Sieg SX3 mill
Early in my use of my mill, I managed to shear the End Shaft (Part #86
in the manual), and I had to install a replacement part. The End Shaft is
part of the mechanism that controls head tilting on the mill; this mechanism is
not documented in the manual or, as far as I can tell, anywhere else. I
got some hints from the CreviceReamer
site, but for the most part I was on my own. I found that the
head-tilt-control mechanism of the SX3 mill works this way:
- Head tilt (that is, rotation of the Spindle Box (Part #33)) is prevented
by the deadbolt-like Orientation Small Gear Shaft (#78), which protrudes
from a hole in the Vertical Slide (#75) into an off-center hole in the
- The Orientation Small Gear Shaft is pushed forward into the Spindle Box by
a compression spring (#80) that is restrained in a well at the rear end of
the Orientation Small Gear Shaft.
- To permit head tilt, the Orientation Small Gear Shaft is retracted by a
rack-and-pinion mechanism whose rack is formed by grooves on the Orientation
Small Gear Shaft.
- The pinion of this mechanism is the fluted left end of the Inlay Shaft
- The Inlay Shaft is held captive within the Vertical Slide by a setscrew
(#84) that enters the Vertical Slide from the rear and engages a journal in
the Inlay Shaft.
- A well in the right end of the Inlay Shaft accepts the socket-headed End
- The Inlay Shaft and End Shaft are cross-drilled, and the Taper Pin (#88)
- Clockwise rotation of the End Shaft is thus transmitted through the Taper
Pin and the Inlay Shaft to retract the Orientation Small Gear Shaft and
allow rotation of the Spindle Box with respect to the Vertical Slide.
The most useful modifications I've made to the mill have been
- addition of a spindle lock, using Paula Stephens'
- addition of a quill stop (inspired by another
design by Paula Stephens, but one for which she has made no drawings
available), installed by
- discarding the Protect Cover (#274) and associated parts;
- attaching a bracket (A) with a 10 mm unthreaded hole to the side of the
Spindle Box, using the M4 holes freed by the removal of the Protect
- gripping the Spindle Sleeve (#10), just above the attachment of the Display Fixed Bracket (part
#8), with a horizontal beam (B);
- connecting the beam to a vertical threaded rod (C), running upward through
the hole in the new bracket; and
- threading a knurled handnut, a washer, and another handnut (D) onto the
vertical rod, so that the assembly resembles, in form and in function,
the quill stops commonly seen on drill presses.
- addition of X-axis carriage stops, installed trivially by
- attaching a vertical barrier (A) to the Saddle, using the two unused M4
holes found a few inches to the left of the midline; and
- attaching pieces of scrap (B, C) to two improvised 13 × 14 × 6-mm
T-nuts, one at each side of the existing T-slot on the front surface of the Work Table (#184).
- addition of a 3-axis digital readout from DRO
Pros. My installation of the DRO followed the method used by Dan
Kautz for the X and Y axes; I initially installed a 150-mm Y scale, but
subsequent failure of the mill's Check Ring 12 (part #167) led to
destruction of that scale's read head, and
I replaced the scale with a 200-mm unit. For the Z axis, I had to improvise,
and I describe my arrangement here;
- replacement of the shoddy factory-supplied Check Ring 12 with an E-clip made of
Short of dealing
directly with Sieg, the only source of replacement parts for the SX3 milling
machine may be Little
Page revised: 07/02/2015 15:12