7 foot ShopBot R/C Heli Mold Plug

[tom_fiddler]

Here is a project I just finished
Thanks to Brady Watson for the tool path.
One of these day's I will get ArtcamPro
These scale guys usually start with a gallon of Bondo and go from there.
Thanks to Brady again.
I have not posted here in a while so its good to be back
Tom
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[tom_fiddler]

More pics.
Tom
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[jay_p]

What is it Tom?

Jay

[gerald_d]

The title of this thread is: 7 foot ShopBot R/C Heli Mold Plug

translates as:

7 foot (84 inches) long, ShopBot cut, radio controlled Hind (http://images.google.com/images?sourceid=navclient&ie=UTF-8&rls=GGLD%2CGGLD:2005-07%2CGGLD:en&q=hind) helicopter model to be used as a "positive" from which to take a mold.


Tom, are those the trademark ShopBot chatter marks running up the leading edge of the tail? If they are, then they are some of the worst I've ever seen.

[Brady Watson]

Hey Tom,
That turned out great! A quick swipe with an orbital sander or sandpaper will quickly remove any of the 'chatter' marks seen on the tail. These marks cannot fairly be blamed on the Bot...they are more a result of stepover marks from the 3D raster. At the cost of time they could be greatly reduced, but a little sanding quickly fixes this and saves a LOAD of machining time.

-B

[tom_fiddler]

Jay
Gerald is correct
The guy I did it for will now fill, sand and put in body panel lines so he can make a mold from this. then sell fiberglass body shells for people to build remote control scale helicopters with


The marks are from the tool path, not the Bot
I had plenty of time to watch them being cut!

Tom

[jhicks]

Tom & Brady, Nice photos and interesting idea. We have considered simular ideas for molding but haven't moved forward yet. Can you tell me what material one would fill such a mold with? If you are saying lay up fiberglass in the 2 sides of a mold I get it. I am thinking about some type of expanding Foam like a "great stuff" to shoot/fill into molds for shapes or unique pieces in low/medium production volumes. Any input on that out there?
Thanks

[Brady Watson]

Jerry,
In this case, the machined part will serve as a 2-pc plug for the heli fuselage. After surface finishing, the model will be sealed, waxed, release applied and prepped for the actual mold making process. Then putty will be applied to areas that need fileting, and cloth added in layers. When complete, the plug will come out and the resulting cavity/shell will be the mold.

In terms of creating foam parts, you will want to use a rigid urethane rubber or silicone mold with rigid shell. Great Stuff is not good for what you want to do. I recommend the R8 foam from PolyTek. Be sure to get the appropriate release agent. You will need to think about the expansion rate of the foam and density you want the part to be. You can totally enclose the mold for the foam cast, but MUST provide venting because the foam will expand like nothing you have ever seen before! It is potentially dangerous in the sense that if not vented properly, everything in the immediate vicinity will be covered in VERY tenacious liquid foam. Open molds will work, but you have to deal with how you are going to trim off the 'miniscus' that flows over the top of the mold as it expands.

-B