Making Models From Scratch

[Bazzer]

A bit more progress - will update with some photos in the next day or so.

Have been working on the front suspension assembly. I've made the brake discs (they're about the size of a 2p coin!) and I've just about got my head around the stub axles. The issue with the latter is that I need to find a suitable compromise between realism and the part being sturdy enough. It's a fairly complicated structure to which several things attach (upper wishbone, lower wishbone, steering arm, brake disc and wheel), and I don't want the thing collapsing on me.
.....

Have you considered making the individual parts and then strengthening them using clear resin? The resin can then be painted once dry, using acrylic paint. Two part resin takes longer to go off than epoxy, giving you time to deal with several parts at the same time.
You could then use the quicker drying two part epoxy to join the parts.

BTW, probably way before your time, but my mate I used to regularly go to stock car racing. Back in the days of Smith (snr) Wainman (snr) and Harrison.

 

[Reynard]

You know, I almost understood that...

LOL... It will be clearer once I post some pictures.

Looking up 'sponson' and 'nerf bars'...

I was doing quite well until I got to that sentence.

Sounds like a great project @Reynard , I for one can't wait to see the finished model.

Oops... Might be a while before I finish it, but I hope it'll be worth the wait.

Have you considered making the individual parts and then strengthening them using clear resin? The resin can then be painted once dry, using acrylic paint. Two part resin takes longer to go off than epoxy, giving you time to deal with several parts at the same time.
You could then use the quicker drying two part epoxy to join the parts.

BTW, probably way before your time, but my mate I used to regularly go to stock car racing. Back in the days of Smith (snr) Wainman (snr) and Harrison.

I have been using 2-part resin for some of the fiddlier bits.

It is, and it isn't. Before my time, that is. I've been into motorsport since I was seven, but circuit racing rather than stock cars. THAT moment at Paddock in the '82 British GP and I was so totally hooked...

 

[MrGrumpy]

He’s been busy blowing things up but it does work and it floats. Still got loads to do ...

 

[Reynard]

As promised, some photos and sketches...

Firstly, I now have both halves of the main chassis rails. I've marked out on the top surface where the edge of the rails are in real life and where the axle lines are located. I've done the same on the underside, so it's easier to know where to put things later.

Plus I've been sketching out the front suspension. It's a fairly standard racing car layout on the front - stub axle, brake disk, outboard shock, double wishbone, but the problem I have is that I don't have clear enough photos to get the exact design of the wishbones. Lower wishbone is far less of a problem than the top, but some guesstimation will be required.

The second sketch is actually 1:5 rather than the 1:10 that I'm working in. Basically it's easier to draw and measure. Spoke to the friend who is giving me techy help, and it turns out I've got the dimensions (especially for the damper length) bang on. Kind of rather pleased with that.

Next, my diddy little brake discs, with a 2p piece for scale. They've since been sanded and base coated etc, and are ready to be painted. But I won't be doing that step just yet. I'm using a mix of titanium white and payne's grey to base coat parts, btw. Thanks for the advice on that @Andy in Germany - it really makes missed bits and flaws stand out.

Been working on the stub axles these last few days. Made, built and discarded a prototype, as it was way over-engineered. The card I'm using sets really solid with the glue, so I can make the component much more true-to-type. Even so, the templates went through several iterations before I ended up with something I'm happy with. I don't dare make it spindlier, because it's a major structural component. I think I've got a good compromise between looking right and being sturdy enough to do the job. Of course, it will look much better when it's sanded and painted up.

So, right hand front stub axle, plus the parts to make the left hand one, bar a wooden peg and a fine upholstery pin. I've drilled the holes to take the steering arm and the lower wishbone, but not the one for the upper wishbone. I'm leaving that until I've got a design for the wishbone that I'm happy with, and that I can actually make.

Rear view of stub axle

And finally, the assembly of wheel, brake disc and stub axle. And, mirabile, after all that faffing, they all fit together! (edited to point out that they're not glued together yet - was just checking the fit!)

OK, some of the bits still need a little finishing and TLC, but right now, I don't have enough good daylight to paint / sand etc all the very fiddly bits. So I'm concentrating on the design work, making parts and making sure stuff fits together as it should. The rest can wait for now.

 

[simongt]

Probably the worst thing that can happen to any model maker is when you have a tiny wee part held in a pair of tweezers ready to attach to the model and suddenly - ping - ! And that's the last you ever see of that one, vital part to finish said model - !
Aarrgghh - !

 

[Andy in Germany]

Probably the worst thing that can happen to any model maker is when you have a tiny wee part held in a pair of tweezers ready to attach to the model and suddenly - ping - ! And that's the last you ever see of that one, vital part to finish said model - !
Aarrgghh - !

And it's always the vital, small, extremely delicate and usually black painted part that does that.

 

[simongt]

Happened yesterday; a hatch hinge from a 1.35 scale AFV suddenly did the ping thing and being about 2mm square and dark green - nae chance pal - !

 

[Andy in Germany]

Happened yesterday; a hatch hinge from a 1.35 scale AFV suddenly did the ping thing and being about 2mm square and dark green - nae chance pal - !

Been there, done that. I guess one advantage of scratchbuilding is that I know I can make a replacement...

 

[Reynard]

Which is exactly why I've just finished building the second stub axle - the glue is drying as we speak - and then I can put it in the box of finished parts.

I also have to contend with a pair of nosey furry "assistants" who like to play with small, interesting things, so I don't dare leave tiny bits lying around unattended. Far too tempting. It's bad enough when I'm sewing...

Never mind that I'm klutzy at the best of times...

 

[Reynard]

Anyways, I've pretty well much sorted out the rest of the chassis design. Or at least I think I have...

I've decided to make the lower wishbones for the front suspension integral with the bottom rails. Strictly speaking, it's not entirely correct, but it simplifies things a LOT by doing it that way. And by the time the car is actually built, I very much doubt anyone would notice. I've also added fillets to the rear section of the bottom rails - again, not quite correct, but it will prevent breakages on what are otherwise quite thin sections. Method of making will be same as the top rails.

The central core of the chassis is a block made from laminated card and ply and faced around the sides with card details - basically taking up the space where the radiator, bottom of the engine and the gearbox would be. On the actual car, the sides of the chassis is masked off with metal plating to protect those bits, and there is a sumpguard fitted too. So it seems like a logical way to do this, given that other than the driveshaft, differential and rear axle, I'm not modelling the whole drivetrain. It's down to a lack of information - although I do know the engine is a 2-litre Pinto unit.

And the block serves another purpose other than to keep the top and bottom rails at the required separation. I've designed things in such a way that the block is the datum point to which everything else fits and is relative to. Three wooden pegs will be fitted vertically through the center line of the block, and protruding from the top and bottom surfaces. There will be corresponding holes drilled in the sections for the top and bottom chassis rails - which means that the pegs will help locate and align all the various bits.

The upshot of this is that I can build the bottom half of the chassis i.e. lower rails, suspension, the bits of the drivetrain that I am actually modelling separately from the top half of the chassis and rollcage. This will definitely make the build easier from what I can see. And then, theoretically, it should just all slot AND fit together...

 

[simongt]

I also have to contend with a pair of nosey furry "assistants"

Yup, we have ten of them and two or three have the uncanny knack knowing EXACTLY when you're in a critical point of fitting a tiny or otherwise vital part to leap onto the workbench - !

 

[Reynard]

Yup, we have ten of them and two or three have the uncanny knack knowing EXACTLY when you're in a critical point of fitting a tiny or otherwise vital part to leap onto the workbench - !

Actually, my current two are worse when I'm sewing... One loves killing the tape measure, and the other likes to rearrange fabric laid out for cutting. As for spools of thread, buttons, tailor's chalk etc, well...

Although I stopped painting in oils about a decade ago after having to de-paint a pair of cats who wanted in on the act. I ended up with a green-pointed black and a yellow-mitted blue...

 

[Reynard]

Major milestone reached! The two halves of the main (upper) chassis rails have now been glued together.

I had to carve out all the channels where I'd laminated in wire pegs. And add two additional on each side (four in total) to take the top wishbones for the front suspension. The links for the rear axle attach elsewhere; two just above the lower rails and two below the y-shaped nerf bar.

The glue is currently curing. I used 2-part epoxy btw, and just as well, as it's a large surface area and a complicated shape.

Muchly relieved, as this had the potential to go very wrong.

 

[Reynard]

Bit of a techy thing regarding paint.

I've got some parts made out of metal that could do with a coat of paint. Will artist's acrylic bond to metal without flaking off? What's the best way of tackling this? Do I need to prepare the surface in any way prior to painting? I could get away with leaving as bare metal, but in the interests of achieving a good level of accuracy, I'd rather not.

Have also discovered that acrylic paint will not stay put on plastic no matter what you do. It flakes off if you so much as look at it. Problem solved by sanding down with wet & dry and then bonding said plastic parts between thin layers of paper. I did a test piece to check first, though.

N.B. I chose plastic for those particular parts because the bits I used were already the shape I wanted. To make them from card would have been fiddly and frustrating.

 

[Andy in Germany]

Bit of a techy thing regarding paint.

I've got some parts made out of metal that could do with a coat of paint. Will artist's acrylic bond to metal without flaking off? What's the best way of tackling this? Do I need to prepare the surface in any way prior to painting? I could get away with leaving as bare metal, but in the interests of achieving a good level of accuracy, I'd rather not.

Have also discovered that acrylic paint will not stay put on plastic no matter what you do. It flakes off if you so much as look at it. Problem solved by sanding down with wet & dry and then bonding said plastic parts between thin layers of paper. I did a test piece to check first, though.

N.B. I chose plastic for those particular parts because the bits I used were already the shape I wanted. To make them from card would have been fiddly and frustrating.

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.