Automated Hotend Swapping For Less Wasteful Multicolor Printing

Multicolor printing on FDM machines can be tricky to get working flawlessly, and purging hotends when changing colors can end up wasting a lot of filament and material. To solve this problem for the popular Prusa i3 and Ender 3 printers, [BigBrain3D] developed the Swapper3D, an automated system that swaps the entire hotend when the material is changed, eliminating the need for purging almost entirely. Video after the break.

The Swapper3D works very similarly to the tool-changing systems on CNC machines, and is just as satisfying to watch. A large circular carousel on the side of the machine holds up to 25 hotends, and in practice, a pair of robotic arms pop out the previous hotend, cut the filament, and load up the specified hotend from the carousel. This means you can have a separate hotend for each color or type of filament. Since most existing hotends also integrate the heating element, [BigBrain3D] created a special hotend assembly that can be robotically removed/inserted into the heater block.

The Swapper3D is designed to be used with existing filament changers like the Prusa MMU and the Mosaic Palette. Using these systems involves a lot of purging, to the point where you sometimes end up using more filament during purging than you need for the actual part. On one five-color demo print, the Swapper3D reduced the print time by 45% and the filament used by a massive 86%. It also helps to eliminate problems like stringing and color fading in multicolor prints. With those advantages, it looks like the Swapper3D might be a worthwhile upgrade if you do a lot of multi-color printing, even though it adds quite a bit of complexity to the printer.

For larger, more expensive machines, swapping the entire toolhead is becoming more popular, with even E3D stepping into the fray.

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A Passive Automatic CNC Tool Changer

[Marius Hornberger] has been busy hacking his “Hammer” CNC router again, and now it sports a much desired feature — an automatic tool-changer. Having wanted one for a while, [Marius] was unhappy sacrificing a big chunk of useable bed area just to park the tool-changer magazine. An obvious solution would be to have the magazine retract away from the bed, outside of the working area. Sadly, the CNC controller had only enough spare outputs to drive the pneumatic tool changer (mounted on the spindle) leaving none spare to control the magazine assembly. So, there was only one obvious route to take, use some simple spring-loaded mechanics to move the magazine into tool-picking range with the Y axis motion instead.

Obviously, the whole thing is CNC machined on the machine itself, taking only a couple of iterations and smidge of table-saw action to get everything to fit well and operate smoothly without binding or colliding with the moving gantry. A cunning pair of levers on each end of the magazine allow it to move much further than the advancing gantry, swinging it quickly into position when the Y axis is at the extreme of its travel, and retracting away when the gantry moves back. Another nice addition to the build was a tool depth sensor (AKA: a switch) mounted off to one side, which allows the machine to find the bottom of each tool, if it is not known, so the Z axis can compensate. When combined with the automatically retracting dust shoe, this is a definitely a CNC build we’d love to see in a shop near us!

We’ve had a fair few CNC hacks over the years, including tool changers, like this one, but 3D printers can use some tool changer love too!

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Hackaday Prize Entry: DIY Automatic Tool Changer

Choosing between manually changing endmill bits on a CNC machine and investing in an expensive automated solution? Not for [Frank Herrmann], who invented the XATC, an eXtremely simple Automated Tool Changer. [Frank’s] ingenious hack achieves the same functionality as an industrial tool changer using only cheap standard hardware you might have lying around the workshop.

xatc_carouselLike many ATCs, this one features a tool carousel. The carousel, which is not motorized, stores each milling bit in the center bore of a Gator Grip wrench tool. To change a tool, a fork wrench, actuated by an RC servo, blocks the spindle shaft, just like you would do it to manually change a tool. The machine then positions the current bit in an empty Gator Grip on the carousel and loosens the collet by performing a circular “magic move” around the carousel. This move utilizes the carousel as a wrench to unscrew the collet. A short reverse spin of the spindle takes care of the rest. It then picks another tool from the carousel and does the whole trick in reverse.

The servo is controlled via a WiFi connected NodeMCU board, which accepts commands from his CNC controller over HTTP. The custom tool change sequences are provided by a few JavaScript macros written for the TinyG workspace on, a browser-based G-code host. Enjoy the video of [Frank Herrmann] explaining his build!

Thanks to Smoothieboard creator [Arthur Wolf], who is currently working on a similar project, for the tip!

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