<p>I am planning to upgrade my printer with a second extruder. Since my printer is a Tronxy X8 it's frame is not exactly vibration resistant, so I'd like to keep the print head weight down. At the same time I really don't want a Bowden setup.</p>
<p>I came up with the idea of making a dual extruder driven only by a single stepper with a gear shift setup that switches the stepper between the two extruders.</p>
<p>The idea seems simple, but googleing didn't turn up anything else.</p>
<p>Is there anything I am missing that would would make such a setup unfeasible?</p>
<p>Did anyone else build something like that?</p>
<p>A clarification, because it came up in an answer:</p>
<p>What I imagine is this:</p>
<p>One stepper motor is connected to a gear shift system that is either connected to Extruder A or Extruder B, depending on the gear. When shifting it just connects the stepper motor to the other extruder. So it is still similar to a regular direct driven dual extruder system, except that it only uses a single stepper to drive two extruders, each connected to it's own hotend.</p>

[{'answer_id': 15085, 'author': 'Trish', 'author_id': 8884, 'author_profile': 'https://3dprinting.stackexchange.com/users/8884', 'pm_score': 0, 'selected': False, 'text': "<p>You'll need a custom firmware.</p>\n<p>Yur custom firmware will have to react to the &quot;Change extruder&quot; command differently than a normal firmware: instead of just swapping to a different extruder, you'll need to perform some operations to alter the gearing (possibly a solenoid?), and possibly include some kind of &quot;break&quot; to make sure that the filament is not slipping back without the extruder attached. However, there already is a setup that pretty much does this: the Prusa MMU2 uses something similar. The MMU does use a Bowden setup, but you could use Bowden and direct drive in combination, especially if both motors run in sync.</p>\n"}, {'answer_id': 18759, 'author': '0scar', 'author_id': 5740, 'author_profile': 'https://3dprinting.stackexchange.com/users/5740', 'pm_score': 1, 'selected': False, 'text': '<p>That is perfectly viable these days in Marlin firmware, there are options for setting this up using the configuration file, e.g.:</p>\n<pre><code>// :[0, 1, 2, 3, 4, 5, 6, 7, 8]\n#define EXTRUDERS 1\n...\n...\n...\n// A dual extruder that uses a single stepper motor\n//#define SWITCHING_EXTRUDER\n#if ENABLED(SWITCHING_EXTRUDER)\n  #define SWITCHING_EXTRUDER_SERVO_NR 0\n  #define SWITCHING_EXTRUDER_SERVO_ANGLES { 0, 90 } // Angles for E0, E1[, E2, E3]\n  #if EXTRUDERS &gt; 3\n    #define SWITCHING_EXTRUDER_E23_SERVO_NR 1\n  #endif\n#endif\n</code></pre>\n'}]
['https://3dprinting.stackexchange.com/questions/15084', 'https://3dprinting.stackexchange.com', 'https://3dprinting.stackexchange.com/users/13550/']