Simple replacement part for a Optimum BF20 Vario Please note that this mods the milling machine to bypass the microswitch So if you need that added security feature, this is not for you! And of course using this mod is at your own risk.

Needed hardware: 6 pcs M3 x 5 mm 6 pcs Heated inserts M3 x 5 mm outer diameter

Print instructions: Print in a functional filament (ABS, PC, ASA) 4-5 walls, 35% infill Use supports

Assembly:

1. Bottom piece with 6x approx 4mm holes gets heated inserts
2. Disconnect power, remove microswitch and wiggle cables through the hole in the bottom.
3. Screw into place with original screws and attach cables to switch again. Might need to wedge it in depending on tolerances.
4. The cover goes on top and screws in place with the M3 screws.
5. I recommend pre-threading the holes in the rod with the original screw. The rod should slide right into the large cover and take the aluminum profile which can be tightened with the screw just as before.

V2 release: 2026-04-21 Change log:

• Added original screw holes for spring and "ball" that trigger the switch
• Added hole for the ball to sit
• Untested as of yet - would love feedback!
• Added STP files for the whole thing if anyone wants to remix/mod

V1: Released on 2026-3-10