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Thread: converting a model airplane plan part to dxf ready for cutting out

  1. #1

    converting a model airplane plan part to dxf ready for cutting out

    thought i would try tracing a aircraft part from an old plan and
    converting it to *.dxf machine ready for cutting

    http://youtu.be/BjQ_0i_46lc
    Attached Images Attached Images

  2. #2
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    Stan,

    Do you use any software like Autocad, Turbocad, Rhinoceros or a number of other cad programs?

    Have you ever tried doing this? Not sure that there is anything any easier.

    1)Scan a file into the computer with a scanner, fax, or even a photo.

    2)Next step import the file into one of the cad programs as a JPG, PNG, Tiff or other bitmap ( most of the newer programs allow you to import backgrounds........ its' not the same as importing a block or other cad file. An example for an architect or surveyor...... he might import a Google Map and trace it....... for location lines, buildings, etc.)

    3)Place it on its on layer. ( at this point we usually scale/rotate the item/bitmap to some known size and orientation but you don't have to. )

    4)Turn snap on and begin to use polyline or other cad tools to trace over the top of the part all the while snapping to the layer below with various snap commands. ( usually easier to use a different color line for the actual trace........... bitmap is best in black or white or grayscale ).

    5)Turn background layer off and you have your part...... (parts that have a match..... we usually mirror for accuracy....... like your tail fin/wing or the front wing we'd only draw half and then mirror the other half...... then do a join/blend or similar command to make the part a whole.)

    6)Finished with drawing... toolpath as you would any other drawn part.

    Blessings,

    Kevin

  3. #3
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    Lets see the parts you made for your plane.
    Glad its my shop I am responsible for - I only have to make me happy.

  4. #4
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    Stan,

    A few examples..... scanned photo of a plan of a HighBoy Dresser..... the craddle post is a Laser 3D scan.....( we'd still do the same thing bring both files in and draw over the top of the background )

    Blessings,

    Kevin

    Craddle Bed Post PointCloudScan.jpg HighBoy Skirt W_Back.jpg HighBoy Skirt No_Back.jpg

  5. #5

    cad draw scan trace.....

    I agree to what you are saying ,my favorite try out cad is rhino but i find i know a little and sometimes
    its a lot of time to get useable results.
    I have had good luck with scanning
    http://youtu.be/AabFmDxDDec (clock dial)
    but it was a lot of clean up work.
    Then there is also the tracing of actual parts ( mind you a photo of it might do the trick too )
    http://youtu.be/ZBPSzPKAu2I cutting a gasket
    Then a lot of the older magazines had the grid pattern and scanning it was a lot of cleanup but it can be done
    the draw routine makes that easier http://youtu.be/E-ESF97iWxQ
    If i was to use a cad program all the time then i would be more comfortable with it ,right now with the variety of work i do
    the draw table semms to be the tool of choice,the owner of the software has a combine prg and a screen trace prg .
    The combine alows
    large objects to be draw and the file stiched together and the screen trace is anything on the screen can be traced
    and outputted to a dxf file format
    I make a lot of my own diagrams and now i can produce them in a dxf format in my head a bit easier and less time spent

  6. #6
    added the cut ,person asked about the cutting


    http://youtu.be/fe4jFXGizFE

  7. #7
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    That looks like a lot of work when you have such a clean image to work with. It would be almost trivial to scan and then auto-trace directly in a program like Vcarve Pro in a matter of minutes.

  8. #8
    you could be right ,it seemed to be good for me for many projects maybe this part copying was not the best example,the best example is when the diagram is on a grid or a lot of
    printing

  9. #9
    stan kern,

    This is the kind of drawing task that CAD does quite easily, but accuracy and allowing for the width of the cuts is a concern.

    Assuming that the part of interest was the stabilizer, the image was copied into a photo editor (e.g. Photoshop, Corel PhotoPaint) as a *.JPG and rotated so the x and y lines are orthogonal. Then, a simple copy and paste into CAD, set up the original drawing on one layer and then created a drawing layer and traced the parts left of the center-line to what appears to be the outside of each piece. The idea was to work to the outside of the original jpg lines which at that scale when zooming in, were quite thick, had indistinct boundaries, and varied. This is an interesting aspect of the drawing as the width of the cut made with relationship to the line- whether it's cut on the center, to the outside or inside would make a large difference in parts that are 1/16th" wide. It seems to me that this kind of drawing would need to be separated into every part to allow for the width of the cuts. This is easy to do as each outline can be copied and moved off to the side and the common boundaries in a sense "shared". The separated parts could then be arranged - aligned for continuous cuts and in a compact arrangement to save material. Another consideration is whether the boundaries of each part should be joined- fused- so that cuts are continuous and ensure that there is not more than one line on top of another as it might be unknowingly instructing two cuts. Also, if inside cuts are made using a rotating tool, they would have the radius of the tool. After neatening up, the left side was mirrored at the center line. This is saved as a *.DXF but depending on the CAD used, can also export to *.STL and an amazing number of other formats, including some exotic ones that appear to be used when making cheeseburgers out of either goat skin or Rhodium. This drawing could also be imported into Sketchup and a 3D model including the airfoil profile done quickly.
    Model Aircraft Stabilizer_4.6.14.jpg
    This drawing may be proportional but is probably out of scale. When doing this kind of tracing project, it is relatively easy to use whatever Scale control is available and most offer the ability to stretch of shorten in one axis a ta time as well a grabbing a corner grip and resizing in two or three axes. The drawing provided when mirrored left to right at this scale has the right side about .145" shorter as it appears the centerline is not exactly centered- and it possible to see that it was redrawn a couple of times. The JPG of the DXF file dimensions show the slight asymmetry. A pleasant aspect of CAD in this task is that the new drawing can correct the original, but it's also a bit like guess work when there are no reference dimensions. I've noticed over the years that no scanner reproduces scale perfectly so the tracing could correct a lot of inaccuracies if there were reference dimensions. A fuss over a mere model airplane you may say, but there is the survival of plastic pilots is at stake!

    Model Aircraft Stabilizer_DXF_4.6.14.jpg

    A good learning project that brings up interesting aspects.

    And thanks to fellow Sawmillian Sotos Patistas for insights into the wonderful world of CNC. Someday, I'm going to have a 3D printer make me a CNC router to produce 12th Century adze handles that are then laser engraved.

    Alan Caro

    There is no art, beauty, joy, purpose, nor magic in life that can not be ruined by the addition of a client.
    Last edited by Alan Caro; 04-07-2014 at 9:31 AM.

  10. #10
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    There is an old saying that "good enough is good enough." In this case, the design appears to have come out of a hobby magazine from a time when i was a boy. In those days, the precision cutting was done with ruler, straight edge and an Exacto knife -- or worse. No CAD, no CNC, no scanner, no photocopy. In spite of those limitations, I'll bet a number of those planes took to the air and were flown successfully. I would also speculate that a number of plastic pilots sacrificed their lives for the cause.

  11. #11
    Art Mann,

    Yes, exactly right-good enough is itself. And, I was interested in looking at the model aircraft plans in that I could see the faint redrawing of many of the lines as well as the noticeable off center center line of the stabilizer. I'm a designer more than draftsman, but I have gotten used to very precise CAD drawings. With automatic dimensioning there are constant checks on precision- you have to deliberately edit the dimensions to cheat. Sketchup even, pretends to be fun and casually intuitive, but tiny artifacts from changed extrusions can cause a plane to snap to the wrong points and never close- it's frustratingly demanding of precision.

    The exercise of the model airplane though was useful to expose that and to bring up the idea of how the CNC would interpret the drawing- which side of the line, as continuous line of multiple, and/or whether multiple overlaid lines would cause multiple passes. I've done a lot of tracing into CAD over the years, but drawing to directly run machines is something I would like to learn.

    All hail the brave pilot, Capt. Paul E. Styrene! He might have been saved if his goggles were transparent instead of painted!

    Alan Caro
    Last edited by Alan Caro; 04-08-2014 at 1:42 AM.

  12. #12
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    At one time running AutoCAD Rel 9, a long long time ago I had a digitizing tablet used for Menus I custom made for running the program.
    If one had something like that, masking tape the printed drawing to the tablet and start tracing. Input directly into a CAD program.
    Retired Guy- Central Iowa.HVAC/R , Cloudray Galvo Fiber , -Windows 10

  13. #13
    Why couldn't you used Corel Draw's tracing function.........I know its not a "CAD" program but it is a very robust program

  14. #14
    why not just have a look at john's software draw direct to dxf

    john.walsh@logicgroup.com logic group 888 362 0648

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