Fixing Misaligned PVC With Kerf Bends

misalignment-coupler

Our old pal [Jeremy Cook] is doing his own remix of [Theo Jansen]‘s Strandbeest, and like the original, he’s using PVC pipe. Unlike the originals, he’s powering it with motors, not wind, and this has caused a few problems in transmitting mechanical power through a piece of PVC. Nothing is perfect, and in a few points in the legs movement the shaft shakes violently. One motor was lost and another nearly so before [Jeremy] came up with a flex coupler made from PVC.

The technique [Jeremy] is using has seen a lot of use with people building laser cut enclosures. It’s called kerf bending, and it works simply by cutting a few slits in a panel that allow it to bend slightly. This technique was replicated by [Jeremy] on a miter saw, cutting eight slots halfway through a one inch PVC pipe, with each successive cut offset 90 degrees.

The new design works well for transmitting power, and he’s not ruining motors any more. Check out the video below.

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Hackaday links: September 7, 2012

MakerSlide, European edition

We’re all familiar with the MakerSlide, right? The linear bearing system that has been turned into everything from motorized camera mounts to 3D printers is apparently very hard to source in Europe. A few folks from the ShapeOko forum have teamed up to produce the MakerSlide in the UK. They’re running a crowdsourced project on Ulule, and the prices for the rewards seem very reasonable; €65/£73 for enough extrusion, v-wheels, and spacers to make an awesome CNC router.

Kerf bending and math

A few days ago, I made an offhand remark asking for an engineering analysis of kerf bending. [Patrick Fenner] of the Liverpool hackerspace DoES already had a blog post covering this, and goes over the theory, equations, and practical examples of bending acrylic with a laser cutter. Thanks for finding this [Adrian].

276 hours well spent

[Dave Langkamp] got his hands on a Makerbot Replicator, one thing led to another, and now he has a 1/6 scale model electric car made nearly entirely out of 3D printed parts. No, the batteries don’t hold a charge, and the motor doesn’t have any metal in it, but we’ve got to admire the dedication that went in to this project.

It was thiiiiiiis big

If you’ve ever tried to demonstrate the size of an object with a photograph, you’ve probably placed a coin of other standard object in the frame. Here’s something a little more useful created by [Phil]. His International Object Sizing Tool is the size of a credit card, has inch and cm markings, as well as pictures of a US quarter, a British pound coin, and a one Euro coin. If you want to print one-off for yourself, here’s the PDF.

Want some documentation on your TV tuner SDR?

The full documentation for the E4000/RTL2832U chipset found in those USB TV tuner dongles is up on reddit. Even though these chips are now out of production (if you haven’t bought a proper tuner dongle yet, you might want to…), maybe a someone looking to replicate this really cool device will find it useful.

Playing around with kerf bending

With laser cutters popping up in hackerspaces and maker’s tool sheds like weeds, it’s no surprise we’re seeing an explosion in manufacturing techniques that would be nearly impossible without a laser cutter. One of these techniques is kerf bending, a method of bending plywood simply by burning patterns along the desired bend. [Martin] just put up a great tutorial on kerf bending with a laser cutter, and even came up with a few very interesting patterns that can be used to build your own case with rounded corners.

[Martin]‘s adventures into kerf bending began with a small radio transmitter case he built. This case used the very common ‘vertical slit’ method, but in the first version of the case, the slits were placed too far apart. By moving the slits closer together, [Martin] was left with a very easy to bend and very strong wooden case.

There are also a few other patterns [Martin] tried out. A herringbone pattern made for a wooden case nearly as bendable (and a little stronger) as the traditional vertical slit method. From there, [Martin] branched out into more esoteric patterns such as a medieval cross and Space Invader pattern, both ideal for your next highly stylized enclosure.

In the end, [Martin] says just about any pattern will work for kerf bending, so long as the design isn’t diagonal to the bend. We’d love to see some proper engineering analysis for kerf bending, so if you can figure out the optimal pattern for high strength, low machine time bends, send it in on the tip line.

Portable radio station gets a beautiful case

[Martin] put together a simple portable radio unit to take some MP3s with him while he’s out and around. The build was simple; just a no-name Chinese MP3 player, a battery, and an FM radio transmitter. To give his project a little more pizzazz, he came up with a very handsome laser cut wooden case to turn what would be a bunch of wires and components into an attractive build.

[Martin]‘s case makes wonderful use of the kerf bending technique. By cutting small staggered lines in a piece of plywood, [Martin] was able to bend his laser cut enclosure into a surprisingly tight radius. With the help of a pair of laser cut forms and a bit of hot water and glue, he was able to make the shape of his case permanent.

The top and bottom of his case are also laser cut plywood, but [Martin] included a translucent plexiglas logo on the top. When his radio unit is activated a LED inside his project box lights up, illuminating his personal logo.

Kerf bending is something we’ve seen before, and we’re looking forward to seeing more project boxes use it in the future, hopefully with the application of a veneer to cover the diamond-shaped holes.

Bending laser cut wood without steam or forms

If you want to pretty up your project boxes, we can’t imagine anything better than [Shaun]‘s walnut plywood, laser-cut, kerf bent Arduino case. Instead of the slot-and-tab construction of traditional laser-cut enclosures, [Shaun] used a technique to bend plywood without steaming, heating, and eventually scorching his somewhat expensive plywood.

This isn’t the first time we’ve seen this accordian style laser-cut kerf bend. By alternating laser cuts along the desired radius, the plywood can be bent by hand. The technique is called kerf bending and is perfect for putting an organic touch on the usual 90° angle project boxes we see.

[Shaun] has an Instructable for the smaller boxes that are part of his Arduino powered wireless sensor network. This Instructable goes over the pattern of laser cuts required to get a nice, smooth kerf bend, and also shows off how beautiful a laser-cut project box can be when cut out of aromatic cedar.

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