Mini Delta 3D Printer in Action at the Monoprice Booth

When I was at Bay Area Maker Faire a few weekends ago I stopped by the Monoprice booth to chat with [Chris Apland], their head of 3D Printing. Earlier in the week, the company had just announced preorders for their new $169 delta-style 3D printer called the MP Mini Delta.

[Brian Benchoff] covered that launch and I don’t have a lot of details about the machine itself to add. I saw it in action, printing tiny waving cat models. The stock printer can use ABS or PLA and has a build volume of 110mm in diameter and 120mm tall and these preorder units (being sold through Indegogo) will begin shipping in August.

What was of interest is to hear the shipping estimates the Monoprice team is throwing around. Chris told me that their conservative estimate is that 20,000 of these printers will ship through this preorder, but he is optimistic that by the end of the fourth quarter they’ll be closer to 100,000 units. That is incredible.

Part of the promise here is the out of the box functionality; [Chris] mentioned having a printed cat in your hands within 5 minutes. If it can actually do that without the need for setup and calibration that’s impressive. But I know that even seasoned printing veterans are interested in seeing how fast they can run this tiny delta and still turn out quality prints.

You’ll find the video interview after the break.

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Printing Bed Off-Kilter? Blu-Tack To The Rescue!

For all their applications, 3D printers can be finicky machines. From extruder problems, misaligned or missing layers, to finding an overnight print turned into a tangled mess, and that’s all assuming your printer bed is perfectly leveled. [Ricardo de Azambuja’s] new linear delta printer was frustrating him. No matter what he did, it wouldn’t retain the bed leveling calibration, so he had to improvise — Blu-Tack to the rescue.

It turns out [Azambuja]’s problem was so bad that the filament wouldn’t even attempt to adhere to the printing bed. So, he turned to Printrun Pronterface and a combination of its homing feature and the piece-of-paper method to get a rough estimate of how much the bed needed to be adjusted — and a similar estimate of how big of a gob of Blu-Tack was needed.

Pressing the bed into place, he re-ran Pronterface to make sure he was on the level. [Azambuja] notes that you would have to redo this for every print, but it was good enough to print off a trio of bed leveling gears he designed so he doesn’t have to go through this headache again for some time.

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Dawn of the Tripteron 3D Printer

Cartesian 3D printers were the original. Then delta printers came along, and they were pretty cool too. Now, you can add tripteron printers to the mix.  The tripteron is an odd mix of cartesian and delta. The system was invented at the robotics laboratory at Université Laval in Quebec, Canada. The team who created it say that it is “isotropic and fully decoupled, i.e. each of the actuators is controlling one Cartesian degree of freedom, independently from the others.” This means that driving the bot will be almost as simple as driving a standard X/Y/Z Cartesian printer. The corollary to that are of course delta robots, which follow a whole different set of kinematic rules.

trioptera-renderA few people have experimented with tripteron printers over the years, but as far as we can see, no one has ever demonstrated a working model. Enter [Apsu], who showed up about a month ago. He started a post on the RepRap forums discussing his particular design. [Apsu] works fast, as he has now demonstrated a working prototype making prints. Sure they’re just calibration cubes, but this is a huge step forward.

[Apsu] admits that he still has a way to go in his research – especially improving the arm and joint implementation. However, he’s quite pleased that his creation has gone from a collection of parts to a new type 3D printer.  We are too — and we can’t wait to see the next iteration!

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The Triple Delta Robot Arm (and Leg)

delta By now you’d think we’ve seen just about every means of robotic actuator possible. We have Cartesian bots, Stewart platforms, SCARA bots, Delta bots, and even some exceedingly bizarre linkages from [Nicholas Seward]. We’re not done with odd robotic arms, it seems, and now we have Delta-ish robots that can move outside their minimum enclosed volume. They’re fresh from the workshop of [Aad van der Geest], and he’s calling them double and triple Deltas.

Previous Delta robots have used three universal joints to move the end effector up and down, and side to side. They’re extremely fast and are a great design for 3D printers and pick and place machines, but they do have a limitation: the tip of a single Delta can not move much further than the base of the robot.

By adding more parallelograms to a Delta, [Aad] greatly increases working volume of a his robots. One of the suggested uses for this style of bot is for palletizers, demonstrated in the video below by stacking Jenga blocks. There is another very interesting application: legs. There’s footage of a small, simple triple Delta scooting around the floor, supported by wire training wheels below. It makes a good cat toy, but we’d love to see a bipedal robot with this style of legs.

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4 Axis Delta Router Says Hello World


[Bart] stood upon the shoulders of the delta 3D printer giants and created this 4 axis delta router. The router was originally created for ORD Camp, an invite only hackers gathering. Each year he creates a new thing with one main purpose: to spark conversation. In his own words “Practicality and suitability are way down the list, so go ahead and snark away. If you do, you are missing the point.”

[Bart] did things a bit differently with his delta. For motors, he went with non captive steppers. “Non captive” means that rather than a shaft, the motor has a hollow threaded nut which rotates. A lead screw (usually with an acme thread) is passed through this nut. As the motor’s nut turns, the screw is pushed or pulled through the motor, creating a linear actuator. The only major downside is that a non captive stepper motor can’t be adjusted by hand. The screw doesn’t turn and neither do any external parts of the motor. For structure, the router uses MakerSlide and v-grove wheels. The spindle is a simple brushless hobby motor and 30 amp speed control. Rather than the outrunner motors we’ve seen lately, [Bart] wisely chose an inrunner motor normally used on R/C cars. Inrunners generally have less torque than their outrunner counterparts, but they make up for this in RPM. [Bart’s] motor is capable of 30,000 RPM, which is plenty for spindle duty. We think the motor bearings will probably need an upgrade, as the original motor bearings weren’t designed for side loads. For a controller, [Bart] utilized an  Azteeg X3 running Repetier.

The router made a great showing at camp, and [Bart] decided it needed a 4th axis. He sourced a rotary axis from eBay. To keep the software simple, he connected the rotary axis to the extruder outputs on his controller. He was then able to hack the mach3 wrapped rotary post processor to output extruder commands. The results look great. [Bart] says the system definitely needs a tailstock, and we agree. We’re looking forward to the next update on this machine!

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World Maker Faire 2013: The Sub-$500 Deltaprintr

There are a few delta bot 3D printers out there such as the Rostock which, while being a very nice printer, is still a little expensive. When [Shai] from SUNY wanted to use a 3D printer for his artistic and academic pursuits, he decided to build his own printer. Thus the Deltaprintr was born.

Instead of printed parts, the Deltaprintr uses laser cut and machined parts for just about all of its bill of materials. The three motors mounted in the base are connected to the delta arms with Spectra fishing line, thus getting rid of the ludicrous cost of belts of the requisite length.

Everything is Open Source, and the guys behind the project should be putting their printr up on Kickstarter sometime next month. Word is the entire thing should be sub-$500, and a little bit of guessing tells me that doesn’t mean $499.

RepRap Simpson puts a new spin on delta RepRaps

Just when you think you’ve seen it all in the 3D printer world, something new pops up! [Nicholas Seward] posted a video of RepRap Simpson, his latest project.  Simpson is a delta robot – but unlike any delta we’ve seen before. Previous offerings vertical rails on which the arms travel. As you can see, this design mounts three articulated arms directly to the base of the printer, using steel cables as part of the joint mechanism.

Judging by [Nicholas’] posts on the RepRap forums, Simpson’s grounded delta design has already gone through a few revisions. The basic geometry though, has remained the same. [Nicholas] calls this edition a “Proportional Gear Drive Joint Simpson”. The name may not roll off the tongue, but the movements are incredibly smooth, organic, and fast.

As with any delta design inverse kinematics play a huge role in the software. [Nicholas] is trying to simplify this with an optical calibration system. For the adventurous, the equations are posted on the forums, and a python Gcode preprocessor is posted on Thingiverse.

Even Simpson’s base received special attention.  It’s built from a water jet cut piece of basalt.  We like the use of opposed helical gears on the large joints, as well as the guitar machine heads used to tension the cable drive. One thing we are not sure of is the longevity of system – will cable stretch play an issue? Will the printed parts suffer wear from the cables? Only time will tell.

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