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OREDIGGER!
08-17-2005, 07:19 PM
Hi guys,

Thanks for the info a while ago on milling copper, it really helped. I was able to mill the peice and and get it almost done. The problem came when I started tapping the 8 blind holes in the peice with a 6-32 tap, on the second hole the tap broke flush. Now, I did a search and found a few suggestions on getting the tap out, and chose to soak the peice in a solution of alum to dissolve the tap.

When I started, I noticed that copper does react with the alum (AL2SO4) but much slower than the tap. After soaking for a night and a day the tap was still to stuck to get out. So, here's what I'm trying: power dissolving, or basic galvanized battery chemistry. I taped the copper block up entirely with electric tape save the hole with the broken tap, with a wire attached to the copper. I then led that wire to the negative of a wall transformer (12V, 500mA) and stuck the positive lead into the solution. The dissolving is occuring at a much faster rate than with just soaking, and if nothing else, I can see this as a possiblity for etching a design into the copper. Or plating aluminum onto the copper (I'll have to check on that). I let you know how it goes.

Nick

[This message has been edited by OREDIGGER! (edited 08-17-2005).]

[This message has been edited by OREDIGGER! (edited 08-17-2005).]