On Thursday, February 23, 2012 02:31:08 AM Jon Elson did opine: > gene heskett wrote: > > Lampblack would be fine IF one could find a binder as effective as the > > krylon that wasn't glossy at low incident angles. A case where thin > > is good, but I expect trying to mill the outside 1/3" of it down to > > the point where knife edge diffraction was the major effect, would be > > pretty frustrating. > > Might be possible to mill it with a ball-end mill so that the > sides were not parallel to the light path. > > Looks cool, anyway! > > Jon
Thanks Jon. I thought of that, but by the time I had it clamped down on a sacrificial slab of HDPE, it was bowed up in the middle by 13 thou or so. Unless I mapped the cut depth carefully, the slot width would have been the largest variable. To get fully thru a 32 thou thick sheet, I actually had to carve 47 thou deep on the final pass. Theoretically I imagine there is a timing error from that, but it should get lost in the noise in spite of it. I thought about reducing the slot count from 45 to 36, but that would stretch the edges to 2.5 degrees apart. If I can't get a good duty cycle and quadrature pattern out of this one after its blacked, then I supposed I'll make another with fewer slots just to widen the dark bars, but we'll see how close to ideal this one is first. I sure wish I had more diameter available though. That would make things a lot easier. 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) My web page: <http://coyoteden.dyndns-free.com:85/gene> Mankind is poised midway between the gods and the beasts. -- Plotinus ------------------------------------------------------------------------------ Virtualization & Cloud Management Using Capacity Planning Cloud computing makes use of virtualization - but cloud computing also focuses on allowing computing to be delivered as a service. http://www.accelacomm.com/jaw/sfnl/114/51521223/ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
