After converting PDF to DWG the scaling is off in the drawing. Help?

[Anonymous]

Hi, I have posted here before somewhere for help for my dad and I've come back because I have another problem.

My dad is working on a project for someone who sent him a PDF and it came in a format that couldn't be converted from PDF to DWG through the usual program he uses. So remembering a problem I had in the past here, I figured it was because the PDF was Raster and I needed Vector. I've previously not had luck converting and he had to redraw it, but I've decided to try and find a way to go about it this time. Here is what I've done so far, and I'll explain the problem afterward:

1. Recieved the original PDF from his client.

2. Converted the PDF to a Vector PDF using Inkscape.

3. Convert PDF to DWG using AnyPDF to DWG Converter.

4. Open in AutoCad to make sure it works (2006 and 2014). The lines are clickable like they should be (I don't know the technical term) I think although it looks a bit ugly.

So I have a working DWG that he can use, I believe. The problem is the scale is wrong. For example, in one part the drawing is measured at 14'2", and the scale written on it is 1/4"=1'0". So if it's 14'2", when I use the linear dimension tool (I hope I'm naming the right thing, I'm learning) it should read at something like 3.54", but it reads at .9974". Here is an image of what I'm looking at, I hope I'm reading it right. (I cannot find the Format tab so I don't know how to change it to fractions like my dad uses -- I tried putting in the Units command and changing to Architectural but I think there is something else I'm missing.)

Is there a way that I can fix the scale here so that it is something my dad can work with? Is there a reason that it reads wrong? Thanks for any help.

[Anonymous · Accepted solution]

The scale of the PDF image is dependent on how the PDF was created.   Think of it this way.  The floor plan is drawn in CAD at full scale (meaning a line representing 10'-0" is actually 10'-0" long).  When printed to a PDF it has to be scaled down to fit on the paper.  You mentioned it is noted the PDF scale is 1/4" =1'-0". This means the plan was shrunk 48 times to fit on the paper. 

The math goes something like this:

1/4" = 1'-0" (match units on both sides of = sign, 1'-0" becomes 12")

1/4" = 12" (multiply both sides by 4)

1" = 48"   (ratio of full scale to plotted scale.)

If the PDF you received has not been adjusted in any way you can SCALE the PDF image by 48 and it will match full scale.  However this is rarely the case as people often reprint PDF with a scale to fit and it screws up the scale slightly.

If that doesn't work you need to use the SCALE command's Reference option.  Find a portion of the design where the length is noted clearly, a long dimension string works best.  If you can pick the centerline of the line, great.  If not, draw a new line adjacent to the dimension string exactly as long as the line.  Then do the following:

1. Type SCALE and select all objects (you can type ALL and everything in the drawing will be selected if it is not frozen or locked)
2. Specify a base point (anywhere will work but it is easier to select an endpoint of the line drawn)
3. Instead of entering a number type R
4. When prompted for a reference length, pick the endpoints of the dimension line length (make sure not to grab the extension beyond the dimension line)
5. Then enter the length that you want it to be (Should be written on the PDF drawing)
6. ZOOM Extents to see the whole drawing.

This enlarges everything in the drawing by the same ratio so the entire plan should be to scale (or as close as you are going to get using a PDF as a base)

[Anonymous]

Wow, this seemed to do it! My dad won't be home for another couple of hours but it looks like this was the fix. Here is what I got with the linear dimension after trying your solution -- Top is the dimension line, bottom is on the drawing (Although I'm sure you could tell!). Does this look like I've got it to the right scale? I appreciate the help so much, this is amazing! Can't say thanks enough!

quick edit: i'll make sure to mark your post as the solution as soon as i make sure i got the scale right, although i think i did!

[Anonymous]

Yes, it looks pretty close. You're right the PDF quality is pretty bad.

I always try to match the longest dimension string and then go back and double check others.

[Anonymous]

Thanks so much! You're absolutely wonderful. I'll try and find the longest one now that I know how to do it, make sure everything lines up. Cannot stress how awesome you've been, thanks thanks thanks!

[Anonymous]

How do I check the scale in PDF without printing and checking it manually?

[Anonymous]

I wonder whether it can be solved by the pdf converter I am testing these days.

[bparker8DXQJ]

Hi Peter. If you have found it to work for that, let me know. We still convert PDF to DWG by redrawing them in AutoCAD.

[Victoria.Studley · Accepted solution]

Hi @bparker8DXQJ, @Anonymous, @Anonymous,

If you're using AutoCAD 2017 or newer, once you get the PDF into a vector format, you might want to try the new PDFIMPORT feature that was added directly to the program.

If one or more of these posts helped answer your question, please click Accept as Solution on the posts that helped you so others in the community can find them easily.

[bparker8DXQJ]

@Victoria.Studley, thank you. I will give that a try.

[Anonymous]

I'm experiencing a similar problem, when I import a PDF the size is displayed as 25.4:1, what does this mean and how should I scale accordingly to get the correct scale?