Projection Mapped Cnc

computer aided design and cnc technology has revolutionized craft and made it easier for the designer to directly create their work but the technology still creates the last mile type of scenario where a piece still requires a level of craft to complete after machining, often times reliant on tools hundreds of years old, as well as remaining expensive. The following project really should be cnc'd this experiment tests whether or not i can use a projector and a track saw in place of a 3-axis cnc if so how well will it work. This is one piece of a desk im building for myself. One end will be supported by a forged steel frame which is visually light. this experiment will focus on the drawer tower which is a solid faceted shape for visual and practical stability. Much of my work as a designer is an exploration of the making of complex asymmetrical shapes, this is a continuation of that.

This is an experiment to test if i can effectively make a complex faceted project without the use of a 3 or more axis cnc.

1. The experiment is as follows:
-I will lay out my cuts with associated cut angles on an image with 4' x8' markings

-to simply the cutting and alignment I will only make ridge forms no valleys

-I will line up my marks with the corners of the 4x8 sheet of 1/2" mdf im using

-using a sharpie ill transfer the projection

-Using a track saw I will cut out the triangles at specified miter angles

Step 1: Digital Design

I) Digital Design

1. using Maya I designed a faceted shap i like with all ridge angles no valleys, valleys would require the miter to go the opposite way I decided that this would ad an unnecessary level of complexity for this experiment. Not only do you need to miter both directions but i would to model out the whole solid in 3d instead of just getting a simple 2d cut profile

2. I've avoided grasshopper for a long time but recently due to this project I learned just enough to search for a definition and use it. I used a def. from "https://www.grasshopper3d.com/forum/topics/measure..." It is a find angle between faces script, although there are many better ones that do the layout for you this one was free. So wrote the numbers onto the drawing manually.

3. If youre a rhino user I used the orient command to lay out solid 3d objects, but since this is just 2d shape profiles i can use the much simpler "unroll" command, this is another reason to avoid valley joints.

4. Now that the shapes are layed out on the sheet ill make sure to put my 48" x 96" corner markers on the image for projections. Double check that the size of you sheet is the same as on the sheet, some products come slightly larger or smaller.

Step 2: Projection and Cutting

1. Alignment is critical, you will need to construct some kind of set up to hold your sheet vertical for projections, you will also need to align your projector as perpendicular as possible. there are keystone features on most projectors and like always you want to use them as little as possible for best results. I found this part to be quite challenging, The adjustment feet on my little projector were not quite sufficient and needed books and blocks to adjust it properly. At some point I decided that i had adjusted it well enough, I probably didnt.

2.Using a sharpie i transferred little dots at the corners with arrows pointed at the next point of the shape. I didnt see a point in a full line because the tracksaw's track will keep the cut straight between the points. I also wrote out the angle of the cut, the rhino script gave me the whole angle so i calculated the half angles for these cuts, luckily they were all within tracksaw's capabilities.

3. I cut out the shapes as explained adjusting the miter angle on the tracksaw with each cut, the first thing i noticed was that i had laid the pieces out too close together and was cutting into one piece while cutting another.

4. With cutting finished I noticed that two pieces did not get made, so I had to re-project them. The major problem with this is that I had to set up a new sheet and readjust the projector, this caused a scaling issue that ill show you in a minute

Step 3: Assembly

1. first round assembly was just tape. There are a couple corners where 3 pieces come together that need to be chizeled out for a better fit. not sure why that happened

2. 2nd round assembly I used biscuits, since i had the half angles this part was a breeze, you mark out where the biscuit goes, set up the angle and depth and send a biscuit. For this scale i used a size 0 biscuit. Holds together really well

3. next I glue the piece Wiping away glue with a wet rag Ill go through with a small brad nailer and put a few short nails in since this piece since it would be hard to clamp.

Step 4: Finishing

1. So the pieces fit together well, and after glue it feels very solid, especially for mdf, in some ways the facets keep the mdf more rigid. At the same time with this many seams many of them are slightly off and messy looking, as well as the 2 piece which were re-projected creating a 3/4" gap, If you attempt this yourself i highly suggest getting everything done in one go to minimize error.

2. Luckily there's bondo, one of the most durable patches you can buy, sands well, paints well. mix it up, patch cracks and sand. The big hole had to be done in 2-3 rounds of bondo, but after a day or so it was ready for paint. 3. The paint ill be using is old fashioned milk paint, first a coat of red, then a coat of black on top, the nice thing about milk paint is that you can layer it up and sand to expose the color beneath.

Step 5: Conclusion

1. Although this process had many problems due to scaling and complexity of assembly, the final piece is acceptable. I would not do this for a piece I intended to sell, but the experiment was worthwhile, from it I created a new system for the chair I'm designing.

2. Due to the act of projecting onto a sheet of plywood needing fine adjustment I would not suggest using a projector but rather printing shapes on paper instead this can limit the size of the object but actually has a chance of being accurate.

For more of my work check @paramorph_ on instagram