Moderators: Dave Moll, Andrew Davie, Steve Anderson
gary wrote:Nice, the problem with printing Nipkow disks must surely be creating the tiny apertures? He did well here to get them down to 1mm which, of course, is far too large for a disk of this size.
HOWEVER, it seems to me these would be ideal for "bead" disks, where the aperture is the size of the optical quality acrylic balls (I use 1/8", 3/16", and 1/4").
What is the (working) size of your 3D printer bed Andrew?
Andrew Davie wrote:gary wrote:Nice, the problem with printing Nipkow disks must surely be creating the tiny apertures? He did well here to get them down to 1mm which, of course, is far too large for a disk of this size.
HOWEVER, it seems to me these would be ideal for "bead" disks, where the aperture is the size of the optical quality acrylic balls (I use 1/8", 3/16", and 1/4").
What is the (working) size of your 3D printer bed Andrew?
Not difficult to create small holes, actually. I could probably do rough holes which are 0.1mm diameter positioned to 0.05mm accuracy and then round 'em off with a drill bit.
I use a Flashforge Dreamer... here are the claimed specs...
Positioning Precision: 0.0001” on Z axis, 0.0004” on XY plane
Resolution: 0.004”
Build Volume: 9.1” x 5.9” x 5.5”
That claimed 0.0004" seems a tad optimistic to me!
But you see the volume - about 15cm max diameter. You could print a disc in multiple parts with a jigsaw-puzzle-like joiner and it should go together pretty accurately.
gary wrote:
Interesting, I have no doubt about the positional accuracy (it is, after all, a CNC machine) but I would have thought the width of the extrusion would be the limiting factor (as is the diameter of an end mill in a CNC machine) but I suppose the fact that it is an additive machine rather than a subtractive machine (CNC) means that can be compensated for?
None-the-less I would still have thought it unlikely that you could get a consistent enough extrusion width to be that accurate (~.01").
Impressive stuff if you can do it - I suppose you have done a test?
$fn=32;
SCANLINES = 32;
DISC_RADIUS = 75;
DISC_THICKNESS = 0.5;
HOLESIZE = .25;
OVERLAP = 0.8; // 1.0 = no overlap, 0.9 = 10% overlap, etc.
OUTER_EDGE = 10; // distance from outer edge to first scanline hole
INNER_EDGE = 10; // distance from inner scanline to sync holes
// Auto calculated - do not change these!
SPACING = HOLESIZE*OVERLAP;
POSITION = DISC_RADIUS - SCANLINES*SPACING - OUTER_EDGE;
SYNC_POSITION = POSITION - INNER_EDGE;
SYNCHOLE_SIZE = 1; // radius
difference() {
// the disc itself
cylinder(r=DISC_RADIUS,h=DISC_THICKNESS,$fn=64);
// a hole in the middle
translate([0,0,-1])
cylinder(r=1,h=2+DISC_THICKNESS);
// do the scanlines and the sync
for (i=[0:(SCANLINES-1)]) {
// The scanline hole
rotate([0,0,i*360/SCANLINES]) {
translate([POSITION+i*SPACING,0,-1])
cylinder(r=HOLESIZE,h=2+DISC_THICKNESS);
// The sync hole
translate([SYNC_POSITION,0,-1])
cylinder(r=SYNCHOLE_SIZE,h=2+DISC_THICKNESS);
}
}
}
gary wrote:Great! Can you send me one for my beads as well? Then I only need one LED .
Andrew Davie wrote:gary wrote:Great! Can you send me one for my beads as well? Then I only need one LED .
So, two of the same? Not sure if you're making fun or not. If not, PM me your address and I'll do some for you.
gary wrote:The bead version would have larger holes (I need to check my supplies but I think I have enough 1/8" beads) - but I could just as easily drill out the smaller apertures, it's just that I have a gut feeling that 1/8" apertures would be more accurate and it would be interesting to see if that is correct.
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