How to cut something round on a vertical mill?

[great white]

First off, I’m still a novice so this is probably my inexperience showing.

I need to make a bit of an odd shaped piece.

Basically, its square edged on one end and rounded on the other.

can’t do it on the lathe, that would just make the whole piece round.

Tried to mount it to my little 3” rotary table but when touched to the side mill…well, lets just say it didn’t work out well. Too much lash in the table screw and if I tigthen it up, it jams the table and eventually the milling cutter grabbed the stock so hard it jammed the table hard. I had to take the rotary table completely apart to get it freed up again.

CNC would be nice, but that waaay outside my current budget.

I tried using the xy wheels to make a circle, but I was never any good with an “etch a sketch” for anything besides straight lines, so you can probably guess how that went.

So I’m stuck. I Just can’t figure out how to mill this piece. I know it can be done, guys make far more complex shapes than this on manual mills.

Any ideas?

 

[extropic]

Without you providing a dimensioned graphic of the part, attempting a reply is only a shot in the dark.

 

[Dan Krager]

Do you have a DRO on the mill? They can help with locating and positioning for XY movements to a circle.

If not, scribe a circle and mill as closely to it as you can (color outside the line....) and file the rest. If you move one axis a thousandth at a time, you will eventually get there.
DanK

 

[Winegrower]

Basically, its square edged on one end and rounded on the other.

So you put the square end in your lathe 4 jaw chuck, make the end that sticks out round. Then move to the mill, hold the round end in the mill vise with V blocks or a collet block, or a spin indexer, or whatever you can figure out, mill a side of the square, and rotate as needed for the other sides.

 

[mickri]

I would start in the mill. Machine the square end square. Lots of videos show how to do that. Then move over to the lathe. Dial in the square end in a 4 jaw chuck Then slowly start removing the corners until the round end is round.

 

[benmychree]

Get a larger more stable rotary table and take lighter cuts. avoiding climb milling.

 

[mattthemuppet2]

Do you mean you want to make a D shape or a bar with one end round and one end square (a spark plug socket for example)?

 

[JimDawson]

Tried to mount it to my little 3” rotary table but when touched to the side mill…well, lets just say it didn’t work out well. Too much lash in the table screw and if I tigthen it up, it jams the table and eventually the milling cutter grabbed the stock so hard it jammed the table hard. I had to take the rotary table completely apart to get it freed up again.

Sounds like you were trying to make a climb cut. In this case, the table need to be turning against the cutter rotation. In other words, both turning clockwise as looking down on the table. Try taking much smaller step over. If you have a band saw, remove as much of the material as possible without cutting into your finish radius.

Without knowing anything about your equipment, available tooling, and part, it's a little hard to offer too much advice.

 

[Cadillac]

Or plunge cut with the cutter step over plunge again rinse and repeat. Once around move in a thou and then side mill.

 

[homebrewed]

Sounds like you were trying to make a climb cut. In this case, the table need to be turning against the cutter rotation. In other words, both turning clockwise as looking down on the table. Try taking much smaller step over. If you have a band saw, remove as much of the material as possible without cutting into your finish radius.

Without knowing anything about your equipment, available tooling, and part, it's a little hard to offer too much advice.

My thoughts too regarding the climb cut hypothesis. I successfully used my 3" RT to machine an aluminum bearing press setup to replace my mini lathe headstock bearings that was 80mm/3.15" in diameter, same OD as the bearing covers. I made certain to rotate the RT so I was conventional-milling during the process. No drama, just took it slow with light cuts and got the job done.