Optical tooling for rebuilding
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    Default Optical tooling for rebuilding

    Does anyone out there use tilting levels, jig transits and auto collimators for leveling and inspection while rebuilding? I have never heard anyone mention them on this site so I am curious. Regards, John

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    Good question John, I suspect those tools are more for the larger machines but I am not sure at what size of travel does a auto collimator not be as useful as other tools. That is how small is too small or at what size does it make sense to start looking for one?

    Charles

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    Charles: with an autocollimator one can determine flatness of as small as an 18x 24 surface plate-- with 2 reflector mirrors (using the British flag pattern) right down to fractions of a millionth of an inch. It is a slow process (about an hr.) to inspect and document, though. An auto collimator like mine -( Hilger Watts) normally has a range of not more than 8 ft. I use the tilting level to level my planers (4ft and 8 ft ) to a plane of .001 and the jig transit to a plumb of the same value, but their range is about 100 ft - after that distance, the planet's curvature gets to be a factor. Regards, John

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    Default optics

    Quote Originally Posted by rifler99 View Post
    Does anyone out there use tilting levels, jig transits and auto collimators for leveling and inspection while rebuilding? I have never heard anyone mention them on this site so I am curious. Regards, John
    .
    i have seen optical level and jig transit used when a company built a mill for making 10 foot long columns and used linear bearing rails to support a milling machine they had. the linear rail was optically shot for level so it was not twisted and jig transit was for straightness of travel. if was about 20 feet long i believe. i believe the tolerance was +/-.001" so they were not trying for super precision

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    Quote Originally Posted by rifler99 View Post
    Charles: with an autocollimator one can determine flatness of as small as an 18x 24 surface plate-- with 2 reflector mirrors (using the British flag pattern) right down to fractions of a millionth of an inch. It is a slow process (about an hr.) to inspect and document, though. An auto collimator like mine -( Hilger Watts) normally has a range of not more than 8 ft. I use the tilting level to level my planers (4ft and 8 ft ) to a plane of .001 and the jig transit to a plumb of the same value, but their range is about 100 ft - after that distance, the planet's curvature gets to be a factor. Regards, John
    .
    at 100 feet all the optics i have used the repeatability of readings at that distance was often +/- 0.030", if the air temperature was stable and no wind currents sometimes you could get readings to +/-0.010"
    .
    the rule of thumb is to take 3 readings and average them
    .
    we had a construction site with ice on floor and steam heater running. we set sole plates level then turned heater off and rechecked every reading. many readings changed 0.250". air temperature differences can seriously distort optical and laser readings

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    Optics is a problem in many ways the biggest problem with optics is people consider it a first choice to solve a problem. Optics is great for setting a center line and a line parallel to it, or bucking in to a line and turning a ninety degree line to set a few rolls as starting points for tramming a web line or paper mill. A surveyors transit mounted on a sliding base will do much of this work as well, some can be fitted with micrometer heads. I like a K&E level for elevations but a two second theodolite with a micrometer head works very well too. A long machine can be difficult to level but once level alignment becomes easier. I still consider the King alignment gage the best thing for machine tools because you get a better reading on the wear pattern.

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    Default optical calibration

    Quote Originally Posted by Dresden View Post
    Optics is a problem in many ways the biggest problem with optics is people consider it a first choice to solve a problem. Optics is great for setting a center line and a line parallel to it, or bucking in to a line and turning a ninety degree line to set a few rolls as starting points for tramming a web line or paper mill. A surveyors transit mounted on a sliding base will do much of this work as well, some can be fitted with micrometer heads. I like a K&E level for elevations but a two second theodolite with a micrometer head works very well too. A long machine can be difficult to level but once level alignment becomes easier. I still consider the King alignment gage the best thing for machine tools because you get a better reading on the wear pattern.
    .
    optical instruments should have calibration tested on job site before use. with older optics like a jig transit and a optical level the more important tests can be done in a 1/2 hour. i have seen many instruments off about .001" per 10 feet and still being used as a adjustment requires adjusting screws and often adjustments have to be done 2 to 4 times. it all depends on your tolerances.
    ........ a electronic theodolite often is blind to close distances (5 feet) and the main calibration test works best at a target at least 20 feet away and after instrument is reversed and set on target, the on board electronic is told to average out the error. i have done this many times and when test is repeated it easily is accurate to .001" per 20 feet so you loose the ability for focusing close, but it is usually 10x faster to calibrate.
    ........ i think the big thing to remember is optical readings over 20 foot distances it is normal to get slightly different readings. if you are expecting readings always repeat within .001" you will be in for a surprise. i have often seen optical readings change as the temperature changes. different materials change size at different rates and usually there is a time delay that is it can take many hours before large objects are temperature stable. i have seen .030" height difference in a outside building column over 6 hours as it was warmed up by the sun during a hot summer day, the zero was a inside column and a second zero target on a 2" thick steel sole plate attached to the floor. just saying you can easily have 3 items and 1 is moving in relation to the 2 others because of temperature differences during the day.

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    Quote Originally Posted by rifler99 View Post
    Charles: with an autocollimator one can determine flatness of as small as an 18x 24 surface plate-- with 2 reflector mirrors (using the British flag pattern) right down to fractions of a millionth of an inch. It is a slow process (about an hr.) to inspect and document, though. An auto collimator like mine -( Hilger Watts) normally has a range of not more than 8 ft. I use the tilting level to level my planers (4ft and 8 ft ) to a plane of .001 and the jig transit to a plumb of the same value, but their range is about 100 ft - after that distance, the planet's curvature gets to be a factor. Regards, John
    John I'm curious as to what limits your autocollimator to 8 ft? The light is collimated and should therefore be good for much more than that I would have thought. Note that I present that as a question and not a statement, as I've only used mine at close range and can't see a circumstance where I'd be using it at more than 8 ft, but was just curious. Are you using the stock light or have you replaced it with an LED?

    For longer distances I'd probably use my alignment telescope, but as I'm almost certain never to need to set up something large enough to require it, that couldn't otherwise be done by other means, it's probably a folly I should sell.

    If you're looking for this type of information it's somewhat more likely to come up in the metrology section of the board, but as I know many don't like posting there due to the "moderator" (I now refuse to completely), it's an area of the forum that possibly isn't as active as it would otherwise be. A shame that, but waddayado


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