Creating mould from Parts ?

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JPL
Posts: 10
Joined: Wed Mar 22, 2017 10:37 pm

Creating mould from Parts ?

Post by JPL »

Hello there,

I'm so impressed with FreeCAD, since with a few hours and some help from a community, I've been able to 3D-print useful pieces, like the one below :

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Screen Shot 2017-03-29 at 22.57.54.png
Screen Shot 2017-03-29 at 22.57.54.png (72.94 KiB) Viewed 4879 times
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It does not compare to the beauties that I've seen here, but at least, it's useful to me (to build live theatre scenaries).

Now, I need 24 of these parts... So the 3D printer will work at night in a production mode.

By the way, is there a way to create a mould from this design ?
i.e. : a cube with the "negative" of the part embodied ?
I can certainly get one using the classical way, with usual powders and resins.

But an algorithme could certainly be used. Or maybe the "boolean cuts" (which I don't know how it work) ?

Once printed, It could be fulfilled with proper resins to get a "positive" one and maybe speed up the delivery or enable the use of other materials ?

Has someone already worked on that subject ? Any experience to share ? Any creator of mechanical chocolates using food-savvy fibers ?

(and thanks again to the different people who helped me to make this very first experience successful)


Jean-Philippe
OS: Mac OS X
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paulfurze
Posts: 15
Joined: Fri Oct 28, 2016 11:59 am

Re: Creating mould from Parts ?

Post by paulfurze »

Hi JPL,

Gonna take a stab at answering this .....
If my suggestion that follows is wrong almost certainly one of the heavyweights here will point it out :)
But that said...what I'd do is....

Create a clone of your part with the draft workbench. (See note below)
Turn off (make invisible) your original part.
Insert a cube that is the same size as the clone. (Personally I'd just draw a sketch and pad it to the correct size so that the clone fits inside it)
Use a boolean cut to remove the clone shape from the cube

That "should" result in the negative of what you've already drawn.

Note:
I'm no expert here but a making a clone means your original part isn't gonna get messed up and further, the clone changes if you change your original shape. I.E your negative would also update should you change anything on your original.

Hope that makes sense ?

Paul.
philem
Posts: 14
Joined: Fri May 27, 2016 4:04 am

Re: Creating mould from Parts ?

Post by philem »

If you are talking about Injection Molding, then Yes a mold can be made to produce these, but the main factor is how many will be molded to offset the cost of building the die.

It would be a fairly complicated mold because of the holes that are in the sides of the part, Pneumatic or Hydraulic slides would probably be needed because of the holes that are in "both sides of the component.
perky
Posts: 33
Joined: Thu Jan 05, 2017 7:36 pm

Re: Creating mould from Parts ?

Post by perky »

There are design rules you should follow when creating parts that will eventually be injection moulded. The main one to consider is including draft angles so that the two halves of the mould can actually come apart. There are techniques for creating clips and undercuts, reducing 'sinking' on surfaces, rules for rib, gusset and boss sizes etc. These are just a set of simple rules to follow, but it's much easier to design something with those rules in mind than have to modify a design later.

Here's a site with some very useful information in it (and I also recommend getting the cube design aid from them, it's free ) :
https://www.protolabs.com/resources/whitepapers

Mark.
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