Aluminum Experiment

[Gil]

The following experiment uses modeling clay to form a mold plug on the glass pane. Petroleum jelly (thinned with in paint thinner) is painted on as a mold release. Fiberglass reinforced casting plaster is poured on top of the plug to make the mold. After it cures, the mold is used as a form to shape a piece of 0.005" thick tooling foil with ball shaped forming tools. A pounce wheel is used to add the rivet lines...

[scon10]

Interesting technique! Maybe a good method to make piston engine covers or hoods and such. Just a few questions for my understanding:

What is petroleum jelly? Is that available in Europe?
Do you need any sort of seperator liquid to avoid the mold sticking to the plug?

Thanks.

[Zakopious]

Probably sold in Europe as Vaseline.

Also known as petrolatum.

See: Petroleum jelly - Wikipedia, the free encyclopedia

[RyanShort]

Impressive!

Ryan

[Bomarc]

Nice Gil. How much pressure is required to press the two halves together to form the part, and is there any "spring back" of the part after separating the halves? I'm assuming the Fiberglas reinforcement is to keep deformation of the negative mold to a minimum while pressing the part?

Mike

[Gil]

Originally Posted by scon10

Interesting technique! Maybe a good method to make piston engine covers or hoods and such. Just a few questions for my understanding:

What is petroleum jelly? Is that available in Europe?
Do you need any sort of seperator liquid to avoid the mold sticking to the plug?

Thanks.

Scon10, It's Sold as "Petrolatum" or "Vaseline" (brand name) in the Europe and serves as the mold release (parting agent). It's thinned it with paint thinner to obtain a very thin layer. The so prepared mold assembly is slightly warmed with a heat gun to "flow" the brush marks out.

Originally Posted by Bomarc

Nice Gil. How much pressure is required to press the two halves together to form the part, and is there any "spring back" of the part after separating the halves? I'm assuming the Fiberglas reinforcement is to keep deformation of the negative mold to a minimum while pressing the part?

Mike

Mike, sorry to give the impression that it's "pressed out". It's really "formed in"; A flat piece of tooling foil is deformed or burnished "into" the mold cavity with a ball shaped tool (dapping punch) so the forming forces are light (finesse is the word) . Technically it's referred to as a "buck" (as in full scale aluminum forming). You can find Hydrocal FGR 95 at "real" ceramics suppliers.

The idea behind the experiment is to find an easy method to quickly make "bucks" for forming compound curved parts. FRG auto body filler is used in the full scale aircraft restoration shops for the same purpose. I wanted one that could be done at home without complaints from the "fumes" department...

+Gil

[Zathros]

Did you start in the center and work your way outward, spiral like following the outline? I must admit the workmanship is awesome. I have a "fumes department" in my house, it is run by my wife. Is this universal?

[Bomarc]

Originally Posted by Gil

Mike, sorry to give the impression that it's "pressed out". It's really "formed in"; A flat piece of tooling foil is deformed or burnished "into" the mold cavity with a ball shaped tool .....

A-Ha! I see, the plug was merely the vehicle to make the mold, which is where all the work on the part took place. Just another fine example of my stellar reading comprehension.

Good technique, thanks.

Mike

[ct ertz]

Originally Posted by Zathros

Did you start in the center and work your way outward, spiral like following the outline? I must admit the workmanship is awesome. I have a "fumes department" in my house, it is run by my wife. Is this universal?

Yes. Even single guys run into this because the married women work over time to stamp out all offensive fumes-that is, any and all fumes related to having fun! In my house I may not sweat, cast pewter, melt plastic for making railing, use toxic glues, eat sardines, paint, or smoke cigars. I may drink an alcoholic beverage as long as it is mixed with something to cut the fun fumes (so I do!):D


This method of forming parts is really cool! Great job Gil.
CT

[rmks2000]

Gil

How did you get the pounce wheel to fit in such a small cavity, and especially along the perimeter of the foil?

Bob