Help me pass my C&G CAD Exam

[sparkyuk]

That must have taking a long time to make ? , they did a good job

[MikeScott]

It's funny how these things come along:

 

http://cadtips.cadalyst.com/curved-objects/draw-tangent-lines-and-arcs

 

 

That's really useful, but entirely useless in this scenario.

 

If you went that route, your arc would start off by going straight up, which isn't what it's supposed to do if you're sticking to the radius given in the exercise.

 

As a result, it wouldn't give you an arc radius that matches what the exercise called for.

 

It's still very useful normally though. Works a bit like the PLine does, in terms of switching from a line to an arc.. I never knew it did that.

[Pablo Ferral]

You don't know what you don't know.

 

I wasnt proposing it as a soloution, just an interesting and (semi) relevant reference for anyone else coming along and reading this thread...

[Seath]

Seath, Eldon's right.. The problem lies in the fact that that vertical line you added shouldn't automatically be at 90/270 degrees. It might work by luck in some instances, but it's not something that takes the upper shape into account.

 

The tangent point (where it hits the upper circle) is a little to the right of the top of your line.. which would put the centerpoint of the required arc a little "off".

 

That vertical line would have to be calulated, because it has to be on that upper tangent point, wherever it is, or it's in the wrong location... resulting in a bad curve transition.

 

I have a question though Seath.. once you had that line.. how did you manage to ensure it touched the two points of the circle (in blue on your diagram)? Did you just keep moving it until it hit? I do that kinda' thing sometimes and hate the fact I can't always nail it, and have to approach it from a different route.

 

I see what I did or rather didn't do now. I do eyeball at times my problem here was not properly thinking all the way through and got trim happy before looking where my circle was.

 

Thanks guys for showing me where I got off track I always welcome constructive criticisms.

[badluci]

I need some help too.I hope i will get it. Can you please show me how can i make them in 3D? PS:save the comands please. Need help quick because next week i must present them.

 

yfrog . com/c9pag12aj

 

My email adress is badluci20022002 yahoo

[JD Mather]

Can you please show me how can i make them in 3D?

 

Use exact same method already shown here but only half side.

Then PE for polyline edit J for join.

Then revolve.

 

This should have been covered in your class. There is no point in certification if you haven't been trained.

[badluci]

I made almost the entire piece but on the edge is a round part with R=2 .But i dont know how can i use "fillet" in 3D , even my teacher doesn't know.

 

I'm sorry for my bad writening.I hope i'mbeeing understood.

[JD Mather]

Attach the file that you have been able to complete so far.

[badluci]

I upload it on a site.

 

fisierul meu. ro/37AC1LQU3K24/Drawing3-dwg. html

[Bill Tillman]

I was a little intrigued by this problem and admit that eldon's solution not only is correct but it also seems to be the simplest and most efficient manner of locating the center of the required radius. I tried a couple of other methods and nothing seemed to work without getting too complicated. In fact, I couldn't really find another solution to this problem. It's unusual that there is only one solution to something but this appears to be one where the simplest method is the only method.

 

Now to draw it in 3D, that's not too challenging since like JD said, just cut it in half, make a PE out of it and revolve it. All in all this was a neat little problem.

[Naddoo]

yes, Pablo i s rite, I have tried and it's perfect.First make a 2p circle from corner of screw driver, then make Tangent, tangent, radius circle that two tangent points are touching uppe and lower circle, then trim the part you want and miror it.

[Pablo Ferral]

Ahem, I wasn't right... But thanks for the support ;-)

[badluci]

Thanks for the support .

[sticks147]

Hi I could use a little help with this, I am currently doing the C&G level 2, 2D CAD Exam. Bizarrely this part of the exam lasts 2 hours, with 1.5 hours one week and 0.5 the next week, this gives a chance to find answers to any problems and I have a problem.

 

We had to draw a screwdriver and a wood screw, fine nice and easy, but I cannot work out how to finish the handle off.

 

I am 42 years old and this is a career change for me due to ill health, used to be a builder but now I am doing the drawings instead. If I can work this out I have a fighting chance of getting a distinction from C&G.

 

As you can see from the picture, the curved section of the handle needs to be inserted and trimmed to suit, I assume eyeing it in is not good enough. But I have no idea how to go about this and despite looking on the interweb, I'm no closer to a solution.

 

Any help or pointers would be appreciated.

 

its all to do with geometry - you have to use 3 circles in all to achieve your goal.

Draw a line offset 12.5 from the top round handle. Then from the section below the top, go to the far right point and draw your next circle with a radius of 12.5.

where the 2 circles intersect is where you draw your final circle with the same radius as before.

this will give you your perfect curve from the handle to the bottom section.

Select all line and use your trim tool to remove unwanted lines.

Job done!

[eoghanoduinn]

Sorry I just realised that I had skipped a couple of pages of replies. I've done C&G level 2 previously and there is notes avalable somewhere for this exercise. They basically want you to figure out the position of the circle geometrially. Check out my drawing for a step by step.

 

You know that the two circles meet at a single point thus the 2 centres are a distance equal to the radius of 1 circle added to the radius of the second circle. In your case 16+12.5, total radius 28.5, so you draw a circle from the centre of the upper circle which you can osnap to at a radius of 28.5. Construction Circle 1c&G SCREWDRIVER.dwg

 

You also know the circle touches point A(indicated in my drawing)so the centre of the circle must be 12.5 away from that point. Draw a circle radius 12.5 with point A as the centre. Construction Circle 2

 

The 2 construction circles will intersect at the centre point of the circle you need to draw to complete the handle.

 

I hope this is helpful, like I say this is the way C&G want it done for this exercise

 

I hope the exam goes well

[ireniplop]

They still use this exercise in C&G, and this thread was very very helpful to me.

 

The suggested method is using Rotate with a Reference angle but I cannot for the life of me complete it correctly using that. This method is far simpler and easier.

[nestly]

Rotate > Reference is a handy tool, however I agree that it's not the most efficient method in this case.

 

[sasmitaprusty]

Hi,

 

Goodmorning

 

Auto CAD is a good subject, it can give a bright career in future. Thanks.