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Thread: How to get a program to accurately print circles of various diameters?

  1. #1
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    How to get a program to accurately print circles of various diameters?

    I am making a birdhouse in the shape of a lighthouse which is circular. I don't have a lathe so I'm making 1" thick circles , reducing each one by 1/8" in diameter. I have to make about 15 of them. I can draw the circles with a compass but I'd like to draw the circles on a computer to increase the accuracy of the circles. I found a program to do this but when I print out the circle it's never the right size. Can anyone tell me how to draw and print out ,accurately,circles of varying diameters?
    Thanks
    Dennis

  2. #2
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    can't be done. That is why blueprints have every dimension marked. paper expands and contracts with humidity. Many inks are water based. Toner fuser heat will also cause differential movement.
    Bil lD.

  3. #3
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    Check the printer settings to make sure there is no scaling. I've used a number of different programs and printers to generate to-scale images and they were very accurate. Except for an old HP inkjet that always printed things a little small.

  4. #4
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    Use compiter software to make a 4 inch circle (larger is better)
    Print it out
    Measure it
    Develop scale factor, for example your 4 in circle is actually 3.5 inches. You need to scale up so 4/3.5 is your scale factor = 1.1428
    Multiply your desired circle diameter by the calculated scale factor and use the computer software to make your x diameter circle scaled up by your scale factor, so, for example you want a 2.5 inch diameter, multiply this by your scale factor, and use the result for your scale corrected diameter, ex 2.5 times 1.1428 is 2.857 inches.

  5. #5
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    Quote Originally Posted by Pat Barry View Post
    Use compiter software to make a 4 inch circle (larger is better)
    Print it out
    Measure it
    Develop scale factor, for example your 4 in circle is actually 3.5 inches. You need to scale up so 4/3.5 is your scale factor = 1.1428
    Multiply your desired circle diameter by the calculated scale factor and use the computer software to make your x diameter circle scaled up by your scale factor, so, for example you want a 2.5 inch diameter, multiply this by your scale factor, and use the result for your scale corrected diameter, ex 2.5 times 1.1428 is 2.857 inches.
    Pat
    Thanks for the advice, I had tried that and after about 20 tries with no success , I went back to my compass
    Dennis

  6. #6
    I use DoubleCad XT to draw circles. Make sure your print settings are set at 100% and hit the print button. The print out will be plenty accurate for woodworking. You can attach the paper to your wood with some spray adhesive. If you are making multiples of the same size you can glue your paper pattern to tablet backing.
    Lee Schierer
    USNA- '71
    Captain USN(Ret)

    My advice, comments and suggestions are free, but it costs money to run the site. If you found something of value here please give a little something back by becoming a contributor! Please Contribute

  7. #7
    dennis thomspn,

    The only method I use to print objects accurately to size is to use the PLT command- plot in AutoCad in which the drawing is done to size by selecting the circle tool, set the center point, type in the radius or diameter- accurate to the desired number of decimal points. To print, select 1:1 in the Plot dialog box and it will print on the plotter of printer quite accurately to size. Many times I've printed house plans on 11" X 17" sheets and the scale is accurate enough to scale dimensions to a useful accuracy. I think that versions of CorelDraw - which can be used to control a CNC, and possibly Adobe Illustrator have the ability to print accurately to scale.

    Overall though I think a careful application of the compass is faster, directly on to the birdhouse facade, so there's not the additional step to transfer it. If you have a ground steel rule that has the marking engraved, set the compass point on the 0 groove and having a really good bevel point on the lead, set the radius.

    I find making any hole smaller than I can get my hand into ends up really a mess as even very fine, narrow jig saw blades meander around a bit and have to be finished considerably. Consider a set of hole cutters 1/4" increments and, sand out to the compass line.I'm getting ready to make a music production /computer desk and the panel cutouts which are either triangles with the side connected by a radius or alternately simply circles. All the curved cuts are planned around standard-size hole cutters.

    Computer & Music Desk_ Back _Closed_Advent 3_1.2.18.jpg

    Computer & Music Desk_24X 4in. holes_1.2.18.jpg

    The alternative plain one:

    Computer & Music Desk_MR824_3.9.18.jpg

    In any event- not fine woodworking!

    Alan

    "Measure twice, saw once, sand to fit"
    Last edited by Alan Caro; 06-23-2019 at 9:18 AM.

  8. #8
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    I'm not sure why you believe that your compass in not accurate enough, nor why Bill says that it is impossible to use a computer application. I can draw circles and have them print to the size that I specify using Sketchup, Photoshop and Paint Shop Pro. I'm sure that there are many others available. I would stick to drawing them with a compass directly onto the wood - no paper template needed - and cutting them out.

    You could use a router on a home made tremel to get them perfectly round. That way, you don't need t draw them before hand with anything.
    Grant
    Ottawa ON

  9. #9
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    plastic template from Office Depot? Thats what I've used.

  10. #10
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  11. #11
    It's easy, really

    I do watchback refurbs using my fiber laser, my elcheapo Canon printer/scanner and Corel.

    My customer sends me a resurfaced back and a pic of the watchback prior to refinishing. I put the watchback on the Canon flatbed scanner, and the scan goes into Corel. I then resize the photo best I can and superimpose it onto the scan of the watchback. Then using available lettering and hand digitizing I superimpose new lettering and artwork onto the scan and pic. When I'm finished the result is a near verbatim copy of the original...
    rado2.jpgstMoritz.jpg
    My point is, basic scanning with a cheap printer into Corel gives me accurate size results. On these jobs, I simply had to line up the new engraving to the backs, no resizing was necessary.

    I just sent a 2" circle I drew in Corel to my Canon (inkjet) and my Samsung (black only laser)
    can.jpgsam.jpg
    -- 2" in, 2" out, +/- .005", which is well within standard engineering tolerances for 2 decimal dims...

    Doesn't need to be Corel to draw a good circle, plenty of free graphics programs to download
    ========================================
    ELEVEN - rotary cutter tool machines
    FOUR - CO2 lasers
    THREE - fiber lasers
    ONE - vinyl cutter
    CASmate, Corel, Gravostyle


  12. #12
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    I do this with PowerPoint and a Brother Laser Printer. It is very accurate.

  13. #13
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    Make a sub-base for a router and space the holes in the sub-base to what you want, use a tilt base router if you want them angled. Once you have the setup perfected you can make them into perpetuity all sized exactly the same with no markings at all.

  14. #14
    Quote Originally Posted by Larry Frank View Post
    I do this with PowerPoint and a Brother Laser Printer. It is very accurate.
    That's what I was thinking too.
    "All that is necessary for the triumph of evil is that good men do nothing."
    - Sir Edmund Burke

  15. #15
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    For representational purposes I use the computer, adjusting as others have described to get the printout to correspond to the size I actually wanted. For actual accuracy in the shop I use either a compass or trammel points on a straightedge for bigger circles. I don't have any technology that would let me cut a wooden circle to greater than 10 thousandths in accuracy, so a knife line or sharp pencil is fine. (nor do I have any wood that would retain that level of accuracy for any period of time with changing temp and humidity).

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