About Lead?

How about casting a blank then pressure (friction) turning the OD. Mount pie shaped top jaws on your chuck. Machine a recess in the jaws to match the OD of your part. Face one side. Flip the part and do all the ID work except the pockets. Mount the chuck with the part still in it on a rotary table on the mill. Tilt the head of the mill and cut the pockets with an end mill reground to the correct diameter and with a flat bottom.

If your chuck does not accept top jaws you can machine a ring of steel so the ID matches your blank. Split one side of the ring. Hold the ring in your chuck.
 
This might be a complete stupid question. Why does it have to be lead? Could some type of plastic work?


Cutting oil is my blood.
 
Illinoyance said:
How about casting a blank then pressure (friction) turning the OD. Mount pie shaped top jaws on your chuck. Machine a recess in the jaws to match the OD of your part. Face one side. Flip the part and do all the ID work except the pockets. Mount the chuck with the part still in it on a rotary table on the mill. Tilt the head of the mill and cut the pockets with an end mill reground to the correct diameter and with a flat bottom.

If your chuck does not accept top jaws you can machine a ring of steel so the ID matches your blank. Split one side of the ring. Hold the ring in your chuck.
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Wow! Thank you! You are the clearly type that gets the sequence of operations pretty much sorted out before you start :)
Yes - my Cormak mill can tilt the head. That seems way easier than tilting a whole rotary table. While it's interesting. I don't have the means to fire up anything. The most that gets to red heat is in my house woodburner. I would probably heat up the lead to melt over a camping gas stove, but I can help it along with a butane torch.

Lead melts easy. I thought it a sneaky plan to pour it into a blank, but on top of a disc of aluminium that already had a few screws in it, sticking up, and ending up set into the lead, this being the way to be able to get a grip on the aluminium, and know that the lead on the end would be forcibly turned.

I do like the friction turn way of securing it. Maybe there is nothing wrong with some CA glue as well. I think this can be done. I admit to being a bit of a purist about the design functionality. I only choose for it to be all lead, to guarantee by design what happens with 6 radioactive sources in there.
 
twhite said:
This might be a complete stupid question. Why does it have to be lead? Could some type of plastic work?


Cutting oil is my blood.
Click to expand...
Lead stops x-rays.
 
Of course one could machine a mold out of aluminum and just cast lead into it. You would have to insert pins into the mold for the pockets, but that is straight forward. Kind of like hollow point pins.
 
twhite said:
This might be a complete stupid question. Why does it have to be lead? Could some type of plastic work?
Cutting oil is my blood.
Click to expand...
In my world, there are no "stupid" questions. The only relatively silly thing is when folk don't ask!

Lead is the only stuff we know where only 2mm can completely stop a gamma ray, and x-rays. It's a shield to ensure that the sensitive electronic x-ray detector in the centre will only see x-rays coming from the material being tested, and the trick shape is all about controlling what goes where.
 
Don't worry about heat sources to melt lead. I used to melt lead on a gas stove to cast sinkers. On second thought worry. Using the kitchen range could lead to divorce.
 
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