Makerbot for Zbrush users : how to get consistent scale across multi-part prints

[Jason Schiedel]

Hi Everyone-

I use Zbrush as a 3d sculpting tool and just got a Makerbot Replicator 5th gen to print my prototypes.

The hurdle I am trying to clear is how to print something larger than the build platform of the bot. 

I know in theory I need to cut up the object into smaller pieces, print them separately and just assemble them.

So what I have done is cut up my model in Zbrush, and exported each piece as its own STL file.

The problem is when I bring the pieces into Makerbot desktop they are not all the same scale.

I suspect my mistake is in how I am using the 3d print export plugin for Zbrush. You must update the size ratios before you export the STL. Because the pieces have different dimensions I think this is skewing something that shows up as this problem in Makerbot desktop. Any ideas about the proper workflow?

Thanks for your help!

Jason  

[Stephen Garrett]

Do you use another package for your base mesh editing like Max, Maya, or Modo? If you do, I would try to do it by exporting back into one of those programs and breaking it up there. Then, export it using the scale in those programs. I export .obj files from Modo. I model everything in meters because it exports into Makeware in millimeters. 3dMax exports obj using a scale ratio which is a little more difficult. I think if you model in millimeters, the scale ratio is 25.4 to export at the correct scale for Makerware.

[Bonekollector]

Ive had this problem recently - Zbrush is a little schizo/inconsistent on how it handles things with importing & exporting. I would suggest you try the following:

Save a copy of your ztl/zpr

Export each subtool through the standard exporter & re-import over itself. Hopefully the scale & position remain consistent. It may be necessary to merge the cut up subtools back to one tool then separating them to subtools again. There seems to be some kind of "construction history" in the background that manifests on export & causes this kind of problem. - the two steps I outlined help to get rid of that.

Export via stl in the 3d exporter, chose mm as your units.

Alternately, if none of this works, you need something consistent in each part to calibrate around.  Insert a cylinder that is taller than your overall object & export it as part of each piece, then in Makerware you can use that as a consistent reference point to scale to - ie you know Z should always be x mm so you scale to that so each piece is calibrated. you could aso use netfabe & do the same then remove the cylinder if you dont want it to print.

S




setting mm as your unit exporting through the 3D print exporter, choose

[Brian33433]

I would go the route of saving it as a obj and then cut it up in Netfabb. You should have no problem that way.

B.

[Bonekollector]

Brian's answer is probably the best solution

[Joe Larson (aka Cymon)]

Doesn't netfab only do that if you've paid $300 for the professional version? And if Andy Cohen's experience is any indication I would not go that route. It slices things up badly.

If it were me I'd use Blender, much more reasonable price. Import, Scale and arrange the parts, use the booltool to Union them together, create a box that is the size of the build platfrom, maybe a little smaller, then duplicate it and use the properties panel to place them until they cover the mesh. Then, heres the clever part, on the box, not the object, add a boolean modifier and intersect it with the mesh. Then export those parts.

The advantage of this method (besides price) is that when you know what your doing you can add tabs and slots to you base blocks so when you assemble them you'll have fitting guides. (Just remember to leave .2mm-.5mm between the tab and the slot so is not to tight a fit. )

[Brian33433]

No the free version will cut it just fine (there is actually no better program for slicing up a model, paid or free)

B. 

[Scott Wells]

No , the free netfabb (download version) does it. I used it to slice a 36" model into parts last month. I shot the pieces back to ZBrush to make keys for final assembly

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[Steve_Criz]

On Sunday, 27 July 2014 00:10:39 UTC+10, Brian33433 wrote:

No the free version will cut it just fine (there is actually no better program for slicing up a model, paid or free)

B. 

Unless you use Meshmixer of course...  In which case - even if you had used Netfabb before hand; you'd be more inclined to say Meshmixer might well be the better option, given all the scaling/chopping/adding registration geometry/custom supports/direct export to Makerware as well as export to a number of commonly used 3D file formats would all be part of the work process.

I've been using Meshmixer almost exclusively for scaling/chopping/prepping/printing/exporting my sculptural 3D figures; especially the latest version with it's "make solid" function for repairing ALL mesh errors that could cause a sculptural item to fail once it's been sent to the printer.

After farting around for month upon month with all the various software options that were recommended for "bullet-proof' 3D or *.stl files... I managed to sort out the perfect path for my figure sculptures, from Lightwave, to Meshmixer using *.obj format.   Depending on how I felt at the time, I'd either chop in Lightwave or chop in Meshmixer, because in the end it didn't really matter!!  So: chopping could be done in whichever app I just felt like using at the time... No big whoop.

But prepping for the actual final print stage - i.e. making the individual bits 100% 'water-tight' without any intersecting geometry like one can get with hair or cloth or even body bits resting on stuff etc,etc, or holes or 'non-manifold edges' or any of the other myriad of things that got past EVERY other app I'd been recommended to use; I always do in Meshmixer now!! 

Even Lightwave's own 'prepare for 3D printing' function was crap compared to Meshmixer! 

Then again; the more tools you have for dealing with this sort of stuff; the better!!!

Oh BTW; I've added a couple of pics of one of my Makerbot Replicator 2 multiple piece (in this particular case 5 individual printed pieces glued together using Plastruct plastic cement with auto repair body putty filler filled seams (you'll still find you get visible seams no matter what you do!!) sanded using medium grit sandpaper - followed up with some wet and dry to get a more traditional polished on the more prominent/raised/rounded surfaces appearance, before cold bronze painting and patinating the finished piece.

Good luck Jason!!

Have fun with your printer - and enjoy the 'magic' - as long as it works, given you've got a 5th Gen!