Making Rubber Stamps With OpenSCAD

December 10, 2017 by Tom Nardi 21 Comments

There’s an old saying that goes “If you can’t beat ’em, join ’em”, but around these parts a better version might be “If you can’t buy ’em, make ’em”. A rather large portion of the projects that have graced these pages have been the product of a hacker or maker not being able to find a commercial product to fit their needs. Or at the very least, not being able to find one that fit their budget.

GitHub user [harout] was in the market for some rubber stamps to help children learn the Armenian alphabet, but couldn’t track down a commercially available set. With a 3D printer and some OpenSCAD code, [harout] was able to turn this commercial shortcoming into a DIY success story.

Rather than having to manually render each stamp, he was able to come up with a simple Bash script that calls OpenSCAD with the “-D” option. When this option is passed to OpenSCAD, it allows you to override a particular variable in the .scad file. A single OpenSCAD file is therefore able to create a stamp of any letter passed to it on the command line. The Bash script uses this option to change the variable holding the letter, renders the STL to a unique file name, and then moves on to the next letter and repeats the process.

This procedural generation of STLs is a fantastic use of OpenSCAD, and is certainly not limited to simple children’s stamps. With some improvements to the code, the script could take any given string and font and spit out a ready to print mold.

With a full set of letter molds generated, they could then be printed out and sealed with a spray acrylic lacquer. A mold release was applied to each sealed mold, and finally they were filled with approximately 200ml of Simpact urethane rubber from Smooth-On. Once the rubber cures, he popped them out of the molds and glued them onto wooden blocks. The end result looks just as good as anything you’d get from an arts and crafts store.

The process used here is very similar to the 3D printed cookie molds we’ve covered recently, though we have to assume these little morsels would not be nearly as tasty. Of course, if you had access to a small CNC machine you could cut the stamps out of the rubber directly and skip the mold step entirely.

Cheap Flamethrower Is Predictably Worrying

November 17, 2017 by Tom Nardi 36 Comments

We’d never criticize somebody for coming up with a creative way to save a few bucks. In truth, pickings would be pretty slim around here if we deleted every project or hack where cost savings was a prime motivator. That being said, there’s still some things you should probably spend a few extra dollars on. You know, the essential things in life that you need to know will be safe and reliable, like your car and…your flamethrower.

While we don’t have any information about what kind of car [Steve Hernandez] is driving, but over on Hackaday.io, he’s posted some info about his 3D printed wrist-mounted flamethrower. The final result does look pretty impressive, but given the subject matter and the lack of any safety gear, we would firmly plant it in the “Don’t try this at home” category.

At the heart of this flamethrower is a solenoid valve recovered from a Glade air freshener. Rather than spraying out the smell of lilacs, this valve has found a new purpose in life by squirting out butane from a pressurized can. The butane is then ignited by a spark gap made up two nails connected to a 300 kV boost coil.

[Steve] designed the frame of this creation in OpenSCAD, and printed it out in a single piece. It holds the butane can and solenoid in position, as well as keeping the nails in the proper orientation for the spark gap to function. Admittedly the head of his printed flamethrower does look very cool, but if there was ever a situation where you should be suspect of the heat tolerance of 3D printed plastic, a flamethrower is probably it.

What’s noticeably lacking of course is any method to keep the flame from potentially traveling back up through the valve and into the butane can. The high-speed flow coming out of the nozzle is probably enough to keep that from happening, but we still wouldn’t feel comfortable strapping his device to our wrist as-is.

You may be surprised to find that wrist-mounted flamethrowers are a relatively popular project here at Hackaday. We’ve covered quite a few over the years, but still aren’t convinced this is something we personally need to add to our collection of gear.

Add Intuitiveness To OpenSCAD With Encoders

November 1, 2017 by Brian McEvoy 44 Comments

The first time I saw 3D modeling and 3D printing used practically was at a hack day event. We printed simple plastic struts to hold a couple of spring-loaded wires apart. Nothing revolutionary as far as parts go but it was the moment I realized the value of a printer.

Since then, I have used OpenSCAD because that is what I saw the first time but the intuitiveness of other programs led me to develop the OpenVectorKB which allowed the ubiquitous vectors in OpenSCAD to be changed at will while keeping the parametric qualities of the program, and even leveraging them.

All three values in a vector, X, Y, and Z, are modified by twisting encoder knobs. The device acts as a keyboard to

select the relevant value
replace it with an updated value
refresh the display
move the cursor back to the starting point

There is no software to install and it runs off a Teensy-LC so reprogramming it for other programs is possible in any program where rotary encoders may be useful. Additional modes include a mouse, arrow keys, Audacity editing controls, and VLC time searching.

Here’s an article in favor of OpenSCAD and here’s one against it. This article does a good job of explaining OpenSCAD.

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A Crash Course In Thingiverse Customizer

June 27, 2017 by Al Williams 19 Comments

OpenSCAD is a great way to create objects for 3D printing (or other purposes), especially if you are already used to programming. For things like front panels, it is great because you can easily make modifications and — if you wrote your code correctly–everything will just adjust itself to new positions.

However, what if you have a general-purpose piece of code, and you want people to have the ability to customize it? For example, consider this code:

$fn=100;
difference()
{
  cube([25,25,5]);
  translate([4,4,-1]) cylinder(h=7,r=2);
  translate([25-4,4,-1]) cylinder(h=7,r=2);
  translate([4,25-4,-1]) cylinder(h=7,r=2);
  translate([25-4,25-4,-1]) cylinder(h=7,r=2);
}

That creates the plate with four drill holes you see on the right.

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Two-Piece Boxes Thanks To Laser-Cut Flex Hinges

April 6, 2017 by Dan Maloney 14 Comments

It sounds like a challenge from a [Martin Gardner] math puzzle from the Scientific American of days gone by: is it possible to build a three-dimensional wooden box with only two surfaces? It turns out it is, if you bend the rules and bend the wood to make living hinge boxes with a laser cutter.

[Martin Raynsford] clearly wasn’t setting out to probe the limits of topology with these boxes, but they’re a pretty neat trick nonetheless. The key to these boxes is the narrow to non-existent kerf left by a laser cutter that makes interference fits with wood a reality. [Martin]’s design leverages the slot and tab connection we’re used to seeing in laser-cut boxes, but adds a living flex-hinge to curve each piece of plywood into a U-shape. The two pieces are then nested together like those old aluminum hobby enclosures from Radio Shack. His GitHub has OpenSCAD scripts to parametrically create two different styles of two-piece boxes so you can scale it up or (somewhat) down according to your needs. There’s also a more traditional three-piece box, and any of them might be a great choice for a control panel or small Arduino enclosure. And as a bonus, the flex-hinge provides ventilation.

Need slots and tabs for boxes but you’re more familiar with FreeCAD? These parametric scripts will get you started, and we’ll bet you can port the flex-hinge bit easily, too.

Endstops That Stay Out Of The Way

March 30, 2017 by Donald Papp 7 Comments

In the course of building a new delta printer, [thehans] decided he needed his own endstop design that used minimal hardware. Endstops are just switches that get hit when the printer moves at the extreme of an axis, but [thehans] wanted something with a bit of refinement for his BigDelta 3D Printer build.

The result is a small unit that cradles a microswitch and needs only a single zip tie that mounts flush, resulting in a super tidy looking piece. In addition, it mounts on the delta’s v-slot rails such that the mount does not take up any of the machine’s range of motion, because the carriage can travel past it. It is a parametric design made in OpenSCAD, so feel free to modify it to accommodate other types of switches.

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DIY Barrel Rifling With 3D Printed Help

March 8, 2017 by Donald Papp 92 Comments

[Jeff Rodriguez] has been busy testing a feasible DIY method for rifling a barrel and has found some success using salt water, a power supply, wire, and 3D printed parts to create the grooves of rifling without the need for any moving parts or cutting tools. Salt water flows between the barrel’s inside surface and a 3D-printed piece that holds wires in a precise pattern. A current flows between the barrel and the wires (which do not actually touch the inside of the barrel) and material is eroded away as a result. 10-15 minutes later there are some promising looking grooves in the test piece thanks to his DIY process.

Rifled barrels have been common since at least the 19th century (although it was certainly an intensive process) and it still remains a job best left to industrial settings; anyone who needs a barrel today normally just purchases a rifled barrel blank from a manufacturer. No one makes their own unless they want to for some reason, but that’s exactly where [Jeff] is coming from. The process looks messy, but [Jeff] has had a lot of space to experiment with a variety of different methods to get different results.

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