Trouble with dimensions on a 2D drawing in Autocad LT 2004

Hi guys,

First time poster - really hoping somebody can help, my Autocad skills are very basic and would really appreciate your input. I've tried to Google the problem and failed miserably.

I inherited countless 2D drawings in my job (fairly simple interior office layouts). On all the drawings (except the one in question), all objects/surfaces are accurately dimensioned and reflect the actual size in the office.

When I use CAD to check a dimension that I already know on this drawing, the figure is wildly inaccurate. For example, I know the width of a door frame is 36 inches. When I use the dimension tool, CAD tells me it's 881 inches!

Would anybody know how I might remedy this?

Any help would be very much appreciated.

Thanks,

Peter

It might be that the drawing units are actually millimetres.

881 mm = 34.68 inches

Thanks very much for the reply, I've checked and the units are in inches.

Can you attach a copy of the DWG file to your next post so we can see this odd behavior for ourselves?

Unfortunately there's a significant amount of confidential info on the drawing so I won't be able to share it

As i know the factor by which the dimensions are off (ie the dimensions are 24.47 times bigger than they should be), is there any global scale factor or something that I might be able to change?

The width of a door frame? There is a stop in a door frame that makes it a little smaller than the actual door. A 3 foot door slab itself is exactly 36 inches wide. The frame opening can be up to 1 1/2" smaller, and the out. to out. dimension of the frame can be 6" larger, especially in commercial construction.

Save As... a copy of the drawing, with a new name, and delete everything but a small part of one floor plan and post the copy.

In 2004 LT there is no real way to check the drawing default units. AutoDesk did not include the command -DWGUNITS in LT until (I think 2013). One has to start out with the proper template from day one. Aparently someone started this one with a metric template Acadltiso.dwt, instead of Acadlt.dwt, which is the imperial one.

The units in the FORMAT >> UNITS dialog are not the drawing units, and the units in the dimension styles are not the drawing units.

You can scale the entire drawing down to make it work in inches. First measure several items that should be a known distance to see if they all work out to the same factor. If they don't, then you will know that the original drafter is more incompetent than you thought and the door is not accurate. Standard distances are Kitchen Countertops, 36" above the floor, a standard bathtub fits in a 61" space stud to stud, things like that.

The scale factor from mm to inches is 25.4. That's too close to say the drawing was not drawn sloppily in millimeters yet. It is definitely not drawn in inches.

Is there any chance that the original office building plans came from Canada or some other place where they use metric units?

Erase everything but the one door you are using as your reference and save the drawing under a different name then attach that drawing to your next post.

I ran -dwgunits command on drawing and it came back inches not millimeters.

You could use the Scale command with the Reference object if you are 100% sure the doorway you have keyed in on is actually 3'-0" wide. Do you have one or two other known dimensions you can cross-check against once the rescaling is complete?

Test it using a scale factor of 0.0408608.

Thanks so much for having a look at it for me!

Yeah I can definitely cross-check with a few other dimensions (desk size etc). What would be the best way to go about it?

Can you show a screen grab that shows the drawing units are inches?

Just because the units dialogue box shows the Drag-and-drop scale units to be Inches, does not tell you what the draftsman intended the units to be.

I would say that you need to scale by 1/25.4. No one would draw in nearly millimetres.

Using a scale factor of 0.0408608 seems to have worked perfectly, thank you all so much for your help. Don't know what I would have done without the advice, probably would have ended up hiding under my desk!

Cheers,

Peter

I hope you saved a copy of the drawing before you scaled it, that 0.0408608 is TOO LARGE.

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I measured a lot of the doors and they are almost all different. It is not the best drawing I have ever seen. Don't depend on the doors being accurate. This drawing was scaled up by 25.4 so the draftsman could work in milimeters in an imperial dwg. They must not have been aware of the disaster this is. It needs to be reverse scaled by a factor of 0.03937 to work with inches. Do NOT depend on the measurements taken from this drawing it is not accurate.

After I scaled the drawing back down, I found the cluster of doors at the bottom to all be about 35.998" wide. That's good enough for me. Even the bathroom stall doors where the draftsman (loosly used) used a block for the doors have opening sizes that vary.