Building many engines ...

Scotaidh · Post by **Scotaidh** » Tue Dec 08, 2009 1:48 pm

Question: Has anyone here made engines from sprue? I'm in need of four (4) jet-type engines for a build, and I don't do casting. I have "ends" - that is, intakes and outfolds that I can attach to make things 'look right'.

My rough plan is to cut sprue in verying lengths and glue them into bundles to act as sort of armatures (amachers?

) which I will then bulk out with putty. Serious attempts will be made to keep them symetrical to each other so the craft looks somewhat professional and not as if it were cobbled together in a Junkyard Wars episode ... Oooh - there's an idea for a Challenge!

So - has anyone actually done this? I'm hoping for advice, comments, warnings - anything, really. I mean - I'm gonna do this one way or another, I was hoping some of you might be able to point out short-cuts, pitfalls, Bad Ideas, Good Ideas, interesting thoughts....

This is for Keptin Barnes' Off-hand Challenge, in case I forgot to mention.

Ciao, and thanks!

Andrew Gorman · Post by **Andrew Gorman** » Tue Dec 08, 2009 2:59 pm

I'd start with plastic tubing or a stack of cylindrical shapes rather than slathering putty over a rough armature. A stack of 1/25 car wheels would be a good start, and easier to glue little detail bits to. What diameter do the engines need to be?

Wug · Post by **Wug** » Tue Dec 08, 2009 3:02 pm

How big do they need to be?

Have you thought about cutting the ends from droptanks, bombs or plastic craft beads?

Instead of sprue, you could use appropriately sized tubing as a core. Cut a form of the profile of the engine from sheet plastic. Build a simple jig to hold the form against the tube. Cover the tube with your favorite putty. Unless your building very small, use polyester putty or epoxy putty. Before the putty sets, put the tube and form in your jig. Rotate the tube and the form will scrape away the excess putty leaving the tube surrounded by jet engine.

This is a bit hard to describe, but there are good illustrations of it in Gundam Scratchbuild Manual.

Mike

Kylwell · Post by **Kylwell** » Tue Dec 08, 2009 4:29 pm

And don't forget large diameter knitting needles.

Scotaidh · Post by **Scotaidh** » Tue Dec 08, 2009 5:39 pm

Size ...hmm - well, they're for a one-seventy-twoth X-wing. I dislike the horrid little hair curlers they stuck on for engines, and I want some that are bigger, stream-lined, and with More POWER!!!!! (:oops: Sorry - I had a Tim Taylor moment there.)

So about three inches long by about three-quarters of an inch max diameter. Steep chamfer at the front, long shallow taper at the back, down to about a half inch diameter exhaust nozzle.

Yes, I said 'stream-lined'. I know, I know I know - but it's all B/s because the thing flies through atmosphere - and quickly too, if I can believe the movies. Clunky exposed innards = drag = heat = component breakdown. The slipstream would also buffet any exposed drag-causers severely, meaning they'd have to be 'overbuilt' to survive. I wish I could tell you about parasitic drag in a submarine application, but my uncle would get cross. Let's just say that reducing drag, from every possible standpoint, is a Good Idea (TM) because it lets you build with materials other than titanium-bound bricks and concrete.

Umm - anyone want this soapbox ... I'm done with it ...

Scotaidh · Post by **Scotaidh** » Tue Dec 08, 2009 8:03 pm

I've found my engines.

Kazoos! I have 4 plastic Kazoos, and with a little trimming, they'll be perfect!

Andrew Gorman · Post by **Andrew Gorman** » Tue Dec 08, 2009 9:11 pm

Good for you! I like the idea.

naoto · Post by **naoto** » Tue Dec 08, 2009 9:14 pm

Scotaidh wrote:I've found my engines. Kazoos! I have 4 plastic Kazoos, and with a little trimming, they'll be perfect!

Kazoo? Why use incorporating a Zatoxian into an X-wing in the first place?
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Oh, wait, that's Gazoo... Never mind...

Scotaidh · Post by **Scotaidh** » Wed Dec 09, 2009 12:35 pm

I just realized that I never thanked any of you for your suggestions ... sorry

Thanks!

Good suggestions they are, too, and not ones I had considered.

Andrew, I don't have any car wheels to speak of - I tend not to build cars (long story), and I think 1/25'd be too big in this scale.

Wug - I like your template idea - I may use it. I had toyed with the thought of chucking the rough shapes into my drill, once the putty had dried, and using chisels and files to shape them. But shaping the damp putty is ... genius!

Kylwell, I have used knitting kneedles before - one good thing about them is that the pointy ends work well for intake spikes.

Thanks again, youz guyz - I appreciate your help.

Thom · Post by **Thom** » Sun Dec 13, 2009 6:45 pm

Buy some formula 1 race car models, just to bash their slender bodies into spaceship hulls - and save the wheels for later...