Best way to turn half a concave sphere in b777 tungsten?

Hello.

I have to make a part that has a concave half sphere of about 1 inch diameter in b777 tungsten. Think a bowl shape. What would be the best way to do it. I was thinking of using a round insert. Are there better solutions. I don't have surfacing in esprit otherwise I would have done it with a ball mill and the y axis. Also do you guys have recommendations on tapping b777.

Thank you

plutoniumsalmon said:

Hello.

I have to make a part that has a concave half sphere of about 1 inch diameter in b777 tungsten. Think a bowl shape. What would be the best way to do it. I was thinking of using a round insert. Are there better solutions. I don't have surfacing in esprit otherwise I would have done it with a ball mill and the y axis. Also do you guys have recommendations on tapping b777.

Thank you

Click to expand...

Generally, a round insert holder will not have clearance at the centre/pole of the hemisphere unless it's a very large radius in the part and very small tool.

Most of the big names make tools specifically for turning ball sockets, using a DCMT insert.

Example from Sandvik:

A20M-SDXCL 11-R

gregormarwick said:

Example from Sandvik:

A20M-SDXCL 11-R

Click to expand...

1 and 1/4" boring bar might not go down to X0. It depends on how much below the centerline your lathe goes.

Fancuku said:

1 and 1/4" boring bar might not go down to X0. It depends on how much below the centerline your lathe goes.

Click to expand...

That's a 20mm bar.

Anyway, it was just an example. They come in different sizes.

OP might need a smaller one still, member TeachMePlease (IIRC) linked some Kyocera solid micro bars with the same geometry last time this came up.

Why aren't you turning a full concave sphere?

R

I used to machine a lot of that stuff and just keep in mind it's like trying to machine a grinding rock because its so abrasive. As far as tapping you need a really good short spiral tip tap. My approach was to back grind the first tap to the point it was only getting about 50% of the thread profile then go back with a full tap and cut the rest out. I've tried dozens of tap fluids and found White-Lead to be the best. If you cant get your hands on that then good ole Molly-D to the rescue. double check the go-nogo since the abrasiveness throws the tap tolerance out the window.

gregormarwick said:

Generally, a round insert holder will not have clearance at the centre/pole of the hemisphere unless it's a very large radius in the part and very small tool.

Most of the big names make tools specifically for turning ball sockets, using a DCMT insert.

Example from Sandvik:

A20M-SDXCL 11-R

Click to expand...

Thank you.
I found this one. A10K-SDXCR 2-R The sphere has a radius of 10.25 mm so it think it should barely fit? Or where would I find a smaller one. Kyocera? What would be its designation. Thank you.

Scratch that. Found it. Thank you. Kyocera for the win.