really get stuck with this one

[SatoshiQ]

I get stuck with this one. I coundn't find out how to find the center for the circle with dim R60. Event some one in the different forum tried to show me the way, I tried pretty hard but I can make sure that I am right and it just seem like not acurate.

[BIGAL]

Start with 2 vertical lines 20 apart the midpoint would be where the top circle is drawn then the outer circle, use trim the circle at bottom using the 2 vertical lines. Do a fillet pick a line then outer circle you should get the reverse arc. The end point is the starting point for further steps. Delete the dummy lines.

 

 

 

[SatoshiQ]

2 minutes ago, BIGAL said:

Start with 2 vertical lines 20 apart the midpoint would be where the top circle is drawn then the outer circle, use trim the circle at bottom using the 2 vertical lines. Do a fillet pick a line then outer circle you should get the reverse arc. The end point is the starting point for further steps. Delete the dummy lines.

 

 

 

yeah I got it but I got stuck with the R60 circle.

[BIGAL]

Draw a horizontal line 60 long from the end point of the left small arc that is the center point of the 60 rad. Similar with the 35 rad.

 

Look carefully at the red lines and their dimensions.

Edited August 22, 2023 by BIGAL

[eldon]

I think that you do not need to know the centre of the 60r circle. You would draw it using TTR. The two tangents are the left hand one of the vertical lines from the top, and the inner circle of the hook.

 

Unfortunately the radius of the inner face of this hook is also not shown, so the diagram as it stands is lacking information.

[CyberAngel]

As eldon notes, TTR is your friend here. You don't need the center of an arc if you have tangents for both ends.

 

I inserted a full-size copy of the blueprint in a drawing and followed the dimensions. The diameter of the central circle should be 15. That's the only size that fits. Why they couldn't call it out, I don't know. I don't see how you could infer it from the other dimensions.

[eldon]

3 hours ago, CyberAngel said:

...... The diameter of the central circle should be 15. ......

 

Perhaps radius should be 15?

[SLW210]

The radius is not 15, but close.

 

All of the information is there.

 

There is a small section of straight where the  20 dimension is. Just draw the arcs as tangents.

[SatoshiQ]

the author of these exercises kind of want us to use trigonometry and geometry to find out these dimension.

[SatoshiQ]

5 hours ago, SLW210 said:

The radius is not 15, but close.

 

All of the information is there.

 

There is a small section of straight where the  20 dimension is. Just draw the arcs as tangents.

yes I think so to but could you explain more details, I think the R80 is the last to draw.

[eldon]

11 hours ago, SLW210 said:

The radius is not 15, but close.

 

All of the information is there.

 

 

 

I too am puzzled at the amount of information, and would be grateful if you could reveal the source of the inner hook radius. I can still learn and improve my powers of observation.

 

In my ignorance and absence of inner hook radius stated dimension, I can draw a figure that satisfies all my observed dimensions, but with differing inner hook dimensions.

 

@SLW210, please clarify for my education where I am going wrong.

 

 

[SLW210]

I'll see if I have time later today. I was hoping the OP would give it a few tries.

 

I never used the image provided. It took a few looks at everything and starting here and there at first.

[SLW210]

3 hours ago, eldon said:

 

I too am puzzled at the amount of information, and would be grateful if you could reveal the source of the inner hook radius. I can still learn and improve my powers of observation.

 

In my ignorance and absence of inner hook radius stated dimension, I can draw a figure that satisfies all my observed dimensions, but with differing inner hook dimensions.

 

@SLW210, please clarify for my education where I am going wrong.

 

 

Yours is not necessarily wrong.

 

Mine is just one solution, I used the straight section of the shank as being equal. That should be the logical solution, as there is no other real point for the R60. It will be interesting to find out what the exercise was expecting as logical it may not be.

[CyberAngel]

19 hours ago, eldon said:

 

Perhaps radius should be 15?

 

Radius, diameter, what's the difference?

[Steven P]

I reckon you need a logical way to work out that inner radius, this is the one I used, and then just pop in the last radius Circle TTR

 

[lrm]

An interesting problem!  We know the location of the R40 arc from which we can determine the location of the R35 arc with circle, TTR (green below). We can assume that the tangent point for the R60 arc on the left vertical line is inline with the tangent point for the R35 arc and therefore know that its center is 60 to the right (cyan point).  The inner hook arc tangent point is at the intersection from this point to the known center which yields a radius of 16.0013.

[eldon]

3 hours ago, CyberAngel said:

 

Radius, diameter, what's the difference?

 

Perhaps you might just be able to spot the difference.

 

 

[eldon]

3 hours ago, SLW210 said:

....

Mine is just one solution, I used the straight section of the shank as being equal.....

 

I have no argument with your solution, but what I am querying is how someone doing 2D drawing exercises would be able to know that? You and I have experience, but for beginners, that would be hard to ascertain.

[Steven P]

Just got to work through it methodically, I think SLW210 and I got a very similar result, am guessing we followed a similar path?

 

- Put in all the stuff you know then you are left with 3 tricky radius to figure out.

 - The R60, which has to start tangentially to the line above it connects to, so you can put in a circle starting 60 to the right. Quite easy to work out, the learning point there is not to be scared of construction and temporary lines I reckon. That is the easiest of the 3 to set out and sets the beginner of in the right direction to follow.

- The unknown radius follows from that circle though it takes a little thought to get 2 edges of 2 circles to be cut and at a tangent to each other - once you know that part it becomes obvious. Learning point here would be how 2 circles can touch, be cut and to get perpendicular to each other

- Finally the last fillet we know the radius and 2 tangents so can fit that in

 

 

However main point I think is just working through it bit by bit and like you say, if the beginner sets off in the wrong direction I think they would struggle. Tricky exercises are the best learning tools.

 

 

 

 

I'll give it till later, see if the OP wants to comment on their solution, but just for fun I have the steps I followed to post (later though)

 

 

 

This is one solution, there are others

 

 

Edited August 23, 2023 by Steven P

[SLW210]

18 hours ago, eldon said:

 

I have no argument with your solution, but what I am querying is how someone doing 2D drawing exercises would be able to know that? You and I have experience, but for beginners, that would be hard to ascertain.

I do believe the OP mentioned it was more a geometry exercise. Or in my opinion, just a problem solving test in general. 

 

Being as this has a high number, I would be led to believe it is a more advanced lesson. I am not even positive if the 15 diameter would be wrong.

 

I did an exercise long ago with all of the information and an image, the correct result looked vaguely like the image, off just enough visually to make you think you messed up somewhere.

 

 

 

I cannot get on the site for the test as it is flagged as a blog site at work, they have a YouTube page, but mostly SolidWorks tutorials.