Replacing the Broken Countershaft Assembly
(Added 11/28/1999)
Ronald Thibault

    I recently had a SERIOUS case of brain fade while trying to replace the damaged sintered bronze bearings in my lathe's countershaft.  Instead of pulling each bearing right at the mount, I ran the puller through both mounts.  Strangely enough when I started to pull the first bearing I broke off one of the bracket's legs!!!  I took it to a local welding shop, but when I got it back the assembly had warped due to the welding heat and the bearings no longer lined up!  The shaft would not go back in place.  They also said that the weld might not hold!  Originally I intended to rebore the twisted mount, so I epoxied a length of angle over the welded joint.  Figure 1 shows the bracket at that point.  After some thought I should have gone this route in the first place!  With the epoxy I could have moved stuff around until the shaft and bearings lined up.


Figure 1

    To rebore the bracket I needed a working countershaft anyway, so I ordered a horizontal countershaft from a later model 10" Atlas.  This installed without much trouble.  It has the advantage that it is bolted directly to the table, thus removing the added twist to the bed that the old "suspended from the lathe" motor mount might have caused.  With the original temporary 1/4 hp motor this was not a big consideration, but I have since acquired a 3/4 hp motor that is much heavier.  The biggest disadvantage is that my old belt guard will not fit the new countershaft.  I'm working on either modifying mine, or buying the correct one.  Figure 2 shows the "new" countershaft installed.


Figure 2
    One problem was that the "new" countershaft had the 4 step pulley frozen in place.  While normally this would not be a problem, it was frozen in a position that caused it to hit on one of the bracket arms!  To free it I used the setup shown in Figure 3.  The puller is two 2X4's and 1/2-NC all-thread.  To protect the end of the countershaft shaft, I glued two PVC pipe end caps end to end.  The shaft was inserted into one cap and the center all-thread into the other.  The free end of the countershaft shaft passed through a hole in the 2X4 on the right.  When the end of the shaft got too close to the pulley to be able to continue with the pipe caps in place, I removed them and wrapped several layers of masking tape around the all-thread.  When everything was apart I found the problem.  The key had an extra tip at one end that had dug into the pulley and locked it tight!

Figure 3

    One useful modification I made to the countershaft involved the lubrication system for the needle bearings.  Atlas provided an axial hole at each end that was then cross drilled inside the bearing area.  This allows you to force grease in with everything assembled.  The holes were sealed by two screw on caps. Unfortunately they were just plain holes with no way to attach the grease gun, and only one of the caps came with the assembly!  I drilled and tapped the axial holes for 1/8 NPT grease fittings.  This makes greasing the bearings simple and does not leave a mess.  The picture in Figure 2 shows the countershaft before this mod.  The end shown has the one existing cap installed
 

Return to Atlas Page