The vertical fine feed of the
X2
mini-mills uses a universal joint and worm
gear to drive the rack
and pinion, and to move the headstock up and down. This feeding
mechanism
creates a problem of having too
much backslash. My mini-mill has cumulative backslash of about 0.1". It
has a lot of problems in controlling the amount of feeding during milling
operation when it needs
to be reversing the direction of vertical movements.
To minimize the backslash, the universal
joint is
replaced by a straight shaft and a ball bearing. Although this
modification still has 0.018" backslash, this is a huge improvement.My mini-mill is a version of X2 and under the brand name of Craftex. It is sold by Busy Bee tools, www.busybeetools.com.
First to detach all the components from the
milling
machine, which are attached to the worm gear and the universal
joint. The universal joint is separated from the worm gear shaft.
)
A 0.5"
diameter X 6.5" steel rod is turned into shape to replace the
universal joint for
the worm gear shaft extension. An
aluminum block mounted with a ball bearing is for replacing the
universal joint block. The dial knob needs to be modified with a step
drill hole of 0.5" and 0.3970" (the size of letter X drill bit) in
diameter on the center for
the insertion and mounting.The ball bearing is used in the modification; 7 mm ID X 22 mm OD X 7mm.
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)
The
ball bearing block assembly and
dial knob modification. The materials of the dial knob is not easy for machining. The step hole is made by drilling and the insert is pressed fit into the drill hole.
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When putting all the components
together on the milling machine, they need to be adjusted for the best
fitting. The bearing block may need to be removed to adjust the
dimensions.The size of the ball bearing block is larger than the original one, the universal joint cover cannot be put back.
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