On 4 April 2011 05:30, Sven Wesley <[email protected]> wrote: > I need to make a tilting head 4-axis, further on also rotating to get the > 5th axis. Before I start making parts, has anyone already made a similar > machine or own one and would like to provide some details?
Chris (I think) has a tiny little 5-axis mill, but I am not sure how well his design would scale up. http://www.youtube.com/watch?v=1EYaM4FkASA It seems to me that if you engineer it like a lathe headstock with big taper rollers then the rotation is relatively easy to achieve. (and co-axial drive to the spindle seems like it ought to work if you do not want to swing the motor). The problem I see is finding a suitably stiff and backlash-free actuator mechanism. I don't have much feel for how stiff toothed belts would be in this application. Chris' mill has the cutting tip very near the axis of rotation, which will mitigate this problem somewhat. My mill has an adjustable-angle head, and I have pondered whether I could make a "sandwich" drive to go between the clamping surfaces, possibly based on a large-diameter crossed-roller bearing (if one ever appears at a good price) You might find a harmonic drive on eBay which would be a good start. Another solution might be a drive mechanism which in "invented"[1] at a previous employer which uses a large internal gear with 3-4 more teeth than an external gear. The external gear has an anti-rotation link (preferably a flexure, but peg-in-slot might work), and is held tightly in mesh with the inner gear by a rotating, eccentric, housing. There are a lot of teeth in mesh, so it is stiff and low-backlash, and the effective gear ratio is the tooth difference divided by the tooth count, so 50:1 or so is pretty easy to achieve. Drive to the eccentric is the "right side" of this ratio, so can probably be a conventional spur or bevel drive. [1] Almost certainly not for the first time so I don't mind describing it here -- atp "Torque wrenches are for the obedience of fools and the guidance of wise men" ------------------------------------------------------------------------------ Xperia(TM) PLAY It's a major breakthrough. An authentic gaming smartphone on the nation's most reliable network. And it wants your games. http://p.sf.net/sfu/verizon-sfdev _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
