cutting steep tapers with robofil 290P
I have a couple of robofil 290P machines and usually cut straight work with an occasional job that needs 1-3 degree or so for die slug clearance. My machines do not have taper expert on them. I took in a job that needed a u shape path cut in it with 17 degrees on the left and right and 20 degrees at the back 1/8 radii in the corners in 5/8 thick 4140ht. Kind of like a 3 sided funnel. I wasn't sure if I could get the 290 to cut those biger angles or if I would end up in a machining center doing it all with a ball end mill . The 290 did it with some tinkering around with the gen settings and the parts turned out close enough for the wide open tolerance +-.003.
The big question in my mind now is just how steep can I go with .010 soft brass before it becomes too much for the guides/wire/flushing etc. The 290 has the same uv travel as the xy so it isn't physically limited on where the guides can be. What I am looking for is how steep of a taper and in what thickness have you guys been able to cut before it became a flushing nightmare or other issues made it unacceptable?
I think Charmilles specifies 30 degree angles can be cut with .010 half hard brass wire with their XX0 machines, like the 300/310 and 500/510. Being submerged helps alot as far as wire breaks go, due to flushing issues. For angles larger than 30 degrees other machine manufacturers specify the use of special guides that reduce wire drag (and wear of the guides) often called C guides or U guides. If you've got the part with the large profile of the cut being generated by the U-V axis you will be in good shape for flushing on skim passes. The use of medium or high taper nozzles is beneficial. They form a wider column of water for flushing, and are worth every penny, for nonsubmerged machines. I've used the same taper nozzles for years with no problems, or lack of flushing efficiency. Consider raising the Z axis 1/4 inch for skim passes to prevent a "bubble" from forming, which can leave your wire cutting dry. Also, if your machine is well maintained, you should be able to hold a couple tenth tolerance with it, no sweat.