CAD File Question

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Lenp
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CAD File Question

Post by Lenp »

I have a need to convert PDF drawings to the DXF file format so they can be edited and updated.
Online there are many offers to convert the file, or to buy software that does the conversion, but so far It has been unsuccessful.
In some instances the 'converted' 'DXF' file is blank when opened in the CAD program, and in others it is not even close in the rendering.
Oddly, DXF files, generated directly from a CAD program, open properly. it's just the 'converted' ones that are bad.

Maybe I am missing a step or a setting?

I would appreciate any comments that would help with this problem, or .... just convince me to forget it!

Thanks all!
Len

“To invent, you need a good imagination and a big pile of junk.” (T. Edison)
"I must be on the way to success since I already have the junk". (Me)
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haklesup
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Re: CAD File Question

Post by haklesup »

you can't do that. PDF was originally designed to thwart copying and editing. We can only grab text at all because the format is open source and OCR has been integrated but the image is no more useful than a photograph. There is no layer or dimensional content in a PDF. Even more complications creep in when you realize that different PDF print drivers like Cute or MS convert the file differently. I had to give up on CutePDF because cutting and pasting from the documents was all scrambled binary junk, at least from the MS PDF driver, you can cut and paste the text like most other documents. there are multiple PDF drivers available to use. if saved as a vector image, maybe but not raster

Native CAD formats from various programs can all be saved as DXF, DWG or STEP in most cases. PDF is a print operation, not a conversion or export. Not sure about 3D PDF but that's probably not what you have. You can usually cut and paste a PDF page, graphic or text into a CAD file but its still just a static unscaled image.

The only viable method is to cut and paste the PDF as an image into the CAD on one layer, then you can trace it on another layer(s) and scale it with the tools. Its messy and for most drawings, might as well start from scratch.

Since many PDF are rotated 2D views of 3D CAD, this can add distortion and its real hard to get back to the Orthogonal views or to rotate that traced 2D image to show the X, Y and Z projections. Certainly using that to program a CNC is going to be risky.

Might be easier with architectural style as compared to 3D objects drawings but I doubt it. I would just copy it side by side.

Have you tried Nanocad. its still free for a while longer. I was using Draftsight until they decided to charge a subscription rate. Nanocad can import vector file formats but not PDF.
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Lenp
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Re: CAD File Question

Post by Lenp »

Hi,
That's what I suspected but, there are a ton of PDF-DXF and PDF-DWG sites and software, and I had hopes! I've tried some and if there is any image at all, it is not anywhere acceptable, or the text is really gibberish. Some renderings allow me to edit lines and other items but generally it seems to be a total time waster. The only hope, aside from redrawing all the PDF's, seems to be if the file owner can unearth their original CAD files.

Thanks for the follow up, and I'll look into Nanocad!
Len

“To invent, you need a good imagination and a big pile of junk.” (T. Edison)
"I must be on the way to success since I already have the junk". (Me)
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CeaSaR
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Re: CAD File Question

Post by CeaSaR »

I'm using AutoCAD Civil3D/2018. I have yet to see a native conversion of PDF to DWG or other CAD format. However, getting a PDF that was created by AutoCAD (not a printed & scanned version) will allow you to snap to the ends of lines in the PDF. So if you align/scale it to proper size, it's a matter of snapping from end to end, etc, etc.

Now if all you have is a raster image, even in PDF form, then you are just better off recreating it manually - offsets, fillets, etc.

DXF, I must assume you need it for something other than just drawing purposes.
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Lenp
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Re: CAD File Question

Post by Lenp »

Hi Ceasar
I am working on a project to add features to some small machine controls. There are about 20 different controls that can be modified and each is a diffferent drawing. So far the only drawings available are as PDF. If I had them as DXF or DWG files I could easily edit them to create the new drawings to show the needed changes, saving many hours.

Thanks
Len

“To invent, you need a good imagination and a big pile of junk.” (T. Edison)
"I must be on the way to success since I already have the junk". (Me)
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haklesup
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Re: CAD File Question

Post by haklesup »

I looked a little deeper into this

Autocad 2017 and later do have import paths but it is not fully automated and you still need to make a lot of choices along the way. Based on instructions I saw online, it may be more flexible than nanoCAD

nanoCAD Pro version has Raster import with object recognition and raster snap which would be very useful in tracing files onto a new layer. I have the free version so I didn't try this feature

nanoCAD free has the raster import but not the raster snap feature, you can try it. I'm not good enough with the program to figure out how to tweak the scale to make the drawing match the image.

Both are not free but both have free trials if you think you can get it all done in a month.

I also looked into the converters, they sure make a lot of promises. I think the way the PDF was created has a lot to do with success. For example Exporting to an PDF direct from the CAD program probably works better than printing a view port in the same CAD to a 3rd party PDF printer driver which works better than a PDF of a document scan of an old hard copy page.

I didn't look into Solid Edge or Solid Works but those are expensive platforms. I expect they have something similar to AutoCad.
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CeaSaR
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Re: CAD File Question

Post by CeaSaR »

Len,

I just tried the PDF import in AutoCAD 2018, and it converted to polylines, arcs, etc. (This was with a Civil Drawing, so tons of info to parse)

Now, this was from a PDF that was created by AutoCAD, so I would expect that to happen. If you want me to try with your PDFs, I can give it a go. I can send a text or email if you'd like.

I'd just need to know what you want for units, Architectural, Decimal, Engineering, Fractional or Scientific. That, and what version of CAD you will be using, I can go from 2018-R14 in DWG and 2018-R12 in DXF.
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Lenp
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Re: CAD File Question

Post by Lenp »

Hi Ceasar,
Thanks to all for your suggestions and I am glad to say that the problem was just resolved this evening!

I located software called AnyDwg, from https://anydwg.com It was a trial package, limited in the total conversions, but that was more than adequate for my immediate needs.

The conversion went fast, 20+ drawings in about 10 minutes, but there was a minor glitch. There were two groups of drawings, and apparently they may have been done at different times, or on different systems. On both groups of drawings, all the line art was rendered correctly, but not the text. In the first group the text fonts were different. Single character text was right, but any text lines were exploded to individual characters, and overlaid on top of other characters. The second batch text was all the wrong ASCII characters, and overlaid like the first text lines.
Those text issues are not worrisome. Since I have the PDF's it will be easy to change the fonts and make any text corrections needed.

There was no scale on these drawings, as is usual for electrical drawings, so I cannot comment on other accuracy issues. Maybe some more professional users would find it useless :???:

In all, it was a huge waste of time searching for that elusive software, but at the end, the time saved to redraw all the drawings was the payback.

Thanks again to all for your suggestions!
Len

“To invent, you need a good imagination and a big pile of junk.” (T. Edison)
"I must be on the way to success since I already have the junk". (Me)
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CeaSaR
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Re: CAD File Question

Post by CeaSaR »

Glad you found something that worked, for the most part. There's always a glitch when you convert from one format to another, regardless of origination or destination. Yeah, it's rough when you have to work with non-CAD formats in CAD. Heck, it's even rough when you have to work with someone else's drawing in the same format. Your conventions and theirs are usually not the same.
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Lenp
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Re: CAD File Question

Post by Lenp »

We've reached the technology pinnacle.
The only thing that is compatible, is incompatibility!
Len

“To invent, you need a good imagination and a big pile of junk.” (T. Edison)
"I must be on the way to success since I already have the junk". (Me)
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CeaSaR
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Re: CAD File Question

Post by CeaSaR »

Lenp wrote: Sat Aug 29, 2020 9:41 am We've reached the technology pinnacle.
The only thing that is compatible, is incompatibility!
Yes it is!
No it isn't!
(Thank you Monty Python!)
Hey, what do I know?
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