AutoCAD plot scale experiment 1

[sudhakarn]

Hi folks,
I am back with the question.i printed a drawing drawn in Autocad and plotted to 1:1 scale into a pdf.when i checked it physically,it was not accurate and 5mm short of what it is supposed to be.

The line was drawn for 10 units in decimal and plotted to 1:1 scale (1unit = 1mm)
Can you clarify the reason please?

 

[IFRs]

You are doing it correctly. Did you check the device that made it paper?

 

[dik]

Can you plot and scale a square, rectangle, and circle, or the 3 space equivalent, and measure them? Maybe try to find out the problem is linear in all directions? I don't know how you calibrate a printer.

Dik

 

[IFRs]

Printers have settings, both buried in their own software and in the plotter/PDF settings in AutCAD. Plotting a square and circle is brilliant.

 

[sudhakarn]

Hi folks,
Thsnks a lot for your insights.it is linear in both the directions as i have drawn a rectangle.it happens in both the length and width.
Should i check the printer settings or Plot settings in Autocad?

 

[IFRs]

Check everything. Leave nothing to chance.

 

[btrueblood]

Paper running through a copier gets heated, losing some of its absorbed moisture, and can shrink. Either give the paper a day to re-absorb some moisture before you measure, or use mylar or acetate sheets.

But that doesn't sound like what you got. You saw a 50% or 2:1 shift in scale from the print? Did you print to an A4 pdf file, and print the A4 file on A4 paper, with no scaling in the printer software? Sounds more like you printed an A2 document on A4 paper (or something like that, maybe switching landscape/portrait orientation too), and the printer scaled accordingly.

 

[sudhakarn]

Hi folks,
Thanks for your interest.
I have drawn a rectangle of size 20 x 10.i have plotted it in AutoCAD pdf documentation print set up with a plot scale of 1:1 (1 unit = 1mm ).i have taken the pdf to a printer.

Please do let me know if you need any other details.

 

[btrueblood]

"I have drawn a rectangle of size 20 x 10.i have plotted it in AutoCAD pdf documentation print set up with a plot scale of 1:1 (1 unit = 1mm ).i have taken the pdf to a printer."

And what does the rectangle measure on the paper? 15 mm x 8 mm? Or 10x5 mm?

Why not directly plot to the printer at 1:1?

 

[sudhakarn]

Hi,
It measures 19.5 cm and 9.5cm which is supposed to be 20 cm and 10cm.
I dont have a printer connected and so made it a pdf and got it printed.

 

[TerryScan]

When printing from a PDF, please be aware of the scaling settings in the program you are printing from.

In Adobe Acrobat, the default "Size Option" is "Fit" - this will scale the document.

In my version of Acrobat, the next option is "Actual Size" - this produces accurate scaling every time on our devices.

I suspect you need to address this with whoever printed the PDF rather than Autocad. However, one CAN perform measurements in a PDF. Can you post an example PDF?

 

[sudhakarn]

Hi terryscan,
Thanks a lot. Will check it out and post it.

 

[Sparweb]

Never tried to calibrate a printer, but I have calibrated a HP 36" wide plotter. It took some time but I got it down to +/- 0.2" per 100 inches.

Sudhakarn,
Getting to print 1:1 scale as accurately as, say, 1.000 : 1.000 can be difficult because the X error rarely matches the Y error. If I had to do this to make it as accurate as possible I would first prepare in CAD a drawing with a series of squares on the same sheet and fill the whole sheet with them. No point measuring 20mm when the paper is 200 mm wide; find out how inaccurate the WHOLE sheet is. There's no reason to believe the printer head feed has a constant speed; it could vary as it traverses the page. Or the feed rate could be variable... this is a deep rabbit hole.

Make sure your ruler is accurate. I am not kidding. There are some terrible rulers out there.
Then determine an appropriate scale to correct for X and if necessary a different scale for Y.
Since you are printing from AutoCAD to PDF and then to paper, you have 2x as many sources of error to deal with.

STF

 

[sudhakarn]

Hi sparweb,
Thanks a ton for your insights.I do not think there is any issue with the ruler.The issue should be with the pdf maker or the printer.
May be next time i should try plotting directly from AutoCAD to plotter.
What do you say folks?

 

[IFRs]

Check your plotter's "unprintable area" for the paper size you are printing to. It may be scaling it down to fit.

 

[berkshire]

sudhakarn,
Make sure that your printer/plotter "shrink to fit available paper" setting is turned off.
B.E.

You are judged not by what you know, but by what you can do.

 

[BUGGAR]

I generally have to use that microsoft paint program to print pdf's at correct scale.