Tag Archives: CNC router

A Wild Bar for a Wild Party

February 25, 2013 Eric Hart

It is a little over a week since Elon University’sÂ Wild Party closed, so I thought I would share some of the props I built while working as the props master on it. First is the sleek Art Deco bar. This production featured a lot of dancing and movement (in fact, the show was more of a dance piece with singing than a traditional musical) and the bar was key in a lot of the dancing. Actors jumped up and down off of it constantly and danced on top of it. Needless to say, it had to be sturdy.

The other hurdle was that I only had a bout a day to build the bar to a point that they could use it in rehearsal; it did not have to be finished, just usable. The bar had a sort of boomerang or banana shape to it. I knew it would take awhile to layout the shape, not to mention all the pieces I would need to cut that followed the shape but were inset or offset by varying amounts. Since the scenic designer, Natalie Taylor Hart, already had the footprint of the bar drafted in CAD, we decided to CNC these pieces and save some time.

The top was two layers of plywood. We were putting lights in the bar that would shine upward, so the top also had squares to hold three pieces of 3/4″ plexiglass; the squares on the top piece were large enough to fit the plexiglass, while the squares on the bottom piece were a touch smaller to create a lip for the plexiglass to sit on.

I also cut the footrest, a piece for a shelf in the middle, and some formers to nail the wiggle wood to. This pile of pieces would have taken awhile to draw and cut by hand, but with CAD, Natalie just had to copy the same shape over and over again, insetting the front curve by whatever measurement I gave. With this pile of pieces, I just had to cut a bunch of formers and uprights to connect them all together.

I decided I wanted some supports to run unbroken from the top to the bottom of the bar for strength, which meant I had to cut some notches and holes in the plywood that they could run through. If I had more time to figure the whole thing out ahead of time, I would have drawn these into the CAD. Since the pieces were already cut, I needed to measure and cut them by hand. See, even with fancy fabrication machines, you still need a solid grasp of traditional tools to build things.

I built the bar up one level at a time, marking carefully to keep the whole thing square and straight. I positioned the supports so they were nearly above the support below them; they were offset just a bit so I would be able to drive a nail in.

The supports along the front of the bar did double duty as formers, providing a nailing surface for the wiggle wood I would add later. I tried to keep the back as open as possible so it could be used as shelving to store all the props; the set was fairly open and skeletal, so the bar served as a place for a lot of the hand props to appear and disappear. The diagonal braces in the photograph above are just to keep the bar sturdy as they use it in rehearsal. Once the wiggle wood was added, I removed them, because the wiggle wood acted as one large piece of diagonal bracing.

I finished the bar onstage in between rehearsals. The curve was longer than eight feet, so I could not cover it with just one piece of wiggle wood. The center is relatively flat, so I placed a small piece directly in the center; I have found it easier to fill and sand seams between wiggle wood when they are on flat areas. The footrest also got a small strip of wiggle wood after the bar was secured to the wagon underneath it. All the faces got a thin coat of joint compound and a light sanding, and then it was on to painting.

You can see the bar is a bit rough around the edges in the photograph above since I did not have time to take a picture until after strike. The Art Deco design painted on the front was a great touch added by Natalie and her crew. As she also pointed out, despite all the climbing and dancing done on this bar, she never saw it sag or wobble.

How-to

CNC Cast Iron Park Bench

January 21, 2013 Eric Hart 1 Comment

Yes, I built this exact same cast iron park bench seven years ago. I even used the same research image you see in the link. I couldn’t build it the same way, though. The first time around, I used a lot of found pieces and details which I did not possess this time. I also needed to build three matching benches, which warranted a different approach then building a single one. I was building and buying all the props for Elon University’s production of Cloud 9, and the whole second act takes place in an English park; the director was keen on basing it off of Kensington Park.Â We decided to cut and carve the ends on the scene shop’s CNC router.

First I built the seats themselves with some stand-in legs and arms. I arranged some slats I had cut into a shape that was comfortable to sit in, than I screwed them together onto supports which kept the whole thing sturdy. The stand-in legs held it all up at the correct height so they could rehearse with the benches while we worked on the real ends. The idea was that when the real ends were ready, we would just unscrew the fake legs and pop on the real ones without having to take apart and reattach all the original slats. This also ensured that the curve and depth of the seat they were using in rehearsal would be exactly the same on the performance benches.

I began by making a line drawing of the bench in Inkscape, an open source vector graphics editor. I drew three layers; the first was a line showing where all the inside “holes” should be cut and the second showing where the outermost profile should be cut. The third layer showed where all the engraving would go. Rather than cutting all the way through the plywood, the router would only cut partway down, and it would use a v-shaped cutting bit (this technique is known as “v-carving”).

With the drawings finished, I gave them to the Natalie Hart, the scene designer (also my wife), to import into AutoCAD. I’m sure you can use the Inkscape drawings directly, but I have no experience with CNC file formats, and Natalie has already successfully used her CAD drawings on the CNC machine. The curves I drew in Inkscape turned into a series of many tiny lines in AutoCAD; this meant when they printed, they looked like many tiny lines rather than a single smooth curve. The curves she redrew in AutoCAD printed as smooth curves, however. I’m not sure I will use Inkscape again to draw for a CNC; if I find myself using the CNC a lot in the future, I may just spring for one of the less-expensive CAD drawing programs out there.

The final piece of the puzzle was getting the drawings into PartWorks, which is the CNC machine’s software that generates the instructions it uses in cutting. Our production manager/lighting designer Bill Webb happily took that on, since the machine is second-nature to him by now. In about three hours, we had all the pieces we needed for all three benches.

You can see in the photograph above that the CNC left a lot of cleanup work to do. I experimented with a number of abrasive flap and wire wheels to see if there was a quick way to sand the whole thing, but it ended up requiring hitting every nook and cranny with a Dremel tool.

We had taken measurements off the rehearsal benches and put them into AutoCAD so the CNC parts would line up exactly with the existing structure. For the inside of the end, we only printed the bottom half and attached it to the outside part. This gave a bit of a lip for the existing bench seat to rest on, while also providing a lot of surface area to screw into from the side. It also helped line up the bench seat to the ends at the correct height.

The faux-verdigris paint treatment was developed by one of the students (good job, Vee Bland!). Natalie and I painted them up, and I quickly assembled them so they would be ready mere minutes before photo call.

Naturally, I would have loved to play around with the software and the drawing to develop a more realistic carving, as well as spend some time learning to run the CNC machine on my own. The time frame on this production was just too intense; 15 days between the first day of rehearsal and opening night, and these benches were but a small part of all the props and furniture I had to build and acquire. Still, it gave me a good idea of how I can integrate CNC fabrication into my prop work when it can come in handy.

Showcases

The Making of the Props for The Making of a King

January 25, 2012 Eric Hart 2 Comments

I recently finished my first major gig down here in North Carolina. I was building props for the productions of Henry IV and Henry V at PlayMakers Repertory Company in Chapel Hill. It was a lot of fun, and also an interesting change of pace to return to a job where I am building all day without any managerial duties.

The base for this chaise lounge was fairly straightforward. I began by building a nice sturdy frame out of oak. The design evolved later to a piece which was completely covered in moulding. The oak ended up being completely obscured by all the moulding. Ah, well.

The king’s headboard had a fairly intricate cut-out design, so the props shop sent a piece of 3/4″ plywood to the scene shop to be CNC routed.

When I got the CNC’d piece back, I cleaned it up and attached some other layers, moulding, posts and finials to make the full headboard.

Above is a nice trestle table base I built for the tavern scene. The feet and the pieces on top of the legs are made of solid wood; I had to laminate a few pieces together to get those thicknesses. The legs themselves are actually boxed out, with a two-by-four hidden inside for strength. The wedged tenons on the sides of the legs are just fake pieces glued on the outside.

The table top had already been built for the rehearsal piece, so I just had to attach it. The scene shop also added some metal diagonal braces, which were needed to keep the table from collapsing under horizontal forces.

Finally, the props shop was building a hammered copper bath tub out of some good old-fashioned papier-mÃ¢chÃ©. I jumped on this project in the middle, adding a few layers to what was already started and attaching the large Ethafoam rod along the top. The initial layers were done with an ordinary flour and water paste. The next few layers were done with strips of paper and a product called “Aqua Form” to make it harder and more water-proof. Aqua Form markets itself as a nontoxic water-based polymer which replaces resins for use in laminates; it worked great with the paper, but it also claims it can be used in lieu of resin for fiberglass. I certainly look forward to learning more about it.

Features

Product versus Process

July 13, 2011 Eric Hart

I heard a story awhile back from a fellow props artisan. A large company was in town, putting on the kind of show that required hundreds of specialty props, all created specifically for their production. They started out working with one of the larger prop shops in the area. The shop was good, but they were still not happy with a number of the props; the performers themselves needed to talk directly to the artisan in order to give all the details and needs they were looking for. When the prop was finished, they wanted to be able to use it in rehearsal for a bit, then work with the artisan again to suggest changes and ask for modifications.

The large prop shop wasn’t set up to do business like this. They were used to taking drawings and draftings from a designer, constructing the prop, and delivering it to the theatre. They could certainly deal with the changes and additions that happen in every production, but the kind of individual one-on-one experimentation with props throughout the rehearsal process that these actors wanted was beyond their capabilities. This is where the fellow props artisan comes in. He was able to provide this kind of daily collaboration. He would talk through the prop with the performer, making notes and asking questions, then head to his shop for the rest of the day. The next morning, he would bring a newly constructed prop to the performer who would try it out and then suggest new changes and additions based on what was learned.

This is the difference between props as a product and as a process, and it is one of the reasons why good props artisans will always be needed. In one case, you are “ordering” a custom prop from a prop shop. In some ways, it is just like you would buy some of your props off of eBay or from a catalog. Having this shop continually make changes and modifications becomes expensive, inconvenient, or even downright impossible. Even if all of the props are built by an outside group, you will still need an artisan on hand who can modify and work with the props to make them do what the show needs them to do. Having an artisan on hand also allows the props department to be a bigger part of the whole collaboration. Like a conductor who lowers the volume of the trumpets or speeds up the tempo at certain parts in the music, an artisan can alter the weight or balance of a prop, change the color, or add a secret handle between rehearsals.

I’m not trying to knock commercial prop shops in this post, but rather make a point about the continuing need for artisans in an age where our industry is seeing more and more computerized fabrication. CNC routers and 3D printers are great technologies, and hold even more promise in the future, but they are no replacement for a good props artisan. They create products. They don’t replace the process.

A CNC router can cut an intricate shape out of a piece of plywood with very precise measurements, and it can do it a thousand times with no difference between all the pieces. A props artisan is more than just his ability to cut out a shape drawn on a piece of plywood. A props artisan takes the needs and wants of a prop, balanced with the input of the director, the designer, the actor and the stage manager, and weighs it against the limitations of the theatre, the shop, her skills, and all the resources available to her. She chooses the materials and techniques which best fit all of these requirements to construct the prop. And she does it knowing that it may need to be changed or modified later, or even cut entirely from the show.

A smart props artisan will keep on top of the changes in technology and tools available to him and learn when to integrate them into his process. We’ve integrated computer printers into our manufacturing of paper props. Even with all the amazing things one can do with graphics software, artisans still use a surprising amount of non-computerized techniques to add life to paper props. A good artisan uses all tools and methods available to him rather than altering the prop so it can be manufactured by a certain machine.

Tools

Thoughts on 3D Printing Technology

September 29, 2010 Eric Hart

I first wrote about desktop fabrication on this blog over a year ago as part of my “Future of Making Props” series. This weekend, I got to see a number of 3D printers in action. For those who don’t know, 3d printers build an object from a 3D CAD file by laying down very thin layers of plastic one at a time. This weekend at Maker Faire, I got to see a number of the cheaper DIY machines in action: MakerBot, RepRap, and Fab@Home were all there.

I’ve been excited about this technology for prop-making for awhile, as you can basically buy a complete MakerBot Cupcake Kit for around $700 and start printing your own three-dimensional plastic pieces. I’m a bit less excited after seeing what the finished pieces look like. They do not have that great a resolution, and there is a lot of clean up you would have to do to it. Let’s say you needed a small bust of Mozart for your play and you wanted to make it yourself. You would have to develop or make a three-dimensional computer file of the finished piece, which takes time and requires a completely different set of skills than sculpting it in clay. You would need to purchase and maintain a 3D printer. The printing process itself is rather slow; for a larger piece, you most likely would need to leave it running overnight. Once the piece is printed, you still need to sand it and clean it up, and only then can you mold it and cast it. Once you combine the time and money it would take to do all that and compare it to an artisan sculpting and carving a piece, the artisan still wins hands down.

That’s not to say they are without merit. At the moment, their draw is less as a means to an end then as an end itself. You should build and modify your own 3d printer if you are interested in building and modifying your own 3d printer. If you just need the objects it can produce, there are far less-circuitous routes to get there. As prop-makers and prop masters though, it is important to keep an eye on this kind of technology and be prepared to take advantage of it when it matures. It is a game-changer. It has the potential to transform prop-making as much as the introduction of synthetic materials has in the past century, or the invention of power tools to replace hand tools.

You can see they kinds of things which can be made by these machines at Thingiverse, which brings up another advantage of these machines. Once you create an object which works, you can make another just by hitting “print”. You can also share the file with anyone else who has a printer. Thingiverse is a site where you can share your own creations or download other people’s. To put it simply, you do not even know how to use 3d computer software to get things to print. Someone else can do it. That other person does not even need to be in the same location. You can email someone on the other side of the world a picture of what you want and they can email back the computer file you need to print it. I can envision a time when prop masters maintain their own library of printable objects much like they share files for paper props now.

This is already happening with websites like 100K garages or shops like TechShop. TechShop has all the fancy machines like CNC routers, 3d printers, laser cutters, plasma cutters, milling machines, as well as the non-fancy but necessary tools like welders and sanders. At Maker Faire, they were advertising that they were opening up a location in New York City in 2011. It’s very exciting.

Prop Agenda