Laser, Lathe, and Long Exposure

I’ve done a lot of experiments with light graffiti on JCoPro, but some things don’t really go anywhere.  This post is about a few shots that don’t necessarily fit into another large post, but I thought were interesting anyway.

The first few pictures in the gallery after the “more” are of me tracing the supposed trajectory of a Ping-Pong ball with a green laser (under $5 on Amazon as of this writing).  Shining it on the ball itself made for a cool effect.  Yay.

The second set of pictures, made with a lathe, was a bit more interesting.  The effects reminded me of a 60′s era sci-fi film.  Think early Star Trek Pheonix Five.  Basically I made a really crude fixture for my laser with a 2 x 4 and attached it to the lathe’s spindle.  Probably not the safest thing to do, so I don’t recommend anyone try it (or anything else on this site for that matter).  A long exposure shot was taken (per my light graffiti intro) and the rest is history.

Light graffiti on the side of my yard

For some other “manual” laser light graffiti ideas, here’s my first experiment with lasers, “painting” some random stuff on the side of my house.  Of course, the “LED and light projects” section is full of automated light graffiti, so be sure to page through that section.

Hello pyMCU - How I did this.

Congratulations to Patrick Gibson on winning the “free pyMCU” contest!*

Richard will be sending the winner one shortly, and if you come up with any cool projects with it, I would love to see it!

In case you’re wondering how I selected the winners, I used a simple Python script (naturally) putting everyone in a list then randomizing it.  Sure, it’s only pseudo-random, but hopefully it’s good enough for readers of this blog.  If I was really good, I’d figure out a way to scrape the comments, but handling the “subscription bonus” would have made it even tougher.

Contest Python Script:

import random
x = ["Dillon", "Dillon", "Bill Hecox", "Patrick Gibson", "Patrick Gibson", "Brian", "Anthony Nystrom", "Shankar Valleru", "Tristen", "Tristen", "Kevin Groce", "Kevin Groce", "Ken Bolton", "Ken Bolton", "Konrad", "Craig Thrall", "Craig Thrall", "Nicholas Day", "R. Burke", "G. Thompson", "Veifler", "Veifler", "AGS", "D", "D", "dhlabs", "MJ Mare", "D. Schumm", "D. Schumm", "Thomas Sileo", "Jordan", "Cathy Lewis", "Cathy Lewis", "Tim McQueen", "Tim McQueen", "Joost Plattel", "Jacks", "Madvoid", "Felix", "Pierre Paul Lefebvre", "Martijn", "McKay", "McKay", "srinath", "John Varga", "Anthony Plunkett", "Anthony Plunkett", "Rob D", "Rob D", "firefighterblu3", "George Hahn"]
random.shuffle(x)
print “Contest Winner “, x[0]

*All names were given publicly in the comments (if you’re worried about privacy).

This was an incredibly successful contest, with nearly 40 people commenting in, many of who subscribed.  Thanks to everyone for reading and commenting.  If you didn’t win one, I really like my pyMCU boards, so you can pick one up for the reasonable price of $24.95.

On a related note, I never really did a follow-up on my last contest, but Miami’s own Nicole won my latest ATST painting and was nice enough to send me a picture of it up in her abode. (and permission to use the photo)

The number of entrants was somewhat less impressive for that contest, so apparently people like free microprocessors more than my weird “art.”  The art is more for my entertainment than anything, so if some people appreciate it, that’s a bonus to me!

*Originally another winner was chosen, however the winner’s address was not in the US as required.  Another winner was selected by the method outlined above.

“Disco sphere” made with 1 line of OpenSCAD code

After my review of Meshcam, it was suggested that OpenSCAD (available on various OS versions, or here’s the Ubuntu install instructions) could be used to turn 2D DXF files into solid parts for cutting on my CNC router.  After trying it out, this solid modelling package is really like nothing I’ve ever seen.  Instead of the mouse-driven interface that you see on ProE or Solidworks, you instead have a text editor where you can enter commands that are used to form a solid part.

Oddly, it felt very intuitive to me to use it, and the fact that you can copy-and-paste text into a drawing makes an example extremely easy to follow along with. With professional 3D CAD packages, you may have to poke through 5 menus to get what you need, in OpenSCAD you just type the needed command in.

AutoCAD (or Draftsight – my review) has a text interface that can optionally be used, but it’s interesting to think about what would have happened if other professional CAD packages evolved this way.  My feeling is that it might have made things harder to use initially, but once the interface is learned it would have been incredibly fast.  Fixing a poorly-programmed design or initially visualizing what you wanted might be harder, however.

Hypothetical thoughts aside, OpenSCAD is really a lot of fun to play with.  To draw a sphere, for example, all you have to do is type in “sphere(30);” and press F5.  A 3D sphere pops up on your screen.  As shown in the video after the “read more” thing, you can modify the number of sides drawn to change the shape.  Apparently this is useful for drawing socket head screws and the like, since a circle can be represented by six sides.

As for what I actually intended to use this for, making 2D DXFs into 3D models, I’ve had mixed results. Info on this command can be found in its manual here, but I used these commands to generate what you see here:

Extruded with OpenSCAD

linear_extrude(file = “/ENTER PATH HERE/FILENAME.dxf”, layer = “0″, height = .5, center = true, convexity = 5);

OpenSCAD is extruding things one layer at a time, so I guess you could draw what you wanted for “2.5D” milling using just this if you were careful. On the other hand, I haven’t fully explored the cut=true modifier, so possibly this would allow you to extrude a DXF as a cut from the top. As in what happens when using my router.

Extrusion issues aside, if you want to get started, or just preview what it is, Jestin Stoffel has some good instructional videos on this package via his youtube page.  Here’s a good introductory video from him:

If I was more ambitious, I would make my own video, but no need to reinvent the wheel. For further reading, this manual section on the 2D subsystem seems quote useful, and here’s another text-based “intermediate” tutorial that seems pretty useful.

In conclusion, I think this is a really fun tool to use to experiment with. On the other hand, this would add an extra step to your toolpath if used for machining. It’s fun to play with, but I don’t know if I’ll be doing any real “work” with it in the future. CAM programs can take care of most of what I intended it for, and I personally doubt I’ll ever get comfortable enough with it to make assemblies.

Even with a foam muffler on my Shop Vac, (‘Vac available from Amazon) it was still louder than I wanted

I could probably box it in even more, but at this point I’m getting a noise level of under 80 decibels where I generally stand.  Because it’s hung from my FastTrack shelving unit in two parts, I can easily lift the front or side to turn the vac on or fix any problems (see my Fasttrack setup howto here).

I wouldn’t call it “whisper quiet” by any means, but probably good enough that it’s not an “active project” anymore.  If I’m running a really long machining cycle on my CNC router I’ll still use hearing protection sometimes, but mostly it’s tolerable.

For the most part, my Shop Vac noise insulation setup is done with scrap material.  I’m always in favor of environmentalism that saves me money (and my hearing in this case).  Maybe there’s a market for a commercial product like this.  On the other hand, if you need your ‘Vac to be mobile, a box like this guy built might be what you need.  He seems to have used scrap as well, although it’s carpet in his case.