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Machine Ball End Including Part Off Questions
- Thread starter munruh
- Start date
- Replies 5
- Views 1,013
EmGo
Diamond
- Joined
- Apr 14, 2018
Sorry, Rob, but ick. For me a Sandvik 1/4" full round insert (actually 6mm I think) then the narrowest partoff tool you can find.
If it's a few, part them almost-off then snap by hand. If it's a lot, get out the bar feeder and parts catcher.
implmex
Diamond
- Joined
- Jun 23, 2002
- Location
- Vancouver BC Canada
Hi All:
I turn a lot of screws with buttonheads, and the heads need to have a very fine finish.
The orientation of the parts is the same as these parts and some of the problems will be the same too.
I've had the following experience:
First, the length of the part influences what you can get away with, and the hard part comes of course, as you approach zero diameter at the tip of the ball and the part starts to wobble just before it falls free.
If it's short and small diameter; no problem.
If it's long, I always lose some that get gouged before they fall free.
With something as big as the ball you intend to turn, I'd expect this problem to get worse.
Second, I've had best success with a very sharp tool and a parting blade has not done it for me until I've removed the edge hone and made it dead sharp.
Of course the smaller the corner rad on the insert, the closer to center you can get before the part falls free, but of course, you can never actually turn to center and dogbone inserts or round inserts make this worse just because the rad is larger, but cutoff blades have a nice small rad so you can get pretty close with care.
Further to the first point, I have not been very successful on bigger parts just turning them with the doors closed and going for it.
I can do far better with the doors open and my fingers supporting the spinning part at cutoff, but of course that violates about a thousand OSHA rules as well as pissing coolant all over the room when the door's open.
When I use this strategy I rough the part first with plunge passes in X to rough the part really close leaving a stem that's as skinny as I dare to go, then finish turn and part off in the same operation with the parting blade.
Last is a hand dress of the tit.
If the ball needs to be very good, I bite the bitter pill and flip the part around to turn the ball with an upsharp 35 degree diamond all in one shot.
I can get it pretty good the other way but not as good as I can get it turning the ball conventionally.
This would be such a nice part for a subspindle lathe!
Cheers
Marcus
Implant Mechanix • Design & Innovation > HOME
Vancouver Wire EDM -- Wire EDM Machining
I turn a lot of screws with buttonheads, and the heads need to have a very fine finish.
The orientation of the parts is the same as these parts and some of the problems will be the same too.
I've had the following experience:
First, the length of the part influences what you can get away with, and the hard part comes of course, as you approach zero diameter at the tip of the ball and the part starts to wobble just before it falls free.
If it's short and small diameter; no problem.
If it's long, I always lose some that get gouged before they fall free.
With something as big as the ball you intend to turn, I'd expect this problem to get worse.
Second, I've had best success with a very sharp tool and a parting blade has not done it for me until I've removed the edge hone and made it dead sharp.
Of course the smaller the corner rad on the insert, the closer to center you can get before the part falls free, but of course, you can never actually turn to center and dogbone inserts or round inserts make this worse just because the rad is larger, but cutoff blades have a nice small rad so you can get pretty close with care.
Further to the first point, I have not been very successful on bigger parts just turning them with the doors closed and going for it.
I can do far better with the doors open and my fingers supporting the spinning part at cutoff, but of course that violates about a thousand OSHA rules as well as pissing coolant all over the room when the door's open.
When I use this strategy I rough the part first with plunge passes in X to rough the part really close leaving a stem that's as skinny as I dare to go, then finish turn and part off in the same operation with the parting blade.
Last is a hand dress of the tit.
If the ball needs to be very good, I bite the bitter pill and flip the part around to turn the ball with an upsharp 35 degree diamond all in one shot.
I can get it pretty good the other way but not as good as I can get it turning the ball conventionally.
This would be such a nice part for a subspindle lathe!
Cheers
Marcus
Implant Mechanix • Design & Innovation > HOME
Vancouver Wire EDM -- Wire EDM Machining
EmGo
Diamond
- Joined
- Apr 14, 2018
Easier to program, easier to keep it truly round. But to use a groover, you'd have to have radiused corners anyhow, so why not use a full-round grooving tool and part off with that ?
Or is that what you meant ? I was thinking of a conventional squared-off one. In that case, we are in agreement
