Sherline Extended Column

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Recently, I found that I needed a little more clearance to end drill an engine cylinder for my latest project. After making up a new steel extended base for my Sherline CNC mill a year or so ago, the solution for this problem wasn't too different. Previously, I had used a piece of 8020 aluminum extrusion and that solved this problem on my manual Sherline mill too.

Bottom Adapter - the bottom adapter is milled down about .320" on the four corners to create the round center. The round section sits where the original Sherline column normally sits.

The two .250" threaded holes are for the Sherline bolts to fasten the adapter to the base.

The four countersunk holes are for the four 5/16" bolts which attach the 8020 extrusion to the base.

The center hole (not yet threaded) is for the 3/8" threaded rod which will hold the Sherline horizontal arm ("Ram" I think Sherline calls it).

The four other small holes were just put there in case I needed more thickness for the center hole. If that were the case, I would have added another piece of .500" aluminum and threaded it 3/8" as well.

This is how the bottom adapter sits on the base. The little divot out of the front it to clear the lead screw.

The 8020 extrusion is designed to be tapped 5/16". I ran the tap in the full length.

Adapter attached to the new 8020 column with 5/16" x 1.50" flat head bolts.

First fit onto the base.

The top adapter - this was much simpler. The 3/8" center hole does not need to be tapped. Just drill .375" to clear the threaded rod. Same for the four holes for the bolts which thread into the 8020 extrusion. The two aluminum dowels are turned on the lathe to about .735" or so. They stop the mill arm from moving. I drilled and tapped two #10-32 holes for machine screws to hold them in place. ( I never move the arm so I wanted it pretty much locked in place.)

I used threaded rod for two reasons. One, so I don't have to cut a bolt to just thread into the base adapter without hitting the mill base. Second, one piece of threaded rod will cover a range of 8020 columns as I have at least one more, but slightly taller one, ready to mount if I need a bit more height. I screwed the threaded rod into the base adapter using a little Blue Loctite as well as a nut to lock it in place. When I remove the top nut, I didn't want the rod unscrewing from the base.

Finished column installed

I bought a bunch of 8020 extrusions from 8020 Surplus who has a store on eBay. Much cheaper this way. I have another piece
which is already tapped and ready to go but is 1.00" taller. You may have to square up the mill when you change columns but
I don't plan on changing them too often so this won't be much of a problem.

If you're so inclined, you can buy T-nuts from 8020 and make some nice tool hangers
 so your tools and accessories hang right on to the 8020 column.

Updated: September 14, 2008