Added linear bearings to round column mill - works

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This is my attempt at fixing the round column registration problem.

Part 1 was replacing the head lift crank with a windshield wiper motor from a saturn Vue (surplus at Princess Auto for $13)

Action video...... https://www.dropbox.com/s/26wb19hzack3i44/VerticalLift Movie-short.wmv?dl=0

Part 2 was adding thrust bearings and permanent handles to the column clamp (the thrust bearings work really well)


Part 3 adding twin parallel 16mm steel rods with linear bearings to maintain registration while un-clamped, seems to work very well, typically less than 0.001" over 4", still need to test over the full 12" span.

My approach:

1) Used a 2x4x1/4” rectangular tube as the “ 2nd “ column, mounted it firmly to the head

2) Milled a ¼” slot to match the tube in a 2” thick aluminum block as the base mount

3) Mounted twin 16mm rods with linear bearings to the tube

4) After a trial fit and a few shims to make sure the rods were parallel to the original column, cut ~12” segment out of the middle of the rectangular tube

 

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Follow-up on full vertical span registration....

I made two really beefy steel round's (one long and one short) turned down to exactly 0.9995" on the bottom to match a 1" bearing that I mounted to the table in a block.

Centered up the short one and zero'd the DRO. Then removed the short test piece and installed the long one after raising the head to the extreme top and then dropped the quill while observing alignment, dropped in without tweaking the location, however I could see it was off by about 0.002, tweaked the X location by -0.002" and perfectly centered within the regular limitations of this machine so I'm pretty happy, no more issues lifting the head mid job.

I need to make some plugs for the now open rectangular tubes