Dumb Acad Question


From original questioner:


I want to draw in millimeters. Ive changed my Units to millimeters and decimal,along with my dim style to decimal, but when I type in L, then 10, it draws a line 10 inches, not 10 mm. What don't I have set right?


From contributor Da

Sounds like you are comparing the new line to existing entities.

It is 10 units, but what is everything else now?

You may need to scale the other items that already exist. The two factors you need are 25.4 and 0.0393700787401575, depending which way you are scaling.

From contributor Mi

I tried changing the parameters within a normal job that I already have my parameters set up in. I even created a new dim style. Maybe I need to completely start a new job with those settings?

Thanks for the imput

From contributor Le

Opening up a new page and setting the new metric setups is what I would do to see if it worked.

From contributor Da

have to go to format menu and pull down to drawing setup. then select drawing units and select millmeters. make sure there is a window which asks you to scale all objects. otherwise you will have a 10 millimeter line.

From contributor Mi

Thanks for everyones' input thus far. The company I work for is a big closet manufacturer of melamine closet systems and we draw everything in CV. I'm trying to do up some drawings in acad and show holes 32 mm apart. I guess if I needed to, I could type in the decimal conversion for 32 mm, a 5 mm hole and the start and finish hole that is 10 mm off the top and bottom of each panel.

Any other ideas/ways, or am I on the only successful track?

Thanks again!

From contributor Ge

There really are no inches or mm's in AutoCAD. You draw everything in units, and you can't have multiple unit sizes in a single drawing.

I do my drawings in inches, and always draw my holes 5mm with 32mm spacing. There are a couple ways to do it and keep your drawings in inches.

The first method uses the 'cal command to let you enter calculations.

To start 10mm from the top, start a line at the top of the panel where you want the hole to be. Drag the cursor towards where the hole will be, and type " 'cal" and enter, then 10/25.4 and enter, and you'll have a 10mm long line.
To draw a 5mm hole, use the circle command, click at the end of your line, type "d" and enter for diameter, then " 'cal" and enter, then 5/25.4 and enter. I then use the array command ( I use -array to avoid the dialog box, which is much slower imo). When it asks for the spacing, I type " 'cal" and enter, then 32/25.4 and enter.

The other method I use uses autolisp commands to scale entities by 25.4 and 1/25.4, which lets me convert them from inches to mm or mm to inches. SO I can actually draw a 10 in line, and a 5in hole with 32in spacing, then select them and click a button and they'll be scaled to mm.

From contributor Ch

OK.. first understand autocad is 'unitless', it doesn't really matter what the setting is, it only controls labelling of units.

Since your drawings are existing and in imperial, the easiest way to work is simply draw what you need to ignoring that it is HUGE compared to everything else. When done, simply select everything you drew, hit 'scale' button and scale it by 10/254. This will shrink it down to the 'real' size. If you want your dimensions to show it in metric either set up a metric dimstyle or enable alternate units for mm for those dims. This is much easier then calculating everything.

If you need to say add this to a cabinet carcass already drawn, simply scale it up 25.4 times, add the metric stuff, then scale it all back down.

From contributor Mi

Thanks chris. How did u come up with the scale factor of 10/254?

From contributor J


To convert mm to inches, divide by 25.4.

To convert inches to mm, multiply by 25.4.
4" x 25.4=101.6mm

this is where Chris came up with 10/254.


From contributor Mi

Please correct me if I'm wrong, but I was talking about a 10mm vs a 10" lime and some how 12 inches came into play. If my math is correct 12*25.4= 304.8, not 305.4.

I just dont get how mathmatically he came up with 10/254.

From contributor Al

1 / 25.4 =0.039370079

10 / 254 = 0.39370
all he did was move the decimal point to the right 1 position which changes 1 to10 and is the same as working in centimeters

It is just units

From contributor J

My bad......304.8mm

I was just giving an example.
10" x 25.4 = 254mm


From contributor Mi

Thank u all for your help


From contributor Ch

Yeah, the reason for the fractional format is just for speed of entry at the keyboard, decimal equivalent would be fine, its just easy for my simple mind to remember, lol.