internal nut fixing

[shipto]

I am struggling for a proper looking solution to some internal nuts for my diehead project and I have decided to throw it out here to see if anyone has a better way than I am currently doing it.
I have the part pictured and need to mill the highlighted part out leaving the tang which prevents this hidden nut from just spinning inside the diehead shank. I have made a fixture that fits into a ER32 collet fitted to my rotary table. I then bring a 5mm cutter down so it just hits the smaller diameter and turn the table through 315 degrees which does the job but i am having to get the cutter closer to the smaller diameter than I would like which is leaving a ridge down the part which wont hurt anything but just looks shoddy in my opinion.

[philf]

I can't visualise how you're doing this. I assume that the axis of the cutter is perpendicular to the axis of the part? In that case how do you get a straight sided key without a radius where the key meets the head?

Phil.

[WeldingRod]

If I grok what you are doing...   you could use a large diameter slotting cutter and avoid se radii in your slot.

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[shipto]

I can't visualise how you're doing this. I assume that the axis of the cutter is perpendicular to the axis of the part? In that case how do you get a straight sided key without a radius where the key meets the head?

Phil.

Sorry should have said the picture would be ideal but no there is a radius each side. I will get a pic of the part in the mill later.

[shipto]

Here we are this is how I am doing it now, I put one already done in place and you can see the problem.

[philf]

Ah - that's clearer. Not as I thought.

Why not mill the whole small diameter instead of turning it first. Or at least leave 0.5mm on. If you plunge down at the required diameter it will almost certainly leave a witness mark. A carbide cutter doesn't flex as much so is much preferable to HSS. CNC CAM programs will usually provide a gentle run in and out which minimises witness marks.

Cheers.

Phil.

[awemawson]

Well can't mill it either radially or axially as if you want a zero radius corner like your illustration you'll need a zero diameter tool.

I would mill an axial slot up the the 'head' and silver solder a rectangular key into it but if you want it to be square right up to the head you will need to file a radius on the end to the depth of your slot and the diameter of your cutter.

[shipto]

Well can't mill it either radially or axially as if you want a zero radius corner like your illustration you'll need a zero diameter tool.

I would mill an axial slot up the the 'head' and silver solder a rectangular key into it but if you want it to be square right up to the head you will need to file a radius on the end to the depth of your slot and the diameter of your cutter.

The zero radius is not really needed because when fitted into the shanks I have to make clearance for them for which I am using a dremel type tool with the 3mm diamond bit (its a bit pot luck because some shafts are hardened while others are not) basically as long as I can stop this turning when the user is adjusting the stop then its doing the job. The plan was to sell these as kits that people could fit themselves which is why I would prefer them to look better.
Thanks Philf I will look into getting a carbide cutter and see if thats any better, The CNC option may be something worth thinking about for the future but you have given me another idea which is to go maybe .2mm or so smaller on the small diameter so it wont touch at all 

[efrench]

Endmills as small as .001" are available

[awemawson]

You'll probably find that just drilling a hole radially just below the head and loctiting a peg in would be perfectly adequate to prevent rotation.

[WeldingRod]

I would relive the cutter where you don't need it to cut.  That will help the marking and chatter.

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