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Author Topic: CAD file conversion query  (Read 460 times)
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Pete Fardell
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« on: October 22, 2021, 04:57:43 PM »

I've been drawing up a build plan for my little Back Garden Bleriot model using a CAD program I got called Draft It Pro. It's a straightfoward model and has been a good way back into CAD for me after a few years off to forget everything I once knew about it (never all that much it has to be said).  I chose Draft It this time because it's nice and simple compared to some of the others (it's 2D only) and after a bit of messing about I got on ok with it. The plan's now just about done barring a few tweaks that might arise once I finish the test model I'm building from it. The CAD drawing gets saved as a .dft file (whatever that means) but I can export it/convert it to a pdf file too which is more convenient to open and for emailing etc. The only issue is that for some reason the conversion to a pdf shrinks it very slightly (close to but not exactly 98%) which is a bit annoying. I know this because I included a cm scale on the CAD drawing itself. My first thought was that it was just a printing issue, but it's not. The actual drawing is slightly smaller once its converted to pdf. Anyone know why this might be or if I can fix it?
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TheLurker
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« Reply #1 on: October 22, 2021, 05:25:16 PM »

Nothing useful on CadLogic's web site and goggling doesn't turn up anything useful.

You say it's not a printing issue. Have you checked your printer's property pages when you print?  Many, not all, have a "Page Handling" tab.  If it has and it has a page scaling drop down, select "None".  The default is usually "best fit", "shrink to printable area" or similar.  If it is the application applying a shrink then you might be able to get around it when you print by applying a >100% zoom (last time I hit this I found 102% about right) on the "Page Setup" tab (different to Page Handling) of the printer's properties.

I'd show you a screenshot from my machine, but there isn't (AFAIK),  a way of getting to the screenshot utility when there's a modal popup showing (Linux Mint)
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Pete Fardell
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« Reply #2 on: October 22, 2021, 05:46:03 PM »

Thanks, Lurker. Good thoughts. The reason I know it's not a printing issue is that my son showed me a tool which lets you take dimensions from a pdf when opened in Adobe before you even try and print it. Lo and behold, my pretty little 60mm ruler in the corner of my plan was only 58 point something mm long.
I can print the drawing at almost the right size (close enough) by putting the print setting at 102%. Ok for me but annoying to have to include printing instructions if I send it to anyone else. I could probably just enlarge the whole PDF drawing too, but that also is annoying having got everything just right in CAD.
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TheLurker
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« Reply #3 on: October 22, 2021, 05:51:17 PM »

I think you have DXF & SVG export options available as well from Draft It?

Mind sending me a couple of test images in those formats?  No need for a full plan, something simple like a rectangle with horiz & vert scales will be more than enough.  There's something I'd like to test.
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Pete Fardell
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« Reply #4 on: October 22, 2021, 06:09:02 PM »

Thanks- I've just emailed you some rectangles with the dimensions written on, as the original DFT file plus the PDF and DXF exports. Couldn't see the SVG option though.
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fred
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« Reply #5 on: October 22, 2021, 10:38:00 PM »

Download this: https://www.tracker-software.com/product/pdf-xchange-viewer-activex-sdk .
Includes a tape measure tool  to easily determine what size the PDF image is.. Then one can readily compensate accurately during the print setup.

Adobe is a greed driven  business requiring payment for what most others include as Free.
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cvasecuk
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« Reply #6 on: October 23, 2021, 05:09:52 AM »

I downloaded Draftit last night and tested it this morning. Using the Pro version my PDF is nearly twice size and using the Architectual version I get a factor of 163.4%. I don't understand what is going on and will go back to using NanoCAD!!!!
Ron
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TheLurker
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« Reply #7 on: October 23, 2021, 05:31:50 AM »

I had a play with the test files Pete sent me this morning and there are ways to get an accurately sized PDF, but it is a faff and requires some tedious mucking about in hyperspace with Inkscape - Pete has the details.  Not difficult, but an extra two or three steps that oughtn't be necessary.

My suspicion, and it is only a suspicion, is that DratIt Smiley hasn't got its own PDF generator but is capturing the output from an internal  "printer" using the OS' generic PDF printer driver.  I see this on my machine if I use the the OS auto-discovered printer rather than the one created when I ran the manufacturer's installation scripts.  The generic driver prints at about 98% of correct size as per Pete's experience, the one installed from Canon's installation kit at 100%.

However, given what you report Ron. I begin to wonder about even that.  Have either of you gone poking around in DraftIt's options and settings?

Lurk.
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cvasecuk
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« Reply #8 on: October 23, 2021, 05:37:45 AM »

I've had a quick look but couldn't find anything.
You could enlarge the whole drawing by 102% before exporting as PDF but not bother to save that version.
Or, are there any free online converters?
Ron

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Yak 52
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« Reply #9 on: October 23, 2021, 06:03:25 AM »

I've not had chance to look at Draft It but there is one other thing you might like to check Pete:

It's usually necessary to reset the zoom scale to 100% before you PLOT (to print or pdf)
In NanoCAD you need to do this for both the viewport (section of the drawing you want to plot) and the Sheet view in question.

In NanoCAD the command is ZOOM1 and I think in AutoCAD its ZOOM 1/1XP so it maybe similar in Draft It. just typing Z into the command bar should come up with the various zoom options to pick one from.

Either way it's worth checking you have 100% zooms at every possible level before plotting.

There are other PDF plotters you can add on (NanoCAD doesn't have one so I use an external program)


Jon
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Pete Fardell
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« Reply #10 on: October 23, 2021, 06:41:00 AM »

Thank you all very much. I now at least have some workarounds and a few more things to try.
Fortunately, absolute  accuracy of size size isn’t all that important  for this particular model, but it probably will be more critical with some future plans I have in mind. I will experiment some more and report back.

Incidentally, another issue with adjusting the size at the printing stage is of course that I can only set the enlargement percentage to an integer. 102% gets me closest but is still nearly 1mm out on a wingspan of about 335mm.
« Last Edit: October 23, 2021, 07:18:01 AM by Pete Fardell » Logged
cvasecuk
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« Reply #11 on: October 23, 2021, 07:05:54 AM »

I will add even more confusion.
I drew a line 100mm long on different size paper and in portrait as well as landscape. The lines were all drawn near the top of the page.
All PDF's had the line in the middle of the page and it was expanded to fill the page. This meant that each drawing resulted in a different line length. For example A5 portrait is 140.6mm up to A3 landscape where it is 399.0mm. I also drew a triangle with 100mm horizontal, down 100mm and back to the start. The PDF was of course in the middle of the page with sides 194.11mm. And a 50mm sided triangle was expanded to give sides of 189.00mm. Make of that what you will!!!!
Ron
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raggedflyer
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« Reply #12 on: October 23, 2021, 07:07:41 AM »

Just a thought on contriving a different enlargement ratio. Is it possible to enlarge to say 185% then reduce by 184% to gain approximately 1 part in 185?. Other number pairs may get you closer as an initial conversion.
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Pete Fardell
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« Reply #13 on: October 23, 2021, 07:25:45 AM »

Just a thought on contriving a different enlargement ratio. Is it possible to enlarge to say 185% then reduce by 184% to gain approximately 1 part in 185?. Other number pairs may get you closer as an initial conversion.
That’s a good thought. I’ve tried just that kind of “up a bit down a bit” resizing before, usually when sneakily making plan copies on my ex-workplace’s photocopier. It does work, but is also a surefire route to madness if you get too anal about getting the exact right size.
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Crabby
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« Reply #14 on: October 23, 2021, 12:20:06 PM »

Quote
but is also a surefire route to madness if you get too anal about getting the exact right size.

HAHAHA there is a fine line dividing "anal" from "a-hole"  Grin Roll Eyes Cheesy






Ratz edit: Fixed "quote"
« Last Edit: October 23, 2021, 12:36:37 PM by Ratz » Logged

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TimWescott
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« Reply #15 on: October 23, 2021, 03:03:41 PM »

... but is still nearly 1mm out on a wingspan of about 335mm.

Just use thicker lines.

Or print it out, and put the paper in a warm, humid room -- or a cold dry one, depending on whether it's too small or too big.
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Pete Fardell
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« Reply #16 on: October 24, 2021, 06:56:21 AM »

Big thanks everyone, for the help with this on here, by PM and by email. Much appreciated.

I haven't tried all of the suggestions yet because I now have a method that works for me. Andrew Darby suggested I try downloading a free pdf printer called Bullzip. A pdf printer creates a pdf of course, rather than literally printing anything, and by "printing" on the Bullzip printer directly from my CAD drawing I got a pdf that was a little too large (101%). This morning I realised that by "printing" it the same way but with the bullzip printer setting at 99%, it comes out just about bang on in pdf form.

Andrew D thinks the descrepencies I've been getting are maybe to do with line thicknesses not being properly allowed for (as Tim W just implied too).

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billdennis747
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« Reply #17 on: October 24, 2021, 07:07:47 AM »

I wish I could build within 1% of what it should be
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fred
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« Reply #18 on: October 24, 2021, 01:13:43 PM »

Thank you all very much. I now at least have some workarounds and a few more things to try.
Fortunately, absolute  accuracy of size size isn’t all that important  for this particular model, but it probably will be more critical with some future plans I have in mind. I will experiment some more and report back.

Incidentally, another issue with adjusting the size at the printing stage is of course that I can only set the enlargement percentage to an integer. 102% gets me closest but is still nearly 1mm out on a wingspan of about 335mm.


Again;  FREE ..PDF program download https://www.tracker-software.com/ 
Capable of 0.1 print size increments.
Horses to water does come to mind.
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Pete Fardell
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« Reply #19 on: October 24, 2021, 02:06:44 PM »

Horses to water does come to mind.
Sorry, I didn’t mean to appear to overlook anyone’s great tips but this particular horse was lucky enough to have several people leading him to various sources of water all at once. Anyway, thank you very much;  I’ll certainly bear your recommendation in mind for the future but physically printing the plan at a new size is no longer an issue now that the main problem (of getting the size right in a pdf file to start with) has been solved by utilising the free bullzip pdf printer.
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