Cross Feed Screw - Insert Repair

Remove the cross feed screw from the lathe.

Measure the total length of the acme screw to the gear face and record.

Cut off the old acme cross feed screw just in front of the power feed drive gear.

Face off the end to clean up and spot drill the center.

Set up and drill and ream to .3125 to a depth of 1.250 inches.

Set up and turn down a 1.500 inch length tang on the new cross feed screw blank for a snug sliding fit in this bore. Finish off the length to measurement recorded. Finish off or cleanup the thread start.

File a little flat on the side of the insert tang or drill a weep hole into the bore at the end so air can escape when you are

installing it into your old lead screw shaft.

Use Loctite 680 (Green- Slip Fit - P/N 68015 10ml small size) on the assembly and allow for full cure of 24 hours.

After cure, set the assembly up in a drill press or mill using a V block and drill and ream to .1247 for press fitting of an 1/8 dowel pin. The position of the dowel pin is at the end of the gear teeth or at about one inch from the end of the gear.

Install the dowel pin.

Set up and finish off the pin area and front of the insert tang if needed.

Follow the South Bend drawing No. ATT. 208 or ATT. 212, which are included, as a guide for the next steps.

Using internal expanding arbors, hold the dial collar or bushing by the 3/8 bore, Set up and face off just a thousand or two to the mating surfaces to clean things up. Do the same thing to the mount bushing and front of drive gear where the bushing contacts.

Here is were you would counter bore the mount bushing if adding the installation of thrust bearings.

Counter bore both the bushing and the dial ring so part of the bearing is in both parts.

Install a set of thrust bearings between the backside of the lead screw gear and the threaded end of the mount bushing.

Measure and then turn off the thickness of the thrust bearing set from the large diameter of the cross slide screw right behind the drive gear.

Assemble the complete lead screw mount bushing dial ring and handle and check the end play in the mount bushing.

To correct any end play use a feeler gage to measure the clearance that is causing the end play.

Machine back the shoulder that the hand crank seats up to the same amount as the feeler gage measurement.

Cleanup and reinstall the cross feed screw in the lathe with lubricant.

The object here is to have a free turning cross slide screw but without end play that gives you unwanted back lash in the screw and nut.