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  1. #101
    John,
    I have found a dirt cheap webcam online which is very easy to dismantle which I plan to play with once my more urgent project of working out how to successfully cut wooden gears proves fruitful.

    Much as I'd love to come and see you at the MSME I'm afraid it's a bit of a long way from here, even though I don't need to show my passport enroute.

    Kit
    An optimist says the glass is half full, a pessimist says the glass is half empty, an engineer says you're using the wrong sized glass.

  2. #102
    Hi Kit,

    Inkscape has an add-on that will draw involute toothed gears and gear racks. I have used this to input a dxf into Fusion360 to extrude it to an stl for 3D printing. I haven't yet had the need to cnc cut one though. If you want helical cut teeth you are on your own.

    Cheers,

    Rob

  3. #103
    Rob,
    Thanks for the information but I use a rather splendid bit of software called 'gearotic' written by Art Fenerty, the creator of MACH3. For anybody interested in creating gears of any kind you can think of, and several kinds you previously couldn't, and especially anyone who wants to design wooden clocks I can heartily recommend it. The program, not unlike Art himself, is a little eccentric and is therefore, in my humble opinion, well suited to many of the regular contributors to MYCNCUK The one-off, minimal license fee entitles you to a lifetime of free upgrades.

    Gearotic is brilliant for creating the basic gear design. I then export a DXF file to CamBam for design editing and G-code output.

    My problem in cutting wooden gears is that those teeth that have the grain running tangential to the gear wheel tend to chip and break off when cutting. Teeth with the grain running radially are fine. I have managed to successfully cut gears from Jarrah blanks created from six segments with the grain running radially all round but the wastage of timber is criminal. I'm currently experimenting with plain pine blanks stabilised with Cactus Juice resin.

    Most wooden clock makers use plywood for the gears but, being me, I want to use various types of better-looking plain timber to produce a more impressive result.

    I had thought about starting a new thread asking for help on how to cut these gears if the current experiments don't work. I'd prefer not to hijack this existing discussion.

    Kit
    An optimist says the glass is half full, a pessimist says the glass is half empty, an engineer says you're using the wrong sized glass.

  4. #104
    Hi All

    Today I ran a test on a webcam generously sent to me as a gift from a forum member. A wonderful gesture.

    I do not know much about the sensor apart from the fact that it appears to be dated 2012.

    The test was made using the sensor and .008" piano wire as done before.

    When I tested it with Joe's software it counted 93.7 pixel lines to measure 0.2mm
    My previous tests with a Microsoft webcam over the same distance of 0.2mm counted 47.56 lines.

    The new tests prove the camera given to me has almost twice the resolution of the Microsoft unit.

    0.0021mm or 0.00008 inches. per pixel line.

    The new camera also displayed less noise and was less sensitive to stray light. All in all a better unit. I will try to find out more about it.

    The latest results have really inspired me to to press on with improving the mounting of the camera and better light control. I will report back here with my results. Maybe the Webcam driver software can be used to adjust the sensitivity. That would be useful.

    There may even be higher resolution webcam sensors available.... technology marches on.

    The accuracy now already achieved will enable the unit to be used to easily test large precision machine tables for flatness if the catenary equation sag corrections can be applied to the measurements.

    All this started with Joe's software, Thanks Joe.

    Regards
    John

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  5. #105
    Quote Originally Posted by John McNamara View Post
    Hi All


    All this started with Joe's software, Thanks Joe.
    Hi John,

    You are very welcome, I've been a bit busy with work, great to see you are making progress.

    Yes it should be possible to grab higher resolution images from the camera giving you the choice of more dynamic range or adjustable sensitivity.

    Cheers, Joe

  6. The Following User Says Thank You to devmonkey For This Useful Post:


  7. #106
    Did anybody test flatness of the laser beam yet? I'm impressed with results you're getting and just that one question remains unanswered.
    I have garde 00 600x400 mm granite plate, one diagonal(720mm) is within 1 micron.
    SJ4000 with large sensor and high resolution and can act as webcam.
    just no laser...checking ebay...

  8. #107
    Hi Sasquatch

    If you study the two test series I did with two different sensors you will see that the resolved measurements taken with the second sensor were better with the higher density (The pixel lines were closer together), sensor used for the second set of tests.

    No lens was used just the wire shadow.

    Devmonkey mentioned that the results were better without a lens when he did tests with a laser. Using a lens with the laser generated distortion? I can also confirm this when I tried using a laser with a lens.

    Maybe the standard lens supplied with a webcam or action cam is not the ideal for working with a laser. I know industrial laser cutters use lenses made from Germanium and other exotic materials.

    A friend who spent his working life as a physics lab tech also mentioned that webcams will probably have a red filter behind the lens and in front of the sensor. He suggested that this should be removed if working with laser light.

    These are only study notes on my part, I wish I knew more about optics. Maybe one of the MYCNCUK members here can give a more qualified view?

    Regards
    John

  9. #108
    Hi John.
    My action cam lost lenses in shooting accident (air rifle ricochet).
    Flare with lenses is an result of partial reflection on each layer of glass/ plastic beam is passing trough.
    My action cam had a infrared filter behind the lenses.
    Sensor is about 3x4 mm 1080p gives higher pixel density than 2 mm wide VGA sensor. Should be good.

    Can't find any lasers with single cylinder lense. No Dewalt dw088 on ebay UK in acceptable price. Any cheap laser recommendations ?
    Edit 1:

    Figured out easy and cheap way of testing projected line straightness.
    Method requires roughly straight surface, aluminium extrusion should do. Surface must only be flat within sensor measurement area.
    line laser
    pointer laser
    2x camera sensors set 90 degrees to each other.
    first camera is following pointer aiming along the beam
    second camera is following projected line
    With some excel magic we can deduct straightness of projected laser line independently of any beam errors.
    Given we can get 3-4 microns resolution on both sensors accumulated measurements arrors should be below 0.01mm in worst case ->just a gut feeling, no real maths behind it so feel free to correct me. That should be more accurate than any straight edge one could buy, as 0.01mm over, say 3 meters, is waay beyond din 874/0. and sag on wire could be greater than 0.01mm too?

    Edit 2:
    Software feature request:
    Can we have adjustable capture resolution,since higher res cameras have bigger sensors allowing wider beams and/or wider measurements range?
    Or at least run in maximum supported resolution, whichever is easiest.
    Also when requesting VGA stream from 1080p sensor camera firmware is scaling each frame introducing errors.

    Edit 3:
    Created pull request on GitHub with more resolutions possible.
    Unfortunately i can't figure out how to add menus to change resolution nor how to pass resolution via command line parameters.
    Just edit settigs.java and rebuild to required resolution, supported are 320x240,640x480,800x600, 1280x720 and 1920x1080.
    Hope that @devmonkey don't mind and will add settings menu in free time.
    Last edited by Sasquatch; 17-10-2019 at 12:54 PM. Reason: new idea

  10. #109
    Sasquatch,

    I haven't got one myself but this laser looks very promising with a glass cylindrical lens.
    https://banggood.app.link/PPKk7DZpR0

    Will integrate your resolution changes when I get time.

    Cheers, Joe

  11. #110
    I've committed a change so that it determines the maximum native resolution of the camera and uses that, please test.

    Cheers, Joe

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