Zesty Nimble V1 NeoBreech - Tension-Adjustable Replacement Breech

The Zesty Nimble V1 is out of production and replacement breeches are very hard to obtain. Keep your OG Nimble running with this tension-adjustable, easy-to-print design!

IMPORTANT: This design has been proven out in short-term testing as of 3-November-2023, but long-term/high-mileage issues may still exist.  Use at your own risk.  Performance not guaranteed. Testing feedback welcome, however I cannot support design variants for specific printer setups or other Nimble versions. Also, THERE ARE NO STEPS, so don't ask.  I work in a mesh editor!

PRINTING NOTES:

All parts are optimized for printing at 0.1mm layers with a 0.4mm nozzle, no slicer supports (one part has custom breakaway supports), 0.2mm first layer.  Toleranced to about .2mm, but bring your print quality A-game to avoid postprocessing for fitment.  All STLs are provided in correct printing orientation. I used Hatchbox PLA. Red is obligatory 😉

Watch the assembly tutorial here (apologies for the trash autofocus):

CURRENT BOM:

• 3x M3 hex nuts
• 1x M3x25mm button head screw (may need to be longer or shorter depending on spring)
• 1x M3x16mm cap head screw
• 1x Compression spring (no suggested source, so you'll have to experiment - it must be big enough to slip over an M3 screw and fairly stiff)*
• 1x 7x3x3mm bearing + 1x 3mm pin from stock Nimble breech OR
• 2x 6x2.5x3mm bearings + 2x M3 6mm cone head grub screws**

* I used a random spring from my collection, probably salvage from an inkjet printer.  Tension requirements aren't super-high, but a pen spring probably won't work.  You could also use no spring and a shorter M3 to run this as a fixed-distance breech, but I have not tested this.

** Depending on your choice of breech block (single or double idler).  Single idler requires no special parts besides what you should have on hand from the Nimble, but the double idler may grip better with reduced tension.  See assembly video for more info.

CONFIG NOTES:

• The NeoBreech may change the E-Steps per mm due to the changed amount of filament “bite" compared to the stock breech.  Mine dropped from about 2700 to about 2600.  Be sure to recalibrate after installation.

DEV NOTES:

Designed from scratch in SketchUp based on direct measurements of my Nimble.  I designed this because the only existing replacement breech(es) I could find either required sending off to a printing service or looked like they might have longevity problems and required a lot of post-processing (no shade on the designer(s) - it's a tough space to design for).  I wanted something that would last, be very easy to print, and be as gentle as possible on the Nimble itself, since the sintered nylon housing isn't that hard to deform or abrade.