Step 05.17 — Fit the first Y backer¶
Step 17 of 48 with a helper · Chapter 05 — Gantry: X and Y axes, XY joints, X carriage, titanium backers
Parts:
- titanium Y backer ×1 · Ti backer set
- M3×8 FHCS ×10 · Ti backer set
- M3 roll-in T-nut ×10 · Fasteners, Tools & Misc box
- T10 Torx driver · tool
Do: Turn the first C extrusion rail-down and work on the opposite face. Roll ten M3 T-nuts in, lay the backer on, and start every screw before tightening any. Tighten M3×8 FHCS from the centre outwards, using Torx.
Check
Backer flat along its whole length, every screw seated in its countersink, and both ends clear of where the idler and drive frames land.
Helper Holds the backer flat on the extrusion while you start every screw.
What you're looking at
You are working on the bare face of the first Y extrusion, which becomes the top of the Y axis. FHCS are countersunk screws whose heads sink flush into the backer's chamfered holes; a hex key cams out, so use the T10 Torx.
Never on the rail face
the whole point is to put steel on the face opposite the rail and cancel the bending couple. Doubling up on the rail side makes the bow worse. src
Source: Ti extrusion-backers README (tanaes) (image x_axis.jpeg)
