TightWire Alignment - Revision history

ChuckH at 05:52, 11 August 2014

2014-08-11T05:52:42Z

← Older revision		Revision as of 05:52, 11 August 2014
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	[[image:TightwireCloseup.jpg\|400px]]		[[image:TightwireCloseup.jpg\|400px]]

	The necessary image processing program has not been written. It could possibly be written as a macro in [[http:~~rsbweb~~.nih.gov/ij/ \|ImageJ]], a great open-source image/vision program.		The necessary image processing program has not been written. It could possibly be written as a macro in [http://imagej.nih.gov/ij/ ImageJ], a great open-source image/vision program.

	Features needed:		Features needed:

ChuckH at 21:23, 19 December 2011

2011-12-19T21:23:33Z

← Older revision		Revision as of 21:23, 19 December 2011
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	* Report table of x- and y- deviations from centerline along travel distance.		* Report table of x- and y- deviations from centerline along travel distance.
	* Report deviations from straightness (i.e. deviation from best-fit straight line)		* Report deviations from straightness (i.e. deviation from best-fit straight line)

	~~== Review ==~~

	~~19 Dec 2011 from: Kevan Hashemi~~

	~~Dear Chuck,~~

	I enjoyed looking at your Open Source Ecology web page. Your idea for two mirros to provide a view of both wires in one camera is ingenious. Our collaboraters at the DESY lab in Germany did the same thing, except they used a prism instead of mirrors. They seemed to be doing well with the idea, but they ended up switching to our devices for various reasons.

	If you make the wire horizontal or vertical in the image, this will make your analysis easier. In your image you see a reflection along the center-line of the wire. If you can rely upon that reflection being there, you could use it to mark the center of the wire, and get it to a few thousandths of an inch.

	~~Yours, Kevan~~

ChuckH at 21:22, 19 December 2011

2011-12-19T21:22:09Z

← Older revision		Revision as of 21:22, 19 December 2011
Line 61:		Line 61:
	* Report table of x- and y- deviations from centerline along travel distance.		* Report table of x- and y- deviations from centerline along travel distance.
	* Report deviations from straightness (i.e. deviation from best-fit straight line)		* Report deviations from straightness (i.e. deviation from best-fit straight line)

			== Review ==

			19 Dec 2011 from: Kevan Hashemi

			Dear Chuck,

			I enjoyed looking at your Open Source Ecology web page. Your idea for two mirros to provide a view of both wires in one camera is ingenious. Our collaboraters at the DESY lab in Germany did the same thing, except they used a prism instead of mirrors. They seemed to be doing well with the idea, but they ended up switching to our devices for various reasons.

			If you make the wire horizontal or vertical in the image, this will make your analysis easier. In your image you see a reflection along the center-line of the wire. If you can rely upon that reflection being there, you could use it to mark the center of the wire, and get it to a few thousandths of an inch.

			Yours, Kevan

ChuckH: /* Set up for checking lathe way straightness */

2011-12-19T06:36:50Z

Set up for checking lathe way straightness

← Older revision		Revision as of 06:36, 19 December 2011
Line 57:		Line 57:
	* Establish displacement of wire image from reference line		* Establish displacement of wire image from reference line
	* Establish scale factor from spacing between the two reference lines		* Establish scale factor from spacing between the two reference lines
	* Adjust angle between the two ~~reflectec~~ sightlines (it won't be exactly 90 degrees)		* Adjust for angle between the two reflected sightlines (it won't be exactly 90 degrees)
	* Adjust for wire sag (need to know tension weight and density of wire material)		* Adjust for wire sag (need to know tension weight and density of wire material)
	* Report table of x- and y- deviations from centerline along travel distance.		* Report table of x- and y- deviations from centerline along travel distance.
	* Report deviations from straightness (i.e. deviation from best-fit straight line)		* Report deviations from straightness (i.e. deviation from best-fit straight line)

ChuckH at 20:13, 18 December 2011

2011-12-18T20:13:11Z

← Older revision		Revision as of 20:13, 18 December 2011
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	Tight wire alignment is a technique for measuring straightness of large equipment components. ([http://www.powerhousetool.com/align.htm example supplier]) It has a long history although it has been largely displaced by optical methods. It may be appropriate for creating straight movement axes in [[http://flowxrg.com/2011/12/01/concrete-lathe-manual-v1-10/ \| lathes]], [[CNC_Torch_Table \| torch tables]], and other machine tools (especially appropriate for [[Shonda_Research \|concrete-bed, grouted-ways designs]]).		Tight wire alignment is a technique for measuring straightness of large equipment components. ([http://www.powerhousetool.com/align.htm example supplier]) It has a long history although it has been largely displaced by optical methods. It may be appropriate for creating straight movement axes in [http://flowxrg.com/2011/12/01/concrete-lathe-manual-v1-10/ lathes], [[CNC_Torch_Table \| torch tables]], and other machine tools (especially appropriate for [[Shonda_Research \|concrete-bed, grouted-ways designs]] in a start-from-scratch model).

	== Principle ==		== Principle ==

ChuckH at 20:11, 18 December 2011

2011-12-18T20:11:33Z

← Older revision		Revision as of 20:11, 18 December 2011
Line 1:		Line 1:
	Tight wire alignment is a technique for measuring straightness of large equipment components. ([http://www.powerhousetool.com/align.htm example supplier]) It has a long history although it has been largely displaced by optical methods. It may be appropriate for creating straight movement axes in lathes, [[CNC_Torch_Table \| torch tables]], and other machine tools (especially appropriate for [[Shonda_Research \|concrete-bed, grouted-ways designs]]).		Tight wire alignment is a technique for measuring straightness of large equipment components. ([http://www.powerhousetool.com/align.htm example supplier]) It has a long history although it has been largely displaced by optical methods. It may be appropriate for creating straight movement axes in [[http://flowxrg.com/2011/12/01/concrete-lathe-manual-v1-10/ \| lathes]], [[CNC_Torch_Table \| torch tables]], and other machine tools (especially appropriate for [[Shonda_Research \|concrete-bed, grouted-ways designs]]).

	== Principle ==		== Principle ==

ChuckH: /* Optical sensor */

2011-12-18T19:58:39Z

Optical sensor

← Older revision		Revision as of 19:58, 18 December 2011
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	== Optical sensor ==		== Optical sensor ==

	As an alternative to manual micrometers, a close-up camera may observe the wire position. Kevan Hashimi at [http://www.opensourceinstruments.com/WPS/ Open Source Instruments] describes such an instrument for scientific work. Here we describe a low-cost adaptation to the machine-alignment task.		As an alternative to manual micrometers, a close-up camera may observe the wire position. Kevan Hashimi at [http://www.opensourceinstruments.com/WPS/ Open Source Instruments] describes such an instrument for scientific work. Here we describe a low-cost adaptation to the machine-alignment task. The procedure for aligning ways is
			* If no carriage exists yet, fabricate a kinematic slider to ride on the ways
			* Place brackets (if necessary) and string a tight wire parallel to the ways.
			* One wire support is a pulley wheel; hang a dead-weight for tension.
			* Mount the mirror assembly (described below) to the carriage or slider, centered on the tight wire.
			* Attach a video camera to the carriage, looking into the mirrors. Close focus ("macro") is useful.
			* Run the carriage up the ways, recording video
			* run processing program on the video, which will report deviations along the travel (sensitivity better than 0.0005 inch should be achievable)
			* adjust ways with shims, repeat tightwire measurement.
			* apply grout and allow to harden, holding ways in permanent alignment.

	This sensor relies on a single camera looking at images of the tight wire in two small mirrors. The assumption is that some kind of electronic camera (webcam, cell phone, etc) will be available on an ad hoc basis, but is not permanently dedicated to the instrument.		This sensor relies on a single camera looking at images of the tight wire in two small mirrors. The assumption is that some kind of electronic camera (webcam, cell phone, etc) will be available on an ad hoc basis, but is not permanently dedicated to the instrument.
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	=== Proof of concept ===		=== Proof of concept ===

	~~For testing~~ I ~~used an LG Optimus cell phone camera. This camera can capture video~~.		''Note:'' This is just a proof on concept "mock up", I don't think this design is stable enough to be usable yet.

	~~Parts of the optical sensor:~~		For testing I used an LG Optimus cell phone camera. This camera can capture stills and moving video.

			==== Parts of the optical sensor: ====
	[[image:TightwireParts.jpg\|400px]]		[[image:TightwireParts.jpg\|400px]]

	~~Assembled:~~		I used nylon "invisible thread" 0.005-inch diameter. Steel would probably be better (more opaque, for starters).

			==== Assembled ====
	[[image:TightwireAssembled.jpg\|400px]]		[[image:TightwireAssembled.jpg\|400px]]

			The mirrors are placed so that the images of the wire (when centered) are colinear with the reference marks. By doing the video measurements relative to the reference marks we make the exact location of the camera non-critical.

	Set up for checking lathe way straightness:		==== Set up for checking lathe way straightness ====

			The company where I work has a lathe, so I set up this trial on it.

	[[image:TightwireOnlathe.jpg\|400px]]		[[image:TightwireOnlathe.jpg\|400px]]

	~~(The "wire" is nylon monofilament sewing thread, 0.005 inch diameter)~~

	Sample camera frame:		Sample camera frame:
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	[[image:TightwireStill.jpg\|400px]]		[[image:TightwireStill.jpg\|400px]]

	Clearly some repositioning of the mirrors would help. Ideally we could get a reflected image comparable to this:		Clearly some repositioning of the mirrors would help. Ideally we could get a reflected image comparable to this (which was taken with the same cellphone camera, but with no mirrors and a more careful setup):

	[[image:TightwireCloseup.jpg\|400px]]		[[image:TightwireCloseup.jpg\|400px]]

	~~Image~~ processing ~~tests TBD~~.		The necessary image processing program has not been written. It could possibly be written as a macro in [[http:rsbweb.nih.gov/ij/ \|ImageJ]], a great open-source image/vision program.

			Features needed:
			* Extract centerlines of wire images (one in each mirror)
			* Extract centerlines of reference lines
			* Establish displacement of wire image from reference line
			* Establish scale factor from spacing between the two reference lines
			* Adjust angle between the two reflectec sightlines (it won't be exactly 90 degrees)
			* Adjust for wire sag (need to know tension weight and density of wire material)
			* Report table of x- and y- deviations from centerline along travel distance.
			* Report deviations from straightness (i.e. deviation from best-fit straight line)

ChuckH at 19:27, 18 December 2011

2011-12-18T19:27:44Z

← Older revision		Revision as of 19:27, 18 December 2011
Line 1:		Line 1:
	Tight wire alignment is a technique for measuring straightness of large equipment components. ([http://www.powerhousetool.com/align.htm example supplier]) It has a long history although it has been largely displaced by optical methods. It may be appropriate for creating straight movement axes in lathes, torch tables, and other machine tools.		Tight wire alignment is a technique for measuring straightness of large equipment components. ([http://www.powerhousetool.com/align.htm example supplier]) It has a long history although it has been largely displaced by optical methods. It may be appropriate for creating straight movement axes in lathes, [[CNC_Torch_Table \| torch tables]], and other machine tools (especially appropriate for [[Shonda_Research \|concrete-bed, grouted-ways designs]]).

	== Principle ==		== Principle ==

ChuckH: /* Proof of concept */

2011-12-18T10:49:21Z

Proof of concept

← Older revision		Revision as of 10:49, 18 December 2011
Line 27:		Line 27:

	[[image:TightwireOnlathe.jpg\|400px]]		[[image:TightwireOnlathe.jpg\|400px]]

	(The "wire" is nylon monofilament sewing thread, 0.005 inch diameter)		(The "wire" is nylon monofilament sewing thread, 0.005 inch diameter)

ChuckH: /* Proof of concept */

2011-12-18T10:48:30Z

Proof of concept

← Older revision		Revision as of 10:48, 18 December 2011
Line 27:		Line 27:

	[[image:TightwireOnlathe.jpg\|400px]]		[[image:TightwireOnlathe.jpg\|400px]]
			(The "wire" is nylon monofilament sewing thread, 0.005 inch diameter)

	Sample camera frame:		Sample camera frame: