accuracy problem

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erol
Posts: 49
Joined: 07 Oct 2017, 17:08

accuracy problem

Post by erol »

Hello friends.

Scans have dimensional accuracy problems (0.2mm-0.4mm).
Part length 55mm

My setup
calibration panel: 60mm (original hp panel)
dual cameras (david sls3)
hp 5.5.0
turntable

calibration values,

camera1 angle: 17.93 ˚ ===> Rms: 0.115
camera2 angle: 17.85 ˚ ===> Rms: 0.178
total: 36 scans

Why the dimensional accuracy is bad and what should I do to fix it.
Attachments
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Micr0
Posts: 586
Joined: 15 Nov 2016, 15:20
Location: New York City

Re: accuracy problem

Post by Micr0 »

How are you deriving those error numbers/ How are you measuring the accuracy?

Also what is the scan subject? what is it made of?

µ
µ
erol
Posts: 49
Joined: 07 Oct 2017, 17:08

Re: accuracy problem

Post by erol »

Thank you Micro for your fast replay.

I made measurements again with my digital calipers tonight and yesterday I was wrong. The part material is silicone. When measuring, the part caused the wrong measurement because it stretched.

I froze the piece deep freeze before the measurement this evening (5 hours).
as a result the accuracy is 0.02mm :)
Attachments
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P_20180829_003013_vHDR_On.jpg
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Micr0
Posts: 586
Joined: 15 Nov 2016, 15:20
Location: New York City

Re: accuracy problem

Post by Micr0 »

erol wrote: 28 Aug 2018, 21:49 Thank you Micro for your fast replay.

I made measurements again with my digital calipers tonight and yesterday I was wrong. The part material is silicone. When measuring, the part caused the wrong measurement because it stretched.

I froze the piece deep freeze before the measurement this evening (5 hours).
as a result the accuracy is 0.02mm :)
Squishy (very technical term) parts are difficult to get accurate measurements from. I had suspected thus. Glad you solved you problem. :D
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mading
Posts: 307
Joined: 31 Jan 2017, 13:09

Re: accuracy problem

Post by mading »

Dear Eol,
Do you use the david Acer K132+?
LG PF50, LG PF1500, RangeVision DIY: 2x DahengMer630, 2X12 and 2X16 mm 5Mp ZK lenses, RV turntable
martan
Posts: 96
Joined: 23 May 2018, 19:18
Location: Sweden

Re: accuracy problem

Post by martan »

Nice scan!

:)
HP 3D Scan, Optoma ML750, 2x IS DMK 23UX236 with Computar 12mm, HP calibration panel, DIY Rotary tables.
erol
Posts: 49
Joined: 07 Oct 2017, 17:08

Re: accuracy problem

Post by erol »

Thank you.

I have a david sls3 scanner (dual camera and v5.5) and original acer k132 +.

Another scan but I did not check accuracy :D
Attachments
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2018-05-26_22-17-47.png
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Micr0
Posts: 586
Joined: 15 Nov 2016, 15:20
Location: New York City

Re: accuracy problem

Post by Micr0 »

Very nice. You seem to be getting excellent results. Are the surfaces of your scan matching in smoothness to that of your subject?
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erol
Posts: 49
Joined: 07 Oct 2017, 17:08

Re: accuracy problem

Post by erol »

Thank you Micr0,

The surface smoothness in the scans is generally good and matches the object.
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