truck aside as far as it will go and work on the screw from a slight offset using a slim screwdriver. In fact, if you take the pony and spring off they can be a bit of a fiddle to refit, and by leaving them in place you again have the option of also leaving the free screw in situ, supported by the centralised pony spring. Again, this saves the job of feeding the screw back in with the pony spring partly in the way.

Body off and tender still attached.

Three more screws, circled here in yellow, hold the superstructure onto the running plate. Once these are out, the superstructure may still not be completely free. The lower front end of the reverse rod is glued into a socket in the running plate and must be persuaded free (I find it usulally breaks of level with the running plate, refusing flatly to un-plug neatly from its hole). The lower edges of the cab may also be slighly stuck in places owing to glue that has crept into the joint from the nearby floor-mounted cab fittings. Gentle easing is called for.

[Atlantic 3279]

Here's the detached superstructure with whitened glued/broken lower end of reverse rod just discernible. I had actually already taken this loco apart long ago, so everything came adrift pretty easily. Don't worry about that reverse rod, it sits back in place quicte nicely with the lower end unattached, so long as you don't bend or break it while the superstructure is detached.
At the cab end you'll also find other items that need attention. The rear handrails for the cab may well remain rooted in the running plate rather than lifting off with the cab, or they may not be able to decide what they want to do. By detaching them carefully from the running plate and gluing them equally carefully just inside the rear edge of the cab roof, they can form part of a complete superstructure that can go back on to the loco at any time. The same goes for four box-like pieces of cab furniture, including the driver's screw reverser, that are plugged and glued into the cab floor by Bachmann. Detach them, clean of the floor mounting pips, and glue them in the correct relative positions on the cab sides.

[Atlantic 3279]

Bill points out the need to do some thinning of the inner lower corners of the cab front. The slot and screw hole between the splashers and cab floor of the running-plate casting has a narrower section "within" than is obvious at its outer edges. The cab won't fit neatly (or at all) and may be damaged or at least have its sides untidily bent if you don't do this thinning. Its a bit fiddly to do without damaging any surrounding surfaces or breaking those flimsy handrails as you try to hold the work. I used a combination of scraping and filing to achieve the desired result.

I don't know if Bill will be able to adjust future prints to eliminate the need for the thinning or other alterations. I'm not sure either of what he thinks of my feeling that the bottom edges of the firebox needed a bit of filing so that the cab would sit down fully. I was actually tempted to file off more than I did, so that screw-tension was not needed to pull the cab down tight. If I file off any more at the firebox though, I may also have to file the base of the saddle so as to keep the boiler level. As there now appear to be at least two versions of the Bachmann running plate casting, I wonder whether Bill's dimensions for the new superstruture were worked out relative to a different running plate.

Bill also advises this bit of trimming.

I hope the following three images are largely self-explanatory.

New hole positions in running-plate "well" for saddle fixing, as seen from front and above

Same from front and below

If, rather than being countersunk, the new front fixing screws are cheesehead, as are mine, then it is important to position these holes with care. The screw heads below the running plate will be in close proximity to the raised heads of the cylinder mounting screws when the loco is assembled. If they clash, you may not be able to get the front of the running plate to go down fully.

It is not in fact very difficult to drill the necessary two new 0.9mm holes in the running plate as the metal is fairly thin in the necessary positions. Drilling further back, or further forward would be a chore as the plate is then more of a block, being built up either on top or beneath. I believe the screw fixing to be a more sound method than the one "reluctantly suggested" by Bill, i.e. glue or double sided adhesive tape / pads, yet I fully understand that suggestion as part of the "plug and play" philosophy to suit those who can't / won't / daren't use a drill.

[Blink Bonny]

Ay up!

Give Bachmann a bell and ask them. Their spares service is pretty damned good.

[2002EarlMarischal]

I was delighted to receive my O4/5 body today and thought I would post some photographs of it in its raw, "unwashed" state.

I am not sure that there is much to learn from these pictures that Graeme has not so ably described, but images of second body demonstrating consistency of finish may help pursuade others to treat themselves in a similar manner!

I'll follow with a couple more pictures but have reached the limit on this post. I hope you find them useful.

[2002EarlMarischal]

Final couple of shots:

I very much look forward to working on this model, and have purchased a fibre-glass brush from eBay to follow Bill's recommendations for removing the unwanted texture which doesn't look so bad on my body in its raw state. As Graeme found, primer may reveal what the naked eye cannot see whilst in the translucent state.

To remove the oily coating, I am tempted to give fairly neat washing up liquid a go, as I always feel that there is a "fattiness" to soap.

I'm not sure I understand why the handrails would stay straight following "heat treatment". To replace them with wire will not be the end of the world.

Anyway, back to Graeme! I'm most grateful for the step by step instructions which certainly bolster my confidence!

[mick b]

One for Bill.


The handrails are clearly are useless on this batch, from seeing pictures that have been posted.

Would it be cheaper on future batches to do away with them? As said earlier their removal/abscence makes it much easier to clean the boiler up. I cannot see many people retaining the moulded handrails.

[Atlantic 3279]

To remove the oily coating, I am tempted to give fairly neat washing up liquid a go, as I always feel that there is a "fattiness" to soap.

I'm not sure I understand why the handrails would stay straight following "heat treatment".

I've not tried it out, but a strong warm solution of washing soda (soda crystals / sodium carbonate, but NOT "bicarb" / sodium bicarbonate / sodium hydrogen carbonate, and certainly not caustic soda) might be a very effective de-greasing agent and safe for the acrylic material too. This removes any risk of leaving artificially "shiny" agents that may be present in miracle washing-up liquids, and the soda is cheaply and readily available in supermarkets etc. But for the little time involved in making up the solution I would have used washing soda myself.

As I understood(?) an explanation once given to me, if you heat thermo-plastics in the right way it is sometimes possible to get the molecular chains that make up the material to "snag together" or "knot up" as the heat energy makes them thrash around more. This can leave the material in a more compact, or shrunken stage after heating. I still don't fully understand why some of my handrails straightened when the heat was on yet others only straightened as they cooled, but I can't say that worries me too much.

[rob]

I've always avoided washing up liquid as I was told most brands contain lanolin,kind to the hands,but leave a potentially "slippery" deposit even with thorough rinseing.....CIF isn't kind to the hands but appears to leave no residue-just note the latest,thinner formula does require very careful rinseing nonetheless.....
Steve what type of wax is it?..I know beeswax and candlewax...the latter is a bugger to get off most surfaces but I presume this is a different type altogether?

[Atso]

I don't know what the wax is, I don't think its every been disclosed by Shapeways.

I've found washing up liquid to work fine in the ultrasonic cleaner with a final round with just water. I don't know how well it would work with regular 'scrubing' but don't see why it wouldn't work. For some additional information and hints from others using 3D printing try: http://www.shapeways.com/forum/index.ph ... frm_id=95&

[IAK]

If you can obtain it, try Neutracon in an ultrasonic - http://www.decon.co.uk/english/neutracon.asp
The weblink should explain all.

Mind this beastie looks amazing.
Wonder if Bachmann will see a spares option here

[2002EarlMarischal]

For those of us who don't have or have never come across one, what is an ultrasonic cleaner and should I, if I dare to call myself a modeller, have one? Can I even afford one?!

[IAK]

Essentially, an ultrasonic cleaning bath is a cleaning device that uses ultrasound (usually from 20–400 KHz.) and an appropriate cleaning solution to clean delicate items. The ultrasound can be used with only water but a form of solvent or cleaning solution is advised for the best results - it enhances the effect of the ultrasound on the item to be cleaned. Ultrasonic cleaning works by using high frequency sound waves to agitate in an aqueous or organic compound. Cavitation bubbles induced by the agitation, act on any contaminants adhering to the brass or any other substance. This action also penetrates blind holes, cracks, and recesses. The intention is to thoroughly remove all traces of contamination tightly adhering or embedded onto the surface of what is being cleaned.

Ultrasonic baths come in all shapes and sizes; the cheapest option available for the modeller probably comes from the Aldi supermarket chain, when available. Failing that check out some of the modeller tool shops, such as Eileen’s Emporium. Neutracon is available from scientific suppliers. However, one wonders if it is the sort of thing that could be sold by the modeller tool shops? I feel maybe some enquiries may be in order.

[Atlantic 3279]

Have been thinking - hence all the choking black smoke and sounds of whirring cogs:

Given that the tendency to rough texture is said to be sensitive to the orientation of the "workpiece" in the prototyping machine, I wonder whether any machine manufacturers have considered the possibility of arranging the necessary parts of the machine in such a way that they, and the workpiece, can remain fully in register and flip-over as a single unit at an appropriate mid-way stage in the process, thus producing a 3D print that is more likely to be clean on all faces?

[Atso]

At present this does not appear to be possible, however sooner or later someone is bound to try it!

I think, at present, the only way to do this would be to print parts, such as the boiler, in two halfs much like the old AirFix (Dapol) plastic kits are. Again though this depends on how the manufacturer orientates the model - which is something we can't control with the 'budget' 3D printers at the moment.

Give it time and I think the technology to do this will become affordable as it is doable: http://www.finelineprototyping.com/reso ... resolution

If anyone is interested the cost to print an N gauge N2 body with Finelines was quoted at about $400 last year.