# Punch and die for making lead rings



## homebrewed (Mar 15, 2022)

As part of the by-now gargantuan "needing more than a spark test" thread that a few of us have been involved with, I needed to make a lead ring to prevent our x-ray detector from being directly exposed to our x-ray sources (Americium-241 used in smoke detectors).  The OD and ID are unique, dependent on the source/detector geometry so I decided to make a punch and die for it.  This is the first time I've done such a thing and it was a fun little project.  Here's a photo of the punch and die, a ring I made using it, and the part of my XRF hardware the ring is supposed to mate with.  It will fit in the bottom of the aluminum piece.  The aluminum piece will be used to aim the x-ray sources toward the sample.




The punch has two sections, a smaller-diameter end that defines the ID and a larger-diameter section that defines the OD.  The die has two bored-out holes to match the punch.  I made both from HRS because lead is very soft.  To make a ring, a small lead sheet is placed over the smaller-diameter hole in the die and the punch is used to make the ID.  The 1/16" thick lead sheet is not removed from the punch.  Then the punch is moved over to the larger hole and the finished ring is punched out.  I know the exact spacing between the two holes so it's easy to get the proper alignment between the punch and die.

The end of the punch has a conical profile to provide a little bit of relief and concentrate force on the perimeter of the disk being punched out.  I used the same small-nose-radius TCMT style insert to cut a relief for the OD portion of the punch as well.  I used a very fine-tooth file while spinning the punch on my lathe to remove the burrs so the punch slid smoothly into the die, and that also gave me a cleaner cut. 

I also used my 1.25" carbide insert mill to level the top of the die where the holes were bored.  That was done _before_ boring the holes so the holes didn't perturb the cutting action of the end mill.

I used my benchtop mill as the "arbor press" for punching out the ring.


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## Parlo (Mar 15, 2022)

There is an old and seldomly used method for blanking parts without making a die. Using Urethane as a die the punch passes through the sheet and the Urethane forms around it cutting the part.
Here is a link that shows it better than my explanation.


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## cathead (Mar 15, 2022)

Some years ago I disassembled a smoke detector and all that remains is a disc with a tidbit of Americium in
the middle.  It could be disposed of in the trash from what I have read but I keep it around.  I do have a
radiation detector that detects beta and gamma but not alpha so might give it a test and see.  One thing I use my radiation
detector for is to test my furnace filter periodically.  Generally it tests about twice the background radiation. 

You did a nice job on the punch and die.  I need to try make one for some copper gaskets.  Thanks for posting.


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## C-Bag (Mar 15, 2022)

homebrewed said:


> As part of the by-now gargantuan "needing more than a spark test" thread that a few of us have been involved with, I needed to make a lead ring to prevent our x-ray detector from being directly exposed to our x-ray sources (Americium-241 used in smoke detectors).  The OD and ID are unique, dependent on the source/detector geometry so I decided to make a punch and die for it.  This is the first time I've done such a thing and it was a fun little project.  Here's a photo of the punch and die, a ring I made using it, and the part of my XRF hardware the ring is supposed to mate with.  It will fit in the bottom of the aluminum piece.  The aluminum piece will be used to aim the x-ray sources toward the sample.
> 
> View attachment 400557
> 
> ...



It’s amazing what you can get into when diving you own rabbit hole. That’s why I love this hobby because more often than not I need something that either nobody makes or I can’t find it. Now I can make it.

nice job.


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## homebrewed (Mar 15, 2022)

Parlo said:


> There is an old and seldomly used method for blanking parts without making a die. Using Urethane as a die the punch passes through the sheet and the Urethane forms around it cutting the part.
> Here is a link that shows it better than my explanation.


That's an interesting technique, I'll have to remember it.  I'm not sure if it would work for something as thick as what I need to make -- I think it would necessary to push the work into the urethane as deep as the material is thick.  The lead is .0625" thick.....

Thanks for the tip!


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## Chewy (Mar 15, 2022)

That really looks like a store bought item. Probably a whole lot better!!!


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