Machining a double D

[Dean jeffery]

Need to machine a double D in some Ti, the best way would be broaching but to expensive for the tool.
The size would be 8mm across flats and 12mm rads oval like, would this be possible would need to go 20mm deep.

Cheers

[EddyCurrent]

I don't know but I read this somewhere else from someone who cuts Titanium;

cobalt endmills give the best service.
paraffin is the best lubricant.
heat build up is a major factor.
use a slow spindle speed but higher feed rate.
you need a strong machine
climb cutting works well

[Dean jeffery]

OK cheers.

[m_c]

Is this external or internal?
Also through or blind?
.
Going by the mention of a broach, I'm guessing internal, in which case you're going to have to either rely on rounded or overcut corners. However without more details, it's just speculation.

[Dean jeffery]

Internal was guessing rounded corners, but ideally with out.
Not sure what the smallest ended end mill would be but any smaller than 4mm this would prob not be possible.
What would be the smallest end mill poss, or max over cut corners.

Cheers

[m_c]

You can get sub mm micro endmills, but none that would manage to go 20mm deep.
Having had a quick look at a catalogue, the smallest diameter that will go 20mm deep is 4mm, so you'd be looking at a 2mm radius on every corner, although you may need to increase that to avoid chatter in the corners.
.
Do you really need to use a double D?

[Dean jeffery]

Cheers dint think it would be possible to mill it, 2mm it would no fit. So would need under cutting, although this is not a problem regards affecting the function because their would be plenty of flat left for drive. But just looks unprofessional, and looks play a part.
Has to be a double D the drive is a double and can't be changed, so this has to be the same.

Cheers

[m_c]

The other possible option is an EDM sinker, but it all depends on how much you want to spend.

[Dean jeffery]

EDM I would have thought be more expensive than standard broaching, I may go the route of drilling out the corners shouldn't look all that bad.

Cheers

[Robin Hewitt]

I suspect this is just a ploy to make me Google for "double D" then have to explain to my wife why I am targeted with lingerie adverts for the foreseeable future

Am I the only one who doesn't know? What is a double D?