X2 Mini-mill vertical feed modification

universal jointThe 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.

v-feed assemblyTo 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.

u-joint worm gearFirst 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.

v-feed partsA 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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dialThe 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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v-feed modificationWhen 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.


Download Drawings (PDF)