Making Models From Scratch

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simongt

Guru
Location
Norwich
acrylic paint will not stay put on plastic no matter what you do
Interesting this one on the basis that there must be different types of acrylic paints, as I've been using acrylics; brush on & rattle cans, on 'plastic' construction kits for several years now without any issues of adhesion at all. :whistle:
 
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Reynard

Reynard

Guru
Interesting this one on the basis that there must be different types of acrylic paints, as I've been using acrylics; brush on & rattle cans, on 'plastic' construction kits for several years now without any issues of adhesion at all. :whistle:

I think it likely depends on the actual type of plastic used.

The stuff I was trying to paint was a clear thermoplastic of some kind, so possibly a high density polythene. It cut and drilled easily and the large bit I was cutting from had a bit of give to it.

Suspect model kits are made out of thermoset, which are harder but more brittle, but easier to injection mould. And likely they have different surface properties.
 
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Reynard

Reynard

Guru
Getting acrylic to stick to plastic and metal is near impossible as far as I'm aware. That's why I've often primed models made from card with a rattle can if they have metal or plastic parts. Flickr is being a pain as usual, but there is an example in this set of pictures. I also found that priming had the added advantage that it made the card fibres expand, so sanding them down made for a better finish. I tened to prime sparingly and use two very thin coats as I've found that you don't need too much to help the acrylic paint bond, but it is incredibly easy to obliterate detail.

Is there anything in particular you would recommend?

I'll do a test piece on the metal later and see where it takes me. But just in case I come a cropper...
 
Is there anything in particular you would recommend?

I'll do a test piece on the metal later and see where it takes me. But just in case I come a cropper...

Not really: I use whatever I happen to have, although I find light grey works better than white. Shake it very well using a timer for at least two minutes after the ball thingy inside has started rattling, I hold the can upside down when I shake it: I have no idea if it helps but it seems a good idea.

I spray very lightly from about 30cm away with a side to side motion: it doesn't matter if you can see colour changes in the surface material through the primer, in fact that's when I usually stop. The "Car" above had a second coat because the card absorbs the paint, but I decided against a third because then I'd start losing details. I generally stop before I think I've put enough on, if you see what I mean.

Definitely do a test piece. Also test on broken bits to see how details come through.

I notice some rattlecans say they contain acrylic: I suspect part of my problem is that I use artists acrylics to paint models, so I need a primed surface.
 
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Reynard

Reynard

Guru
Not really: I use whatever I happen to have, although I find light grey works better than white. Shake it very well using a timer for at least two minutes after the ball thingy inside has started rattling, I hold the can upside down when I shake it: I have no idea if it helps but it seems a good idea.

I spray very lightly from about 30cm away with a side to side motion: it doesn't matter if you can see colour changes in the surface material through the primer, in fact that's when I usually stop. The "Car" above had a second coat because the card absorbs the paint, but I decided against a third because then I'd start losing details. I generally stop before I think I've put enough on, if you see what I mean.

Definitely do a test piece. Also test on broken bits to see how details come through.

I notice some rattlecans say they contain acrylic: I suspect part of my problem is that I use artists acrylics to paint models, so I need a primed surface.

I only have artists acrylics to hand, and I can't think of anywhere locally that's currently open under lockdown restrictions that would have anything suitable in a rattle can. Will have a squiz on Amazon and the Bay of E later. Unless some old rattle cans of car paint I know are lurking in the garage might do the trick. One is burgundy and the other is a blue-green, but hey ho...

Am also in need of more wire, as I don't think I have enough left to finish the project - not when I take the rollcage and suspension linkages into account. One of the parts (well four identical parts) really ate into my supply. I need something that's like paperclip wire, but a heavier gauge and in decent lengths e.g. 12 inches.
 
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Reynard

Reynard

Guru
Anyways, another pictoral update...

As mentioned upthread, I sorted out the front and rear suspension geometry, which meant I could laminate in the last four wire pegs (for the front wishbones) into the chassis. And *finally* stick the two halves of the main rails together. I've yet to sand all the edges etc, but it's too damn cold in the garage to spend a lot of time in there, *and* I need good daylight for fiddly stuff...

NR1F6968_small.jpg


I also made the solid block that will sit between the upper and lower chassis rails. As I'm not modelling the engine and gearbox, it was the easiest way to do this - and gives me a stronger structure. I've applied some card detailing to the block and drilled out the hole to take the driveshaft. I've photographed this upside down to how it would be in real life.

NR1F6969_small.jpg


I've also completed the design for the lower chassis rails. I decided to make the lower front wishbone integral with the lower rails - a bit of a pain at this stage of the build, but a lot easier later on.

NR1F6972_small.jpg


While I was sorting the front suspension geometry, one of the issues was the two upper wishbones, and how to make them. You can see how I thought me way through the iterations (from left to right) as I worked out whether laminated card with different sized layers would be best, or whether bent card would work. And the shape, size etc. The one on the right is roughly the shape and size required, but I can't make the parts yet until I've sorted out the lower rails. And the best way to get the shape I need is a mid of bent card and different laminations.

NR1F6965_small.jpg


Then I've also been working on the shock absorbers, as I can't finalize some of the components on the rear axle assembly until I've made the shocks and checked for layout and clearances. I've been using 40mm lengths of 3mm diameter wooden knitting needle, and using strips of paper to get the shape I need. I found that paper glue (pritt stick type stuff) was ideal to keep the paper in place, and then a regular dab of superglue to harden the structure.

NR1F6966_small.jpg


I've only drilled holes in the piston / reservoir end, as those will be pinned in place. The upper ends I've left plain for now, as they will most likely get bonded into the mount. Also, the shocks are a little bit too long - I'm working on the premise that it's easier to sand the top end down a bit than to find myself with a set that's too short. All of the components for the shocks are in place, they just need finishing off and finessing. The wee white doodads are what keep the spring in place - they're the plastic bits that were causing me painting headaches earlier...

NR1F6971_small.jpg


And finally, all four wheels are completed at last. As are both front stub axles. The wheels are all sanded, shaped and ready for priming, although they still might want a little tweaking here and there. I've noticed that priming stuff highlights where things need to be worked on a bit...

NR1F6967_small.jpg


And that's the sum of my latest update...
 
For reasons which I'm sure seemed sensible at the time, I've taken a couple of pictures of models being primed and posted them on my modelmaking blog, and one shows the sort of effect I aim for with primer:

van_01_18.jpg


The I have no idea how I managed to have a number "3" on a van with two ends, but that shows how thick the primer is when I paint over it: any random marks underneath are still visible.

You'll probably have to go over it a couple of times with the artists acrylics but you'll need to do that anyway...
 
So as not to clog up the Mundane News thread with the minutiae of my 1:10 scale Higman Superstox project, thought I'd start a new thread on the ins and outs of scratch-built models.

I have to confess that I'm a modelling newbie - my only previous experience is with a few cheap plastic kits well over three decades ago. You know, the ones that never fit together right, where the glue doesn't set completely and the paint and decals refused to stay put... My background is in automotive engineering, so the design work itself isn't the issue. Where I could use advice is in making that leap from drawings on a page to actually making parts. So methods, materials, hints and tips, that sort of thing, from heads wiser than mine.

Was hoping to make the main part of the chassis (which includes the mount points for the side irons and front & rear bumpers) from fibreboard. Unfortunately the piece that I have is warped, which means it's no go. The alternative I have to hand is 5mm thick plywood, but am not sure if it is the right material for what is a pretty complicated shape.

View attachment 571311

This piece is the structural "backbone" of the whole model, so I have to get it right...

Oh, and this is what I'm trying to build... (#221)

View attachment 571313
What would that chassis have been constructed from on the actual car, steel tubing?
The rectangle on the drawing, is that a transcription of the full size chassis, a floor pan?
 
Anyways, another pictoral update...

As mentioned upthread, I sorted out the front and rear suspension geometry, which meant I could laminate in the last four wire pegs (for the front wishbones) into the chassis. And *finally* stick the two halves of the main rails together. I've yet to sand all the edges etc, but it's too damn cold in the garage to spend a lot of time in there, *and* I need good daylight for fiddly stuff...

View attachment 576879

I also made the solid block that will sit between the upper and lower chassis rails. As I'm not modelling the engine and gearbox, it was the easiest way to do this - and gives me a stronger structure. I've applied some card detailing to the block and drilled out the hole to take the driveshaft. I've photographed this upside down to how it would be in real life.

View attachment 576884

I've also completed the design for the lower chassis rails. I decided to make the lower front wishbone integral with the lower rails - a bit of a pain at this stage of the build, but a lot easier later on.

View attachment 576885

While I was sorting the front suspension geometry, one of the issues was the two upper wishbones, and how to make them. You can see how I thought me way through the iterations (from left to right) as I worked out whether laminated card with different sized layers would be best, or whether bent card would work. And the shape, size etc. The one on the right is roughly the shape and size required, but I can't make the parts yet until I've sorted out the lower rails. And the best way to get the shape I need is a mid of bent card and different laminations.

View attachment 576888

Then I've also been working on the shock absorbers, as I can't finalize some of the components on the rear axle assembly until I've made the shocks and checked for layout and clearances. I've been using 40mm lengths of 3mm diameter wooden knitting needle, and using strips of paper to get the shape I need. I found that paper glue (pritt stick type stuff) was ideal to keep the paper in place, and then a regular dab of superglue to harden the structure.

View attachment 576890

I've only drilled holes in the piston / reservoir end, as those will be pinned in place. The upper ends I've left plain for now, as they will most likely get bonded into the mount. Also, the shocks are a little bit too long - I'm working on the premise that it's easier to sand the top end down a bit than to find myself with a set that's too short. All of the components for the shocks are in place, they just need finishing off and finessing. The wee white doodads are what keep the spring in place - they're the plastic bits that were causing me painting headaches earlier...

View attachment 576893

And finally, all four wheels are completed at last. As are both front stub axles. The wheels are all sanded, shaped and ready for priming, although they still might want a little tweaking here and there. I've noticed that priming stuff highlights where things need to be worked on a bit...

View attachment 576896

And that's the sum of my latest update...
All becomes clear as old me reads the thread backwards.
I doubt you have seen the back of scale model making.
Obtain a razor saw, x-acto are good, for your next endeavour.
If you don't have soldering skill then you might benefit to learn, it's not difficult at all, preparation is nearly all.
Brass tube in square, round and oval is your friend in all things with a chassis under 50cm length.
 
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Reynard

Reynard

Guru
What would that chassis have been constructed from on the actual car, steel tubing?
The rectangle on the drawing, is that a transcription of the full size chassis, a floor pan?

Yep, 50mm square section for the top rails and the roll cage, 30mm square section for the other metalwork. I'm not modelling the engine and gearbox, hence the solid block. Just makes life easier. :smile:

I have these moments where I wonder what the hell I was thinking, as i have no prior modelling experience, but then, when something works, I'm like "you got this, girl!" :blush:

And then I have mad thoughts about modelling his older brother's Superstox... :wacko:

And i can't blame that on the demon drink, as I'm teetotal :laugh:
 
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Reynard

Reynard

Guru
A late evening update...

Have primed the wheels and I can now see where I need to tweak things. I definitely did get better at building them as I went along! :laugh:

On the downside, the paint scratches off with a fingernail. That's no real huhu at this stage, as all the wheels still need work to some degree or other. So I've caved in and just ordered the Tamiya light grey primer off Amazon. The blurb says for plastic and metal models, so this *should* cover all my bases.

If I'm going to do this, I may as well do it properly. Including the time spent scaling photos and doing design work, I've probably invested over a hundred hours in the project so far. Seems stupid to do things by halves, really...
 
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