Friday, September 11, 2015

layout 101: digital craft research lab style

School is back in session and this week we were looking at layout and drilling in my Intro to Industrial Craft/Industrial Processes course. As you can see the demo table is full of layout tools and measuring devices. The first project we'll be working on will be a letter opener. We will be hydraulic die forming 3003 aluminum handles and making a 316 stainless steel blade. We'll be making 6061 aluminum dies for the hydraulic forming as this gives us a great opportunity to practice our layout skills in being as accurate as possible. The dies could be made in acrylic, wood, or PVC, but metal is good practice since many of the students have never worked with a thick piece of aluminum. Making tooling is good practice and opens the mind to the possibilities that can be carried through in the actual product or piece that is created with the tooling. In the Digital Craft Research Lab I stress the adaptation of digital tools along with the use of traditional techniques. This post should demonstrate one of the small ways in which this happens in the Intro course. Let's get started...

We talked about traditional layout techniques and tools associated with transferring a design to Metal. We have the option of doing an Adhesion Transfer where our paper template is glued to the metal (not good if you're using coolants and cutting fluids), Direct Transfer where the drawing is rubbed and the graphite from the pencil mark is transferred to a white painted surface of the metal (rubs off too easily), and Scribe Transfer where Dykem Blue or Sharpie is used to layout the design with a scribe and measuring tools.

Here is an example of my quick sketch for a letter opener/knife.

This is where things shift to digital. In my Design for Digital Fabrication prerequisite course I teach our students how to make the jump from a sketch to a virtual modeling space by photographing the sketch (a scale or ruler could be included in this photograph if need be). The sketch is imported to Rhino via the Background Bitmap or Picture Frame command. From there students can utilize a control point curve to "trace" their drawing so that a vector drawing is created. I go one step farther and have them create layers in the program that will represent the blade, handle, die, and have them account for handle mounting holes and die formed flange. Since we are making the dies in aluminum and we are doing this by hand (rather than CNC), I teach them to drill the majority of their die out if possible. Using software to map out those drill holes is an intelligent way to create center punch marks that can place those holes as close as possible so there is minimized cutting (you will see that my design is not completely laid out with these holes as I was in the middle of the demo when the screen shot was taken).

The creation of the vector drawing allows us to move across the hall to our  40 watt laser cutter. Note: this is where the laser cutter could be used to cut acrylic dies if we stacked the 1/4" acrylic; since our laser cutter can only cut up to 1/4" acrylic.  Our 40 watt laser cutter is limited to non-metal materials for laser cutting, but that shouldn't stop us from using it's capabilities with metal in other ways. Remember the laser cutter can engrave in non-metal materials as well.

Here you can see that the remaining drill holes were added for the die. I use the dimension tool in Rhino to locate my center punch marks.

The Dykem Blue coated aluminum is placed in the laser cutter and the focus is set and the piece is aligned with our virtual "print window".

Settings are selected to do a raster engraving operation and we use the preset settings that the Epilog has for Painted Brass at 500DPI.

The job is sent to the laser and we hit GO.

In a few minutes we are left with a marked surface that we can use to mark layout with our scribe, prick punch, center punch, etc.

As you can see the lines are faint, but it's good enough for us to use our curves and other various drawing tools to transfer the design easily. Just pick up a good scribe and get to work.

Another alternative is to paint the aluminum with spray paint, let it dry, and then place the piece in the laser cutter. The engraved lines will have a deeper effect since the paint is thicker than the Dykem and you can skip the scribing step. Just center punch your holes and you're ready to drill. 

If you do not have an optical center punch then you need one. John Saunders of NYCCNC recently did a great video on traditional layout techniques which can be found here. By the way check out John's site as well as his You Tube channel; great stuff here! While you're there check out Tom Lipton's Ox Tools channel as John's layout content originated with Tom. Tom's book is on the list of required texts for my students to read; I wish I new half of what knowledge he has tucked away inside his head. Anyway, John listed the optical center punch in the video and I had to get one for the DCRL. It's simply amazing! Every maker/machinist should have one. You can find it here. It's gone WAY up in price since I purchased mine, but I think Grizzly sells a cheaper one and there may be other resources as well.

The punch as a ground acrylic resin piece with a dot that is accurately placed in the piece. You insert this into the holder, position over the crosshairs that you've just located with the help of the laser cutter and then you replace the acrylic piece with the precision ground center punch.

Strike the punch with a hammer (I used a rawhide as it was close by, but a steel hammer would be better) and then you can remove the tool and use a center punch to deepen the hole slightly if need be.

I covered drilling operations the next class period and drilled a few holes while I was at it. Still a few more holes to go, but this should give you a basis for how a laser cutter/engraver can aid in speeding up the  layout process. Not to mention I find that having the students transfer their drawing to a drafted format makes a big difference in the finish product. In future courses in the curriculum, students will be introduced to CNC, but I feel that it's absolutely imperative to lay a good foundation. This first assignment sets the precedent for the kind of precision and craft that is necessary to be successful in the course and hopefully the demo starts some good habits that students will continue when they leave the bubble of school and they start to put their skills to work for themselves.

I'll see if I can continue to do a few of these write-up's as we work in class. Even if no one out there happens to be interested in the topic, at least this becomes a refresher for the students in the course.


Chad BridgeWater said...

I love it!!!

Frankie Flood said...

Thanks; I was thinking of you when I wrote it...