Wednesday, June 03, 2009

Diesel in a day: DFT part 2

DB says: The time is 1:10pm. Gentlemen, start your modeling knives.

Let’s do the painful bits first, so grab those plan copies (you did print out some plans didn’t you?)and we'll make some hood sides. A long time ago I used to painstakingly scribe the hood doors into plasticard, but hit on this idea in the late 80s when I used to have 1/64 vision: cut out the doors from a photocopied plan and stick them on the styrene long hood. It gives the model a 3d look, the panels are marked out nice and square for you, the printed panel, hinge and door latch detail will faintly show through the paint (then again you could always cut those out too if you were mad). And if that hasn't swayed you: it’s less work than scribing and virtually impossible to screw up. Of course if you're more comfortable scribing, scribe away.

Cutting around all the panels and door hinges can be time consuming, but the work can be sped by making all the (mainly longer) up-down cuts in one go and then spinning the plan 90 degrees to do the short ones.

We’ll cut the cab out of paper as well (gasp - I'm sure this is not how Alec Fenton made his masterpiece 1:64 DF), but instead of sticking it onto styrene, we’ll use clear plastic instead. This will give the cab structural rigidity, gives flush windows, the paper is much easier to cut holes in than plastic, you should be able to see the printed ‘window rubbers’ through the paint, and again, it’s all marked up nice and square for you. In the plan attached to the first DFT post, I included some cab fronts devoid of handrails, horns and other stuff that might show through the paint later on as well as the two different cabside window layouts. Yes, I should have included two cab sides of each….

I use a SHARP knife and a metal ruler for the really long cuts and the all-important cab parts, while doing the rest freehand. Do the cab windows before cutting the cab out, or you’ll likely break the really thin windowframe sections. I do the ‘rounded corner’ windows by cutting the four sides into the start of the curve and then use the point of the knife to ‘cut the corner’ straight. If that makes sense… so in actuality mine are octogons with long vertical/horizontal sides and tiny sides in the corners. That still doesn’t make sense does it… When you’re done with your cab, turn it over to the unprinted side and check out your windows – sometimes the black window outlines can disguise a window that’s not so square. you could cut all the panels out individually, but I tend to keep them together in a long string and scribe the 5 or six in-between panel lines after everthing has set. This time I didn't do this until the paint was on. Now it’s time to cut out some plastic to stick your paper whotsits to (above). If you have your chassis handy, now would be a good time to check how wide it is by eyeballing it against the back wall of the plan and determining whether you can fit it inside a scale-width hood, or whether you’ll have to fatten up the hood and have thinner walkways. The Kato SD40-2 lets me do a narrow hood with quite thick (about 1.5mm) plasticard sides for strength, the older Bachman Spectrum -2s require thinner plasticard and/or a wider hood to fit.

I cut out some holes for rear radiators and rear horn, and then attached the paper cutouts with a thin smear of PVA as I’ve always done (not too much or your panels will wrinkle). A wee way in, I noticed a problem with some of them not sticking, so I used plastic glue from then on in. I swear I’ve never had this problem before (as the bishop said to the actress). For the cab sides, I cut the clear plastic backing a little smaller than the paper in the fore-aft dimension so the paper wrapper would overlap the cab front and rear walls and give neat corners.

If you get PVA on the actual windows, a cotton bud works wonders. If you get others glues on them, well, you’re screwed really. It’s all or nothing here folks!
(Above) So here we go – paper cutouts are stuck on the hood sides, the port-side blower duct and side air ducts (from layered rectangular styrene rod) have been built (one attached), the cab paper bits have been stuck onto clear styrene and a floor plate has been cut out of 1.5 mm plasticard to fit the chassis snugly.

I’ve made a rear cab wall out of plastic to give the cab more strength as well, made in reference to the front cab wall, not to the plan. If I made it to the plan, inevitably I’d end up with different front and rear roof profiles, and this is quite the pain to deal with later.

Walls assembled.

I spent some time thinking about the corner angles on the long hood roof, but fell back on an old ‘cheat’, where I added one thin piece of sheet on top to keep the sides together, and then attached a 1mm thick piece the width of the roof-top surface on top. This gives a stepped profile that you can see in the pictures rather than the nice flat angle you'd expect - but never fear, we’ll cover that with paper (the new miracle product) in the next step. The reason I do this rather than scrawking styrene to the angle or sanding balsa is that this gives me a nice straight roof profile – there’s no way I’d sand something this straight. The paper with its glue and paint is plenty strong as well - the DF6277 and 6064 shells were built about 16 years ago with this technique.
And here it is. You can see the ‘stepped plastic profile’ in the foreground above the blower duct and at the rear, while paper panels cover the middle engine room section with a nice angled profile. These roof panel pieces are cut out individually (again to add some ‘3d’ to the roof) using the plan as a guide. Luckily :) the DF and DFT side drawings line up on the plan, so you can put a ruler between the roof sections of them both, cut some lines vertically to get the panels the right widths (note that the are not all the same width). and then cut the panels to length so they will wrap over the roof – do one first to get it right, then cut all the others in one foul swoop to match.

OK, this a moster read already, so I'll split the story over a number of posts to be released over the next few days at our Dandruffy CEO's whim.

2 comments:

lalover said...

Well done and very interesting DB!

The best traditions of the Pikipiki (if it was dieselised) upheld and super-refined.

Almost makes me want to change scales.....

ben scaro said...

What brand of plastic glue did you end up using to stick the cut out paper hood sides to the styrene sides?

Cheers, Ben