scales, scales, scales problem

Hi All,

I'm still struggling with scaling my drawing properly. I have a drawing of a floor plan, I set the units to say meters (menu > format > units), and scale the drawing so that one of the windows is 2.4 units, so 2.4 meters I assume. Which ought to be correct. Now I set up a layout. I have an ISO A3 paper size, so I'm plotting in mm. I set up a viewport and set the scale of the viewport, and it looks good when the scale is set to 1:3 . Which is ridiculous. I'm attaching the file here (see layout 2). Can someone help to set it up properly? I would like to have the drawing in meters or milimeters, and the scale should be more something like between 1:25 or 1:100 to be realistic.

Thanks very much!

plan-07b.dwg

When you set the scale for a viewport, unless you are using a standard scale, you must set the custom scale by entering the reciprocal of the required scale.

But as AutoCAD only knows mm or inches, and you want to use metres, you have to start with the formula "Drawing units in mm divided by the scale"

In your case, a metre drawing unit is 1000 mm, so your custom scale should be 1000/25 for a 1 to 25 scale and 1000/100 for a 100 scale.

In the custom scale box, you can actually enter the scale as 1000/25. You do not have to get your calculator out.

Thank you for help. I think I got it at last. I got a scale of 1:30 which makes sense I think. Ciao!

My previous advice was given without opening your drawing. Now that I have opened your drawing, I can see why you are having so much difficulty.

A layout should be sized so that it is the full size of the sheet of paper that it will be printed on. Then the plot scale is 1 to 1. The viewport should be the only thing that is scaled.

If the layout is set up to the wrong system (imperial or metric), the plot will then have to be scaled to fit on the sheet. Because of the plot scaling, you also have the viewport scaling which must take into account the plot scaling. All very confusing, and if you do not get the layout size correct, you will be in a permanent state of confusion as to how to get a scaled plot.

One simple way to check the size of the sheet in the layout, is to measure the distance across the image of the sheet of paper.

In your Layout1, the dimensions of the sheet are 16.5 by 11.5 (approximately).

Remembering that AutoCAD only knows inches and millimetres, this sheet size is for an A3 in imperial dimensions. You must set up your layout for metric dimensions, otherwise you will be permanently struggling

Thank you for help. I think I got it at last. I got a scale of 1:30 which makes sense I think. Ciao!

I don't think that you have got it right. That scale will plot on paper at 1 to 118.1102362.

It is usual practice that drawings on paper are plotted to conventional scales that are available on scale rules. Your clients are in for a shock

If you want to get a plot at 1 to 100, then your custom viewport scale should be altered to 0.393700787.

This figure is derived from the fact that you are using metre units in an imperial layout, and combining several scale factors

Ok, I can barely understand. I think I fixed half of the issue then. I'm working on Layout 2 (forget Layout 1). Layout 2 is set to ISO A3. I drew a line across and measured it, it's 420, so an A3 size paper in mm. You say, the only thing that should be scaled is the viewport. So I set up the viewport, and I come to a scale of 10:1 - then I get a reasonable size of the drawing in the viewport, it more or less fills the viewport. But 10:1 doesn't make sense I think, it means that the drawing is enlarged 10 times right? That would mean that I drew the drawing to wrong scale, there is something wrong with the actual dimensions. Is that right? I'm attaching a newer version of the file - see layout 2.

By the way, now that the viewport is in scale 10:1 I lost all nice arcs and curves, they got chunky...

plan-07c.dwg

AutoCAD is peculiar in that it does not allow the scale to be put in so that you can easily recognize it. It needs the custom scale to be set at the reciprocal of the plotted scale, i.e. one divided by the scale.

But because you are not using millimetres as your drawing unit. You are using metres which are equal to 1000 mm.

So the figures to put into the custom scale box are 1000/100 to give a 1 to 100 plot. This simplifies to 10, as you saw, so that is correct.

The display will probably get less chunky if you do a regen.

Just to prove that AutoCAD DOES recognize some scales, just enter 1/48 into the custom scale box, and that is recognized as 1/4" to 1'.

Ok, I assume it is correct then. Thank you for help. I unfortunatelly lack proper technical background to fully grasp it. Hopefully I will with more practice.

The REGEN command did help.

Oh, one more question. So 10 is correct. What do I write on the drawing then? There is a scale field in the bottom right corner. So I need to write there 1:100 or 10:1?

Oh, one more question. So 10 is correct. What do I write on the drawing then? There is a scale field in the bottom right corner. So I need to write there 1:100 or 10:1?

You need to write 1:100.

It is only because of AutoCAD's peculiarities that it uses 10:1 for its own needs. The rest of the world doesn't mind if you use metre units or millimetre units. The final plot IS at 1 to 100.

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4,5 cadtutor forums make it 1 pdf for knowing layouts

thank you

Things you should know about Viewports.pdf

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but this pdf may useful check it

If you use millimetres as a drawing unit, that is very good information.

But some metric users, being perverse, choose to use units such as Centimetres, Decimetres and even Metres

When they do that, they are on their own

You have to get your head round the fact that plotting scales are inverse scales, which are not easily recognized in the dialogue boxes. Plotting scale is Drawing units in millimetres divided by the plot scale.

If you plot from Model space, you can at least put this plotting scale in directly, so that it looks familiar.

One of the trickier aspects of Paper space is that in one drawing, you can have layouts with paper sheet sizes in imperial or metric, with no easy way of telling which is which. I think the only way is to actually measure the paper sheet, and see whether the units give an imperial sheet or a metric sheet. Checking DWGUNITS does not give the answer.