3D Printer X-Carriage
The exisiting hotend carriage on my 3D printer was bulky, heavy and produced lackluster print quality due to extrusion issues.
The solution was to completely redesign the carriage to accomodate a new direct-drive extruder & hotend whilst increasing ridgidty and minimising the overall envelope as much as possible to maximise bed area.
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I decided to use 6061 aluminium for the body of the carraige due to it's high strength to weight ratio and excellent machining characteristics.
The addition of a BL Touch inductive bed probe enabled the bed-levelling procedure to be much more accurate and consistent, leading to better print bed adhesion whilst improving reliability. The probe was mounted using a relatively low strength 3D printed bracket to break easily and protect the printer in the event of the probe snagging on the print.
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The existing carriage used a bulky microswitch to home the x-axis, however I elected to use a much more compact hall-effect sensor with no moving parts to reduce the width of the carraiage, whilst simplifying assembly.
The existing x-carriage did not facilitate adjusting the tension of the belts at all, meaning the print quality would suffer as a resulst of inequal tension on the belts, a major problem for any core-x-y style 3D printer.
After investigating a number of possible solutions including integrated belt tensioning via. a stepped pulley I decided to go with the lightest, most compact and simplest solution which was to anchor the belts around posts on the carriage, using the teeth on the belt to interlock and prevent slippage. Similar solutions are used on a wide variety of 3D printers and whilst it is not the prettiest solution it is a design that has been proven to work well.
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It was necessary to ensure the hotend heat break heatsink had adequate airflow to ensure there was no heat creep from the nozzle heat block up to the rest of the hotend assembly. Heat creep is a major cause of hotend jamming so it was essential that this was minimized. Therefore the design includes generous clearance around the heatsink exhaust areas.
I modeled the carraige in Solidworks before exporting to Fusion 360 to utilise its CAM tools to generate the G-Code for the milling machine. Design intent was incorporated into the design process to minimise the number of machining ops and toolchanges required, as well as simplifying assembly by reducing the number of parts.
