Unfortunately I found projects perfectly working in theory but then evidentiating mechanical issues making them almost useless or very difficult to use or build.
So the solution was to design and make a working project including all the components.
For more details and the full project read the Element 14 article https://www.element14.com/community/groups/3d-pri...
The full assembled version (two complete supports) is also available on Drobott.
Insert the 10% discount code for the Instructables.com users DWQ0H19J when buying!
Step 1: The Design
The components has been designed with Rhino 4; the images shows some rendering views of the components needed to create one of the both rotating support modules.
The moving elements
It was needed an efficient solution for the moving elements (where the filament roll lies rotating) without involving too complex and expensive components. First of all I had to search an alternative to use bearings to make the roll guide rotating free.
The second issue was reducing the pulleys complexity making them easy and almost fast to 3D print.
Every pulley is built of three separate parts rotating free: two side guides and the internal part of a smaller diameter: the assembly order of every pulley will be external part + internal part + external part.
Fixing the pulleys on the axis
If we use just a screw to lock the pulleys components to the support some mechanical problem arises:
- It is difficult to keep the screws closed in the right way risking to Block the rotation
- The central part of the pulley usually will support 1-2 Kg of filament roll. The PLA axis rotating on the screw tends to consume the part very fast.
- I have experimentally identified non-uniform rotation with this solution.
As shown in the quoted design of the pulley components the solution is an internal axes (the red one in the design) 1 mm wider than the compound pulley. So the screw lock the axis against the support sides while the pulleys components rotates freely.
To definitely reduce the friction of the rotation a few amount of vaseline based plastic grease (the same used to lubricate the plastic moving components in the printers) gives the optimum performance.
Step 2: The Printed Components
The printed components includes:
- N.2 pulleys axis support (for 2 pulleys)
- N.2 pulleys central component (2 pulleys)
- N.4 pulleys side components (for 2 pulleys)
- N.1 pulleys support (for 2 pulleys)
To create the entire support it is needed to print two series of components. As the two parts are independent it is possible to setup them in the most comfortable position despite the width of the filament roll.
Step 3: Assembling the Components
After all the plastic components are printed, you need to provide four 20mm M3 Allen screws and four M3 nuts.
I suggest to insert a couple of times the Allen screws inside the axis supports to be sure that can be inserted without difficulty. Then assemble the four compound pulley inside the support holes as explained in the following steps:
- Insert the three pulley components in the order external - internal - external in the small axis support. The best result is obtained adding very few vaseline grease on the support.
- Insert the compound assembled pulley in correspondence of one of the support holes.
- Insert the Allen screw through the hole
- Firmly lock the screw with one of the nuts. As you can see the assembled component are locked by the internal axis support while the pulley is free to rotate.
When the components assembly is finished place the two rotating supports under the filament roll and start printing!