On Wednesday, June 15, 2011 12:21:07 PM Viesturs Lācis did opine: > 2011/6/15 andy pugh <[email protected]>: > > On 15 June 2011 11:49, Dave <[email protected]> wrote: > >>>>A better solution might be a custom kinematics module. > >> > >> That sounds interesting! > > > > Let me have a fiddle over the next few days, it might not be all that > > difficult to get something basic, then it is just a case of doing the > > hard sums. > > Well, I think that the code can be derived in following way: > 1) draw the required shape;
Not a viable method today folks, at least when applied to dependable, high performance engines. Most cam profiles for IC engines today are computer generated to compensate for the flex characteristics in the valve train, and to reduce as much as possible, the instant forces, both of which can prolong the life of the valve train parts by an order of magnitude while maintaining the desired timing characteristics and staying within the limits of the tappet faces diameter and profile. Not having the software to do that 30 years ago is likely the reason that 305/327/350 Chevies had a cam & tappet life of about 5k miles, after which the performance went down and the fuel mileage went down even faster. I have seen 350 Chevy cams with 30k miles on them that had less than 1/16" of lift left at the valve. And got 2.5 mpg at 50 mph with an empty 14' box van box. A fresh cam & lifters and they were back to 12 mpg at 65 mph. That software is likely not allowed in the same room with an internet connection so we're not likely going to be able to draw a profile that competes. > 2) offset by radius of grinding wheel; > 3) that would produce the shape in XY coordinates; > 4) now these XY coordinates have to be transformed to polar > coordinates, where angle is A and radius is X, Z or whichever > coordinate that moves the grinding wheel; > > That transformation can be done in following way: > 1) origin of XY should be in the point, which corresponds to > centerline (axis of rotation) of CAMshaft; > 2) split the code in very small linear moves; > 3) sqrt of X^2 + Y^2 is the position of grinding wheel; > 4) atan2(Y,X) is the position of angular axis; > > The code will not be very optimized, but at least it should work. > When placed in a subroutine, repeating the moves, each time a > little-bit closer to center, should make the final code pretty usable. > > Viesturs > > ------------------------------------------------------------------------ > ------ EditLive Enterprise is the world's most technically advanced > content authoring tool. Experience the power of Track Changes, Inline > Image Editing and ensure content is compliant with Accessibility > Checking. http://p.sf.net/sfu/ephox-dev2dev > _______________________________________________ > Emc-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users Cheers, gene -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) Flattery is like cologne -- to be smelled, but not swallowed. -- Josh Billings ------------------------------------------------------------------------------ EditLive Enterprise is the world's most technically advanced content authoring tool. Experience the power of Track Changes, Inline Image Editing and ensure content is compliant with Accessibility Checking. http://p.sf.net/sfu/ephox-dev2dev _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
