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    Default Building Rapid Prototype 3D Models from Zbrush Files Tutorial

    Hi All,
    After a couple posts to Hiroshi’s 3D Print for Toys thread, I have received a huge amount of interest & requests regarding 3D printing. When I say printing I mean building a 3 dimensional part via a Rapid Prototyping (RP) process. Rather than hijack that thread I thought it would be helpful to post a tutorial covering the basics of creating & prepping your file for output to a buildable database, RP choices with their respective pros & cons for building your models, as well as some approximate costs for making parts. We happen to provide all these services through my company Paradigm Development Group but all this should apply no matter who you use. This process can get very tedious as we start to deal more & more with ever increasing huge file sizes. As always, anybody who has insight to streamlining the process please share. My apologies for some of the pix. I will try to add additional images taken under better lighting soon.

    Hopefully I haven't missed any glaring details.
    CHEERS!
    Josh Harker

    objet-parts.jpg

    Creating your digital model:
    Create your model with 3D output as an intention. For CG & illustration it may not matter if the model has holes, unwelded verts, open shells, forms that don’t touch, etc. All of this matters greatly when you intend to output to 3D part.

    - Avoid extreme “wrinkles” in your mesh that overlap into a mess of polygons. Your surface does not need to be smooth but take care not to compromise the skin into a crumpled mess. This does not translate well into 3D and can render the file useless for printing.

    -All parts need to be “closed”. There can be no open holes or gaps in meshes. The .ZTL “Demo Head” for instance is not buildable as is. The bottom is completely open and the printers cannot read a zero thickness open skin. I had to close the bottom in another program and create an .STL from that.

    -When working with subtools you must combine all subtools before exporting. In a nutshell: “Make Polymesh 3D” of each subtool, then insert those PM3D’s (see “insert mesh” under “Geometry”) into a single tool & save the .ZTL or export as an .OBJ using the Quads setting. Subtools or components that can be separated from the model and attached physically after the build (swords, bases, guns, extended arms, hair, etc.) can all lower the models poly count by spreading it out over a few parts. This can also decrease the dimensional extents of the model which directly effects the printing costs.

    - Subtools need to overlap. If they are “line to line” or floating, they will lift off the model when its printed. This has not been a problem as far as overlapping meshes and multiple shells regarding file corruption since the intersections are clean and make sense as opposed to a wrinkled or crumpled mess of polygons. This is very apparent in the DemoSoldier file (see picture). If you take a close look at the .ZTL file you can see where the shoulder pads, goggles, backpack straps, etc are not well attached or are floating. The picture shows how those features ended up lifting off or breaking in the printed part. demosoldier-2.jpg

    -An exception to overlapping subtools is when you want the parts to be “attached” but not cohesive (i.e. chain links or other interlocked assemblies).



    -The lower the poly count the better. 2 million polys has proved to be nearly the maximum workable amount. Again, less is better. Model sizes should be 250MB MAX. There are a few ways to keep the file size (poly counts) under control:
    -Decimate the poylgons/triangles data using Softimage XSI,Geomagic Studio or similar. We use Magics & MeshLab. MeshLab imports & exports .OBJ & .STL, effectively decimates the data, & is free! Unfortunately it likes to crash with larger files which kind of defeats the purpose but you can't really complain when it's free.-Try to foresee areas that may not need the mesh density of highly detailed areas & avoid dividing them. Technically speaking, the poly count or mesh density makes no difference to the machine as far as ability to build but the file sizes & processing times like to crash even the most robust workstations.

    -There is a point where, even when printing on a high resolution Objet Polyjet printer, the extreme detail of a highly subdivided model will never be reproduceable unless you were to create a monumentally large part from the file. You can always lower the resolution slider of highly subdivided models to a level appropriate for printing. A SDiv level of 4 or 5 seems to be plenty for even finely detailed models. Much lower SDiv levels (2 or 3) can be fine for simpler shapes.
    -What seems like a perfect fix is to create a new topology of the model without losing any details. I believe that is what Plakkie covers in his thread Topology & Flow Lab but I have had difficulty making use of this in any kind of reasonable time frame. Hopefully I’m simply missing the crux of how to effectively apply it. Anyone who is adept at this please post your secrets! It could help make the final prepped file infinitely better.

    -From there, import your OBJ into whatever software you may have and convert to an .STL. We use a variety of programs to convert, repair, cut, etc. including Magics RP, Solidview, Solidworks, & Rhino. It would be a wet dream if Zbrush offered STL as an export option! Once you have the STL you can have the model 3D Polyjet Printed, SLA’d, CNC’d or a variety of other RP processes.




    RP Processes (as they apply to High-Res Zbrush models):

    These images attempt show the resolution & detail from an Objet versus an SLA part. Unfortunately I do not have an SLA build of the same part for reference but it should demonstrate the difference in build layers. You can see the Objet DemoHead print has build lines much finer than even a fingerprint while the SLA model has much more severe "stair stepping".
    demohead-1.jpg demohead-2.jpg sla-build-lines.jpg

    Objet Polyjet 3D Printer
    Resolution/Accuracy: 600x600 dpi (.0015”) X&Y, 1600dpi (.0006”) Z layers (.0012” on High Speed setting) per inch
    Max Single Build Size: 19.3"x 15.4"x 7.9" (larger models can be built in pieces & reassembled
    Pros: Highest resolution & accuracy available. Variety of materials & color options.
    Cons: Consumable support material adds considerably to cost. On smaller models it is not an issue but become prohibitive as the parts get larger. Solutions are: to cut the model into pieces to help facilitate laying them flatter against the tray for building which requires less support material, Shelling the models so they are hollow (.030”-.100” wall thickness appropriate to model size) then splitting them into halves so the can be built open saving material consumption. These operations generally need to be executed in another program as ZB does not have the tool set.

    SLA (stereolithography)
    Resolution/Accuracy: +/- .006” in X&Y, .004” Z layers per inch
    Max Single Build Size: 25"x 29"x 25" (larger models can be built in pieces & reassembled)
    Pros: Economical larger models.
    Cons: Much lower resolution than Objet Polyjet, “stair stepped” build lines, rigid supports that mar & chip the surface when removed. Limited material choices.

    CNC Machining
    Resolution/Accuracy: +/- .002” or better over entire part in X,Y&Z
    Max Build Size: unlimited (models can be built in pieces & reassembled.
    Pros: Can be cut from variety materials including:
    -plastics (i.e. clear acrylic & polycarbonate can be polished to a glass clarity)
    -metals (i.e. aluminum polishes nicely to mirror finish)
    -wax
    -modeling/foam boards (i.e. can be economical for very large to monument size models)
    Cons: While extremely accurate, tooling marks & minimum cutter diameters can limit details & resolution. This becomes less of an issue on larger models where the details & resolution are relative to the size. Cannot reproduce complicated or multi-axis undercuts.

    SLS (Stereo Laser Sintering)
    Resolution/Accuracy: +/- .008” to .015 per inch in X,Y&Z
    Max Single Build Size: 11"x 13"x 17" (larger models can be built in pieces & reassembled.
    Pros: Extremely Strong. Variety of material choices.
    Cons: Powdery/porous/textured surface. Poor accuracy & resolution.

    Perfactory
    Resolution/Accuracy: varies depending on material & settings from extremely high to poor
    Max Single Build Size: 7.5"x 5.6"x 9" (larger models can be built in pieces & reassembled)
    Pros: Very High resolution. Variety of material choices
    Cons: While detail is good, accuracy is not. Small build envelope. Limited or no available service bureaus.

    FDM, ZCorp, Dimension Printer & Others
    Resolution/Accuracy: varies but generally poor to awful
    Max Build Size: Varies (large models can be built in pieces & reassembled)
    Pros: Economical
    Cons: Poor tolerances & accuracy, poor resolution & details, extensive post finishing required. Dimension Printer parts finish & paint poorly due to wax ingredient in material.

    *Objet, SLA, SLS, & CNC models can all be sanded, painted, electroplated, etc.



    RP Process Approximate Cost Comparisons:
    - Prices in the industry can vary wildly depending on process, who’s trying to undercut whom, if the industry is busy or in a downturn, individual workloads at different service bureaus, quality of customer service, quality of product, delivery time requirements, etc.

    - Each model will vary in price considerably depending upon dimensional extents, volume, quantity of parts ordered, complexity of cleanup, if it’s to be built solid or hollow, material choices, print quality settings, etc.

    - Quantity can effect price significantly. The more parts you order at one time typically the lower the price per part.

    - Hollow parts are cheaper than solid parts obviously because of material consumption. Beware when comparing Objet quotes with SLA quotes that they are both quoted for either solid or hollow. You need to compare apples to apples so to speak. Hollow parts could be as much as 50% less on larger models

    -These prices do not include CAD time for repairing, converting, combining subtools, shelling, cutting, etc.

    The approx. cost for the "Demo Head" Zbrush tool file @ approx 1mil polygons is as follows:
    1.3" tall (approx. 1” from tip of nose to back of head)
    Objet Polyjet 3D printed model "High Quality" (.0006" layers): $100 (solid)
    SLA Model (.004”-.006” layers): $130 (solid)
    CNC Machining/Renshape Urethane Board (+/- .002” or better in X,Y,Z): $425 (solid)

    3.9" tall (approx. 1” from tip of nose to back of head)
    Objet Polyjet 3D printed model "High Quality" (.0006" layers): $500 (solid)
    SLA Model (.004”-.006” layers): $470 (solid)
    CNC Machining/Renshape Urethane Board (+/- .002” or better in X,Y,Z): $850 (solid)

    10.4” tall (approx. 8” from tip of nose to back of head)
    Objet Polyjet 3D printed model "High Speed" (.0012" layers): $2120 (hollow)
    SLA Model (.004”-.006” layers): $880 (hollow)
    SLS Model (.008”-.015” layers): $1625 (hollow)
    CNC Machining/Renshape Urethane Board (+/- .002” or better in X,Y,Z): $2000 (solid)

    The approx. cost for the "DemoSoldier" Zbrush tool file @ approx 850K polygons is as follows:
    3.1" tall
    Objet Polyjet 3D printed model "High Quality" (.0006" layers): $135 (solid)
    SLA Model (.004”-.006” layers): $130 (solid)
    CNC Machining/Renshape Urethane Board (+/- .002” or better in X,Y,Z): $450 (solid)

    6.25" tall
    Objet Polyjet 3D printed model "High Quality" (.0006" layers): $365 (solid)
    SLA Model (.004”-.006” layers): $260 (solid)
    CNC Machining/Renshape Urethane Board (+/- .002” or better in X,Y,Z): $900 (solid)

    12.5" tall
    Objet Polyjet 3D printed model "High Quality" (.0006" layers): $1375 (solid)
    Objet Polyjet 3D printed model "High Speed" (.0012" layers): $1100 (solid)
    SLA Model (.004”-.006” layers): $1100 (solid)
    CNC Machining/Renshape Urethane Board (+/- .002” or better in X,Y,Z): $1800 (solid)


    How to Get Parts Built:
    For an accurate quote, best thing is to send an .STL file that material consumption & build time #'s can be generated from.

    -STL’s are best since this is the format needed by most process software to build. Also, the less work we have to do (converting, repairing, cutting, etc) the cheaper the part will be for you.

    -ZTL’s are good because you can lower the res slider to 1 and save the file & end up with a very small file size considering all the information contained. Quick & easy to email for quotes but we have to do the conversions here which may increase the cost to you.

    -OBJ’s work too but they are large & cumbersome & still need conversion before they can be used.

    -If possible (especially for Objet Polyjet builds) cut your model into parts to help reduce the Z height of the build as much as possible. The lower the Z height of Objet builds the less time required to complete which translates into lower cost. For instance, a figure with an arm extended straight out in front of it could be laid flat on it’s back, but the arm would require many additional passes to build. If the arm was cut at the shoulder, it could be built along side of the body to reduce build time and reassembled after the print.

    -For files that are too large to email (10MB+) contact us to get an FTP account username & password to post your files on our server. If more convenient, we can access your FTP site and pick the files.

    Email (10MB or less) to:
    info@pardev.com
    To request FTP access, submit an RFQ, or contact us with any questions:
    Paradigm Development Group, Inc.
    www.pardev.com


    Additional ZBCentral 3D printing threads:
    Hiroshi’s 3D Print for Toys
    Scott Spencer’s Halloween Boy
    Jim McPherson’s Dragon & Halloween Kid

  2. #2
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    Default

    Thank you for putting all this info together for everyone. I hope this thread will grow and we will see personal trials for RP. It is a very exciting time to be a digital 3D artist and things will only get better.

    I can't wait for the day when you can just hit the print button in ZBrush and you will be able to send out your water tight model straight to a 3D printer.

  3. #3

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    Great info Josh! It's great to see all this info in one place! I posted a thread about my experience with 3D printing here: http://www.zbrushcentral.com/zbc/showthread.php?t=57055
    though it is no where as informative as yours.

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    Nice compilation!

    I just would like to add that CNC machining does perform undercutting rather well on a multi axis machine. The cutting tool's geometry and size is the limiting factor, but if you use Z-Tools which HAVE that geometry during the creation of the model, then the system can do a much better job.

    Cheers
    Rainer

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    Quite informative...thanks for sharing your info, shhark!
    ~

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    Thanks Josh! A comprehensive thread about 3D printing would certainly be a great help. Good start, interesting read.
    Elfquest Sculpting Odyssee
    The continuing diary of my first sculpt

    The Topology and Flow Lab
    Everything you need to know about topology (and more)

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    Thanks All but I fear very few will find it now. This thread was moved for some reason to the Community forum which sees very little activity. 2-1/2 weeks of writing, compiling #'s & data, gathering comparative quote's from other vendors, prepping & converting .ZTL's for 3d printing, & actually printing 3D parts for this post to have it buried within an hour in the Community forum (All non-ZBrush topics ... computers, movies, books, hobbies, and life in general).

    I figured that the 100,000+(!!!) views that the other three 3D printing threads I listed at the end of my post meant that the forum was interested in 3D printing & that it applied directly to what people would like to use ZBrush for. My mistake. Anybody else agree or am I missing something?

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    Actually, I think you'll have more chance of it being viewed here as there's
    generally less posts to bury it. Also, it will get lost much faster in the 'Main'
    forum with WIPs and it doesn't really belong in the 'Questions' forum (and
    would quickly get buried there as well).

    Just bump it from time to time if you feel it's getting lost (or add more info).

    ~

  9. #9

    Thumbs up thanks!

    this is a gold mine of information!!! thanks for setting it all up!!! I agree that this has got to be the hottest thing since normal mapping....

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    Thanks for the info! Unfortunately, the cost for printing these days are still too high for most to afford.

    I read about the Desktop Factory 3D printer, but couldn't find any decent models that have been printed using the machine. Have you seen or heard anything about that machine?

  11. #11

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    Hey Josh, Great information! Thanks for putting this together. I have featured this at SPC here.

    Best,

    Ryan

    edit: Oh and thanks for printing the DemoHead and Soldier! It's very cool to see them in the "real world".

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    It is unfortunate that the prices are still high for the average Joe. They will come down over time but that could be a while. Materials & machine costs are still crazy high which translates into high part costs. The Desktop Factory printer is a great start down the road to affordable parts but the quality of the print is terrible at best compared to an Objet model. I guess that it's all relative to what your needs are but for the highly detailed ZBrush models I think it would be a disappointment.

    I was considering attempting to offer a group build every month or so where it would make it possible to offer discounted prices for ZB users. The build would be limited in material choice, delivery schedule, polycounts, and overall individual part sizes but would offer an opportunity for more digital sculptors to try out 3D printing. If there's interest I'll look into it further.

    Josh Harker
    Paradigm Development Group

  13. #13

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    Hey Josh, One thing Tom Meeks pointed out to me with the Desktop Factory is that you could use it to print your mold instead of your 3d model. This way you could do a clay or wax pour and work the surface of it for final casting.

    That sounded like a pretty cool approach.

    ryan

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    must-have article, thanks!

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    That's a brilliant approach particularly if you plan to do post work on the wax anyway (you can make Objet molds too). Your resolution or detail will be no better or even worse than the original print however. Again not a problem if you plan to do all the detailing by hand. Unfortunately all that post work would not be in your file and could not be reproduced except my remolding the model and casting (or getting a high res scan?). I think the beauty of the digital file is the ability to keep an archival database that can be scaled, modified, or otherwise manipulated endlessly without losing that original information. That being said, there are many situations where this may not be important & this strikes me as yet another great way to integrate ZBrush & 3D printing to develop real 3 Dimensional sculpture.

    I'm glad to see a few have liked the post & thanks Ryan for adding me to your blog which has already become a great resource all it's own.

    shhark

    Josh Harker
    Paradigm Development Group

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