"Falcon": bodywork question.

[JeffP]

Hi to all again.

 

My project to scratch-build Falcon moves forwards slowly. However, I have now HAD the surgery on my spine, so hopefully, after the wound site heals and the soreness goes, will be able to sit and model something. Instead of just posting on here.

 

Anyway, on to today's question. This is for anyone with experience of modelling with styrene sheet.

 

I'm still looking at the bodywork in styrene. I have been advised to do a thick floor pan, (2 x 80thou), slightly thinner sides (80 thou), and body formers to help in rigidity and to hold the roof, which will be brass sheet. The cab rear bulkheads will make up two of the body formers.

 

Work is going ahead to produce etchings for grille-work, fan grilles, window surrounds, headcode surrounds etc. These will be fitted with glue to the sides and solder to the roof.

 

So.......when working with larger sheets of styrene, (the loco body is some 55 feet long, cab-rear to cab-rear), how do I stop the dreaded warping? And around 455mm length, what sort of distance between formers?

 

I had an idea to cut the formers out after cutting large apertures in them for lightness and wiring, speakers, etc. This won't effect stiffness will it?

 

Also, should I brace any 90 degree joints with more styrene? ( "L" angles?) (Eg: floor:side, formers: sides?)

 

And should/could the floor pan have cutouts to aid fitting the roof? I wondered about a triple layer of styrene, the top two with holes and glued together, the bottom one fitting by screws, NOT glued and solid? The lower one would carry the bogies, fuel tanks etc, maybe even buffer beam fairings, although those should be attached to the body.

 

Thanks for any advice/links.

Hoping to make a start this month, fingers crossed, and don't want to be at home to Mr. C0ck up from day one

[The Fatadder]

Regarding avoiding distortion of plasticard

I've used a couple of methods

First was using multiple sheets (with inch and a half diameter holes drilled in the other layers to assist with gluing and let the vapour escape

 

The other approach was reinforcement, for which I've used strip wood, and H section channel in plastic, the latter worked particularly well when you can't see it

 

Finally I have used flat brass strip, which can when using 40 thou plus laminations be glued flush with the inner laminations cut into a channel

 

[David C]

385mm is well over a foot long .... The usual advice is to use an odd number of laminations, i.e. 3 or 5 rather than 2 or 4. That way, the stresses are evened out. Having used an even number of laminations in the past on locos, I can testify that they do warp - and it will ruin your model!

 

These days, I only scratchbuild structures and I use double sided tape to stick laminations together rather than Mek Pak or similar. I do reinforce 90 degree joints and provide as much bracing as possible and also vent holes from where I do apply liquid cement. I have no experience of 80thou sheet - in 4mm scale, I go for 30 or 40 thou sheet and use formers every 5-8cm.

 

Hope that helps. Best of luck with Falcon!

 

David C

[Trevor H]

Can I recommend when laminating plasticard together you do it in odd numbered quantity's ie. 3, 5, 7, 9. This will greatly reduce the chances of any warping and twisting, much the same as plywood or anything that is laminated.

 

Trevor.

[roundhouse]

I laminate plastic sheets in structures , both walls floors and roof elements with plenty of bracing. I often thicken up the insides of walls and roof using the cut out bits from doing windows. I use Humbrol liquid poly.

 

The station building on Fort Myers is now 18 years old and has not warped at all.

 

Ian

[JeffP]

Thanks for the replies so far.

Sorry to update, but I've done a proper measurement and Falcon's sides to front of cab are around 455mm! But onlt 46mm high.

 

I was going to laminate the floor, but use a single sheet of 80 thou for each side, braced vertically at suitable intervals, and where the grilles wil allow, but this was more to give strength than stability.

 

The floor, I suppose I'll do in 3 layers now, to be sure, but I might set it higher in the side to allow me to screw a false floor underneath, NOT glued, carrying the bogies. This will allow me to have holes in the floor to get at roof fixings, and stuff like that, so I can have working fans, sound etc.

 

OR: the lower, false floor COULD form the small tumblehome at the base of each side, and have the bogie fairings attached........

[simon br blue]

Just a thought about the cabs- I think BRM had an article several years ago about making a 4mm version of Falcon and I think they used a lima 31 and 47 cab joined together to get the shape. If you can find the article and it you can see what parts of each were used you could see if MMP will sell you a resin 31 and 47 cab from their spares.

[ozzyo]

Hello Jeff,

 

you may find this of some use to you, the larger sized sheets of plastikard that Slater's do.

 

 

 

OzzyO.

[JeffP]

I've seen that on their website, Ozzy, I thought I might get it cheaper, saince theirs is not only expensive but costs quite a lot for P&P too

 

Oh well.........

[Bob Reid]

I realise Jeff, you've probably given it plenty of thought but what is the reason behind not using etched brass sides? It seems like an ideal candidate (given the lack of curves in the profile) for relative stiffness with resin or the like for the cabs and perhaps even the roof?

[Re6/6]

Jeff, I've built some 7mm long coach coach bodies using laminates of 10, 20, 30 and 60 thou plasticard in various combinations 30+ years ago and did notice recently when I found a part built body that there was some noticeable distortion.

 

Perhaps a totally different method/materials might be worth considering. Some years ago I was shown at an exhibition demo by Gordon Gravett his method of construction that he used for his French autocars. He makes the main supporting 'box' structure from perspex sheet with and an external cladding of (IIRC) 20 thou ABS sheet (not Plasticard) fixed to the perspex side structure with cyano glue. 2 or 3 mm holes were drilled at (again IIRC) 10mm centres, to allow the cyano fumes to escape whilst drying.

 

They had quite complicated shapes which were beautifully created by sanding the combined perspex/ABS.

 

There was an article in Continental Modeller some years ago. So someone on here may have a reference.

[Pugsley]

For ease, and longevity, I wouldn't use anything other than etched brass for a 7mm scale loco body, personally.

[ozzyo]

Hello Jeff,

 

if you are going to do Falcon in plastikard, I would recommend that you get hold of a book by David Jenkinson. The title was something like "Building 7mm Coaches in plastikard". I know it may seem wrong, but I've seen some of the coaches he built over twenty years ago and none of them had any warp or twist to them.A lot of his coaches had tumbelhome and or panels to them so if it worked for him it should work for you. Also your sides wont have as many holes in them as D.Js. had.

 

So why reinvent the wheel?

 

OzzyO.

[Fay Singpoint]

if you are going to do Falcon in plastikard, I would recommend that you get hold of a book by David Jenkinson. The title was something like "Building 7mm Coaches in plastikard".

 

Hi,

 

David Jenkinson's book is titled "Carriage Modelling Made Easy". I am using some of his techniques in my 2012 scratchbuild challenge entry. There has been some slight warping of the coach sides on my project but the completed body shell is square and true.

[14Steve14]

The simple answer has to be that if your model is warping and not staying straight, it isnt strong enough. You have the option of increasing the thickness, or adding strengtheners. It really is that simple.

[JeffP]

So..........on the above premise, do we think that 80 thou (2mm), for the sides is thick enough, with ribs across the width of the loco, made to roof profile, at both ends, and at, say 50mm intervals, allowing for any openings?