I am working out the details on this coin for a friend.
I wanted to show and get input from others on a good way to create the registration for doing both sides.
Here is what I have so far. Its 50mm diameter.
This was carved at 15IPM with 3 bits. 1st bit was a .098 dia. end mill. 2nd bit was a 2mil dia ball nose, 3rd bit was a 1mil ball nose.
This is a test to see how things will go and it turned out pretty good. I will be running it down to a .5mil ball nose bit however I wanted to get others ideas on using a Vbit. I have heard others using a Vbit to do the fine details but I am not sure how to do it because if your not careful they will break. I have lots of them I bought 10° bits and they are coated but they are very easy to break the tips.
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the 10 and 20 degree bits are a nightmare and break instantly. 30 degree work well in aluminum though. I cut at .001" per pass with those little 30 degree engraving bits. Also, to do two sided, I found the best way is to cut the coin out. Then mill a pocket in aluminum or MDF and then do not turn off the machine, leave the steppers powered and rubber mallet the coin into your pocket and your circles will align perfectly, then zero z only and carve away.
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I made this to engrave coins
bolt goes through the hole to tighten it up.
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Wow thanks for the input.
That coin clamp is interesting. I never thought of doing it that way before. 
Well done Stephen. Your coin is turning out nice. I’ve used v bits in the past and the detail came out great. Another thing you might want to try… I used my 3D printer to create a base that would hold a 2"x2" aluminum square. I know you have a 3D printer, just add some of your ingenuity and I’m sure you can make something work.
Quick question
If I cut out the coin first. There will be tabs. How do you file down the tabs so that is evenly round?
I could use CA glue and glue it down to a board to cut but I didn’t know of there is any other way.
Thanks for the input.
I use a 1" belt sander, takes seconds.
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