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Engraving with the cheap 30 degree engraving bits (.2 mm point) available at Amazon - very cheap. Using V-Carve tool path, engraving at .003" per pass, and setting the flat bottom at .01" total DOC at 40-50" IPM. Each coin takes about an hour per side but I “walk away” and let it run. Then, they coins are sanded with 100, 400 then 2000. Then, buff on buffing wheel. Then, cleaned in paint thinner, then soap and water. Then, soaked in brass darkening solution. Then, lightly sanded with 2000 so the recesses stay stained.
4 x 12" x .25" thick brass bar stock. Face mill each side down .03" prior to engraving, that way, I know the engraving bit will finish the coin with no low or high spots. The coin or medal comes out to be about .1875" thick. After the first side is engraved, I profile it, sand off the tabs and insert it into an aluminum jig to do the other side. The aluminum jig has a set screw on the side to hold the coin tight. The set screw leaves a mark, but sands off nicely.
Typically a .125" viper two flute. A couple of these, I experimented with a .25" viper two flute, which is a little noisier, but I think it might last longer than the smaller bit and seems to provide a slightly better finish… but that could be because it is new.
You can try this code: ERF8B - it should give you 15% off through June 30th - over $30! I think it will work for you - this is the offer I received from them at the beginning of the month and I don’t think it is tied to my account.
If that’s the place off of 24th and Hiawatha, I grew up in that neighborhood and was baptized in the church with the really tall steeple you can see right nearby… It brought a smile to my face when you posted the name.
You’ve definitely inspired me to go ahead and give this a try. I’ve been wanting to for a while, but this was the push I needed! Great work and thanks for the tips on the run parameters!
That is great work. I think you may be using the same cheapie amazon bits I’m using, lol. I never thought to try them on metal, though. How are you getting the toolpath marks off the pockets? Are you blasting them?
