Introduction: How to 3d Print and Finish BIG STUFF...with a Little Printer.
Some of you may have seen a few of my previous instructables and know that i have a history with 3d printing.Recently i was in a local electronics store and saw an XYZ davinci 1.0 on sale for $399. This machine basically had the same specs as the first stratasys machine i ever used nearly 15 years ago that cost over $30k. Even after 3d printers started to become available on a consumer level i never really considered bringing one in to my home, apparently $399 was the price point that made me consider it.
The machine sat in my home studio for a month or so, pumping out little prints here and there. I decided to give it a real test so i created a digital model of a robot with tentacles that i had drawn almost 10 years earlier and printed it. I was quite surprised at how well it turned out. It was about the same time that i got a last minute invite to participate in a local gallery show of custom toys. I thought this was a great opportunity to scale my robot up to Jumbo Machinder size and give this inexpensive printer a real test.
In this instructable i will explain how i took a large model and split it up for 3d printing in a small machine and then reassembled and finished it... in less than 3 weeks.
Major tools and process:
Solidworks, Zbrush, freecad, Netfabb, illustrator
Xyz Davinci 1.0
250 hours of 3d printing using ABS filament and standard resolution.
40 hours of assembly
Smoothon XTC3d, bondo, sand paper, rustoleum filler primer, rustoleum spray paint, testors acrylic airbrush paints
Creation Pcut plotter and cut vinyl
Step 1: The Initial Model
I've been working with Solidworks longer that I've been 3d printing so it's generally where all my digital models start, even if i am just roughing out form and volume. I used my 10 year old drawing as a reference to start modeling. The robotic features were a breeze for this software and i put the body together in a couple hours.
Next i had to import the solidworks data in to Zbrush, I exported my model as an stl and then used the STL import feature in Zbrush to bring the data over.
Since i am a novice Zbrusher it took me way longer to figure out what i was doing and finally model the tentacles than it did to model the main body. The first thing i had to do was create a tool from the imported stl data and then multiple subtools to be able to use the body as a reference buck while sculpting the tentacles. I initially sculpted the right tentacle and then used a mirror feature to create the left side.
After a couple days of learning and messing around i was done... not happy but DONE.
So i exported a complete stl and sent it off to the printer at a 7.5" scale.
The model was oriented face and chest up with supports and raft, printed at the highest resolution.
Step 2: Make It Better
Once i got the call to participate in the show and made the decision to blow this thing up, i knew i had to fix the one thing that was bothering me. The tentacles were not nearly as dynamic and balanced as they were in my original drawing.
So back to zbrush... but now i had a little more time behind the wheel and the process wasn't nearly as painful.
Step 3: Chop It Up
since the original solidworks model was never intended to be a 24" tall 3d printed model, i had to now do the work to figure out how to slice it in to parts that would fit in my printer (7"x7"x7" build area) but still be able to be reassembled without looking like a mess.
the features were all hard edge and mechanical so this wasn't very difficult. I drew boxes around the sections i wanted to convert to individual parts and used the extrude cut feature to extract them and save them as separate files.
Once all the pieces were separated i dropped them all in to an assembly, and since they were all cut from a single solid model they all dropped in to the correct location based on the origin.
I added a few bosses and pockets to each piece to help with alignment during assembly but i left a lot of wiggle room since i had no idea of the quality of joints id be getting out of the printer. I knew i could just used epoxy and steel pins (nails) to tighten it all up during assembly.
The tentacles were a bit more difficult since they are a much more organic form. I used zbrush to split the parts using projected cut lines and the z remesher to create individual subtools.
Since i am very familiar with solidworks, i mirrored my parts and features as i needed them but since i am so much slower with zbrush i only split 1 tentacle in to printable parts then exported stl files and used freeCAD to simply mirror the stl files, perhaps this wasn't the most efficient way to do it but for me it was easier than fumbling through zbrush commands that i am still learning.
Step 4: Print Print Print
i ended up with 19 total pieces that needed to be printed.
Head, shoulders, chest, V chest emblem, waist, upper leg left, upper leg right, knee cap left, knee cap right, lower leg and foot left, lower leg and foot right, left tentacle part A, left tentacle part B, left tentacle part C, left tentacle part D, right tentacle part A, right tentacle part B, right tentacle part C, right tentacle part D
Unfortunately the process for estimating build time and calculating material usage in the proprietary XYZ software is not very good, so i had to have a handful of extra material cartridges on hand (amazon prime was fantastic for getting material very fast) i also had to do a lot of guessing as to the most efficient part combinations for each print job.
I knew i didn't have time to print everything in high resolution, i just didn't know how close i was going to come to my deadline using standard resolution.
I ended up running 14 separate print jobs for a total of 250+ hours of printing.
This machine took it like a champ the only hiccups were when i didn't use enough glue on the print bed and one of the prints delaminated and shifted and the second hiccup was when i used too much glue and shattered the print bed trying o remove the part. Fortunately the local retailer i purchased it from exchanged the whole machine since i had also purchased and extended, no questions asked warranty.
After that experience i applied Kapton tape to the glass print bed which has worked out quite well.
Step 5: If You Build It... You Will Sand
once again the robotic parts were very straight forward.
I used some dental tools to scrape off any excess support material, this machine is quite good at actually producing clean break away supports and there wasn't much to deal with other than the expected stepping and resolution issues.
I ordered a kit of Smooth-on's XTC3d to try out on this model and it was fantastic.
I expect it would be much more problematic on smaller prints since it is a fairly heavy coating and dulls sharp detail but since this piece is so massive all the details were large enough to show through.
The application process is fairly simple, mix part A and part B by volume and use a brush to spread an even coat over your model. The kit comes with a foam brush which worked ok, i got better results with an inexpensive 1.5" bristle brush from home depot. I'd recommend a $2-$3 brush over the $0.93 brush as the cheapest brushes tend to drop a lot of bristles in the process.
I did 2 coats on all parts and used a simple box oven to speed up the cure process. i set an electric oil heater on my garage floor and stood up insulation foam around it creating a small box that i could heat up to kick over the resin faster.
The tentacles were not quite as easy, although the prints came out clean there was a ton of dimensional variation at the joints and nothing lined up clean. I drilled some very sloppy holes in all the mating surfaces then used 2" finishing nails as registers and support between the parts. after test fitting everything i used 5 minute 2 ton epoxy to put it all together. There was no good way to clamp anything so i simply spread the epoxy over the mating surfaces and nails then held the parts in place until the epoxy kicked.
While i was assembling the first tentacle the second tentacle was still printing and i only had 3 days left until the piece was due.
After all the epoxy set i broke out the bondo and started filling the huge gaps in the seams on the tentacles... then i sanded... then i bondoed... then i sanded... then i bondoed.... then i sanded.
I was really worried about the seams on the sucker side of the tentacle because they were much harder to clean up but once again the Smooth-on XTC3d kicked ass. Two coats and most of my assembly was hidden. plus these parts were going to get an organic paint job so there would still be opportunity to hide imperfections in the paint.
After all the pieces were coated and dry they got hit with some rustoleum automotive filler primer if there were still any major issues they got a little bondo and sanding and some more primer.
Step 6: Oh Man... Now I Have to Paint This Thing
I am a 3d guy... not very comfortable with color
so i made a basic render of the character and started stacking layers and color in photoshop to explore possible paint jobs.
I really wanted to reference some of the Shogun Warrior color schemes that inspired this whole project but the theme of the show was "the recruits" which i interpret as a military theme so i wanted to convey that as well.
My wife is an illustrator and was instrumental in helping me resolve my paint issue and keep me from going way overboard.
I used rustoleum rattle cans to paint most of the body parts, the silver and gold were krylon metallic finish and the head was detailed with a brush using the new testors line of acrylic airbrush paints which are absolutely amazing to use in both an airbrush and a with a bristle brush.
The tentacles have about 7 layers of transparent and opaque paint, all done with Testors acrylic airbrush paint and a top coat of Krylon acrylic clear from a rattle can.
The decals were drawn up in Illustrator and cut using my Creation Pcut vinyl plotter.
This project was a ton of experiments and i can't believe they all worked out as well as they did and on a timeline with no room for error.
Prior to this project i had little to no experience with zbrush, the davinci 1.0 3d printer, smooth-on xtc3d or the testors acrylic airbrush paint.
Step 7: I Think It Came Out Ok
It's this big!