How to make a reverse mold from a stl file?

Discussion in 'General Discussion' started by kronos242, Sep 19, 2015.

  1. kronos242
    kronos242 Member
    Any one have any experience making molds From an .stl file or .obj file. whats the best way to go about it . or best software.



    Thanks

     
  2. andrewsmodels
    andrewsmodels Well-Known Member
    Hi,
    I may not completely understand your question, because once you have the stl or obj it means that you already have the models done so you just have to print them and make molds from those prints, but if you would like to print directly the molds I would commander you to use zbrush, isn't quite that simple but it gives great results, and it lets you easily create molds once you have your molds done by using a single tool to carve models out from molds.
    And you can also find out more about zbrush , 3d printing and molds from these guys https://www.youtube.com/channel/UCYlDRd5eYjT54xG-BD6-V9g
    I hope I could provide just a little bit to help.
    Cheers.
    Andrei
     
  3. kronos242
    kronos242 Member
    Thank you for your reply

    I want to make a reversea mold for a bust i created with Zbrush (love the program for character creation) that i want to fill with silicone . so basically i want to make a reverse old from a .obj file or .stl file or if i could do it with zbrush that would be awesome!!

    I found this https://blog.pinshape.com/how-to-generate-a-3d-printed-mold- for-an-object/ but. openscad gave me an error message i do not understand (yes i googled the message to no avail).


    Any direction would be appreciated

    thanks again
     
  4. andrewsmodels
    andrewsmodels Well-Known Member
    but if you're already using zbrush why don't you use dynamesh tool to carve out the bust from a box ,then split he box into two different groups close the holes from geometry / modify topology/ close holes and take care to leave spaces to pour silicone also you should place pins to be able to put together the two half's of the mold you're good to go.
    I can't find an tutorial addressing the exact problem you need to solve but this is a great one to help with dynamesh in case you're not familiar with that https://www.youtube.com/watch?v=9ZQtkvSHhF8
     
  5. andrewsmodels
    andrewsmodels Well-Known Member
    I have tried to see if i could get the molds from a ship i'm working on here is the result
    Capture.JPG
    I have done almost what i have described in the previous message and I think it could be refined and get cool detailed molds,
     
  6. kronos242
    kronos242 Member
    Thank you for your time and reply ill check into doing it with dynamesh . zbrush is so powerful,you never know what it can do till you try..


    thanks again really


     
  7. numarul7
    numarul7 Well-Known Member
    You better do it traditional way. The mold printed at Shapeways will land at very big price.

    Print a model -> do a cast in rubber -> do a cast in wax / resin out of it , it is the cheapest way to go.

    If you really need to make a mold and use your printer to print it then you can do a boolean substract operation -> figurine inside a cube -> cut the cube with a plane in half after two times (if the model is not symmetric) and add the vents for the cast material.

    It can be done in Blender 3D or MeshMixer.
     
    Last edited: Sep 20, 2015
  8. MikeR44
    MikeR44 Member
    I have a similar problem. I've used Shapeways to produce prototypes of potential products, but for selling them the expense and turn around time of Shapeways is prohibitive. Therefore, I'm wanting to inexpensively create reverse molds from my model files for plastic injection molding mass production. How can I do that?
     
  9. UniverseBecoming
    UniverseBecoming Well-Known Member
    Plastic injection is very expensive because the molds are very expensive to make. There are extream pressures involved with plastic injection molding so the molds need to be CNC machined from steel. CNC machining has always been very expensive to do. If you are in a money no object situation you can look in the Thomas Register to find a manufacturer that does plastic injection production.

    There is low volume plastic injection molding available too you can search for that have lower startup costs.

    What do your products look like? Are they small? If small you can get them spin cast in a number of materials at reasonable costs

    When talking about molds you can make yourself, checkout Smooth-On, in particular, their tutorials section. There are all kinds of ways to make your own molds using Smooth-On products.

    If your question is about the 3D modeling aspect @andrewsmodels explanation from years ago using Zbrush is one way, but traditionally solid modeling software is used, software like SpaceClaim, Solidworks, Solidedge. This kind of software lets one easily design in draft angles in the walls of your mold that allow the ejection of a rigid part.
     
  10. Youknowwho4eva
    Youknowwho4eva Well-Known Member
    I just sent you a message @MikeR44 about how I could help you. In my experience, if you have a factory, you send them a file and they worry about making the tooling.
     
  11. stiingya
    stiingya Member
    I've only just started to think about higher volume production and have only inquired with a couple of places, but they wouldn't even be able to use the files generated from Zbrush. I'd need to reverse engineer them with "traditional" modeling software to get files they could use to CNC the molds as your describing. Which when it comes to textures, micro details, etc. I wouldn't know how that's possible?? :) (granted my modeling skills/knowledge are pretty basic)

    Anyway, all of those "highly textured" action figures in the toy isles have to come from somewhere! But I can't seem to find anyplace at least in the U.S. where this is done. (granted I've only just started looking, but I feel like I'm searching for something that "hidden"?? :) doesn't exist?)

    This vid shows exactly the workflow I'm looking for. I would assume something very similar has to be done for most detailed/textured toys and action figures. Anyone have any ideas?



    Actually, Shapeways should partner with, or start this kind of mid level volume production service so that their 3D print customers could easily "flow" into higher volume and still keep their business...?

    thanks!
     
  12. UniverseBecoming
    UniverseBecoming Well-Known Member
    Based on what I've seen since Shapeways first opened its doors in the very beginning, Shapeways is an extremely conservative and extremely cautious company. I feel Shapeways will never venture into this area but it's a very good suggestion. If I were running Shapeways I would get into injection molding immediately.

    Look in the Thomas Register for injection molding companies. Those that cannot take your STL file you should ignore because they are incompetent.
     
  13. Shea_Design
    Shea_Design Well-Known Member
    Or they only offer hard tooling (for large qtys) and thus require 'solid' model formats that allow for draft angle analysis, digitally derived parting lines, volume, shrink and flow characteristic etc. Zinc can be poured into vulcanized rubber molds and even aluminum is considered soft compared to A2 Tool Steel (57-62 HRC).

    I have local guy that can do investment castings in Zinc and Pewter. Many 3D print shops offer limited production runs in vinyl and resins complete with finishing and sometimes even order fulfillment capabilities. -S
     
  14. UniverseBecoming
    UniverseBecoming Well-Known Member
    STL can be converted to solid if it doesn't have millions of facets comprising a lot of texture. SpaceClaim does it in one mouse click. If I'm looking for an injection molding manufacturer to make a mold for my highly detailed Zbrush sculpt and they tell me I need a solid model I'm going to write them off as incompetent and look for someone that has more diverse capabilities.

    Yeah, good point, Stiingya be sure to look into spin casting. Much much cheaper to make a rubber spin cast mold.

    The dinosaur in the video, though it was made by casting the mold in zinc alloy, there is still a lot of expensive machining that needs to be done to in steel to back it up, provide cooling, and mate it up with the injection molding machine.
     
  15. stiingya
    stiingya Member
    Thanks for the replies. Shea/Universe you are both very talented and knowledgeable! The first three places I looked wouldn't take the .STL so I thought it was common. I'll keep looking, thanks for the suggestions!!!

    Much appreciated...
     
    UniverseBecoming likes this.
  16. Shea_Design
    Shea_Design Well-Known Member
    The problem with mesh to nurbs is generating G code from that mess. As a designer I'm hooked on investment casting so I don't have to consider undercuts and mold release etc. -Cheers and thanks for the positive remarks
     
  17. UniverseBecoming
    UniverseBecoming Well-Known Member
    @edwardoo22edward, you quoted me but it appears your question or comment didn't come through. Can you tell us or ask us again?
     
  18. SGDesigns
    SGDesigns Member
    I’m looking for the same thing. I want to print a reverse mold so I can mass produce resin copies of my design.