RepRap Mendel Akimbo
Copyright 2012 by Ron Aldrich.
Licensed under GNU GPL v2
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Akimbo is a re-imagining of the Mendel frame, designed to address specific goals.
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Improve the frame's clearance, particularly for the X carriage and extruders, with particular focus on dual-extruder clearance.
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Make the frame easier to assemble correctly.
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Make the frame more rigid.
Akimbo differs from other designs in several important ways, in order to address those goals.
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The top horizontal rods are further apart than the original Sells and Prusa designs; This allows an extruder to utilize the space between the motors, increasing build height.
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The top of the frame is tilted outward; This improves clearance for the X axis, by insuring that the A frame is outside of most of the moving parts, when the Z axis is at it's uppermost range.
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The Z linear rod mounts are connected to bottom rod of the A frame, improving frame rigidity, and ease of assembly.
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The Y linear rod mounts recall the older (Sells) design, which insures that the spacing between the Y linear rods and the frame horizontal rods is consistent, making it easier to align the print bed.
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The X ends are inverted, with the X linear rods mounted at the top of the X end, rather than at the bottom; This allows the X linear rods to move higher than they otherwise would be able to.
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On all 3 axis, one side is fully constrained (using LM8UU bearings, or equivalent bushings), and one side is constrained only against rotation, using a pair of roller bearings; This prevents mis-aligned, or slightly bent Linear rods from causing the axis to bind.
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The design supports dual extruders, each with its own carriage, and X axis motor; This allows differences between hot-end length on the two extruders to easily be adjusted for in software, and allows one carriage to be parked offsides while the other is in use (no drooling all over the print in progress).