Scratchbuilding techniques

[Cees Broere]

Thanks chaps,

I am aware of that and I have made several attempts at scratchbuilding such as a 1/28 and 1/32 HO 0/400, and scratchbuilding Whitley and Hampden tails from laminated plastic. I am looking for a relatively simple way to achieve complex shapes. I noticed Vaughn ( Spacewolf) that he creates complex scifi model shapes very quickly with the plank on frame method although the vacform way is my preferred method but a master has to be created first.

[GuildAero]

If you're going to go the master and vac-form way, try creating your master in Ureol. Also known as epoxy modelling board, tooling board or (in America) Renshape. It's easy to work with saws and files.  I even use chisels till the very late stages to keep dust down. It vac-forms well despite the heat.  In fact, as it is basically a self skinning foam it vac-forms exceptionally well, the suction seeming to pull through the structure of the pattern.  It can be bought off ebay or you can (and should!) beg off cuts from rapid prototyping companies found in your local Yellow Pages. I have only ever bought Ureol once!

To see it in action have a look at the DH89 thread, where I made the whole model in Ureol, with a little styrene here and there for detailing.

 

Cheers,

Martin

[Cees Broere]

Thanks Martin.

[Lee White]

Cees,

 

I have scratch built 3 different models. The first was crap, the second was pretty good and the third I am quite proud of.

 

Bottomline, you have to build to get better. And you have to start somewhere.

 

Start with something easy and progress to your dream project. Check out my 1:32 Skyshark here on the forum. I was learning every step of the way. You will too.

 

Dan

 

 

 

 Excellent advice.

[Cees Broere]

Lee, you are an experience pattern maker, any advice?

[Starfighter]

Ureol is an excellent material to carve complex masters - it can also be machined in most ways one can imagine. Sadly, it is pretty expensive.

[Hubert Boillot]

"pretty expensive" is an understatement ... Martin is lucky to have some stocks given to him by a friend.

 

When I asked for a price quote for my company, the price per board was 2 to 3 times more than I expected. And that was for a company, in a BtoB standard sale. I passed.

 

For the average "Mr Modeller", buying Renshape from a reseller with VAT and mark-up makes it a steep investment.

 

Hubert

[Starfighter]

I only use Ureol for small, complex parts. For bigger parts, I use a medium density PU foam combined with an ABS 'skeleton' (see http://forum.largescaleplanes.com/index.php?showtopic=52725&hl= for example) which is later sealed with resin or super glue and finished with automotive filler before being scribed and primed. 

Edited August 30, 2016 by Starfighter

[Lee White]

Lee, you are an experience pattern maker, any advice?

 

 

The only thing that I can add, Cees, is that everything I learned I learned from the Alcorn book with the Keystone bomber on the front- I found plans for my first attempt, an OV-10, back in 1994. I chose that plane for it's simplicity- square cross-section, constant chord wing, etc., and it was a great learning experience. Our LSP friend Jack actually finished it, (did a great job, too, if I may say so) before I went on to my next attempt, the XB-51. That was a bit more of a chore than I had expected, just because of it's size. I carved the molds from Basswood, as I have for all my projects except for the Yak-38 and XF-103, which were Balsa. I personally like the harder wood, as it is harder to accidentally remove a huge chunk when I get distracted. The carving itself is a very pleasant pastime in and of itself, very relaxing, until I screw up, and turn the air blue. Basswood also sands about the same as Aves, so when I patch my mistake, I don't have to worry about sanding away the wood at a different rate than the filler, easy to do with Balsa. Try and make your molds with a logical breakdown, I usually buy a kit of the subject in a smaller scale to see how the pros did it (F-111).  Also, try and avoid undercuts when vacuforming, they can be a pain. I have also been experimenting with plank-on-frame modeling similar to Vaughn's Barracuda with my F3H Demon, and it is a nice alternative. Definitely the way to go for 1-off projects, IMHO. I hope this helps!  

[Hubert Boillot]

Lee, a few questions :

 

- Did you finish the XB-51 masters ?

- Were they 1/32 ?

- If yes to both above, did you keep them ?

- If yes, can you still pull a copy of these masters ?

 

Because, if you have not guessed it by now, this is one I'd love to have a got at. A 1/32 XB-51 ?    

 

Hubert

Edited August 31, 2016 by MostlyRacers

[wunwinglow]

Values vary. Balsa, in fact any wood, is cheaper to buy than ureol. But if you put a value on the time taken to finish it satisfactorily, wood is way more expensive. Hobby modellers of course don't have that issue, so industrial materials can look expensive. But I haven't used wood for a model for over 30 years..... Even my own projects! Once you try the modern materials, they work so well, don't warp, shake, irritate, splinter. They don't need sealing with nasty varnishes and dopes. You can wet and dry sand it, drill it, tap it, glue it instantly with cyanos or longer with epoxies. You can fill it with P38 or filler primers, and the finer grained ones will score pretty well too.

 

I do have a few off cuts so if anyone wants to try some, drop me a pm.

[Red Five]

Hmmm...I've been making a framework out of styrene sheet and sculpting over it with Milliput or covering with drinks can aluminium since the 1980s!  Makes my methods sound very antiquated.

 

 

Andrew

[Lee White]

^ Nothing wrong with going Old-School!!^

[Cees Broere]

Andrew,

Any pics to show how that would turn out?

[Wegener]

I just did a quick search online for 'ureol uk price' and found some at under £16 plus VAT for a 25x25x5cm block, which doesn't sound extortionate to me at least. Now I just need a CNC machine.....

 

The site listed three densities; this is the medium one, suitable for hand carving and machining. High density (same dims) is £18.40 and low density is c.£40 for 50x50x10cm, so eight times the volume. Not sure which is preferable though.