How to cut something round on a vertical mill?

looks like the round end shares the same radius as the square end, so turning it on the lathe probably won't work. Straightforward hack if you don't have a DRO - scribe out the round end, cut off most of it with a saw and then plunge cut with an endmill as close to the line as you can. Then either finish up with a file/ belt sander OR do the rotary cut hack. Drill into one of those flats, which I'm guessing will be for the lock screw to secure the plinth to the cross slide. Make a long bar to fit into that hole/ thread. Drill the center hole and then bolt the plinth to something in your vise or on your table. Set it up to the correct radius using your XY, then take LIGHT conventional sidemilling cuts while you rotate the plinth with the handle. That'll get you close enough for some light finishing work. Don't get greedy with the cut OR climb mill or it'll get away from you very quickly :)
 
Maybe I'll have a go at the rotary table again. Seems the easiest way out here....as long as I can get it cutting without the horrible chattering and jaming I got last time.
 
Ok, probably shouldn't even admit this, but what I've done in a similar circumstance is to clamp a long lever onto the RT along with the part, and use that lever to stabilize the table chatter. Conventional milling and very light cuts.
 
rabler said:
Ok, probably shouldn't even admit this, but what I've done in a similar circumstance is to clamp a long lever onto the RT along with the part, and use that lever to stabilize the table chatter. Conventional milling and very light cuts.
Click to expand...
interesting solution.

I think I'll first try and see what can be done to make the rotary table more...solid.

But a stabilizer is an option I guess, I'm just not sure if I can dampen out the chatter with my body and a lever. lots of forces going on there that I generally like to keep my "soft parts" away from.....
 
I can't really help you on a setup to get it made as I'm still pretty green on this stuff. On top of that I can't get a good picture in my mind of what you're making. Does it look something like this.
Screenshot 2022-07-16 133059.jpg
 
If you have a through hole concentric with the radius, you can mount a pin for an axle. Then clamp the part in your vise with the pin resting on top of the two jaws of the vise. With the flat of the part parallel to the table, set your end mill to just touch. Loosen the part and rotate it slightly and make a pass with the end mill. Continue this procedure until you have worked your way around the radius. Clean up with a file as necessary. Depending upon how many steps you use, you can machine a very precise radius.

No through hole? Then machine two round bosses on the ends of the part that are concentric with the radius. This can easily be done on the lathe using a four jaw chuck. When you are finished cutting the radius, you can mill off the bosses.
 
Last edited:
If you cannot have a hole, just mark your curve in bluing and create a scratch, then mill the plate to the line.
 
With the addition of a 45º gage, you can use the setup above to cut the chamfers as well.
 
RJSakowski said:
If you have a through hole concentric with the radius, you can mount a pin for an axle. Then clamp the paer in your vuse with the pin resting on top of the two jaws of the vise. With the flat of the part parallel to the table, set your end mill to just touch. Loosen the part and rotate it sligtly and mak a pass with the end mill. Continue this procedure until you have worked your way around the radius. Clean up with a file as necessary. Depending upon how many steps you use, you can machine a very precise radius.

No through hole? Then machine two tound bosses on the ends of the part that are concentric with the radius. This can easily be done on the lathe using a four jaw chuck. When you are finished cutting the radius, you can mill off the bosses.
Click to expand...
Great minds think alike, see post #21 :D
 
You must log in or register to reply here.
Back
Top