Help with basic polyline drawing
No worries! Just takes some getting used to.
Hopefully this helps.. We just need to understand what we're looking at on the screen. Here I have started my polyline. I made my first 250 unit segment and have just started an arc. (my polyline is magenta, and my cursor is orange) You can see that I have 2 numbers showing on my screen here and one of them is by default already waiting for input. We can also see that there are some gray dashed lines (some helpful dimension lines) and these represent what the numbers will affect. I have added a red bracket and labeled it "C" since we can tell by the gray dimension lines that this input appears to be the CHORD of the arc.. So therefore, when you input your first value of 45, this represents the CHORD length of the arc:
Now, when I hit the Tab button, we can see that the 45 we input as our chord is locked, and we have moved to the next input box. This appears to be an angle of some kind. In my image below I have added a red identifier and labeled it as "A".
...but that's weird, the bottom part of the angle seems to arbitrarily going flatly from left to right in that picture. Wonder why that is? Well, let's head down to our next corner and see what happens when I input my values over there:
...hmmmm, even at this corner it still maintains a left to right orientation, and now instead of 45 degrees upward, I am opening 45 degrees downward. So when I enter 45->Tab->45, then this still checks out ok. Let's check the next corner:
Well look here now! When I do my 45 unit chord, then tab to my angle, it is now shaping up to be about 135 degrees! So it is always opening from the right (or Eastern) side of my model space. And this is why Sometimes you need 45 degrees, and sometimes 135 degrees.
But why does it always open from the Easterly direction? Well, you will have to run your UNITS command, then open the default "Direction":
...which shows us the default Base Angle of East. (so that's where your 45's and 135's come from):
Hope that helps!
Best,
~DD
@watsongrace2022 wrote:
What I am meant to do is draw a polyline with Line at 250 then type A and then type 45 tab 45 and this makes this little arc piece. What do the 45 and 45 mean? Am I doing radius, direction, center, angle? I don't know what this even means? Then I understand to change it back to Line and 250 and then A for Arc again but this time he types 45 tab 135? Why is this?
Turn Ortho Off after drawing a polyline at 250, then type A or select "Arc" from the command line.
Make sure your Dynamic Input in the Status Bar is ON, then type 45 for the Chord Distance and 45 for the Angle.
The 135 is adding to the previous angles - see example:
