Hi - I'm still pretty new at machining. We got our CNC router only a few months ago and so far all I've used it for its making parts from wood. Now I'm getting into some brass projects and am having problems.
Our situation is that we'd like to cut out lots of small levers from .032" sheet brass. Each piece has a part number engraved on it and a .065" pivot hole. My feeds & speeds testing seems to tell me that the .0394" 2-flute cutter bit will work fine to cut the parts out in one pass at F24 S20,000.
The problem is the engraving and pivot hole.
As the engraving number is so small the Z has to be incredibly precise and my table is off level by several thou. I've been asking around and it seems to be that I can level it (the waste/backer board) using some sort of planer bit? What do they mean by that and where can I get one? Our machine has a ER16 collet.
I've been using a plywood waste/backer board for our woodworking but now with using lubricant I'll need to find another product. Some sort of plastic sheet? Suggestions? I must be Googling with the wrong words as nothing seems to be coming up.
Someone had suggested using a variable pressure engraving holder but the only one I've found is very expensive and too large for my machine.
The pivot hole.... ugh. I've broken a half dozen bits trying to find a feed & speed for it. After asking around I'm finding that I have to hold the brass sheet down. It's 12"x12" and I have it clamped around all the edges but it the sheet raises somewhat when the bit gets extracted - which is usually when the bit breaks (though it's broken trying to enter a couple times).
Asking around they say that I have to hold the material down well. The machine doesn't have a pressure foot attachment. It think it would be great to find one that also vacs stuff away as well. Googling around I see a lot of home-made jobs but can't seem to find any commercial after-market ones.
-- Rich --