So I've got an interesting project to try on my lab's Tormach. Basically we just want to cut some masks out of thin sheets (in the 1/16" ~ 1/64" range) of molybdenum, or failing that, aluminum. What makes it interesting is that the patterns in the mask have features fractions of a millimeter wide, and we might also need good alignment between different patterns on different masks.
So, first question - I'm thinking that milling it all in one setup is the only way to get the desired accuracy, which leads me to think I should glue the sheet to some sacrificial aluminum. That way I don't need to do any fancy edge finding, just roughly center the sheet, mill the patterns, cut out a circle around the patterns with an alignment notch, then release the mask from the sacrificial aluminum block. So, can anybody recommend a good glue for this type of workholding? Preferably it could be released with some acetone or heating.
Secondly - I have some really tiny end mills (0.02", 0.016", 0.01"), but I'm afraid of using and breaking them (haven't worked with them before). It occurred to me that since this is a mask, we don't care about having slots with vertical sidewalls, a \ / shaped slot would be just fine so long as the narrowest width at the bottom meets our specs. Hence I was thinking about using a drill mill like
http://www.mcmaster.com/#3723a11/=22kwy5 pushed just barely through the sheet to make thin lines. Anybody do fine detailing work with these on a Tormach? I'm trying to figure out if there's some kind radius on the tip - I'd love to be able to make 0.004" wide slots, but 0.01" might do. I'm also a little confused about the speeds and feeds - it seems like since the tool diameter ranges from 1/8" or whatever down to effectively zero that you'll end up essentially dragging the point through the material rather than really cutting. Do you just set the speed/feeds based on the smallest diameter at which you care about the surface quality? Machining time is not important to us - if it takes us 10 hours to cut that part that's ok since the mask will save us a lot of time in the long run.
Finally, has anybody worked with molybdenum before? Anything important to consider with cutting it on a tormach?