Step 05.34 — Fit the X backer to the rear face¶
Step 34 of 48 · Chapter 05 — Gantry: X and Y axes, XY joints, X carriage, titanium backers
Parts:
- titanium X backer ×1 · Ti backer set
- M3×6 FHCS ×9 · Ti backer set
- M3 roll-in T-nut ×9 · Fasteners, Tools & Misc box
- T10 Torx driver · tool
Do: Turn the D extrusion so the MGN12 rail faces you. The backer goes on the rear face, opposite the rail, not on top. Roll nine M3 T-nuts in, start every screw, then tighten centre-outwards. Use M3×6 FHCS for X.
Check
Backer on the face opposite the MGN12, flat, all screws M3×6 and seated; the top face of the D extrusion still clear.
What you're looking at
The X backer goes on the rear face, the one opposite the rail, same as on the Y axes: steel on one face, titanium on the other, the bows cancelling. The top face stays bare for the XY joints and cable bridge.
Caution
"For X axes, in most cases you'll want to install them on the rear of the X extrusion, opposite the MGN12 rail… If you have a single MGN12 but decide to put a backer on top, you will be actively contributing to the problem of bimetallic expansion!" src
Source: Ti extrusion-backers README (tanaes) (image fusion_x_chainmount.png)
