Another Complicated Arc Question

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45 minutes ago, eldon said:

That is exactly what I did. @Irm 's diagram is not the same as your diagram.

So either you want to draw something like @Irm 's diagram, or you want to draw something like your diagram. If you want to draw something like your diagram, then solving @Irm 's diagram will not supply your answer.

For example, @Irm's diagram shows the r2100 arc tangential to the R30 arc. That simply does not happen in your diagram.

OK, now I can spot the difference between what lrm's posted with mine.

So, this case is not solved yet.

Does anyone able to solve this problem for me?

Edited by basty

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Suspect that IRMs sketch was based on your first post here which suggests different dimensions to the full sketch you posted.

In reproducing this, how far have you got and which parts are difficult for you? Noting that a step by step guide is possible but impractical here for most to do, it would take too long, however small hints and tips and you will get a lot more advice.

I'd chose a point to start at, perhaps the radius 30 circle and draw everything that has a specified location.

There is a 30 radius circle, draw it.

There is a 2690 circle vertically above the 30 radius circle, draw it so the lines intersect at their lowest point [EDIT: Draw a 2690 radius circle at the centre point of the 30 circle, and move the larger circle 2660 upwards. Use Centre snap to locate the same centre of circles and Ortho mode to move the circle vertically]

There is a 335 radius circle (670 diameter) 920 right of the 30 circle and 190 upwards, draw that [EDIT:  As above, the simplest way is draw a 335 radius circle centred on the 30 circle - same snaps - and then move 920 right, 190 upwards is the simplest way]

From the lowest point of this circle there is a line 3500 long to the right, draw that

At the end of this line there is another 335 radius circle, draw that, join the centres of the 2, 335 radius circle. [EDIT: copy the previous circle and paste 3500 away]

There is a line on the left edge of the 30 circle, length 190, draw that

Use temporary construction lines and colours to help you along.

Now for some thinking.

The top of the 30 circle is trimmed between a line and the 2690 circle. This line starts at a point (920 - 120) right and (190 + 218.5) upwards, Draw a line from this point to the 30 circle using tangent snap at the circle.

Working out wards from this line, I don't see the point for the centre of the 1190 radius arc, but we can work it out. Draw a circle (circles are your friend),1190 radius, anywhere, and copy your last line to the centre of this circle. Extend this temporary construction line to the circle circumference and rotate it 90 / 270 degrees so it intersects where you might guess it should be. This is the start of the arc from the last line drawn. Move this circle / line temporary lines intersection to the end of the last line drawn

Now try and repeat the same for the 3 degree line continuing from here and this should give you something like this:

A lot of these, and CAD in general, is  just finding a start point and working through the problem systematically.

Have a go at getting this far and further, asking specifically where you get stuck

Edited by Steven P
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1 hour ago, Steven P said:

There is a 2690 circle vertically above the 30 radius circle, draw it so the lines intersect at their lowest point

How do you draw it? Show me please.

Edited by basty
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It's in the text description step by step. Lines, circles, copy and paste which are the basics you should be mastering by now,

I've added some [EDIT: ..... ] to the above to give further hints but after than I can't do more without physically showing you what to do.....

Edited by Steven P
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How far have you got doing some of this yourself? It will be no good us showing that we can do it, and giving you an image on the screen, you will still be in a point where you have no CAD file until you open CAD and try it out.

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2 hours ago, Steven P said:

There is a 2690 circle vertically above the 30 radius circle, draw it so the lines intersect at their lowest point

How do I know if it's the lowest point?

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If it is a circle, a line drawn from its centre point and straight down will intersect with the lowest point of the circle. See below, You can rotate the circle as much as you want but the lowest point will always be vertically below the centre point.

Magenta construction line shows what I mean. Use object snaps and select 'centre' if you don't have them on all the time to 'snap' to the circle centre, and for orthogonal lines (straight up, down, left, right) use Ortho mode, function key f8 is the default to turn them on or off, you can toggle them on / off mostly any time. Probably I am forgetting that this seams obvious... if you have been using CAD for a while, a new user maybe not so much.

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3 hours ago, Steven P said:

There is a 2690 circle vertically above the 30 radius circle, draw it so the lines intersect at their lowest point [EDIT: Draw a 2690 radius circle at the centre point of the 30 circle, and move the larger circle 2660 upwards. Use Centre snap to locate the same centre of circles and Ortho mode to move the circle vertically]

I added an edit here for an easier way to draw the second circle, see above. Basic geometry that the edges will intersect if you draw them both with the same origin and move one by it's radius and then in the opposite direction by the other radius (in this case ( 2690 - 30) - move up by 2660)

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42 minutes ago, Steven P said:

If it is a circle, a line drawn from its centre point and straight down will intersect with the lowest point of the circle. See below, You can rotate the circle as much as you want but the lowest point will always be vertically below the centre point.

Magenta construction line shows what I mean. Use object snaps and select 'centre' if you don't have them on all the time to 'snap' to the circle centre, and for orthogonal lines (straight up, down, left, right) use Ortho mode, function key f8 is the default to turn them on or off, you can toggle them on / off mostly any time. Probably I am forgetting that this seams obvious... if you have been using CAD for a while, a new user maybe not so much.

What is the diameter/radius of the black circle?

Edited by basty
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On another of the various pictures posted, the tangent point of the R30 circle and the R2690 circle does not seem to be vertically below the centre of the R30 circle.

Perhaps it is easier drawn in SolidWorks than AutoCAD. The constraint images are quite confusing and block vital parts of the linework image.

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5 minutes ago, eldon said:

On another of the various pictures posted, the tangent point of the R30 circle and the R2690 circle does not seem to be vertically below the centre of the R30 circle.

Yes, you're right.

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8 minutes ago, basty said:

What is the diameter/radius of the black circle?

That is not so important, drawn to show the point a bit more clearly.

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12 minutes ago, eldon said:

On another of the various pictures posted, the tangent point of the R30 circle and the R2690 circle does not seem to be vertically below the centre of the R30 circle.

If that is the case then ignore that circle for now, it should become obvious later, Draw the entities where the locations are known.

These should be easy to locate and draw:

Edited by Steven P
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1 hour ago, Steven P said:

If that is the case then ignore that circle for now, it should become obvious later, Draw the entities where the locations are known.

These should be easy to locate and draw:

How do you draw that magenta circle? Is that the R1190 arc?

Edited by basty
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Magenta circle, has a radius of 1190 (from the drawing). The line 30 radius circle to magenta circle is a tangent to this circle - so geometry  that a 90 degree angle to any tangent on the circle passes its centre. Rotate and copy the line by 90 degrees and also extend it to 1190 long, this is the centre of the circle. You can use the extend command or draw another temporary circle 1190 radius at its end and extend to that ones circumference, then delete the temp line.

The top line is the reverse, from 1190 circle centre the magenta upright line is rotated by the angle, and then rotated and copied 90 degrees to get the next one

After that look for any other points you can draw - there are a few more without too much thinking

After that post a snippet of where you are at for the next hints

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OK, now I know the location of the point B. How do you find the point C?

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so point C is similar method to point B, the grey line hits the magenta circle at a tangent, a right angle to this line will pass the centre of the circle - point A. We know from the map that this grey line is angled at 3 degrees, so..... draw a vertical line from A to the circumference or further, and if it makes it clearer the grey line, then rotate it so the grey line is at 3 degrees (rotate 3 degrees.....)

the sketch below might demonstrate better how circles work.

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15 hours ago, Steven P said:

so point C is similar method to point B, the grey line hits the magenta circle at a tangent, a right angle to this line will pass the centre of the circle - point A. We know from the map that this grey line is angled at 3 degrees, so..... draw a vertical line from A to the circumference or further, and if it makes it clearer the grey line, then rotate it so the grey line is at 3 degrees (rotate 3 degrees.....)

the sketch below might demonstrate better how circles work.

Is this the magenta circle?

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Yes, it is taken from that, but showing the way it works above, a right angle from line centre of circle to circumference will be a tangent to the circle - which is the fundamental behind a lot of this exercise to understand I think

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Which one I should draw first, the vertical 3 deg line or the horizontal 3 deg line?

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