Rapid-Prototyping Aero Parts

[aerohead]

Hello all.This is a follow on to an update on the trailer project I posted over at the Aerodynamics Forum.Al is busy but has promised to help get the photos.Let me get this text up,so you all will know what's going on.----------------------------- I've been fabricating the fairings and using a technique from one of my composite books.It's relatively quick and dirty and can get you in the game in short order.---------------- From any design,a set of patterns are generated which are transferred to something structural.You can use anything you want.I've been using cedar.It's light,dimensionally stable,easy to cut and form.---------- From the photos you'll see a photo-enlargement of a strut section I've transferred to cedar,then cut out,sanded to net shape to create a rib which creates the "base" for the fairing.------------ The next operation is to drill, countersink,and install a 1/4" X 2" carriage bolt,which will anchor the faring to the trailer.----------------- Next,the main vertical spar is glued/clamped/screwed,using carpenter's weatherproof glue and drywall screws.-------------- Same goes for Rib # 2,and Bottom cap (wingtip).----------------- After the superstructure is complete,the whole thing is covered with sections of Styrofoam open cell foam,glued on and held overnight with masking tape.--------------- Next day,you can lose the tape and sand the foam to net shape.I use an 18-inch quick-release sanding board from an automotive finishing supply with #36-grit paper.------------ When your happy with your form,a liberal coat of polyurethane spar varnish will create a barrier shield which will protect the foam from polyester-based body filler and resin and fiberglass which follows after the varnish cures.After completion,the vehicle ( trailer in my case ) is through-drilled,part attached from inside,leaving a clean invisible bond.--------------------- Entire car bodies can be created in this manner.Many human-powered submarine and competition bicycle bodies have been created this way.-------------- Your finished piece can be used directly or used as a male mold(plug) to create a female mold to create a wet layup composite component.------------ Everything can be purchased at the home improvement center.----------- I'll go ahead and post this part and hopefully,photos aren't far behind.

[aerohead]

Here are the shots of the monstrosity taking form:

[Cd]

Rapid prototyping, as I am familiar with it, is creating something in 3D and then having a machine mill it out of a soft resin.

http://www.youtube.com/watch?v=PDLOmoQj4H0

Off topic here, but is the 'Enter' key on your keyboard not working ?

[itsmedc]

Originally Posted by Cd

Rapid prototyping, as I am familiar with it, is creating something in 3D and then having a machine mill it out of a soft resin.

uuhm Cd
While the rapid prototyping you are refering to, the type discussed in the video link, is very cool there in no "machine mill" involved. It is actually a "printed" part using UV light flashing on the surface of a vat of liquid polymer that instantally forms a small layer of solid material. It keeps "printing" and building up layers until the whole solid piece is formed. The only "machining" that takes place is when some of the more complex parts are dropped in acid to remove a support structure material. I know Formula 1 teams have these and have even seen one at an Air Force tech school.

I think aerohead's point was a type of rapid prototyping that is a bit more accesible/affordable by the average ecomodder that will still produce a professional looking part.

And to follow up on your off topic point about the "Enter" key on aerohead's keyoard...

The point being to open up some white space between his thoughts.

I do wish he would use it too but, I picture my dad using a keyboard and just accept it as the price of reading aerohead's opinions and first hand accounts of the very interesting/effective things he does.

[NeilBlanchard]

Hi,

Printing in 3D is now quite possible, but you are limited to the dimensions of the printing chamber of the printer. Often this is 8"x8"x10", but things can be glued together from pieces.

First, you have to have a CAD model, though.

[botsapper]

Hopefully this is not too wonky but here's a primer for rapid prototyping. Guess any fast model maker could be good in 'rapid prototyping'.

http://www.prm.ucl.ac.be/cours/meca2...rototyping.pdf

The cliche CNC 5 axis machining & milling is a dance of the workpiece & cutter precisely controlled via digital automation. Design studios' most favorite tool on metal, wood, clay, foam, etc. workpiece prototypes.

http://www.youtube.com/watch?v=vnuH5No_aXM

http://www.youtube.com/watch?v=8I3diD1lpho

[aerohead]

Originally Posted by Cd

Rapid prototyping, as I am familiar with it, is creating something in 3D and then having a machine mill it out of a soft resin.

Off topic here, but is the 'Enter' key on your keyboard not working ?

Right Cd,with today's technology a "virtual" part could be created within CAD,then CAM could actually create the prototype part.------------------Short of all the gee-whiz gadgetry to make that happen,what I posted is definitely low-tech,although has been the mainstay of manufacturing design for most of recorded history.------------------ Since it doesn't involve Chrysler's Technology Center or anything like it,is is within the domain of any individual wishing to cobble up something for testing or permanent modification.--------------------- With respect to posting,I'll apologize for the umpteenth time.I've never had typing class,never learned a word-processing program.I don't create documents and then export them anywhere.When I get here to the copy center,it's just balls to the wall hunt and peck 'til the clock runs out.------------------ These series of dashes are an attempt to do paragraph breaks so the whole post isn't one single smear.I know it's lacking in presentation,my only hope is that it delivers some useful content.

[Whoops]

Well, I think that your sharing your ideas and experience is a great resource and you have my thanks. As far as the typing is concerned, you type whatever you want and it's not a problem. Anybody that complaining, just doesn't have enough to do. Thanks, for the tutorial.

[anthonye81]

Cd's point is that the term "rapid prototyping" refers to a specific practice of model making with all the 3D CAD and resin moulding equipment. Using this term for something else can be confusing.

[aerohead]

Originally Posted by anthonye81

Cd's point is that the term "rapid prototyping" refers to a specific practice of model making with all the 3D CAD and resin moulding equipment. Using this term for something else can be confusing.

Okay,how about that it is rapid,in the context of do-it-yourselfers as the forum implies.
There was a time when cement plaster supplanted all-wood prototypes,and it was more "rapid."

Then came clay which was faster.
Then body-filler over foam.
Sure,stereo-lithography is an amazing process although you've got to have your design fixed,pre-digitized, and all the vectors established before you even begin to build up laminations.Okay for an engine block,but a car maker would never do a body this way.They'd use their 5-axis router/mill to cut down clay.And again,the "virtual" vehicle must already fully designed.
Again,it's all great but certainly beyond the scope of the backyard shop or garage.
The foam/wood/fiberglass is low tech,can be modified instantaneously,and designed on the fly.
CAD/CAM is today's state -of -the-art,although for a knuckle-dragger like me,born before dirt,this home-brewed tech has been one way to see things come together and on the road before the engine wears out.