Anyone ever indexed the round column on a drill/mill. I have a HF 12 speed mill and the column will rotate on occasion. Last night while cutting a part, the bit dug in and the head rotated a bit. The part was not hurt, but I had to realign the head to get the program back on track. This got me to thinking that I need a way to index or home the head back to a consistent point.

My thought is to drill a hole in the base and use a pin to orient the column. I could drill holes up the column 1" or so apart. This would allow me to raise or lower the head when needed, but still have it aligned properly.

Would this work? Any suggestions? :cool:

that would probably help but I have had nothing but problems with the round column milsl. One of the reasons that i converted mine into a square column variety.

The only usefull thing about round column mills is the ability to reposition off the table ect.. and I have found the headache far outways the return.

If you want to keep it for long term, one of the ideas I was toying with was puting a motor/indexer on the column with feed back so it could hold position and also move with coding input. Would be a cool way to make a tool changer!

I guess you could replace the rack & pinion with a ball screw through the column. The ball screw could raise & lower the column. This would allow you to put a pully & belt around the column to rotate it in the base.

One thing that I have seen done and I'm not sure where I saw it... But what they had done was to add a second round rail bahind the column attached to the base and top of the column itself and they attached a linear bearing mount to the head this kept the head from rotating... I'd imagine that it'd need to be a pretty hefty shaft maybe 1.5" to 2" in diameter. A simple bronze sleeve bearing setup in the bearing block should be plenty to handle the limited linear movement that you'd be doing with moving the head up and down the column.

That's one of the things that has kept me from dropping the money down on one of the big HF round column mills is that using fixturing would be a serious pain if the head ever moved on the column.

I remember seeing that somewhere. Seems the design completely eliminated any movement of the head. That could be viewed as a negative. Sometimes you need to move the head for changing bits or milling in a location that can't be reached in the normal table travel.

try this www.pathcom.com/~vhchan/cnc/cnc.html
it works quite well ,you could always double up the guides
mike