Finishing FDM Prints With SLS Resin

[Thomas Sanladerer] has a filament-based 3D printer and a resin one. Can the two types of raw material combine to make something better? [Thomas] did some experiments using some magnets to suspend the parts and a hot air soldering gun to heat things up.

The trick turns out to be cutting the resin with alcohol. Of course, you also need to use a UV light for curing.

The parts looked pretty good, although he did get different results depending on a few factors. To see how it would work on a practical part, he took a very large printed alien egg. The problem is, the egg won’t fit in the curing station. A few minutes with a heat sink, a drill press, and an LED module was all it took to build a handheld UV curing light.

The good news is you don’t need a resin printer to take advantage of the process — just the resin. He also points out that if you had parts which needed to maintain their dimensions because they mate with something else, you could easily mask the part to keep the resin away from those areas.

If this video (and the results it shows) has you interested, then you’ll love the in-depth account that [Donald Papp] wrote up last year about his own attempts to smooth 3D printed parts with UV resin.

Continue reading “Finishing FDM Prints With SLS Resin”

Quadruped Robot Disguises Itself As A Ball

When the Skynet baseball bot swarms attack, we’ll be throwing [Carl Bugeja] some dirty looks for getting them started. He’s been working on 4B, a little quadruped robot that can transform itself into a sphere almost perfectly.

Before [Carl] was distracted by the wonders of PCB actuators more than a year ago, he started working on this little guy. He finally found some time to get it moving on its own, and the preliminary results look promising to say the least. Inside the 6 cm sphere is a total of 12 servos, 3 for each leg. All of the mechanical parts were 3D printed in nylon on an SLS machine, and the custom PCB has a BLE microcontroller module, an IMU and IR proximity sensors onboard. Everything is open source with all the files available on the Hackaday.io project page.

The microcontroller runs a full inverse kinematic model, so only the desired tip and base coordinate for each leg is input and the servo angles are automatically calculated. Ultimately [Carl] aims to have the robot both walking and rolling controllably. So far he’s achieved some degree of success in both, but it still needs some work (see the videos below. We’re eager to see what the future holds for this delightfully creepy bot.

Walking robots are always an interesting challenge. For more of our future overlords, check out this adorable little cat and this truly terrifying strandbeest.

Metal 3D Printing — A Dose Of Reality

We have no doubt that hundreds of times a day a hacker is watching a 3D printer spew hot plastic and fantasizes about being able to print directly using metal. While metal printers are more common than ever, they are still out of reach for most people printing as a hobby. But as Mr. Spock once observed: “…you may find that having is not so pleasing a thing after all as wanting. It is not logical, but it is often true.” However, metal 3D printing has its own unique set of challenges. Texas A&M recently produced a short video explaining some of the design issues that you’ll encounter trying to make practical metal prints on an SLS (Selective Laser Melting) printer. You can see the video below.

The description says “It is more challenging to ‘metal 3D print’ a part than most people think. We’ve noticed the same even with plastic printers as friends will expect us to print the most outlandish things for them. What we like about this video is it helps to set expectations of the current state of the art so we’re not expecting far more than today’s metal printers can produce.

Among the features covered in the video are overhangs, which require supports. After removal, the surface is about like 80 grit sandpaper unless you perform further finishing. Just like plastic parts, warping and curling of large areas is a problem with metal. If you’ve ever been frustrated removing plastic support material, try having to ceramic grind metal supports off. They also use an EDM machine to cut especially tough supports, but it causes a lot of effort since it is likely to run through EDM wires and clog the filters.

We looked at recent advances in metal printing last year. We’ve seen homebrew machines that were little more than welders under computer control and we’ve seen plans by big players like HP to create metal prints, but at a steep price. Still, you can’t stop the march of 3D printing progress.

Continue reading “Metal 3D Printing — A Dose Of Reality”

Could Orion Ride Falcon Heavy To The Moon?

Things aren’t looking good for NASA’s Space Launch System (SLS). Occasionally referred to as the “Senate Launch System”, or even less graciously, the “Rocket to Nowhere”, the super heavy-lift booster has long been a bone of contention for those in the industry. Designed as an evolution of core Space Shuttle technology, the SLS promised to reuse existing infrastructure to deliver higher payload capacities and lower operating costs than its infamous winged predecessor. But in the face of increased competition from commercial launch providers and proposed budget cuts targeting future upgrades and expansions of the core booster, the significantly over budget and behind schedule program is in a very precarious position.

Which is not to say the SLS doesn’t look impressive, at least on paper. In its initial configuration it would easily take the title as the world’s most powerful rocket, capable of lifting nearly 105 tons into low Earth orbit (LEO), compared to 70 tons for SpaceX’s Falcon Heavy. It would still fall short of the mighty Saturn V’s 155 tons to LEO, but the proposed “Block 2” upgrades would increase SLS payload capability to within striking distance of the iconic Apollo-era booster at 145 tons. Since the retirement of the Space Shuttle in 2011, NASA has been adamant that the might of SLS was the only way the agency could accomplish bigger and more ambitious missions to the Moon, Mars, and beyond.

Or at least, they were. On March 13th, NASA Administrator Jim Bridenstine testified to Congress that in an effort to avoid further delays, the agency is exploring the possibility of sending their Orion spacecraft to the Moon with a commercial launcher. The statement came as a shock to many in the aerospace community, as it would seem to call into question the future of the entire SLS program. If commercial rockets can do the job of SLS, at least in some cases, why does the agency need it?

NASA is currently preparing a report which investigates what physical and logistical modifications would need to be made to missions originally slated to fly on SLS; a document which is sure to be scrutinized by SLS supporters and critics alike. Until the report is released, we can speculate about what this hypothetical flight to the Moon might look like.

Continue reading “Could Orion Ride Falcon Heavy To The Moon?”

Proposed NASA Budget Signals Changes To Space Launch System

The White House’s proposed budget for 2020 is out, and with it comes cuts to NASA. The most important item of note in the proposed budget is a delay of the Space Launch System, the SLS, a super-heavy lifting launch vehicle designed for single use. The proposed delay would defer work on the enhanced version of the SLS, the Block 1B with the Exploration Upper Stage.

The current plans for the Space Launch System include a flight using NASA’s Orion spacecraft in June 2020 for a flight around the moon. This uncrewed flight, Exploration Mission 1, or EM-1, would use the SLS Block 1 Crew rocket. A later flight, EM-2, would fly a crewed Orion capsule around the moon in 2022. A third proposed flight in 2023 would send the Europa Clipper to Jupiter. The proposed 2020 budget puts these flights in jeopardy.

Continue reading “Proposed NASA Budget Signals Changes To Space Launch System”

One-key Keyboard Is Exercise In Sub-millimeter Design

As [Glen] describes it, the only real goal in his decision to design his single-key USB keyboard was to see how small he could build a functional keyboard using a Cherry MX key switch, and every fraction of a millimeter counted. Making a one-key USB keyboard is one thing, but making it from scratch complete with form-fitting enclosure that’s easy to assemble required careful design, and luckily for all of us, [Glen] has documented it wonderfully. (Incidentally, Cherry MX switches come in a variety of qualities and features, the different models being identified by their color. [Glen] is using a Cherry MX Blue, common in keyboards due to its tactile bump and audible click.)

[Glen] steps though the design challenges of making a device where seemingly every detail counts, and explains problems and solutions from beginning to end. A PIC16F1459, a USB micro-B connector, and three capacitors are all that’s needed to implement USB 2.0, but a few other components including LED were added to help things along. The enclosure took some extra care, because not only is it necessary to fit the board and the mounted components, but other design considerations needed to be addressed such as the depth and angle of the countersink for the screws, seating depth and clearance around the USB connector, and taking into account the height of the overmold on the USB cable itself so that the small device actually rests on the enclosure, and not on any part of the cable’s molding. To top it off, it was also necessary to adhere to the some design rules for minimum feature size and wall thicknesses for the enclosure itself, which was SLS 3D printed in nylon.

PCB, enclosure, software, and bill of materials (for single and triple-key versions of the keyboard) are all documented and available in the project’s GitHub repository. [Glen] also highlights the possibility of using a light pipe to redirect the embedded LED to somewhere else on the enclosure; which recalls his earlier work in using 3D printing to make custom LED bar graphs.

The 3D Printer Packing Problem

Form Labs recently announced the launch of the Fuse 1, a desktop SLS printer that will print all your parts using nylon powder and a laser. This a fundamentally different method of 3D printing as compared to filament-based machines, and the best way to use a Fuse 1 is to fill the entire volume of the machine with 3D printed parts. [Michael Fogelman] decided to investigate the 3D packing problem, and managed to fill this printer with the maximum number of 3D printed tugboats. If you’re wondering, it’s 113, as compared with 82 tiny Benchies using naive bin packing.

The formal definition of this sort of problem is the bin packing problem, or simply calculating the maximum number of items can be packed into a finite volume. There is no general solution to this problem, and it’s probably impossible to create an algorithm that will solve this problem for any collection of 3D models. Nevertheless, it’s possible to create a solution that shows marked improvement over a naive solution.

[Michael]’s solution involves simulated annealing. This algorithm begins by randomly placing tugboats, then mutating the position or rotation of one of the boats for each iteration. The code is less than 1000 lines of Go and is available on GitHub if you already have an SLS printer at your disposal.

It should be noted this type of problem isn’t particularly new to the world of 3D printers. There have been a few tools to solve the bin-packing problem for filament-based printers, but the solutions to these problems are two-dimensional; since filling a bed is a problem that only uses the ‘shadow’ of the Z-axis of each part, it’s a slightly easier problem to solve.

Now that Form Labs’ Fuse 1 SLS printer has been announced, there is a new application for this type of problem in the space of 3D printers. It’s not a perfect solution — and it’s doubtful there will ever be a perfect solution — but if you’re looking for a way to fill the volume of your powder printer with parts, this is the best you’re going to do.