About Paul Williamson

Paul is the lead operator of the Colab laser.

Kerf size for finger joints

Finger joints, such as the ones used by the web-based box designer at http://boxmaker.rahulbotics.com, depend on accurate dimensions to provide a tight fit. If you take the standard settings, it assumes that the parts are cut out with no loss of material. Since there is always some loss, that creates a box that fits together, but loosely.

To get a tight fit, you need to click on Advanced Options and enter the real kerf width where it says Cut Width.

I ran some tests with quarter-inch acrylic (pretty typical for boxes) and found that a Cut Width of 0.005″ is about right for our laser today. That’s right in the middle of what the web page says are typical values. You can probably get away with just using 0.005 for your project. Of course, if you need the best fit, you’ll have to run your own tests on your material on the day you’re cutting it.

You’ll also want to use an accurate setting for Material Thickness. It turns out that quarter-inch acrylic is nominally 0.22″, and half-inch is 0.472″, and both of those numbers vary a bit. For perfect results, use a micrometer on your material.

Laser cut box made out of quarter-inch acrylic using a design generated by http://boxmaker.rahulbotics.com

Laser cut box made out of quarter-inch acrylic using a design generated by http://boxmaker.rahulbotics.com

Rotary Adapter Arrived

We now have the rotary adapter for the laser at Colab. This enables us to engrave on cylindrical objects, including tapered cylinders such as beer glasses.

I’ll update here when I’ve tested it out. If you have an urgent job that needs the rotary adapter, let me know and we’ll try it out together.

Rotary adapter for engraving cylindrical objects on the laser.

Rotary adapter for engraving cylindrical objects on the laser.

CorelDraw X7 Installed

We now have CorelDraw Graphics Suite X7 installed on the Colaser computer. It’s a very full-featured vector drawing program, and it also comes with Photo-Paint (a bitmap editing program), PowerTrace (for converting bitmaps to vector), and a bunch of other stuff.

If you’re still trying to decide what vector drawing package to learn, CorelDraw is a reasonable choice. You can get the Home & Student edition for about $130. We have the full version at Colab, since it supports more import file formats you might want to use, but for original drawings the Home & Student version is probably fine.

Laser Scheduling

Now that we have some people trained and checked out on the laser, we need a scheduling mechanism to reserve time on the laser. Eventually this should be automated and easy, but for now Meg <meggieking@gmail.com> has agreed to handle the scheduling manually. Please contact Meg to arrange time on the laser.

Between now and YouTopia, priority will be given to people working on the Temple and art projects for YouTopia. If you have other projects, let Meg know and she will still try to find a timeslot for you.

Laser Classes

Training classes to use the laser will be held at Colab on Sunday, September 14 beginning at noon, and again on Thursday, September 18 at 7pm. These two sessions may already be full; if you need to laser something before YouTopia contact Meg to see if you can get on the schedule. More classes will be scheduled as needed.

Expect to spend about 90 minutes in the classroom, followed by hands-on time in the laser loft.

Souk Table decorated

Dave on behalf of Sol Diego volunteered to construct the furniture for the San Diego presence at the Souk at Burning Man 2014. The table top is to be the centerpiece, decorated with a pattern blended with the Quemaduras del Sol sun. The technique is to mask the wood with masking tape, cut patterns in the tape with the laser, and then spray paint the masked areas (rinse, repeat).

Look! Actual Burning Man art being created on the laser! That’s a milestone.

First test of raster engraving

This 8×8-inch square of plywood was engraved at medium resolution, 529.2×529.2dpi. The original image was a grayscale and resolution test image intended for photography, and it was dithered by the built-in “simple dither” operation. The results are decent, but it took over an hour to engrave. That’s a lot slower than I expected. This machine seems to be quite a bit slower at rastering than the Hurricane laser at MakerPlace.

8×8-inch test pattern engraved at 529.2dpi.

8×8-inch test pattern engraved at 529.2dpi.

Attempt to cut thick plywood

Tried to cut some half-inch and three-quarter-inch plywood. Results, not so good.

Trying to cut 3/4" plywood from the scrap heap with the standard lens. The test matrix of squares increases power top to bottom and increases speed left to right. The slower settings  set fire to everything in the vicinity, which fire was then stoked by the air assist jet. At no speed or power did it actually cut all the way through. I think the problem is depth of focus, and I have a longer focal length lens that should help somewhat.

Trying to cut 3/4″ plywood from the scrap heap with the standard lens. The test matrix of squares increases power top to bottom and increases speed left to right. The slower settings set fire to everything in the vicinity, which fire was then stoked by the air assist jet. At no speed or power did it actually cut all the way through. I think the problem is depth of focus, and I have a longer focal length lens that should help somewhat.

First Jobs Run on the Laser

With the exhaust blower installed and ducted, and wired up enough to be used, the laser is now capable of doing work! I successfully ran vector engraving and cutting jobs on paper, thin plywood, and corrugated cardboard.

Running at full power seems to be more than our existing circuit breaker can handle. The circuit is wired for 20A but only has a 15A breaker, so there’s reason to hope that a simple breaker upgrade will solve the problem. If not, we’ll need to do more wiring work.

I’m waiting for word from the manufacturer on how best to level the Z table, which is far enough out of level to cause problems for large jobs.

Exhaust Ducting Installation

Today the ducting for the exhaust blower was completed and the blower was mounted in its new doghouse on the roof of Colab. Thanks Natural and Joe!