each unit represents one ???

[tails]

Type

Sets the current format for units of measure. The values include Architectural, Decimal, Engineering, Fractional, and Scientific. The Engineering and Architectural formats produce feet-and-inches displays and assume that each drawing unit represents one inch. The other formats can represent any real-world unit.

 

So does that mean I have to set my mm units so that, each drawing unit represents one mm?

[Tiger]

If you draw in millimeters, you set your units to millimeters yes. You don't have to, as in the drawing fails if you don't, but it helps.

[tails]

Excuse me if this is obvious but AC The Engineering and Architectural formats produce feet-and-inches displays and assume that each drawing unit represents one inch. The other formats can represent any real-world unit

 

So as the other formats can represent any real world unit, where can a go to set this up?

[ReMark]

Make it easy on yourself and start with a metric template.

[Tiger]

Excuse me if this is obvious but AC The Engineering and Architectural formats produce feet-and-inches displays and assume that each drawing unit represents one inch. The other formats can represent any real-world unit

 

So as the other formats can represent any real world unit, where can a go to set this up?

 

You set the units in the Units dialogue box, easiest to acess by typing UNITS and hitting enter.

[tails]

I am using the acadiso.dwt which I believe is metric. In the units dialogue box I have selected Decimal which I believe is metric.

 

How do I know if my metric set up is operating in mm, cm or m as there is no choice? Perhaps it is missing on a mac.

 

Also how do I know an autocad unit = one mm, cm or m. Once again I see no command, although I assume it would always work like this.

[ReMark]

It's whatever YOU want it to represent. If you want one unit to represent 1 mm so be it. If you want it to represent 1 cm so be it. Those of us who work in the "imperial" world suffer under the handicap of not having a system as easy as the metric system. If we weren't so stubborn we would have changed this a long, long time ago. All you have to do is move a decimal point.

[ReMark]

Quoted from the academics.triton.edu website:

 

"...draw the building in metric system right from the start, and plot in metric system. This is the simplest approach. To do this, you set up the units as decimal units, select mm as the dimension for plotting in the plot dialogue box, and select a metric plot scale and a metric sheet size. Note that in plotting in paper space, use the metric plot scale directly as a fractional zoom xp factor. For instance, if you want to plot a viewport at 1:50 scale, switch to model space, make the viewport you want to set at a scale current, and change the paper space zoom factor by typing the following: z1/50xp"

Since you are using the latest version of AutoCAD there is no reason to use the Zoom > Scale Factor option. You can easily set the scale of your viewport via the Viewport toolbar, Quick Properties or Properties.

Are we clear now?

[tails]

Thanks for the help, I'm going to leave it for now as I have broken my brain with all the different settings!

[SLW210]

It's whatever YOU want it to represent. If you want one unit to represent 1 mm so be it. If you want it to represent 1 cm so be it. Those of us who work in the "imperial" world suffer under the handicap of not having a system as easy as the metric system. If we weren't so stubborn we would have changed this a long, long time ago. All you have to do is move a decimal point.

 

The longest of journeys begins with one step. If only we could switch today.

[dbroada]

Thanks for the help, I'm going to leave it for now as I have broken my brain with all the different settings!

when I started we never set the units and accepted the unitless default. For us we would assume a line 10 units long was 10mm but we could just as easily assumed it to be 10m if we had wanted. You can use the unit setting to declare the units to be mm, cm, m etc. if you want to. It helps if you are sharing files with other companies but for a small office it isn't that much of a problem.

 

setting DECIMAL only affects the way dimensions (or lists) are displayed. A decimal display will show 10.00 or 100.00000 where some of the other settings add spaces and feet & inch formatting.

 

the other thing you can do it set the number of decimal places THAT WIL BE DISPLAYED. This does NOT affect the accuracy of the drawing. If you set no decimal places and draw a line 7.87mm long it will dimension as 8mm until you increase the number of decimal places.

[Blam]

Type

Sets the current format for units of measure. The values include Architectural, Decimal, Engineering, Fractional, and Scientific. The Engineering and Architectural formats produce feet-and-inches displays and assume that each drawing unit represents one inch. The other formats can represent any real-world unit.

 

So does that mean I have to set my mm units so that, each drawing unit represents one mm?

 

Just to add my 2 cents and hopefully not add to your confusion.

 

Say you draw a line in modelspace 12 units long. Then you type UNITS and set it to Architectural or Engineering. If you use the DISTANCE command on that line, it will return a value of "1'-0", because it assumes each unit is an inch and display it accordingly. If you set it to Decimal, Frac, or Sci it would return "12.0".

[tails]

If you set it to Decimal, Frac, or Sci it would return "12.0".

 

So I guess my question is what is the 12 in Decimal, Frac or Sci. Is it mm, cm or m? I think mm from my reading.

 

thanks for the help.

[Blam]

The Type of unit only matters in how distances are displayed. Such as when you use the distance command OR in dimension styles (Dimension Style > Primary Units > Linear Unit Format).

 

The real place assigning units matter is in the Insertion Scale. When you assign an Insertion Scale (Unitless, Inches, Millimeters, etc.) it will affect some important things. When you assign an Insertion Scale to a drawing, let's say millimeters, you are telling AutoCAD that "In this drawing, when I draw a line 1 unit long, it shall be 1 millimeter." AutoCAD says "fine." Then let's say you want to insert block drawing that was created in Imperial units. This block drawings Insertion Scale is set to inches. AutoCAD says "Oh hey, let me scale that for you, because 1 unit in that drawing is 1 inch. I need to scale the distance up by a factor of 25.4 because it will be teeny tiny if you try to insert as though it's units were millimeters."

 

What about Unitless. A lot of people set blocks to 'Unitless' thinking they won't have to mess with AutoCAD scaling things for them. Not true. Go to Options > User Preference tab. Look at the Insertion Scale box. See where it says "Default settings when units are set to unitless". That is how AutoCAD treats Unitless blocks. Say they are both set to inches. If you have a drawing set to Unitless, AutoCAD will pretend it is inches for the purpose of handling thing inserted into that drawing. If the outside block coming into a drawing is Unitless (the Target), then AutoCAD will scale it as though it were in inches.

 

So bottom line. What units are your titleblocks in? Inches or millimeters? What units were your outside blocks drawn in?

[irneb]

If you set it to Decimal, Frac, or Sci it would return "12.0".

 

So I guess my question is what is the 12 in Decimal, Frac or Sci. Is it mm, cm or m? I think mm from my reading.

 

thanks for the help.

In reality ACad doesn't care what the "unit" is. It simply draws in Model Space units - they don't have any physical analogue without you imposing it. Thus if you draw 12 units in model space, ACad sees it as 12 units, irrespective of what you are "thinking" in (be it inches, meters, millimetres, yards, miles, km, angstroms, etc.)

 

Where it starts mattering is when you plot. Since the paper has a real-world size it is measured in either inches / mm. You can see this if you open the Plot dialog. In the plot scale box there's a drop-down to the right of tthe 1st custom value under the normal scale drop-down. This shows either inches or mm. So for paper sizing you're stuck with only one of those 2 measurement units. But in model space you could draw in any unit you choose (inches, feet, yards, miles, mm, cm, m, dm, km, etc.). Just remember that you then have to adjust for the conversion factor in the viewport you place onto the paper space (since the paper space is either mm or inches). You can easily get hold of the conversion factor using the QuickCalc palette in ACad (it's got a Units Conversion function).

 

Another place where it may matter is if you mix different DWGs together (e.g. inserting one into another as a block / xref). If both DWG's MS are drawn using the same unit, you don't have a problem. But what if one was drawn with the intention of m and the other with inches? In this case you either need to scale the new stuff manually when you "join" the 2 DWGs so you end up with one drawing in either m or in inches (bot not both). Another (more automatic way) is to use the Units command in each of the drawing beforehand.

In the middle is an Insertion scale ... this is named a bit wrongly (IMO) since it's the unit you tell ACad the current DWG's model space is drawn in. This is used when you insert/xref the current drawing into another. So say you have DWG A set to m, and B set to Inches. If you insert A into B it will automatically scale the new block with a factor of 39.3700787... the other way round would produce a factor of 0.0254. As Blam states, most people set this to Unitless (and some even set the defaults to Unitless as well). This is usually due to not using this feature correctly in the first place, if you're strict in using this exactly as it should be it works pretty nicely.

 

Note also you could have your number formatting in anything - this is not tied to the unit. In the dialog above I've got Decimal numbers, but the drawing is in Inches. You could theoretically also have Arch/Eng numbers with millimetres, but it would make no sense.

[tails]

Test.dwg

 

This was done on a mac if that's important.

 

Hi again, Thanks for the help I feel as though I have learnt something. Unfortunately I appear to have got to a point, if you see my attached .dwg and look at layout A2 which I believe is an A2 sized plot.

 

I have scaled it at 1:100 not the 1:500 in the title block, now we don't have an A2 printer but just from my knowledge from past drawings, I feel that is scaling incorrectly.

 

Can anyone confirm it is wrong? If it is wrong where I have gone wrong?

 

Thanks for all the help, it's much appreciated.

[tails]

 

This is what I'm looking at, incase it appears differently on your screens.

[irneb]

Nope, that drawing is correct. I think, although it's set in the UNITS command as if it's drawn in Inches it still performs correctly as if you're drawing in mm. E.g. the wall height (I'm assuming) of 2400 sounds close to a minimum ceiling height (so I'm assuming you are actually drawing in mm). If that's not the case, then disregard this - there's some more info I would then need.

 

Anyhow, if I measure the dimension in the paper space I get a value of 24.0 ... which is correct for a distance of 2400 @ 1:100. So in this instance it appears that both the paper space and model space are in mm - which makes life a lot simpler than mixing mm with inches. I'd advise however, you set the Insertion scale in the Units command accordingly - it would just make your life simpler in the future.

[tails]

Thanks for your advice, I'll make the change you mention. I want to work in mm 100%, unfortunately some drawings we are supplied with come in meters, so should I set "insertion scale" to meters.

 

I'll be pleased if the drawing is correct it just looks so wrong.

[irneb]

Thanks for your advice, I'll make the change you mention. I want to work in mm 100%, unfortunately some drawings we are supplied with come in meters, so should I set "insertion scale" to meters.

If those drawings aren't set to meters already, then you might have some problems - since you'll need to modify them to suit. Usually I take a drawing from another consultant and create a prepared version of it (auditing errors, making sure there's no circular references to other xrefs, doing some layer cleanup & purging, setting everything to ByLayer using the SetByLayer command, and then also setting the units correctly).

 

So to make sure we both understand each other correctly, here's an example. I receive a drawing from the surveyor called X.DWG. I open it, do some cleanup (as mentioned). Do a distance command to check one of the dimensions to see which unit it's drawn in. Then type Units and set the insertion scale accordingly (if it's not already set correctly). SaveAS to X-prepared.DWG, then xref that into my siteplan which is set to mm in the insertion scale. Automatically the xref will get scaled up by 1000 do "convert" it from m to mm. Then when I receive an update for drawing X, I clean it up again and SaveAs overwriting the prepared version - the drawing(s) where I xrefed it in would still have it scaled correctly.

 

I don't need to think about what scale factor to use - the 1000 is easy since both units are metric, but when you start mixing imperial and metric those factors become nightmares, which makes this method a lot simpler. I've got a few projects where some consultants are working in inches, others in cm, yet others in m, etc. While I work near exclusively in mm. If I follow this procedure I don't have any scaling issues.

 

I'll be pleased if the drawing is correct it just looks so wrong.

As a final test (to set your mind at ease) print it out and use a scale ruler to check if it's done correctly. You can print an A4/A3 portion of the paperspace using window (as the What to plot) in the plot dialog - don't use the scaled to fit, just leave it at 1:1. You'll end up with a cropped portion of the A2 page, thus it should still be at the same scale as if you printed the entire page onto an A2 - it would just have cut off those portions which don't fit on the A4/A3.

 

BTW, you could use any other page size - you don't need to stick with the ISO sizes, e.g. you could use a Letter size instead of A4 (if your printer only handles Letter size). It should still print at the correct scale if your settings are set to mm in the plot dialog. If you change the plot settings to Inches (in your case) you'll find it prints a whole lot larger than you're expecting (25.4 times larger so 1:100 would become 25.4:100 ~ 1:4).