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  1. Sep 24, 2019 #1

    Dennis DeFrange

    Dennis DeFrange

    Dennis DeFrange

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    I'm looking for a source that would print out actual size , 36'' cord prints of three different airfoils . I need the prints for the Clark Y , M6 , and NACA 23012 . If anyone on here knows of a reliable source I'd definitely appreciate hearing from ya . Thanx
     
  2. Sep 24, 2019 #2

    Aerowerx

    Aerowerx

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    Someplace that does computer graphics designing? Computer drafting and blueprints?

    Office Depot?

    Check your local phone book or friendly neighborhood Google?
     
  3. Sep 24, 2019 #3

    Hephaestus

    Hephaestus

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  4. Sep 24, 2019 #4

    flyboy2160

    flyboy2160

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    You need to have a referenced dimensioned line somewhere on the print. The repro can be off. Tell the repro worker that you'll need to check the length after the first copy and make magnification adjustments before printing your real copy. Print on Mylar if you can.
     
  5. Sep 24, 2019 #5

    FritzW

    FritzW

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    Printers can have all sorts of distortions. Along the page, across the page or diagonal. If you have scales going in every direction it's easy to check everything.

    ie...
    template.jpg


    Do you have the coordinates for the airfoils you want in the right scale? If you have them ready to go I could knock out a quick PDF.
     
  6. Sep 24, 2019 #6

    Hot Wings

    Hot Wings

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    Reference line for the vertical as well.

    Mylar may be a bit much for those airfoils unless the OP has large changes in humidity. A few thousands here and there aren't going to make much difference.
     
  7. Sep 24, 2019 #7

    Topaz

    Topaz

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    Thank you. Yes, most commercial printers are garbage in this respect. The ones at retail copy stores are among the worst, as they get so much usage. Always check your prints in both X and Y axes. If you need a really accurate print, try and find a commercial plotting service for engineering firms. They're getting harder to find, and are usually co-located with what's left of the commercial blueprint shops, but they'll have the most-accurate plots. You'll need a CAD file format, though. Pretty sure most of these don't take PDF.
     
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  8. Sep 24, 2019 #8

    pictsidhe

    pictsidhe

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    Copy places are often highly skeptical of mylar: "It's plastic, it will melt"

    It could be worth just getting a grid printed out at your local copy store to check if their machine is useable before looking for a nice plotter. I've seen great and awful. Ask nicely, and they may do it on the back of a reject for free.
     
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  9. Sep 24, 2019 #9

    Andy_RR

    Andy_RR

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    Get them laser cut from aluminium sheet. It won't cost a bomb, will be more accurate and stable.
     
  10. Sep 24, 2019 #10

    Dana

    Dana

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    You can draw them by hand; it was done that way for years before computers. Get the table of airfoil ordinates, lay out the points, and connect them using french curves and ships curves.
     
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  11. Sep 24, 2019 #11

    Pops

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    Yes, The BC way. ( Before Computers).
     
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  12. Sep 24, 2019 #12

    Jay Kempf

    Jay Kempf

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    I actually find printing in CAD formats unreliable for lots of reasons. Always used HP inkjet large format machines. Have one now with unlimited ink mods. I print almost everything from PDF save as of whatever it is native. Dunno why it works but it does. I do a lot of posters for an artist friend of mine and a bunch of full scale black line weights CAD stuff.
     
  13. Sep 24, 2019 #13

    Hot Wings

    Hot Wings

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    I preferred BTPS over French curves.

    Big Thick Plumbers Solder. :D

    The airfoil templates for the Quickie - a laminar flow airfoil - were hand drawn on grid paper and them copied for the templates provided with the plans. You can still see the remnants of the grid on the prints. There were plenty of these successfully used to cut templates and build flyable aircraft. So the airfoils were in essence 4 generation from the ordinates. They did end up resorting to vortex generators........;)

    Edit: My plotter also seems to do a good enough, as in I can't find any difference between DXF/eprt, job with my PDF files.
     
    Last edited: Sep 24, 2019
  14. Sep 24, 2019 #14

    Dennis DeFrange

    Dennis DeFrange

    Dennis DeFrange

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    WOW , thanx folks . I wasn't totally ready for a vast response like this . You guy's really come to the table when the cookin is in the air . This helps when someone like myself try's to tackle a project that they know very little about ie. printers and anything connected to them . I definately appreciate the offers and input . I'll check out the local capabilities and definately put all of the above in motion like I know what I'm doing . Pretty good at digging through resources especially with a heads up on do's and don'ts . More than helpful , Thanx .
     
  15. Sep 24, 2019 #15

    Topaz

    Topaz

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    You shouldn't. PDF is a super-set of the Postscript page-description language. When you create a PDF from a vector drawing program, including CAD programs, the interpreter is just translating the native vectors to Postscript vectors and wrapping that all in a PDF shell for portability. Adobe gives away the interpreters for free (or at least they used to - I'm not sure if that's still the case) for companies to include in their software for "PDF export", which is why you see that option everywhere. If the type (text) in the source file being sent to PDF is composed of system-installed fonts, the interpreter copies the font file (or a subset of it, depending on settings) into the PDF file as a Postscript library, and font references in the PDF point internally to that particular library.

    Raster images are pretty much just included into a PDF file as-is, with the appropriate headers in Postscript for page placement, scaling, etc., and then the PDF "wrapper" is put around that. Creating a PDF from a raster file does exactly zero to improve the quality of the image, because of this. If you see any "improvement" in the output of a raster image printed "raw" or first made into a PDF (a claim I hear from time to time), it's that the latter is forcing your printer to use a Postscript interpreter driver instead of whatever native raster image processor driver is built into the printer. For most consumer-grade printers, the native RIP driver is set up to make photographs be smooth and bright color - exactly the opposite of what you want for engineering drawings.
     
    Last edited: Sep 24, 2019
  16. Sep 24, 2019 #16

    Hot Wings

    Hot Wings

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    Thanks for the explanation! So if i take my Solidworks generated PDF files to the local Staples they should be able to print as accurately as my plotter - provided they have their hardware calibrated?
     
  17. Sep 24, 2019 #17

    Topaz

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    1) Presuming their machine was capable of that kind of accuracy in the first place, which it isn't. Most laser and ink-jet devices are capable of ±1-2% dimensional accuracy brand-new out of the box. Large-format machine are generally much, much worse than that. I worked at a national top-ten prepress house for eight years. During the transition from traditional bluelines to digital ink-jet "bluelines," we had a top-of-the-line Epson large-format ink-jet printer set up with specialized software for printing "digital bluelines" and then overlays to show die-cuts. The best we were able to "calibrate" it was within about 0.0625" across a 48" print area. Changing humidity, changing paper stretch because of the amount of paper on the roll decreasing over time, changing paper stretch because of the amount of ink being put down across different areas of an individual print, and so on, all made "calibarating" it virtually impossible. The solution was easy: We discovered that the customers just didn't care. Most people who aren't trying to make parts from the drawing as a template, don't care at all.

    And...

    2) Presuming they "calibrate" their hardware. Most consumer- and even "prosumer"-grade large-format printers don't have discrete X-, Y-axis scaling "calibration". At best, it's in the print-driving software, and even that is uncommon for anything but top-flight prosumer-grade equipment. Most have, at best, a simple size-scaling adjustment. And this even presumes that the copy center involved actually does any "calibration" of the dimensional accuracy of their equipment. In college, I worked at a commercial copy center and, having used others later in my life (generally FedEX Office, not Staples), I can virtually guarantee that, unless you ask for it specifically, they never calibrate their equipment. It just gets used, and service is called when it breaks down. If you ask them to calibrate it dimensionally, you're going to get blank looks, then be told that it can't be done and, if you press them, someone will go and try to find a manual that's been getting dusty on a back shelf for years. They'll ask you to come back on Thursday night because "the guy who's really good on that machine" will be on-shift then, and when you come Thursday night, you'll run through the same cycle until he finally finds the manual and sits down to read it.

    In theory, yes, you should be able to get reasonably accurate prints. But it's not going to be true in practice, unless that particular location just happens to have customers who need and request dimensional accuracy on a regular basis. And, if they do, the center probably has an engineering plotter for that work.

    If you go ahead, a better test than a grid is to print a large-diameter circle and have them make a print. Go back the next day and get a second, identical print. Measure the diameter to see if the basic scaling is correct. Then lay them on top of each other, with light shining through, and see if the circles align all the way around their circumference. Then rotate one print 90°. See if they still line up. Any X-Y errors - and inconsistencies between print runs on different days - will jump right out at you.

    In the end, it really depends on what you really need out of these printers. If their accuracy is better than your shop accuracy on the same part, it's "good enough." If you can - and need to - make things more accurately than those printers can print, then they're not "good enough." Whether or not you "need to" is subject enough for an entire thread on its own. Unless you're building something with a highly laminar-flow shape, and are capable of achieving the needed accuracy in your own shop, you can probably get away with less printing accuracy than you might think.
     
    Last edited: Sep 24, 2019
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  18. Sep 24, 2019 #18

    Norman

    Norman

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    Reprographics shops (surveying supply shop) usually would have a plotter. With these airfoils tight tolerances aren't really very important so any large format printer would probably be OK although, if the slop is as bad as Topaz describes, old fashioned hand plotting could actually be closer to the nominal shape.
     
  19. Sep 24, 2019 #19

    Hephaestus

    Hephaestus

    Hephaestus

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    If you need it accurate. Laser cut stainless steel would be the correct way.

    But I'm 100% sure the fact that you're putting it on paper - the error induced by the printer will be the least of your concerns. Parallax error will introduce more than printing errors.
     
  20. Sep 24, 2019 #20

    Hot Wings

    Hot Wings

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    Thanks for the reply. As Hephaestus and others have noted if we need really accurate airfoil templates they maybe should be made via CNC and just skip the paper all together? Or better yet just cut the foam cores with CNC. For hand build wood or metal planes I've often wondered if we are too worried about plans accuracy? I was taught way back in the old days to never scale off the prints, only use the dimensions given. It is nice to have full size templates to glue to the metal for rough shaping but when it comes time to cut the holes they probably need to be done with blueing, scribes and measuring tools.
     

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