Better 3D Printing Through Holography

When most of us think about 3D printing, we usually think about a machine that melts plastic filament and extrudes it through a nozzle. But we all know that there are other technologies out there that range from cutting and laminating paper, to printing with molten metal or glass. Many of those are out of range for the common hacker. Probably the second most common method uses photo resin and some light source to build the layers in the resin. Researchers at Lawrence Livermore National Laboratory (LLNL) and several universities are experimenting with a new technique that exposes photo resin using three lasers, printing an entire object at one time. You can see a cube formed using the technique in the video below.

In all fairness, the process really isn’t holography but LLNL refers to it as “hologram-like.” In fact, it appears the lasers project more like an oblique projection (you know, like in drafting) which is considerably simpler. Simple enough, that we can’t help but wonder if the hacker community couldn’t develop machines based on this principle. The key would be arranging for the resin to only cure where laser light overlaps.

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How Cheap Can A 3D Printer Get? The Anet A8

The short answer: something like $200, if your time is worth $0/hour. How is this possible? Cheap kit printers, with laser-cut acrylic frames, but otherwise reasonably solid components. In particular, for this review, an Anet A8. If you’re willing to add a little sweat equity and fix up some of the bugs, an A8 can be turned into a good 3D printer on a shoestring budget.

That said, the A8 is a printer kit, not a printer. You’re going to be responsible for assembly of every last M3 screw, and there are many. Building the thing took me eight or ten hours over three evenings. It’s not rocket surgery, though. There are very accessible videos available online, and a community of people dedicated to turning this box of parts into a great machine. You can do it if you want to.

This article is half how-to guide and half review, and while the fun of a how-to is in the details, the review part is easy enough to sum up: if you want the experience of building a 3D printer, and don’t mind tweaking to get things just right, you should absolutely look into the A8. If you want a backup printer that can print well enough right after assembly, the A8 is a good deal as well; most of the work I’ve put into mine is in chasing perfection. But there are a couple reasons that I’d hesitate to recommend it to a rank beginner, and one of them is fire.

Still, I’ve put 1,615 m (1.0035 miles) of filament through my A8 over 330 hours of run-time spread across the last three months — it’s been actively running for 15% of its lifetime! Some parts have broken, and some have “needed” improving, but basically, it’s been a very functional machine with only three or four hours of unintentional downtime. My expectations going in were naturally fairly low, but the A8 has turned out to be not just a workhorse but also a decent performer, with a little TLC. In short, it’s a hacker’s printer, and I love it.

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Cable Bots, Arise! Domination Of The Universe Is At Hand

Most CNC robots people see involve belts and rails, gantries, lead screws, linear bearings, and so forth. Those components need a rigid chassis to support them and to keep them from wobbling during fabrication and adding imperfections to the design. As a result, the scale is necessarily small — hobbyist bots max out at cabinet-sized, for the most part. Their rigid axes are often laid out at Cartesian right angles.

One of the exceptions to this common configuration is the delta robot. Deltas might be the flashiest of CNC robots, moving the end effector on three arms that move to position it anywhere in the build envelope. A lot of these robots are super fast and precise when charged with carrying a light load, and they get put to work as pick-and-place machines and that sort of thing. It doesn’t hurt that delta bots are also parallel manipulators, which means that the motors work together to move the end effector, with one motor pulling while the matching motor pulls.

But while Cartesian CNC bots are sturdy workhorses, and deltas are fly-weight racehorces, neither can really cut it when you want to go gigantic. In terms of simplicity and scale, nothing beats cable bots.

Cable Bots

Cable bots use wires or strings pulled by reel-mounted motors, with dimensions limited only by the room to mount the motors and the tensile strength of the cables used. When the strings are tensioned you can get a surprising degree of accuracy. Why not? Are they not computer-controlled motors? As long as your kinematic chain accounts for the end effector’s movement in one direction by unwinding another cable (for instance) you can very accurately control the end effector over a very wide scale.

The following are some fun cable bots that have caught my eye.

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This 3D Cable Printer Remixes The Delta

When last we ran into [Daren Schwenke] he was showing off his 6-color delta printer that changes colors seamless mid-print. Right now he’s working on a printer that uses tensioned cables to precisely move a toolhead while maintaining enough solidity that [Daren] can tap on the toolhead without it budging at all.

It’s much more simple a rig than a gantry-style 3D printer, with a chassis shaped like a geodesic polyhedron consisting of fiberglass trusses (those driveway markers) secured by 3D-printed lugs, all controlled by a Beaglebone Green and four steppers. A key element of the build is the central steel rod, a 4′ repurposed garden stake which serves to stabilize the whole toolhead. In terms of  build diameter it can scale from around 200 mm to 600 mm. [Daren] aims to using Machinekit’s tripod kinematics for control and he also learned a bunch from RepRap’s Flying SkyDelta project.

For more 3D-printing goodness, be sure to check out [Daren]’s aforementioned 6-color delta.

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Monoprice Mini Delta Review

For the last year or so, Monoprice has been teasing their follow-up to the fantastic $200 MP Select Mini. This is the $150 mini delta printer. We got a look at it last January at CES, it was on display at the Bay Area Maker Faire last May. Now there’s one on the Hackaday review desk.

Over the last few years, 3D printing has settled down into what most of us expected way back in 2010. No, not everyone wants, or arguably needs, a 3D printer on their desks. This is a far cry from the hype of a few years ago, leaving us with what we have today. 3D printers are just tools, much like a drill press or a laser cutter.

With that said, there still are some fantastic advances in 3D printing coming down from on high. Prusa will be shipping the 4-color multi-extruder add-on for the i3 Mk 2 shortly, and somehow or another we have infinite build volume printers. Still, there’s space to democratize 3D printing, and an opportunity for someone to release a very cheap, very good printer.

Monoprice was kind enough to send me a review unit of the MP Mini Delta before it officially hit their website. This is one of the first off the production line, alongside the few hundred pre ordered on an Indiegogo campaign earlier this year.  Does this printer live up to expectations? It sure does, and that’s not just because it’s a $150 printer.

This would be an excellent printer at three times the price, and evidence enough that 3D printing is changing from a weird hobbyist thing to a proper tool.

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Hackaday Links: July 16, 2017

[Carl Bass] has joined the board at Formlabs. This is interesting, and further proof that Print The Legend is now absurdly out of date and should not be used as evidence of anything in the world of 3D printing.

Here’s something cool: a breadboardable dev board for the Parallax Propeller.

Finally, after years of hard work, there’s a change.org petition to stop me. I must congratulate [Peter] for the wonderful graphic for this petition.

Want some flexible circuits? OSHPark is testing something out. If you have an idea for a circuit that would look good on Kapton instead of FR4, shoot OSHPark an email.

SeeMeCNC has some new digs. SeeMeCNC are the creators of the awesome Rostock Max 3D printer and hosts of the Midwest RepRap Festival every March. If you’ve attended MRRF, you’re probably aware their old shop was a bit on the small side. As far as I can figure, they’ll soon have ten times the space as the old shop. What does this mean for the future of MRRF? Probably not much; we’ll find out in February or something.

Rumors of SoundCloud’s impending demise abound. There is some speculation that SoundCloud simply won’t exist by this time next year. There’s a lot of data on the SoundCloud servers, and when it comes to preserving our digital heritage, the Internet Archive (and [Jason Scott]) are the go-to people. Unfortunately, it’s going to cost a fortune to back up SoundCloud, and it would be (one of?) the largest projects the archive team has ever undertaken. Here’s your donation link.

If you’re looking for a place to buy a Raspberry Pi Zero or a Pi Zero W, there’s the Pi Locator, a site that pings stores and tells you where these computers are in stock. Now this site has been expanded to compare the price and stock of 2200 products from ModMyPi, ThePiHut, Pi-Supply, and Kubii.

Printrbot Teases Infinite Build Volume Printer

[Brook Drumm] of Printrbot is teasing a new 3D printer. This is no ordinary 3D printer; this is an infinite build volume 3D printer, the Next Big Thing™ in desktop fabrication.

The world was introduced to the infinite build volume 3D printer last March at the Midwest RepRap Festival with a built by [Bill Steele] from Polar 3D. The design of [Bill]’s printer began as simply a middle finger to MakerBot’s Automated Build Platform patent. This was patent engineering — [Bill] noticed the MakerBot patent didn’t cover build plates that weren’t offset to the plane of the print head, and it just so happened a printer with a tilted bed could also build infinitely long plastic parts.

While [Bill Steele]’s unnamed printer introduced the idea of an infinite build volume printer to the community, a few pieces of prior art popped up in the weeks and months after MRRF. Several years ago, [Andreas Bastian] developed the Lum Printer, an unbounded conveyor belt printer. A month after MRRF, Blackbelt 3D introduced their mega-scale tilted bed printer and later started a Kickstarter that has already reached $100,000 in pledges.

Right now, details are sparse on the Printrbelt, but there are a few educated guesses we can make. The belt of the Printrbelt appears to be Kapton film attached to some sort of substrate. The hotend and extruder are standard Printrbot accouterments, and the conveyor is powered by a geared stepper motor. All in all, pretty much what you would expect.

We do know that [Brook] and [Bill Steele] are working together on this printer, apparently with [Brook] in charge of the hardware and [Bill] taking either his slicing algorithm or firmware modifications (we’re not exactly sure where the ’tilt’ in the Gcode comes from) and getting this printer running.

While the Printrbelt isn’t ready for production quite yet, this is a fantastic advance in the state of consumer, desktop 3D printing. You can check out [Brook]’s teaser videos below.

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