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  • #16
    Question: In the same vain, would it work to Google a "How to read a vernier" web site, run the examples to printer, scale them to double size, (you could half the answer and improve resolution). Would that work too? I really like the idea. I'm a backyard guy and DRO's are a bit out of my league at the moment. Nice tip and I'll bet it gets a lot of folks thinking! My guess is we'll see more on this!
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    Thank you to our families of soldiers, many of whom have given so much more then the rest of us for the Freedom we enjoy.

    It is true, there is nothing free about freedom, don't be so quick to give it away.

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    • #17
      Your Old Dog, it might take a lot of trial and error to get it right.

      The version of Corel Draw that I have is an OEM version. Something a computor maker could put in as one of those 'Software Included' type of deals. The real version of Corel is very expensive. This one cost about $60. It does do quite a bit of what the real version does but some of the features are either crippled or not there.

      What's neat about is that you can for instance, measure the diameter of a machine dial, using pi you can get the exact circumfrance and basically type across the work area lines and numbers, 0 to 50 say, then all you need to do is punch in the circumfrence and bingo it will change whatever you have typed to that dimension. A vernier could also be made this way. Trying to figure that out myself.

      Excuse my crude explanation. I am an amature at this kind of stuff. That's why I was wondering about the accuracy.

      Maybe some one could suggest a cheap cad program that could also perform this function. Or some other solution?



      ------------------
      Gene
      Gene

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      • #18
        Why not just use a 12",18",or 24" scale in .100 graduations fastened to table, and even in "y"axis, with an adjustable witness fixed?

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        • #19
          Neat Idea!
          I just need one more tool,just one!

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          • #20
            <font face="Verdana, Arial" size="2">Originally posted by Iquithadenuff:
            Why not just use a 12",18",or 24" scale in .100 graduations fastened to table, and even in "y"axis, with an adjustable witness fixed?</font>
            Back in the late 60's I ran an Index milling machine that had a vernier scale mounted on both X & Y axis. Took out any leadscrew error, but was a pain bending over and using a loupe to read it.
            Ed

            Ed Pacenka

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            • #21
              Re: Accuracy

              I have had some experience with various drawing programs and printers. I like to use a drawing on self adhesive label stock for things like sheet metal work. I have a job comming up and I just got a pack of 17 x 22 label stock today. Cost $75 from a printer I use. It will save a lot of layout time. A LOT! It will pay for itself on this job alone.

              Back to accuracy. My experience over a period of about 15 years is that vector based graphics programs, especially all CAD programs, are usually able to provide more accuracy than I need on any drawing of an object that will actually fit in my shop - or yours. This preserves internal accuracy.

              Printers are another story. They vary widely and it's not just the printer but the driver software that Windows uses to operate them. Worse yet, you can get different error factors in the X and Y directions. A printer may be within 1/4% across the page and be off over 2% or 3% down the length. You can easily draw and print an XY scale that fills the page (7.5" x 10") and measure it with a good scale (one divided into hundreths is best). Measure the difference and calculate the percentage of error and then you can correct from there. I do this with every new printer I use and at intervals with the old ones. BTW, the type or cost of the printer is not a factor. I have seen very expensive lasers that were way off and cheap dot matrix types that were spot on. The resolution of the printer (DPI) is important as you can not get any finer than the smallest dot spacing you can print. An 8 or 9 pin dot matrix is almost worthless. A 24 pin is acceptable - barely. Lasers and ink jets are far better and they vary among different models.

              The CAD program I use allows me to enter a scale factor at the time I print. I can enter numbers up to five decimal places so 1.00000 : 1.00015 would be a possible entry. So I can make fine adjustments but they are to both X and Y axies at once. Not the best approach. But I can choose one axis to have 100% accurate and live with the other. This is acceptable for printing scales.

              Another trick is to print it 1:1 and take it to a good copy machine. Most modern copy machines will allow a size adjustment in 1% steps.

              I have seen CAD programs and print drivers that did have separate calibration factors for the X and Y axies. Plotters frequently have this feature. Use them if you got em.

              Like on the lathe and milling machine, accuracy is not totally automatic, it takes some thought, knowledge, and skill. But it is attainable.

              Paul A.
              Paul A.
              SE Texas

              And if you look REAL close at an analog signal,
              You will find that it has discrete steps.

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              • #22
                I agree with Paul, my earlier post recommended using a caliper to measure tick marks. Once I used Generic Cadd 6.1 to layout a 6 foot long stair stringer. I printed it out on my old 9 pin Epson wide carriage printer. When the printout finished, I found it to be nuts on over the 6 foot length! On the other hand, one laser printer I used at work on another project yielded a .070 over 6 inches. I do get great results with my B-size HP pen plotter. It's definitely going to depend on both your hardware and software.
                Ed
                Ed Pacenka

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