Intro: Sculptural Explorations in Plywood, Concrete and Glass Using 123D Make
I am trained as a painter and sculptor so I come from an analog world of making. While an AiR at Autodesk I began researching and prototyping concepts for sculptural translations from 2D into 3D using 123D Make's "slice" technology. Testing forms in wood, concrete and glass all while considering how to hybridize the digital and analog process in one project. I started with creating a 3D model in Fusion360 using the sculpt environment. This wave like form has a complex surface that presents both the aesthetic qualities and technical complexities I would seek in public art or an environmental installation so it was a good form to start with. Conceptually, this project is about the undercurrents of the Bay Area’s recent shifts and resulting tensions. The sculptural form explores the tensions between digital and natural aesthetics and ways of making.
STEP 1: Slicing 3D Model in 123D Make
Once the 3D model was finished I exported the final model from Fusion360 as an OBJ. Then opened it in 123D Make & imported the .obj file.
I played a lot with "Construction Technique" I used "Stacked Slices" but had a lot of fun playing with the various construction options and angles. Type in the dimensions of the laser cutter you are using. The bed size of the one I used is 36"x24". My material thickness was .125 or 1/8" & kerf at 0.010". Select "Get Plans" & the software automatically slices, lays out & numbers all of the parts for your model. This particular size of model requires 25 sheets of birch ply resulting in over 120 parts.
When I used this process for the second time I used 3/4" apple plywood. and scaled my model to fit all of the nested parts onto a 4x 8 ft sheet of ply.
- Change slice direction (see image 2) by rotating the arrow icons to get more dynamic stack patterns
- Choose Nested Layout to save some material.
Step 1: Laser Cutting Model
Next I laser cut all the plywood sheets. This took several hours. The nesting feature in 123D make didn't nest them very efficiently for these particular parts so I rearranged the auto-generated patterns to be more efficient.
This part of the process is mostly straight forward. Remember to make all your Vector cuts line stroke dimension = 0.001". Follow the guide lines for your laser cutter for the correct settings to cut 1/8" ply. The process of cutting out all of the parts for this sculpture took about 4 hours.
Step 2: Assembling 123D Parts: Gluing Up Plywood / Wood Lamination
Gluing/ laminating wave form.
Apply a thick even coat of glue to one surface, place face down and apply even pressure with clamps. Apply flue next part and repeat.
This process took me over 6 hours to complete. I recommend opening 123D and following the step by step assembly animation because without that its hard to know exactly in what order and how exactly all slices assemble together.
The 3 last photos shows a graphite rub I applied to the plywood parts. I wanted to change color and experiment with gradients.
*20/20 in hindsight* I should have stained after all the parts were assembled, though somehow I got lucky and was they still glued together well. It was faster and easier to stain edges after stacking several parts and rubbing all edges at once.
Step 3: Polyurethane Rubber Mold Making Using Smooth-On 50 With a Hard Plaster Shell
After I glued up the plywood form, I became increasingly fascinated with the slices texture which resembled natural rock formations. This inspired me to make a mold of the form so I can translate the digital texture into a stone like material, specifically concrete or Hydrocal.
Due to the complex form and fairly large size I didn't want to spend $500+ on silicone to pour a two part mold. So I talked to Artie at Douglas and Sturgess who recommended I use a Brush On 50 Polyurethane Rubber $118 for gallon of part A and part B. I never created a rubber mold before, so it was a great learning experience.
I prepared my part for molding by coating it with wood lacquer 2-3 times. This sealed all holes and porous surfaces and create a smooth finish on my wood sculpture. Then I got all necessary protective gear such as gloves, buckets, sticks, cups, etc and was ready to begin mixing.
I mixed a 1:1 batch of part A with Part B (note Part A is liquid and Part B is a thick paste so mix very thoroughly) I followed this video as close as possible. Applying 5 separate layers of Rubber/Polyurethane mix with a brush, allowing each layer to dry in between coats.
As a way to ensure even coverage with each layer I added just a small spoon full of dry pigment into every 2nd batch of Smooth on. This tinted the color of the mixture so you can see where the coverage was insufficient. When I pulled off the mold it was clear to see where my first and second layers were poorly applied so it was a good thing i added the pigments.
Even though I followed the mixing ratio 1:1 I had some of the liquid one left over as shown in last photo-
As you can see I made a big mess, and waited to clean up once all latex was set. I scraped it off with a blade and steel wool then cleaned with soap and water.
Last photo is of the beautiful detritus from the rubber mixing bucket1
Step 4: Rubber Mold-Making: Casting a Hard Plaster Shell for Your Rubber Mold.
After the rubber cured fully, I trimmed the rubber base, drew a parting line with a sharpie on the widest point of the mold so I can add a hard shell to my soft mold, so the mold would not deform but hold its shape when I poured the concrete into it. At that moment I felt that 2 part hard shell would work fine, but in hindsight my shape had too many grooves for 2 parts which caused my plaster to break apart and needed reinforcement so in hindsight I would have split the hard shell it into 3 parts instead of 2. Hindsight is always 20/20
Using basic white (ceramics) clay I rolled out 3/4" thick slabs and sliced them into 1.5" high strips. Using these strips I created a parting wall that sat on the edge of my parting line. Adding clay supports on the backside as shown in photos.
I added a registration groove to the clay as well as cut registration holes in my rubber. These proved to be VERY helpful. I might have made a few more ridged registrations on the actual rubber mold when I was adding my last layer of rubber, but I didn't. In that you tube video they show this process pretty well.
Pro Tip* Cut the registration holes large enough for plaster cast to have some structural bulk, in order to hold rubber mold in place. Mine were about 3/4" square. It worked better when they were placed away from the thin edge closer to my part where the rubber was thickest.
Step 5: Mixing Plaster of Paris/ Hydrocal or Plaster/Silica Invenstment
Mixing plaster is one of the first "sculptural" processes I learned in college. These are the basics:)
*Pro Tip: Plaster is notorious for clogging drains so keep a smaller bucket of water near by for hand washing and tool cleaning. Let plaster dry out and dump into trash. NEVER pour plaster down the drain even if it looks very runny. It will set and clog your drains! I also like to wear gloves, safety glasses and a respirator when working with any chemicals. SAFETY FIRST!
Pour clean cold water into a bucket. (Volume of water will depend on volume of plaster needed, so do read the label on the packaging instructions) Typically the plaster will not add much volume to the water so look at how much water is in your bucket, this is pretty close to how much plaster you have to work with.
Start slowly sifting handfuls of plaster powder into the water, allowing the plaster to sink to the bottom without mixing. Continue to do this slowly until you see what is referred to as the "dry lake bed" effect (see photo).
I would describe it like this, as you sift your hand fulls of plaster note the sink rate of your mounds. Once your plaster stops sinking rapidly into the water and starts to form little dry mounds that do not sink. This is the approximate saturation point. You can add a bit more until you see a wet dry plaster terrain. The plaster can sit for about 20min in this state but I usually mix right away.
Mix with your hand to break apart any clumps and ensure an even mixture. Once you start mixing the plaster the clock is ON! Your working time is 10 min apx before plaster starts to catalyze and set.
The target mixture consistency is similar to drinkable yogurt. You want to be able to dip your hand in and it come out white. The plaster will start to warm up and eventually get hot. You do not want to pour this directly onto any skin.
Step 6: Pouring and Laying Down a Plaster Shell
Once my plaster was set, I had to work quick. I sprayed everything with mold release, especially the clay and base. Then I poured some of the liquid plaster into the grooves of my mold (tilting the mold at an angle to make sure plaster didn't spill out). Then I proceeded to dip a bunch of fabric into the plaster, then molding this plaster soaked fabric to the contours of the mold and adding more setting plaster to the face of it. Your target thickness should be at least 2" or more!
In retrospect I wish I reinforced my plaster with Fiberglass or mesh wire as it was not very sturdy using plaster of paris alone and I had some failure in the plaster at weak points that want to bend. Again this would have been solved by splitting my hard shell into 3 parts, alleviating the stress on weaker points.
Once I plastered side A and let it set. I pulled off my clay to reveal the registration marks. I repeated Step 6 and sprayed mold release on second side. Then repeated Step 7. Once mistake I made was sealing up my edges. I had high hopes that the plaster would magically separate, But it didn't and I had to pry the two plaster halves apart with a flat head screw driver, breaking some of my plaster edges.
I reinforces my plaster again then the mold was finished and the part ready to be pulled out!! This was an exciting day!
Step 7: Casting: Mixing and Pouring Concrete and Hydrocal
Pulling part out of mold: I slowly removed hard shell and used a blade to cut along my parting line. Cutting only area that were absolutely necessary to pull part out of the rubber mold. The smaller your seams the less room for error, spills and misalignments. I only cut one side of my mold, pulled my part out, sprayed mold release again., placed it back into the plaster hard shell and now, finally my mold was ready to make multiples! This took over a weeks time to get the mold made and everything ready to cast.
I purchased two 80lbs bags of concrete. I talked to the people at Cheng Concrete and purchased some of their Countertop color additive as well.
I built a wooden box to situate the mold in it. Trying many ways to seal up my rubber seam. If your hard shell is very well made you would not need to seal up your seams. the registration marks will take care of that, but we all learn through experience, so next time I will do it better but you can learn from my mistakes and do it right the first time:)
I Used straps and clamps to keep mold upright leveled and in place. I found that using a stapler to "stitch up" my seam worked best. Imagine Frankenstein sutures :)
I flipped my mold over so the opening that sat upon the wood base was now on top and open to pouring into it.
Mixing concrete was hard, I found that using a shallow wide trough of wheelbarrow is best because you need to add what seems like very little water to a lot of concrete and mixing it evenly proved to be very hard in 20 gallon bucket.
The first concrete pour I did failed somewhat, I used a bucket to mix it and tried to get even mixture with a mixing drill but the stones in the concrete kept jamming my drill so I finished mixing by hand. I kept adding water to get it to mix well and ended up with a concrete thick soup adding way too much water so my first concrete piece broke at a weak point when I pulled it out of the mold. I actually really like some of the failed casts, they have a lot of character! See image 1 and 2.
I then repeated this entire casting process with Hydrocal a concrete reinforced plaster. I mixed it just like plaster (see step 6) and pulled a nearly perfect mold out of it. See images 4-7. Image 7 shows a graphite and mica patina on it for greater depth of tone.
I also cast a second version in concrete, this time using a wide shallow plastic bin, or trough to mix it in and followed the guidelines on the concrete more exactly, adding way less water and no pigment which resulted in me pulling a pretty good part the second time around. See Image 1 top left!
Step 8: Scorched Earth: a Plywood Laminated Sculpture
All while I was working on these molds, I decided to use the OMAX water-jet to quickly cut new parts for a new iteration on the same form, made out of ply wood. This time using 3/4" dense apple plywood and playing more with slice directions and exploiting the striated nature of this material
I went back to 123D and generated new cut sheets for the 3/4" ply using one 4x 8ft sheet to nest all my parts on.
I used OMAX layout to generate my tool path's. Because plywood tends to swell and pop up in water I had to make sure my tool head never crossed over a cut part, and always moved with the "heads up traverse" function, this took a bit of work and many hours or frustration but with a little guidance and patience I figured out all the nuances of OMAX layout and then it was rather quick to do the second time around. Isn't that how it always goes!? Sigh!
I got up before dawn to be first on the OMAX water-jet. So I got to the pier just as the sun was rising that morning (see photo of rising sun under bay Bridge) The cuts were fine and the wood didn't swell as much as I though. I did drop the water level down all the way so the ply never sat soaking in water. The cuts only took about 1 hour.
See step 3 for gluing and assembly instructions. Because the water-jet couldn't distinguish between cut and etch lines (part numbers etc) I deleted all that data and plugged my parts back into the cut patterns (see photo 3) to number them afte they were cut. I followed my 123D Assembly steps very closely to glue this up.
Step 9: Grinding & Sanding + Flame Treatment and an Oil Finish
This part was fun messy and a not very typical process for Pier 9. Hand grinding sanding and finishing is something I am used to so that kind of manual labor does not scare me. The headache of programming G-Code to have a 5axis DMS cut this is more stress then doing it with air tools. So that is what I did.
Starting with a pretty cool looking glue up, I grabbed a bunch of air tools with various grinders and started hacking away. The GIF time-lapse shows 2 days of sanding the rough cut off. Then there was 2 more days of hand sanding to finish. Lots of coffee between sanding sessions!
Once the sculpture was sanded to a 220 finish I did a light flame finish on some of the parts, to vary the color and surface. Then rubbed it down with Rubio Monocoat (natural oil) and TA-DA!
Step 10: Water-Jet Cutting and Fusing Soda Lime Bullseye Glass
Water jet cutting glass was fairly easy to do. The few tips and tricks I can offer is to use non tempered glass. I used Bullseye brand fusing /slumping glass. After you have your 123D make cut files ready, generating tool paths in OMAX layout is a bit of a chore.
First the geometry generated created a million tiny straight lines instead of one continuous curve. This made O-Max layout glitchy. So I had to clean up my files by combine components and reduce the amount of nodes in each part in Corel Draw but it could have also be done in Adobe Illustrator. I also had to erase all of the etch lines because omax layout would process them as cuts. I also wanted my glass colors to alternate in color (part 1 clear, part 2 black, part 3 white, etc) I had to manually lay out the parts in 3 sheets to make sure each part was cut on the right color glass.
Once my .dxf files were cleaned up, sorted and ready to go I imported then into OMAX and auto generated cut paths. Using the #5 or very fine setting, heads up traverse for all traverses and checked yes on the low pressure pierce setting and yes on very brittle material setting and it all pierced and cut quite well.
I had to make 2 plywood fixturing boards to hold my glass sheets in the water so the glass didn't sit directly on the metal slots, otherwise the vibration would break it.
During the cutting a few of the tiny pieces fell in and got lost in the murky water during the cut but I added duplicated to the cut file so I had all my parts in the end.
Next I cleaned sorted and stacked glass in a kiln at GlowGlass studio in Oakland. Pier 9 will be getting a kiln soon I hear:) the fusing took 3 days and got up to 1400 degrees. Results were dubious.