Need help with difficult 3d drawing

[Safwah]

Hi, its great to find an autocad forum, im sure ill be here more often

Anyway im studying cert3 in autocad, i pretty much know it already because i self taught myself in high school and finished everything the high school could give me plus more. So when doing this cert3 course they can see i can already do what they are teaching and decided to give me a challenge. This drawing is just frustrating the hell out me. It seems simple but when u get into the fillets of R3 at odd angles joining from a straight line to the edge of a circle that is just slightly off from the center argh! brain damage! Ill post some pics and show what im having trouble with here.

So this is the plan of the drawing that i have to recreate in 3d.
http://www.users.on.net/~sketch/CAD/angguide.JPG

Now this is the part im up to and pretty much stuck on.


The blue circlers show the R3 fillets that are easy enough to do. All i did was create a region of the fillet needed, extruded it, then using the curve going up create another circle, extrude that and subtract it from the fillet.

The yellow circles show the parts that i just cant get my head around.

.

Now the problem here is because the tube is at a 30 angle going from the ground up to the quadrant/base point of the circle is fine, but the offset to the sides where the fillet should be dont directly aline with the fillet, leaving a sligh cut out. Ill try to explain with the following pics of close ups from ISO and TOP views.
Showing a close up on yellow circle #1 in the next pics


See how it cuts in slightly? So the trouble at this point is getting smooth continueous fillet from the tube to the block its connected to without any sudden cut offs as you can see in the close ups.

Ill let you ponder on this then edit the post when i move onto yellow circle #2 which is proving alot harder.

[Safwah]

Ok so part 2.


The red circles show the R3 fillets im trying to create. Im really really stumped on this one.

Once again here is the progress to date.


Ive tried a few things here but no luck. Theres always a gap or a sudden ledge that shouldnt be there, it should be a smooth 3R fillet going around the underside of the tubing until it meets the block underneath.

First thing i tried was to make the fillet region and revolve it <90, then using this fillet wedging, rotate it to the same angle as the tube and attempt to union the fillet to the rest of the main object. But because of the <30 rotate of the fillet there will always be a slight gap between the fillet and the base block. Trying something else now. But im am so stuck on these fillets.

[Safwah]

Stress lvl increasing 10 fold here.

Tried something else, yet still not working right. Im sure im going about this completely the wrong way.

Here are some pics of the latest attempt.
zoom>all>shaded


zoom>all>wire


zoomed in>shaded


zoomed in>wire



So here you can see ive created a region, revolved it then moved it into position. Due to the 30 angle of the tube tho, the tube cuts into it. If the tube was horizontal it would be fine, that methed would work, but not thinking due to the 30 angle the tube becomes an elipse at the point where the fillet is attached. As far as i know you cant revolve around and elipse. Once again im stuck and pulling my hair out.

[CarlB]

I don't see the pics so don't quite know the problem...wait, they are slowly popping up (slow connection)

But regarding revolving around an ellipse - create the ellipse with PELLIPSE variable set to 0, then it will be a polyline, which you could extrude along. I believe you can only revolve around an axis/straight line.

[aledtaylor]

Try using the fillet command to create the fillets. Surprisingly, it works with 3D solids.

[Spacepig]

Hi Safwah

Welcome to the forum...

Here's a render I did from the dimensions you gave




I just did the base, 2 webs and the guide. Unioned them together, and then filleted them using a radius of 3. As aledtaylor says, you can fillet around an ellipse as well as stright line or circle..

Hope this helps :-)

Spacepig

[Safwah]

omg! lol

Damnit i gota go to the gym now to but im so trying this when i get home.

[Safwah]

Can you show me a close up of the underside of these 2 areas.

[Spacepig]

Hi Safwah

I think I can see what you're problem is...here's a picture of the top of the guide...Your problem is the interface between the straight web and the circular guide



As you can see from above, there is a small flat area that you might want to profile along the edge of the circular guide. What I did below was to set the ucs to the end of the guide, then draw a polyline from the centre of the circle to point "A". Since then delta-z value of a polyline is 0 it will finish at point "C". Point "B" is defined by the intersection of this polyline and the circle defining the top end of the guide.



If you set your ucs to 3 point using points A, B & C you can now draw a closed polyline from point A to point B to point C. Resetting your ucs to the guide again, revolve the closed polyline along the axis of the guide by 360 degrees. If you subtract this solid from the body of the guide you will end with the picture shown below.



As for the bottom end simply repeat the above procedure , but use a profile of the 6mm quadrant revolved around the axis to trim it nicely

All the best

Spacepig

[Safwah]

Ill give that a shot. I noticed something, i think theres an error in this drawing.


In the red circle here shows the point of contact of the webbing and cylinder, the 2 points where there fillets are should be at the same angle as the cylinder, <30. With the height of 100 given from the dimensions i could not get the angle without sudden cuts or ledges. But with the total height of 119 the <30 fits snugs and basically does it by itself with a simple slice.