DIY Calibration panels for HP/David

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Farquarl
Posts: 3
Joined: 08 Oct 2018, 18:12

DIY Calibration panels for HP/David

Post by Farquarl » 09 Oct 2018, 04:21

Hello,

I would be really glad if some of you could share how they build their calibration panels.
I am not statisfied with mine, the scans get warped and are therfore hard to align.

Best regards,
Thore

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Micr0
Posts: 295
Joined: 15 Nov 2016, 15:20

Re: DIY Calibration panels for HP/David

Post by Micr0 » 09 Oct 2018, 15:39

I've used a number of different methods to make panels ranging from 60mm to 1000mm. The best panels (the ones that produce the most accurate scans I made on one of my VMCs. The smaller ones I made by milling away white vinyl that was layered over 2 layers of black vinyl on glass plates. The larger ones were made from white Laminate Melamine and I milled the circles .1mm deep, then filled then with black paint. These were held by 3D printed holders for the small panels and CNC'd Aluminum holders for the larger ones. I''v tried printing patterns with a laser printer, Roland vinyl cutter and having anodized aluminum laser engraved. None were as accurate as the CNC'd parts.
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Farquarl
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Joined: 08 Oct 2018, 18:12

Re: DIY Calibration panels for HP/David

Post by Farquarl » 11 Oct 2018, 04:40

Thank you for your input!
I don't own a vmc sadly but i'll buy a CNC router. Maybe i should go this route than. I want to scan really small items and therefore precision of the panels ist crucial.
Is there a list of sone sort that shows the important factors?
90° is important ofc and the distance between the dots as well. But what ist about the distance between the twp sides of the panel, their rotation and alignment?

Cheers

goldenfab
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Joined: 01 Nov 2018, 02:55

Re: DIY Calibration panels for HP/David

Post by goldenfab » 01 Nov 2018, 02:58

I just purchased the software (v5) and it did not come with the pdf file for the calibration panels. Does anyone know where I can download them?

[Edited: I just fond out they are in my program file directory C:\Program Files\HP 3D Scan 5\printout]

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Micr0
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Re: DIY Calibration panels for HP/David

Post by Micr0 » 05 Nov 2018, 14:22

goldenfab wrote:
01 Nov 2018, 02:58
I just purchased the software (v5) and it did not come with the pdf file for the calibration panels. Does anyone know where I can download them?

[Edited: I just fond out they are in my program file directory C:\Program Files\HP 3D Scan 5\printout]
They are also available on Davids old download site. Just google david laserscanner and it comes up.
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Micr0
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Re: DIY Calibration panels for HP/David

Post by Micr0 » 05 Nov 2018, 14:45

Farquarl wrote:
11 Oct 2018, 04:40
Thank you for your input!
I don't own a vmc sadly but i'll buy a CNC router. Maybe i should go this route than. I want to scan really small items and therefore precision of the panels ist crucial.
Is there a list of sone sort that shows the important factors?
90° is important ofc and the distance between the dots as well. But what ist about the distance between the twp sides of the panel, their rotation and alignment?

Cheers
My understanding, and big bomber understands this better than I is that the most crucial parameter is the positioning of the dots and the flatness of the panels. David can compensate for the panels not being perfectly normal to each other. And it has compensation for the panels being slightly rotated retaliative to each other. That said, it is always better to not have errors that to try to compensate for them.

As for the VMC slash Router. Most CNC routers use stepper motors without encoders. Even with encoders, steppers are not anywhere near as good as servos when it comes to positional accuracy. Not to mention the difference in the mechanism for translating the rotational force of the motor to linear motion of the machine. Linear rails with preloaded ball screws will be far more precise than V rail and rack and pinion or gear reduction to timing belt drive.

However, all this is really mostly academic. You can still get good calibration results with less than laboratory grade calibration panels. It will take a little bit of work to tweak it till you get it where you get acceptable results. Read some of the threads on the forum about RMS error and calibration to understand better what you are shooting for.
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Farquarl
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Joined: 08 Oct 2018, 18:12

Re: DIY Calibration panels for HP/David

Post by Farquarl » 06 Nov 2018, 05:53

Good to know!
My router will have servos and preoloaded hiwin rails, so in that regard im set. Well at least i should have betrer precsion than my laserprinter.
Thanks for your input.
Cheers

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