Help with drawing a walkway

[redglobe]

Hello I need help with exercise 3.12 drawing a walk way . I did as instructed making the center line first and drawing the R20 arc. I getting stuck on the making a circle tangent to the 45 line. If some can provide step by step simple instructions on what to do.

 

Thank you for your time 

[BIGAL]

Try this of the top of my head

 

Draw a line 20 units up. 

Rotate it 45 deg's.

Draw a line from top 20 units down

Draw a circle radius 20 from top of line

Draw a circle radius 40 from top of line

Extend 45 line to new circle, erase new circle

Draw a circle radius 20 from bottom of line

Add a few lines at correct location like line length = 5. 

Do some trimming and you should have it 

 

 

 

Edited March 4, 2019 by BIGAL

[eldon]

I would start by drawing the known lines, i.e. 19' vertical and 45' horizontal (black dashed lines in picture).

Then I would draw the known straight parts of the center line, i.e. the 5' horizontal line, and a vertical line going through the right hand end of the 45' line (red lines in picture).

Then I would offset the 5' line upwards 20' to give the centre of the 20' circle (blue). Then the last circle can be drawn as TTR with the blue circle and the red line being tangent points.

Trim, join the bits of the centre line as a polyline, and offset both ways 2.25 to give walkway.

 

 

Edited March 4, 2019 by eldon

[steven-g]

There are two very important dimensions that are not given in the image but can be worked out from the information that is given. And once you "see" those it is very easy to construct the drawing.

 

[redglobe]

Thank you for your help I understood it better.

[eldon]

However those dimensions are not needed according to the exercise instructions!!

[BIGAL]

The left R20 is like a red herring to not provide some clues in how to draw required when you look at the Steven-g R40 which is the way I was suggesting. This is something that appears in so many tutorials a subtle item missing.

[eldon]

9 hours ago, BIGAL said:

......... This is something that appears in so many tutorials a subtle item missing.

 

Isn't this the very essence of a tutorial, to make one think.

 

If the Steven-g dimensions are provided then the other circle can be drawn from the centre point, thus nullifying the whole point of the exercise which was to use circle TTR!

[steven-g]

I agree the point is to learn the TTR option, I missed that, but I do think the other method is quicker/easier, as you only need use copy, offset and trim with simple object snaps like End and Quadrant. There was however one bold word in the exercise, "Hint:" which I would read as allowing for alternative approaches.

[eldon]

If you carry on like that, it will be the student teaching the professor.