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KRALYN / PositronV3

A upside-down, fast, portable, and compact 3D printer
Creative Commons Attribution 4.0 International
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Improoved cable tensioning, using sliding End Holder Block #22

Closed Harry-Loud closed 2 years ago

Harry-Loud commented 2 years ago

Hello There,

This is a working, and tested PR.

The basic idea is this; current cable tensioning on the V3 is crap. It would be nice to be able to tension the cables using a screw. Thus, Audiotronix and I (harryloud on discord) have modified the End Holder Block to sit on the Y rail, and slide. A screw coming from the back of the Z Holder Block is then connected to this sliding block, and can be used to pull the block back, tightening the cable.

Testing

MellonColley has gracefully tested this design for us (as he has a nearly complete working printer), and after a few itterations we are very happy with the results. The tolerances on the print are perfect and the block slides beautifully on the rail. The block is versatile as it accepts either an M3 insert or an M3 nut inserted from the front. The m3 screws that hold the pulleys are designed to thread directly into the 3d printed block, no inserts are required. (and integrated washers)

MellonColley had this to say about the mod: "500% better than the current system", "I gotta say, this is a winning design. The belts are so tight they ring when plucked"

Included Files

2 versions are included in this PR: 1) A single part. However the Side Ledges that interface with the Z axis bottom holder plates also move with the block. This will likley be a problem, however, we were unable to test this as we do not yet have access to a completed printer. End Holder Block - Tensioning Mod, 1 part, moving ledges.stp

Thus, if these moving ledges are a problem 2) This design splits the block into 3 parts. 2 fixed ledges that are bolted to the Z block, and 1 sliding tensioner block. End Holder Block - Tensioning Mod, Fixed Ledges.stp

Things to note when integrating this design

A cbored or csinked hole is required in the Z holder Block for the M3 tensioning bolt. There may be a slight interference between the enclosure wall and the sliding block. Shallow Grooves may have to be milled into the Z Holder Block to accomodate the full range of motion of the tensioner block, like this (but more milling machine friendly):

Thank you, You will hear more from us soon, a lot more modifications are in the works.

Harry and Rene (harryloud and Audiotronix)

KRALYN commented 2 years ago

Thank you very much for this wonderful design, the only problem I can see is Z-axis stability, you might have to increase material to account for the material removed for the sliding block. especially that it cannot be machined.