Any Ideas how to ............

[CrewCab]

Hi gang,

I'm sat here wondering how to produce the part shown in the attached C-o-C it will either be Aluminium or Brass (to replace the existing Plastic one) ......... the turning and threading are obviously simple but its the 14mm radius groove I'm scratching my head about ............... am I missing something obvious  

Cheers

CC

[sbwhart]

Hi C C

Turn it up then set it up on the mill so that it looks like a mushroom them mill the 14 rad out with a fly cutter or a 14mm end mill etc

Hope this helps

Stew

[CrewCab]

Fly cutter is a possibility Stew as I haven't got a 28mm dia bit, I'm pondering about holding it securely enough, thanks for that 

CC

[Stilldrillin]

David,
I agree with Stew.....

You could hacksaw off the excess, then flycut. Shouldn`t need too much holding then..... Maybe! 

David D

[CrewCab]

Bearing in mind the groove runs along the whole part I suspect it would probably be better to make it longer at both ends then finish off to length onece the groove is cut.  I thought about a 28 mm router cutter but the only one's I've found are bloomin dear ......... certainly not worth it for this one off button.  Wondered about mounting it horizontally on the mill, then it's a case of grinding up a cutter ........... if I milled out some of the excess first perhaps an old wood bit (spade type) might grind up OK to finish off.

It's not too important, just trying to add a bit of bling to something ............ so no rush either, ................   

CC

[John Hill]

I have no mill so of course my technique would be lathe only..

1. Mount stock off-centre in lathe  by mounting in the 4 jaw or packing off centre in the 3 jaw.

2. Use a boring bar to cut out the radius

3. Mount stock centred in the lathe and for turning and threading the hole

4. Part off.

[Bernd]

I'm with John. Make it a bit longer and off set in 4 jaw chuck.

Bernd

[John Stevenson]

What mill have you got ?

John S.

[CrewCab]

What mill have you got ?

Chester 626

[CrewCab]

Is this a better picture 

[CrewCab]

JH, Bernd, if I offset the workpiece in the chuck won't that give me a convex cut rather than concave ........... or am I losing the plot 

CC

[Darren]

It'll do both, depends how you set it, think of boring from the inside.

[John Hill]

JH, Bernd, if I offset the workpiece in the chuck won't that give me a convex cut rather than concave ........... or am I losing the plot  

CC

You have to set the workpiece so that it is entirely outside the axis of the lathe spindle, it might even be impossible to do with a 3 jaw, I do not know.  The axis of the lathe spindle must coincide with the axis of the concavity.

[CrewCab]

Thanks guys, the lathe technique has filtered through the old grey matter now ......    ....... well I certainly have a few options now 
   
CC

[kvom]

How about a 14mm ball endmill? 

[CrewCab]

Needs to be a 28mm ball Kvom, problem is they are about £100 which is not worth it for a 1 off little bit of bling, thanks for the input though 

CC

[Bernd]

Well CC sounds like it's time to make Ralph's ball turnner and turn up a 28mm ball. Cut a couple of grooves in it, harden and have at it.

Bernd.

P.S. I sure you will find use for the ball turner after your done withthis project.