[danshapiro]

CEO/Founder of Glowforge here. There are a bunch of lasers billed as 40W on ebay and amazon, but please look really carefully before you buy one. The mostly-harmless part is the lousy interface, overrated tube, and inability to cut (the motion controller only supports raster mode). The worrisome parts are the ungrounded case, high voltage wires that are usually but not always firmly attached, and lack of an interlock or other safety precautions.

If you're excited about making a laser work, they're a worthwhile project. If you want to use a laser to make things, you probably want something that is closer to working out of the box. (Speaking as someone who shipped 770 lbs of laser from China, then spent way too long getting it to work... sometimes.)

[saidajigumi]

> the lousy interface

Which, on one such cutter I used, involved having to pre-process DXF files through Corel Draw (!!) in order to get the cutter software to read them at all. In my case, that meant a workflow of:

  CAD software
  -- export-to-DXF
  pre-process in Illustrator
  -- laser kerf allowance
  -- layout parts on material
  pre-process in Corel Draw
  -- load and reexport the DXF, just 'cause
  load in cutter software
  -- mark up paths for cutter parameters 
     (speed, power, cut/raster mode)

For comparison, Ponoko cuts out the last two pieces of software. AI or Inkscape can be used for all required workflow steps. The (necessary) tradeoff is that you have less control: only "cut" or "engrave" to parameters pre-determined for the requested materials.

[thefabfamily]

You're right! Removing workflow steps is key to allow anyone to access to laser cutting, but there is no inexpensive and intuitive dedicated cad-cam software out there to do this job. That's why we developped a cloud-based easy-to-use editor with a bunch of features and much more if you want to share and sell your designs. BTW we already use a Speedy Trotec 300 but this machine could fit on our desktop.

[xrjn]

Could you elaborate on how you do laser kerf allowance in Illustrator?

[saidajigumi]

First, determine the kerf of your cutter. For service bureaus like Ponoko, they may be able to tell you the kerf for the cutter and material you'll be using. Otherwise do some test cuts, e.g. a set of 1cm squares, and measure the average kerf using a good digital caliper.

From there in reasonably recent versions of Illustrator, select your path, then use Object > Path > Offset Path...

In the Offset Path dialog, enter your measured kerf value. E.g. I've been working with a 0.19mm kerf lately, so I would enter half that in the dialog (literally ".19mm/2") and confirm.

A few notes:

* Make sure your path is fully joined (select everything then Object > Path > Join) before using Offset Path. If you zoom in and see your path looks like a series of disjoint rectangles, it wasn't joined; start over.

* IMPORTANT!: Offset Path creates an additional path, instead of modifying the selected one. At this scale, this is impossible to see. You'll need to zoom waaay in to see the pair of paths, ungroup them, then select and delete the inner one. If you don't, you'll end-up double cutting the same path, which can be a good way to make fire. :-/ (Ponoko checks for and will usually flag these kind of errors.)

Cheers!

[gaze]

Can you talk a bit about the tube? Is it DC or RF excited? Who is making it?

[danshapiro]

It's a custom glass DC tube with some cool engineering to improve the mode quality to TEM00, which gives us tighter spot size / higher power density. Similar effect to cranking up the power, except you also get tighter kerf and you don't have to make the tube longer.