Problems with two 'basic drawings'.

Hi all,

I am currently doing a home learning course studying an Introduction to AutoCad (2010). It is my only experience of AutoCad and I am teaching myself.

I am struggling on a few diagrams for my assessment. (link below).

http://dl.dropbox.com/u/22748810/Image%20%282%29.tif

The first part I am struggling with is the right hand drawing next to the 'SIGNAL ARM' title. I can draw the two circles (diagrams of 60) but it is more the 'arm' (far right hand side) part of the drawing I am struggling with. I can't figure out out to draw the 'arm'. I can't draw the far right hand curve with the required radius of 12 as shown in the diagram. It tends to appear a lot more 'squashed'. Perhaps someone may be able to advise me how best to complete the diagram to the required dimensions? (my knowledge of angles etc. is not very good!)

The second drawing (of the propeller) I can't even figure out how to start. I can literally only draw the two base circles (radii 10 and 18). I don't know how to create the required 15 degree angle as shown or how to create the radii of the other sections of the propeller blade. I have tried drawing as a rectangle and 'filleting' but I have had no success. If this is done by using tan tan radius then this is something I am not too familiar with. Please help if possible.

As I said above I am currently doing a course and these are two exercises I will be assessed on. I have been working through a coursebook so I have done more than just these drawings, but my knowledge of the AutoCad programme is a beginner level so I hope the above explanation makes sense. I also hope you can see the linked drawings ok and the dimensions used if not then I can give these. Also if you need more specific detail then I can give also.

Many thanks,

Jacob (cad and forum newbie!)

Everything you need, information-wise, to draw the Signal Arm is included in the diagram. You will need to use the Circle and Trim commands for starters and it wouldn't hurt to make use of Offset as well. A couple of the arcs can be created using the Circle command with the TTR option and following this up with some more trimming. This drawing should take you no more than a couple of minutes to layout the geometry. That does not include any dimensioning.

I drew my angled construction lines using direct-distance entry at the command line. Example: @120

I cannot advise you on the propeller drawing because I was unable to find it.

Thanks for the reply.

I will do the propeller arm as a separate thread, it doesn't appear to have come out. Concentrate on this drawing first.

The TTR option is something I am not familiar with. I am still confused as to how to get the angle of the arm correct. (Sorry may need to explain in idiots language to me! Sorry I am very beginner). Is there any links of drawings you may be able to use to explain better?

Many thanks again

In your first drawing, the R12 is the radius of the fillet between the arm and the main body. The radius of the outside of the arm is R90 plus the half the width of the arm (20) = R110.

Here's one way to do it. http://screencast.com/t/BEGpRvpM5d

(BTW, If I could have read the dimensions for the slot, I would have drawn that first, but since I couldn't, I only did the arm.)

Propeller http://screencast.com/t/ETKxGCsZpB

@ nestly Nice video tuts m8, explains/shows how easy it be when you know how, that program Jing you used is easy to use ? and can you edit the final video or do you have to do it in one take ?

Nestly, thanks very much for the videos, make this look very easy. Hopefully now I can complete the drawings.