Bill Bedford's New O4/5 Conversion Arrives

[rob]

$400..!...but I suppose any new technology costs at first,this will come down whilst improving quality at the same time...quite quickly too I'd imagine....

[Atso]

$400..!...but I suppose any new technology costs at first,this will come down whilst improving quality at the same time...quite quickly too I'd imagine....

Yes it was a bit steep but I'm sure you're right and the price will come down sooner or later!

[Atlantic 3279]

Coming along.

I actually did most of the first round of "blemish removal" from the primed structure using that wood-chisel, fresly sharpened, as a scraper, dragged lightly across the surfaces. By keeping the blade as nearly as possible at right angles to any ridge-lines on the surface, and dragging it along those lines, it worked very nicely, taking the peaks off but leaving the primer undisturbed in the troughs. In the areas that had a lot of rough, random texture I used the scraper in three or four different directions in order to arrive at the smoothest possible finish. I think the use of a decent-sized chisel as a scraper has other advantages compared to alternative means of smoothing-down, such as:
1. It is a big-enough tool on which to get a good steady grip, with resultant excellent control.
2. Used as described it takes the surface down to a nice smooth face, it doesn't merely "round off" the ridges and pips.
3. It doesn't leave thousands of glass fibre splinters all over the model, the workbench, and stuck in your fingers.
4. You don't have to buy refills for it!
5. It gets right into corners, and can be angled under handrails a bit too.
6. You can see and feel where the cutting edge is at any time, allowing boiler bands and suchlike to be avoided. These remain sharply defined, not "rounded off".
7. There's no possibility of clogging, as with dry abrasive paper, and no need to clear up water and "slurry" from wet abrasives.

The scraper made a quick easy job of taking the unintended contour steps down to a level surface on the cabsides too. In one or two places I was even able to use it very lightly and carefully as an advancing blade to almost "plane" irregularites from the surface. The small square file was useful for cleaning under the chimney rim. The glass fibre pencil was eventually useful for a final light general tidy-up of the scraped surface (and I managed to snap the handle off the smokebox fastening with it, having avoided that with the much bigger chisel). A final clean off with a soft brush and all was ready for another coat of primer.

Ah, yes, I worked mostly with the structure screwed to the running plate, as that gave me some more areas of the thing that I could actually hold without bending and breaking yet more handrails. Whilst I've still left them on at this stage, so as to give them a "fair chance", I still intend ultimately to replace them and I suspect Mick's blunt assessment of the usefulness or otherwise of these printed handrails is about right. On future models nothing more than dimples for the pillar positions would be preferable.

Here's that area of boiler that had loads of rough texture originally, after the first clean-down:

A general look at the other side, from the front, including the smokebox door with its many concentric circular ridges removed. It looked almost as if it had been turned with a rough tool and not skimmed or polished to a finish

Cabside with its "stepped layers" sorted out. Representation of the clearance "blister" for the screw reverser.

The worst area of boiler with another coat of primer.

I've since gone over the whole lot again with fine dry abrasive paper, and applied yet another coat of primer. In strong light some areas still show faint ridges. Another light rub-down with care not to break through the primer, followed by a coat or two of black may well suffice.

[Atso]

Graeme, I hate you!!! After all these years of carefully rubbing down with fine wet and dry you show me that the answer was hanging up next to me all the time - a wood chisel!

Amazing clean up, I think depending on what kind of black paint you use, you might well be there!

[Atlantic 3279]

I don't mind being hated for sharing what may be a good idea .

N.B. Although the rounding is very slight indeed, my wood chisels have, through use and my probably imperfect sharpening technique, acquired very slightly rounded corners to the blade, although the blade edge itself is straight. This, coupled with careful handling and having the thing properly SHARP in the first place so that it cuts with absolutley minimal applied pressure, does provide some safeguard against digging the corners in and creating horrible scartches!

NOW SOME QUESTIONS FOR BILL, IF HE'S OF A MIND TO COMMENT. BASED ON OBSERVATION OF PHOTOGRAPHS, why does this superstructure print have:

a) Pillars / knobs for the short horizontal cabside handrails, rather than plain turned-in ends to the rails?
b) No shallow rainstrips inset from the edges of the cab roof?
c) A pronounced discrepancy between the positions of the vertical front edges of the lower firebox sides and the nearest boiler band - should these features not abut?
d) A well-rounded lower half of the screw-reverse blister on the cabside, rather than a slightly rounded "square edge"?

Features seen on photos of other locos that I haven't seen? Expedients of production? Provision for easier clean-up (roof)? Correctable errors?

One more thought for those about to embark on this conversion. If you want a "correct" model, do your research. Look at screw or three link couplings, evidence of vacuum brake, type of smokebox fastening, shape of top of dome cover, firebox washout plugs and/or handholes, rear loco sandbox positions, and probability of water-scoop on tender. I think Bill's firebox, with washout plugs only, is correct as it stands only for the boiler first fitted to the very first O4/5 conversion, No 5008, and his dome shape suits the 1932 batch of 4 conversions, but boilers changed engines later.

[Atlantic 3279]

I mentioned some way back that I'd had to file the lower edges of the O4/5 firebox to get the cab to sit down more closely on the running plate, but had stopped short of getting it perfectly flush as I didn't want to upset the horizontal centre-line of the boiler. Having now done some measuring of the cleaned-up, snug-fitted structure at the front of the loco, in good daylight, I'm now suspecting that I shall have to go further with the filing of the firebox and trim the lower edges of the saddle somewhat also.

According to RCTS 6B, all of the LNER reboilerings of O4s maintained the original 8K / ROD / O4 boiler pitch of 8' 6 1/2", or just a shade over 34mm in scale. The centre of my smokebox fastening is currently about 35.5 mm above rail level, and the chimney top is over 53mm. As the rebuilds were kept within group standard loading gauge using 1' 4" tall O2 type chimneys then the chimney height should not be more than 52mm. The excess of height approaching 1.5mm is definitely evident when compared directly with the original Bachmann boiler.

If I file around the base of the saddle to correct this I shall have to take care to keep the edges, straight, tidy and level. I shall also have to put a transverse slot in the cladding on the underside of the boiler to clear the cross-linkage for the sanders. Bachmann's boiler, smaller in diameter, has such a slot. The lack of apparent "need" for a similar slot in Bill's boiler as supplied was one of the things that got me wondering about the height business......

[Bill Bedford]

Thanks to everyone for all encouragement. I've been away for the last few days so I'm only just catching up with the postings. A lot of what I am going to say is going to be at variance to what has been the accepted way of modelling for very many years. But these are new materials and everyone involved, from the guys running the machines onwards are still working out the best way of using them.

Surface Finish.
As you know this material is built with a wax support material which allows overhangs and curved surfaces. This wax is removed from the model simply by heating until the wax melts and flows away. The piece is then put into oil to remove any wax residue that could collect in the more intricate part. A light vegetable oil is used for this sometimes coconut, but more often sunflower or rapeseed. So simple domestic washing up liquid or liquid soap is all that is needed to remove the oil. If more aggressive solutions, such as solvents or ultrasonic cleaners, are attempted then the wax will be removed from deeper within the material and the surface will take on a rough etched appearance.

I am convinced that the designers of this process intended that some wax should be left in the stairstepping to give a smoother surface. The question then becomes one of finding a suitable primer that will bond with both the wax and the acrylic plastic. The Halford's primers which are acrylic with a solvent base seem to mange this quite well. The process I have used is to wash well in hot soapy water, spray with primer, sand with a glass fibre brush and spray again. The sanding/spraying cycle is then repeated until a satisfactory surface results. This may sound onerous, but surface of this material is, in general, better than most white-metal kits.

I will do some experiments with washing soda.

Build Orientation
This model was built upside down, hence the lower part of the boiler is smoother than the top. The orientation is usually chosen to minimise the amount of support wax used. I suspect, therefore, that given the nature of the chimney, safety valves and cab roof that this is almost always going to be the preferred orientation.

Handrails
According to the drawing I have of these locos the boiler handrails were 1 3/4" diameter. The ones on the model are drawn 0.7mm so they are slightly heavy. However if brass wire is used as a substitute then neither the common sizes of 0.45mm or 0.7mm are going to be correct.
The acrylic material softens at about 80 deg C. This is hotter than most people can hold things comfortably. It also seem to have a 'memory'. If, for instance, you have a piece that has been distorted then pouring boiling water over it and allowing it to cool will remove the distortion. I tried to straighten the handrails with hot water from the tap, and could straighten one but when the other was attempted the first always buckled again. This is why I suggested a more localised form of heating such as a soldering iron held close, but not touching, the handrail.

Fit
The areas marked out in the instructions as needing attention will be changed before I order any more boilers. I will also look at the heights of various pieces to see if I can get a better fit around the cab.

[Bill Bedford]

:
a) Pillars / knobs for the short horizontal cabside handrails, rather than plain turned-in ends to the rails?

Cos that's how they looked to me when I looked at the photos, and knobs seemed to be a more robust solution

b) No shallow rainstrips inset from the edges of the cab roof?

pass

c) A pronounced discrepancy between the positions of the vertical front edges of the lower firebox sides and the nearest boiler band - should these features not abut?

Yes, I've used the firebox length from the original Bachmann model

d) A well-rounded lower half of the screw-reverse blister on the cabside, rather than a slightly rounded "square edge"?

When I look closely at the photo you are right.

All the above can be corrected. The hand rail may be supplied as wire.

Features seen on photos of other locos that I haven't seen? Expedients of production? Provision for easier clean-up (roof)? Correctable errors?

One more thought for those about to embark on this conversion. If you want a "correct" model, do your research. Look at screw or three link couplings, evidence of vacuum brake, type of smokebox fastening, shape of top of dome cover, firebox washout plugs and/or handholes, rear loco sandbox positions, and probability of water-scoop on tender. I think Bill's firebox, with washout plugs only, is correct as it stands only for the boiler first fitted to the very first O4/5 conversion, No 5008, and his dome shape suits the 1932 batch of 4 conversions, but boilers changed engines later.

It is more complicated than that. There were 3 different patterns of these boilers fitted to nine locos. They could have had fire box washout plugs, handholds or both. In addition all the locos kept the brake arrangement they had before rebuilding. So with the vacuum ejector pipe there are six possible variation in boiler for nine locos. I felt this was a bit over the top for what was in essence a proof of concept design.

[Bill Bedford]

According to RCTS 6B, all of the LNER reboilerings of O4s maintained the original 8K / ROD / O4 boiler pitch of 8' 6 1/2", or just a shade over 34mm in scale. The centre of my smokebox fastening is currently about 35.5 mm above rail level, and the chimney top is over 53mm. As the rebuilds were kept within group standard loading gauge using 1' 4" tall O2 type chimneys then the chimney height should not be more than 52mm. The excess of height approaching 1.5mm is definitely evident when compared directly with the original Bachmann boiler.

I've just checked this and found that the distance from the top of the footplate to the boiler centre line on my model is 17mm against 4' 2.5" from dimensions on the drawings I've used. The height for the Bachmann moulding from the bottom of the saddle to the top of the chimney is 30.75mm against 31.5mm on mine. So it looks as if Bachmann have made their footplate thicker than scale and lowered the boiler/cab to compensate.

I'm not sure what I should do about this -- ideas?

If I file around the base of the saddle to correct this I shall have to take care to keep the edges, straight, tidy and level. I shall also have to put a transverse slot in the cladding on the underside of the boiler to clear the cross-linkage for the sanders. Bachmann's boiler, smaller in diameter, has such a slot. The lack of apparent "need" for a similar slot in Bill's boiler as supplied was one of the things that got me wondering about the height business......

That cross linkage for the sanders is at footplate level on the O4/5s.

[2002EarlMarischal]

Loads of useful information thanks chaps. I'm lagging way behind due to spending almost the whole day lining some of the other locos I have on the go.

However, I did wash my loco body with strong washing up liquid today and interestingly it looks whiter now and the surface texture is more pronounced, but on the opposite side of the boiler to Graeme's.

Even being very careful with the stiff paint brush I used to wash the body, I managed to break off the LHS upright cab handrail.

If I have a chance tomorrow I will give it the first coat of Halfords primer. The fibre glass brush arrived in yesterday's post - I've never used or seen one before, so it's all a learning process. Fascinating stuff!

Oh, and many thanks to IAK for the explanation of ultrasonic cleaners!

[Atlantic 3279]

Thanks for the replies Bill,

By the way, regarding these remarks:

"One more thought for those about to embark on this conversion. If you want a "correct" model, do your research. Look at screw or three link couplings, evidence of vacuum brake, type of smokebox fastening, shape of top of dome cover, firebox washout plugs and/or handholes, rear loco sandbox positions, and probability of water-scoop on tender. I think Bill's firebox, with washout plugs only, is correct as it stands only for the boiler first fitted to the very first O4/5 conversion, No 5008, and his dome shape suits the 1932 batch of 4 conversions, but boilers changed engines later."

I was really aiming those at the end-users of the model (I tried to clarify that in the original passage), I realise they can't be incorporated into every print.

[jukebox]

Build Orientation
This model was built upside down, hence the lower part of the boiler is smoother than the top. The orientation is usually chosen to minimise the amount of support wax used. I suspect, therefore, that given the nature of the chimney, safety valves and cab roof that this is almost always going to be the preferred orientation.

Bill - just a follow up from my original comment on this matter: how much more trouble would it be, therefore, to reverse the orientation? Is it just a matter of minimising wax, or do other factors come into play. The reason I ask is, and I know I'm stating the obvious, but we will always view our models from the side or above, therefore it seems to me that if it is practicable without doubling the base cost, that arranging the print so the highest quality reproduction is on that side we see the most is the preferred way forward, if not the easiest/cheapest...

Scott

[IAK]

Oh, and many thanks to IAK for the explanation of ultrasonic cleaners!

No worries...
Its a very useful tool believe me

[Atlantic 3279]

Can I just emphasize that although I've not fully responded to Bill's observations on the "dimension problems" that I previously mentioned, I am giving it thought and checking possibilities. I was planning to say more before 9am today, but the phone rang, I discovered that a certain amount of **** had hit the fan at work, and I had to get there rather quickly!

No matter what the minor teething troubles regarding fit and details, this add-on for the Bachmann loco still in my opinion offers major advantages over full kit or scratch building, so I'm not "knocking" Bill's work in any way.

I've now had a certain amount of success in re-straightening the handrails that I had bent while handling the loco, using a more controlled / localised method of applying heat:
Get one end of a thin steel rule reasonably hot (but not to extreme plastic-wilting or outright sizzling heat) and use it to try to push the bent section of handrail back to (or slightly beyond) the intended straight line. Keep it there until the heat dissipates a bit and then remove the rule. Start with the applied heat on the low /safe side and then try more heat if the handrails are simply springing back to their original bent shapes. It takes several goes to get the desired result but you can work on one section of rail at a time with minimal effect on others. Keep the model itself well away from the heat source that you are using to heat the steel rule.

[mick b]

Graeme
From what Bill said the handrails are moulded 0.7mm ? if that is correct they are a tad chunky .
What is your opinion on using the usual 0.45mm version , which will be much stronger and better looking too. Much better surely to remove them ?.
This saves all this aggravation with straightening the moulding and allows smoothing of the body to be done much easier.
I am still undecided to go for one of these when the O4/8 body is available.