CAD CAM tutorial

CAD CAM tutorial
by D.  Scott Williamson

This tutorial will show you how to use Computer Aided Design and Computer Aided Manufacturing or CAD CAM tools to create and preview a Gcode file of the Workshop 88 logo that can be run in a 3 axis CNC Mill.


There are 5 main types of machine operations

  1. Engrave (follow path): The tool tip will follow the 3D path provided.
  2. Profile: The tool edge will follow either the inside or outside contour of a path down to the specified depth.
  3. Pocket: The tool will remove all the material within a contour down to the specified depth.
  4. Drill: A drill routine will be executed at each point location.  Drill routines come in 2 flavors:
    1. “Peck” used with drill bits, drills to successively deeper depths liftig the bit out of the work regularly to clear chips from the flutes.
    2. “Spiral” used with endmills that are a smaller diameter than the finished hole.
  5. 3D relief: The tool tip will remove material above a 3D surface usually specified in a 3D model or a 2D height map image.  There are two main modes:
    1. “Waterline” similar to inverted pocket operations where bulk material is efficiently removed outside the 3D model to a number of stepped depths resembling waterline in a topological map.  Typically used in a first pass with a large roughing bit to remove the bulk of the material.
    2. “Raster” moves the tip of the bit smoothly over the model in a raster pattern.

Gcode is a “numerically controlled programming language” which is why a Gcode file extension is typically .nc.  It is a human and machine readable text file.  You will rarely if ever need to look at or edit the Gcode.


This tutorial will demonstrate Engrave, Profile, and Pocket operations, which are the most popular.

There are 4 steps to this tutorial:

  1. Create a .svg file containing paths needed for machine operations
  2. Create machine operations
  3. Export Gcode
  4. Simulate, visualize and validate

Continue reading

Last Thursday night @ Workshop 88

Last Thursday we had quite a bit going on at the weekly open house:

Ray connected the chassis of a motorized wheelchair to a remote control unit and was able to drive it around the front room.  Here’s a video:

The laser cutter was being used extensively to cut out some tesselating lizards and geckos, as well as to make stencils for an ammo box intended to hold plastic eggs. The project is called “Hen Grenades”.

Later in the evening Rachel came in and showed off her new LEGO compatible circuit boards – they are really awesome!  We were having so much fun playing with them that no one remembered to take photos.  Come in next week and ask her about them!

Mathematica on the raspberry-pi – a library class

I really like teaching classes through Workshop 88 at the libraries.  Over the summer, I had a chance to teach a few of the classes Workshop 88 offers at some of the local libraries. One library that we like going to wanted a class to introduce their teens and preteens to the Raspberry Pi.

I recruited a few helpers and we gathered up several Raspberry Pis, keyboards, mouses, and power supplies to have enough supplies that the kids would be working in pairs or at their own Raspberry Pi.  We set up before the kids arrived and had everything ready to go. At the start of class we talked about the idea of the Raspberry Pi as a low-cost single board computer and we pointed out all the hardware features of the Pi.  Then we showed off all of the distributions that we had brought examples of.

That took all of 25 minutes for a 90 minute class. Oops.

So, I asked how many of the kids were familar with Scratch, and it turned out that more than half of them had already used Scratch in school.  I decided that they should get a chance to work with Mathematica, so that they would be exposed to something new.

There is a pretty good introduction to Mathematica for the Raspberry Pi on the Raspberry Pi Foundation website. (The actual Mathematica tutorial starts here.)

We did a bunch of things that I think worked really well:

1.) Showed basic math operations
2.) Showed how to make graphs
(One of the kids said at this point that Mathematica is basically just a less powerful calculator. That’s when we kicked it up a notch.)
3.) Kids explored how many digits of pi they could get out of Mathematica.
4.) Kids played with displaying 3D shapes using the Graphics3D function. Examples: Graphics3D[{PolyhedronData[{Antiprism, 4}, “Faces”]}]
Graphics3D[{Opacity[.4], Glow[RGBColor[1, 0, .5]],
PolyhedronData[“JessensOrthogonalIcosahedron”, “Faces”]}]
5.) Kids played with 2D shapes.  Examples: Graphics[Polygon[{pentagon, 1 + .5 pentagon, 1.5 + .2 pentagon}]]
hexagon = Table[{Sin[2 Pi n/6], Cos[2 Pi n/6]}, {n, 6}]

Lastly, we tried to generate some sound files with Mathematica, but it didn’t seem to work too well on the Raspberry Pis.

Overall, I think the kids had a great time playing with Mathematica and trying out a bunch of things that they had no idea a $35 computer could do.


Tesla Coil demonstration on September 17!

Workshop 88 member Phil Strons will be giving a demonstration of his Tesla coil at Workshop 88 this coming Saturday, September 17th, from 1:00 to 5:00pm.

Here’s what Phil has to say about what to expect from this demonstration: “Last year I had 20-inch sparks, but I’ve since done some modifications & repairs. I’m hoping for closer to 30-inch long sparks this time.”
WARNING – This device generates electric fields with high voltages of 1,000,000 Volts or more and has potential to interfere with medical devices such as pacemakers.


A member review

A member of the Workshop 88 mailing list posted a review of a new sewing machine she recently acquired.  With her permission, we’re posting it here:

Sewing Machine Review

Janome /  New Home Derby 1/2 Size, 10 basic stitches
I purchased this as a second machine, because it is simple, small, and very light — the opposite of my complex computerized full-size heavy motor Elna 9000 machine.
     Don’t get me wrong, I still love the Elna.  Truly.  But the idea of an ultra portable machine, that I could take along when I’m meeting up with other crafters had a lot of appeal.  And then I saw the Derby models online at Amazon, in 10 beautiful color choices, and it was time to save up my coins to get one.
     What’s in the box?  The sewing machine itself, user manual,and a small plastic bag containing the foot pedal, power brick/cord, 2 spare bobbins, 1 spare needle, and a needle threader.
     Setup:  It took only about 5 minutes to unpack, plug in, thread up the machine to wind a bottom full of thread, load the bobbin into the machine, and rethread the machine for sewing.  The threading diagrams were clear and instructions straight forward.
     Sewing:  Ok, the machine was ready, and it was time to sew.  I started with a piece of polarfleece.  I was turning the raw edges of the fleece over to give a stadium blanket a nice solid hem, so I was using the largest zig zag stitch, stitching through 2 layers of polar fleece.  I left the upper and lower tension on the factory presets. Unlike most machines, the foot pedal does not control sewing speed; it’s more of an on-off switch. There is only one speed. This feels a little weird when you’re used to speed control, but isn’t bothersome once you’ve sewn for 10 minutes or so.  Overall, the machine was smooth and even, and less noisy than I expected from a primarily plastic machine.  The machine had no problem sewing the polar fleece, and the feed dogs advanced the fleece evenly.
     Switching to cotton fabric, the machine breezed through a a simple seam. Next I sewed in a zipper.  The machine has no zipper foot, but it does have one stitch that moves the needle to the far left position so you can sew alongside the zipper coil.  It was old school sewing, but it got the job done.
     Next I sewed a cotton panel onto a sturdy canvas bag. It required sewing through the tough canvas (multiple layers) and seams. It required using the reverse stitch, straight stitch, and using the free arm to sew “into” the bag. (The cotton band creates a set of organizer pockets on the outside of the bag, and the fabric adds a nice accent.)  I was concerned that the small size of the machine would make it hard to sew things that are complex shapes (not flat) and that need to be stitched “inside”.  The machine passed with flying colors!  Janome / New Home did a good job designing the machine so that there is ample clearance, so you can sew things like cuffs, collars, and other items that are dimensional. The machine handled the medium weight canvas well, even up to 3 layers.  But I would not recommend the machine for sewing heavier materials than that, because of the power limitations of the machine.
     Pluses:  The machine is really cute, and very light.  It sews well.  It meets all expectations.
     Minuses:  There is no built in light, so you might want a portable lamp to help see during needle threading.  The machine has only one speed, which takes a little getting used to.
     Overall: 4.5/5.0  Would recommend as a second machine, or a starter machine.

W88 at Southland Mini Maker Faire

Andrew+Kids5559Andrew and Jim represented Workshop 88 at the Southland Mini Maker Faire in Mokena August 27th.  That Faire is run by Jay Margalus, one of Workshop 88’s founders.

Andrew’s workshop for kids to create their own hand-dipped paint-film artworks was a big hit, with dozens of delighted artists taking home their masterpieces.  Foam balls were the canvas; a bucket of water was the studio.

spray_paint_1024AThe technique, invented by Andrew using a film of spray paint on a tub of water, was inspired by a similar approach he’d seen using nail polish.  Less-than-perfect results with the polish caused him to test and perfect the paint approach.  Results were spectacular.

The laser toys box was there, as TrayAndLizardsCq65vvhW8AADHjVusual, and its Escher lizards provided entertainment and education for many little (and not-so little!) hands.  Having the back sides of the laser-cut pieces engraved with three different patterns provided an additional level of challenge based on the 3-way tessellation as a 3 color map problem.  The laser engraved wording on what used to be the bottom of the tray used to be obscured by the toys.  With the addition of the new slightly smaller lower box, that old tray is now both a useful top cover and a convenient display card!

GearsCq6wHU5XgAAxTWC-600Jim’s UV-lit fluorescent non-round gears caused lots of folks to stop and take a look.  Their graceful turning, speeding up, slowing down, reversing and repeating mesmerized a few visitors.  Their stepper controller and Tiny85 processor mostly worked, but required some discreet wiggling several times to keep it all going.  The flaky solderless breadboard that hosted them has since been replaced by a much more reliable dedicated PCB.

Display+TabletHis hexagonal WS2812 individually addressable RGB LED wall display made its debut as an actual interactive device at this Faire.  Controlled by a 16-button app on an Android tablet, connected via Bluetooth to a cheap radio on the Arduino that runs the display, the display was fun to make dancing patterns with to music from a small sound system on the table.  Next upgrade will be a better drum pad app with velocity and aftertouch, and lots more controls.

Thanks and a tip of the W88 hat to Drew Fustini for some of these pictures!