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Author Topic: Augs inverted image woes  (Read 243 times)
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Richard Cullin
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« on: July 18, 2017, 09:39:26 PM »

i'm still playing around with making pcbs  , now trying out auggie's image rastering,  the TRACKS when lasered with a positive image are
correct width {although quite useless for pcb etching }  When the image is inverted the TRACKS and PADS all seem to shrink ,
 it all looks good on the screen but the result is disappoin ting when lasered.
looks to me that the laser dot with is being subtracte d from the region .
attached are the org pattern and the pos/neg results  , raster was 30mm wide .5mm overscan, @.15mm raster




* augs_neg_vs_pos.jpg (1965.74 KB, 3264x2448 - viewed 26 times.)

* bpcb.bmp (65.51 KB, 118x142 - viewed 67 times.)
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Richard Cullin
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« Reply #1 on: July 18, 2017, 10:50:00 PM »

I inverted the image elsewhere and retried augs  , I still feel the tracks are cropped .
is there any scope for laser dot size adjustmen t ?


* bpcb.bmp (65.51 KB, 118x142 - viewed 67 times.)

* augs_neg.jpg (335.35 KB, 1313x1373 - viewed 9 times.)
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ArtF
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« Reply #2 on: July 20, 2017, 08:45:42 PM »

Hi Richard:

  Id have thought it would get slightly larger.. due to the laser being considere d in auggie to be infinitel y small
in diameter. ( I havent tried any engraving such as your doing.. ). I don't think I added any option to make it turn on sooner or shut off later. It IS odd though, I can picture th eon taking a bit too long to occur, thus shrinking the leading edge, but Id have thought the same effect would lengthen the lagging edge, for an equal or wider line width,
not smaller.

   To make a line rastering across thinner would take a delay in turning on perhaps with no off delay. That I could
see thinning such a line out. You may want to simply try going slower to see if it alleviate s it any? That would
make logical sense if it is an on delay issue...

Art
 
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Richard Cullin
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« Reply #3 on: July 21, 2017, 01:08:07 AM »

hi art
I don't think its a timing thing , traces are thinned n/s as well as e/w . I did try though ,slowing from 500 to 200mm/m makes little differenc e.
it looks more like milling a shape with a 4mm bit when all the offsets were calculate d for a 3mm bit. 
traces and pads I can be oversized to compensat e but it would be nice for etching logo's and such if negative images were true to form

ps trying  dmap2gcod e , results so far no better


* augs_200_v_500.jpg (247.62 KB, 1512x828 - viewed 11 times.)

* bpcbhd.bmp (432.88 KB, 355x415 - viewed 5 times.)
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Richard Cullin
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« Reply #4 on: July 21, 2017, 02:02:14 AM »

ps
I increased the dpi of the source image x 4   thinking it may be a rounding issue .  makes negligibl e differenc e
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ArtF
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« Reply #5 on: July 21, 2017, 06:02:04 AM »

Ahh, I can see it then, makes a kind of sense. Since it thinks a beam is infinitel y small, when it turns on it cuts a
radial distance into anything its cutting. My laser has a very small kerf, so I may not notice it as much, though
I probably would if I tried something like a circuit board trace.

   Other than somehow offsettin g the image, Im not sure I can do anything about it in the raster engraving,
it would entail turning on the beam early and off late to make up for the diameter, and that'd be true in
both e/w and n/s direction s..thats hard to do on the fly with images, not impossibl e, just hard.
 
   Be better to have something that grows the image a bit in all dimension s or something that focuses the
beam a bit tighter..  This does seem to be something Ill face eventuall y though, as I can see where trying to
do inlays will be affected as the positive and negative images wont match... Ill give this some thought..

Art



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Art
tweakie
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« Reply #6 on: November 07, 2017, 03:05:42 AM »

Hi Richard,

Did you manage to solve your track width etching problem ?

Looking at your pictures my thoughts are ( as you have said ‘milling a shape with a 4mm bit when all the offsets were calculate d for a 3mm bit’ ) that your laser focussed ‘dot’ size is too large.

Just to see if I could replicate the problem I copied your pic. and generated the code for Auggie and this was the result.

Hope this helps.

Tweakie.




* DSC02093a.JPG (193.67 KB, 1024x685 - viewed 13 times.)
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Richard Cullin
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« Reply #7 on: November 07, 2017, 04:49:26 AM »

Quote
Did you manage to solve your track width etching problem ?

not really ,i have gone back to gcode generated by the isolation milling pgm for the laser. its a bit slow but i get good results.

my diode laser is fixed focus @18mm focal length and a dot size approx .12mm ,the dot is not perfectly circular either
your laser has done a better job , that would etch quite well.
i'm looking to upgrade to a chinese 50w job  and  will definitel y convert it to auggie running gear.



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