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Topic: molds for making hollow objects?

I've seen the "lost PLA/ABS" technique for making metal objects from 3d printed plastic ones.
However I have a question, is there a way to make hollow metal objects some way from 3d printed plastic ones? Otherwise the object might just end up unnecessarily heavy and not cheap to make.

Solidoodle 4

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Re: molds for making hollow objects?

Do you mean you want to make a metal mold that you can cast plastic items in?

Either way you could just use lost plastic molding of a negative of your form right?
What I mean is:
1: model your object
2: place a cube surrounding your model
3: subtract the model from the cube
4: print hollowed out cube
5: lost plastic casting

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Re: molds for making hollow objects?

Print the object hollow, core out the bottom and pack it with sand or sand/kitty litter like some use, replace the plastic you removed, then follow the rest of the instructions. Or, simply print two halves of the model then cast them separately.

If you have no experience in casting, it is recommended you either do this only alongside someone who is experienced, or not at all for safety reasons. If it is the video I am thinking of, the potentially fatal risks are stated.

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Re: molds for making hollow objects?

redbarret wrote:

I've seen the "lost PLA/ABS" technique for making metal objects from 3d printed plastic ones.
However I have a question, is there a way to make hollow metal objects some way from 3d printed plastic ones? Otherwise the object might just end up unnecessarily heavy and not cheap to make.

I think what you mean is whats called a slush mold. Gilbert toys made one for lead solders where you pored the molten lead into mold then b4 it cooled through center you rotate the mold and poor out extra metal making a hollow solder similar to hollow chocolate bunny. using less material to do the job. that is not possible using lost wax technique like the plastic is used.
the sacrificial material would just melt away letting metal fill in where the hollow area in plastic had been.

in cub scouts we done lost wax using ice as the sacrificial item and pored wax into milk carton of ice cubelets which cooled the wax then melted. so when we peeled the carton away the water drained out leaving a very odd cube full of holes shaped like the ice and a string wick so it was a candle. so the lost material cooled/hardened the wax. this is likely not feasible for metal using plastic as it wont quench the metal, but instead is like a sand mold where the model is incinerated or melted away oozing out of mold crucible made of ceramic or clay in place of the sand used for cast iron.

Solidoodle 2 with Deluxe kit cover & glass bed with heater. and 2nd board SD2 used not 3rd and alum platform not installed yet still wood. also need cooling fan installed to board. use Repetier Host couple vers. Slic3r also have all free ware STL programs

5 (edited by redbarret 2014-12-02 17:56:34)

Re: molds for making hollow objects?

@JoelEdin: I don't mean I want to know how to make a metal mold that I can cast plastic items in. I mean I want to know if it's possible to make a hollow metal object when having a (3d printed) plastic object or (3d printed) plastic mold of the object.

@AZERATE: Sorry, I don't think I understood.

@n2ri: Thanks for letting me know about "slush mold". Hadn't heard about it, neat technique. I've only started researching this so correct me if I'm wrong, but looks like the mold will have to be made out of metal, and of higher melting temp than the metal you want the hollow object to be made of for this to work, so this method can't be used to make hollow metal objects from 3d printed plastic objects/molds.

And yes I'm aware how dangerous this can be. At this point just interested if it's possible at all to make hollow metal objects when having plastic objects/molds.

I was thinking of this maybe being possible with using metal powders or maybe metal clays in some way.

Solidoodle 4

6 (edited by n2ri 2014-12-02 19:17:00)

Re: molds for making hollow objects?

redbarret wrote:

@JoelEdin: I don't mean I want to know how to make a metal mold that I can cast plastic items in. I mean I want to know if it's possible to make a hollow metal object when having a (3d printed) plastic object or (3d printed) plastic mold of the object.

@AZERATE: Sorry, I don't think I understood.

@n2ri: Thanks for letting me know about "slush mold". Hadn't heard about it, neat technique. I've only started researching this so correct me if I'm wrong, but looks like the mold will have to be made out of metal, and of higher melting temp than the metal you want the hollow object to be made of for this to work, so this method can't be used to make hollow metal objects from 3d printed plastic objects/molds.

And yes I'm aware how dangerous this can be. At this point just interested if it's possible at all to make hollow metal objects when having plastic objects/molds.

I was thinking of this maybe being possible with using metal powders or maybe metal clays in some way.


correct.
or some material with much higher melt point than molding material, hence sand molding etc for steel, as it can be thick enough to allow steel to cool enough to form a solid shell with minimal finish work. some methods also cool the mold in some fashion so molten material dont melt mold but this is a very tricky method to do without causing an explosive result. also some materials react violently if certain materials come in contact with them while molten or during "change of state".
some of these seemingly bad effects are used to form alloys etc. all part of the age old art of 'alchemy'. also extruding steel is done like making pipe/tube. there is a manufacturer of this style in Gerald, MO called 'Bull Moose Tube' I think still active.

I too am not an expert on all of this, rather another student apprentice. learning needed trade secrets to better my work.

Solidoodle 2 with Deluxe kit cover & glass bed with heater. and 2nd board SD2 used not 3rd and alum platform not installed yet still wood. also need cooling fan installed to board. use Repetier Host couple vers. Slic3r also have all free ware STL programs

7 (edited by redbarret 2014-12-02 21:22:03)

Re: molds for making hollow objects?

Well, I don't know if a sand mold will survive slushing with something like rotomolding machine.

Maybe there's some other technique someone else knows which can work.
I remember back in the day there was one old man in a local flea market who offered to make hollow bronze copies of any object. Haven't seen him for years though.

EDIT: maybe some multiple step procedure using electroplating?

Solidoodle 4

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Re: molds for making hollow objects?

slush mold cant be done with sand. was talking about how other materials are used for molding some materials at extream temps.

Solidoodle 2 with Deluxe kit cover & glass bed with heater. and 2nd board SD2 used not 3rd and alum platform not installed yet still wood. also need cooling fan installed to board. use Repetier Host couple vers. Slic3r also have all free ware STL programs

9 (edited by n2ri 2014-12-03 02:38:50)

Re: molds for making hollow objects?

there are steps to take to determine what material will meet all aspects of finished item from cost, amount of detail, safety in use and melting, strength need of material, etc. then once a suitable material/s is found find ways to turn it into what you need. also read tech specs and MSDS info on all materials  being considered. you will find out feasibility soon that way.

become an expert on it, as there are few experts on difficult subjects lately, and fewer still are experts that will share what they know as they make a living with it. thats what I learned years ago. many old crafts have died with the last masters of them.

the WWW is loaded with free info (trick is figuring out whats fact and whats BS) download anything found on info you may need later before it gets removed from the site like so much has. the future will be ruled by who holds the knowledge.

also just because something cant be done now, dont mean tech cant come along making it possible some day soon.

Solidoodle 2 with Deluxe kit cover & glass bed with heater. and 2nd board SD2 used not 3rd and alum platform not installed yet still wood. also need cooling fan installed to board. use Repetier Host couple vers. Slic3r also have all free ware STL programs

10 (edited by redbarret 2014-12-03 06:44:11)

Re: molds for making hollow objects?

n2ri wrote:

slush mold cant be done with sand

is there any article or video on the internet about this? I honestly can't find anything.

I was thinking about something like a rotomolding machine + sand mold and melted aluminum, etc.
http://www.instructables.com/id/Make-A- … Under-150/

Solidoodle 4

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Re: molds for making hollow objects?

redbarret wrote:
n2ri wrote:

slush mold cant be done with sand

is there any article or video on the internet about this? I honestly can't find anything.

I was thinking about something like a rotomolding machine + sand mold and melted aluminum, etc.
http://www.instructables.com/id/Make-A- … Under-150/

there ya go. kinda how Maytag done the aluminum tubs on their wringer washers in the 1920s-1930s so it spread the aluminum all over filling all cavities then dumped excess while stile liquid. very hazardous and extreamly hot work area. die-casting or plain aluminum casting rooms exceed 135f even with ventilation. Fasco motors had this issue just doing the end caps on their motors. employees had to take 15 min shifts to lower odds of heat stroke. but at least Aluminum is not as toxic of fumes as most other metals when molten.

Solidoodle 2 with Deluxe kit cover & glass bed with heater. and 2nd board SD2 used not 3rd and alum platform not installed yet still wood. also need cooling fan installed to board. use Repetier Host couple vers. Slic3r also have all free ware STL programs