Need help with modelling / geometry problem

Hi Guys

New here, and quite new to 3D modelling in Autocad. Really hope you can help me out with a problem.

See attached .dwg file, the client has asked me to detail this in about 20 places on a structure.

Its an SHS edge beam joining a CHS rafter.

Both are at different angles.

The CHS has a cleat plate, as does the edge beam.

The 2 need to align and connect. The bolt hole must be 40mm off the face of the rafter.

The rafter CL & edge beam CL need to coincide at a setting out point.

Where the rafter cleat plate connects to its rafter it has to be in alignment with the rafters plane.

SHS edge beam will need to have its sides vertical and horizontal, so the edge beam cleat won’t be aligned with the SHS faces .

Even though I have the autocad file as an example, have tried to draw this about 100 times but cant get it right – I have been unable to contact the draftsman who did it. Does anyone have any ideas on how to draw it and what commands to use?

As I said very new to modelling, not experienced in 3D Autocad and unsure about how to use UCS and other modelling operations.

Very frustrated!!!!

Thanks Guys!

geometry check.dwg

You want to know how to draw this?

Looks almost like a davit arm. You have both square and cylindrical tube shapes.

What kind of structure is this being used on?

Yes I need to know how to do it as I have to replicate it about 20 times. It must be simple but I cant get it to work out.

Its for a series of shade sail parasols, umbrella like structures. Thanks for your reply

The cylinders are just extruded circles.

The square tube shapes can be created by extruding a profile of the shape. Same goes for the tabs that are welded to the post. There's nothing complicated about any of the objects other than getting anything that is not parallel or perpendicular to the column put in at the correct angle.

I'd suggest using the PressPull command over Extrude but either way it would work.

As far as orienting your UCS you can use the Dynamic UCS (there is a toggle for it in the Task Bar at the bottom of your screen) or you can use the Ribbon or even do it (old school) manually at the command line. Just make sure you are in the 3D Modelling workspace.

Quick example of using PRESSPULL.

Draw the baseplate for the column with the anchor bolt holes in 2D. Use the PRESSPULL command to give it height.

Its the angles that I cannot get right. I have managed to draw an extruded cylinder for the rafter, and an extruded 2d shape for the tabs on the rafter, made this into a block that I can re-use for every location and explode once it once it is in place- then modify to fit. Trouble is every location all the angles are different. If I can just get the tab correctly orientated, on the CL of the edge beam and joining to the rafter in line with the rafters axis - then the edge beam alignment should come easy. Not sure how to use the dynamic ucs for this?

The angles for the tabs on the column?

tabs on the column are fine, because they are all the same. Its the tab at the end of the rafter that Im struggling with

Your terminology is throwing me off. Are you referring to the yellow arm that is attached to the column as the rafter or the square tube shape?

Sorry - Ignore the column (green) and where the rafter (yellow) connects to it. That is fine. Its the other end of the rafter that I am concerned with

You already have the "rafter" at the correct angle and is the tab connected to it?

Looking at your drawing I have to ask, are the tabs located correctly on the column?

The column (green) is absolutely fine, that has already been fabricated and checked off. The rafter and the edge beam are drawn correctly. The whole drawing I posted is correct. Where the problem lies is that there are other rafters similar but with edge beams connecting at different angles. Basically I need to know how to replicate this detail but where edge beam and rafter angles differ

Start laying everything out from TOP view, like ReMark uses in the image in his previous post.

Are all of the rafters identical, save for their placement and clevis positions, or are they all unique?

I understand that their orientations are either varied or unique.

You will want to familiarize yourself with the 3DALIGN command, which you will find quite helpful.

It seems like it would only be a matter of rotating the tab and edge beam relative to the end of the rafter. I would make one master rafter/tab/beam with the beam parallel to the ground then after you insert each assembly rotate the tab/beam. Remember that as far as AutoCAD is concerned the base angle of 0 degrees is East (at the 3 o'clock position) and the direction of rotation is counter-clockwise. Use the 3DROTATE command.

I think I see what you are saying. I have tried using the correctly drawn copy that the client has provided me with, then rotating it so the rafter is paralell to the ground. Ive then tried to rotate the end tab to suit the CL of the edge beam - but then where the cleat meets the face of the rafter it is misaligned, it should run along the same plane where cleat meets rafter. All of the rafters are at different angles & heights. some of the cleats point up and to the left and some down and to the left at varying angles. Ive never used 3D rotate, tried this but keep ending up with the same problem

geometry check 2.dwg

Guys have attached another file, if you take a look and compare it to the first file it will demonstrate where I am going wrong

It would help if we had a drawing we could actually work with. For example. The rafter has to be exploded to get at the tabs. But it appears the tabs, which should be separate, are not. There is also a small object (circled in red) that is embedded in the rafter and there also appears to be some 'extra' geometry on the backside of one of the tabs (arrow points at it). These tabs should be independent of each other until such time as their final position is arrived at then they should be unioned to the rafter.

Are the two tabs supposed to have the same width?

After a closer look at your drawing I don't believe the tabs at the end of the rafter are parallel with the rafter itself. That will throw things off right there. I'm speaking of the portion of each tab that would be welded to the circumference of the rafter.

This is how I would do it.

1) Create the rafter and add the two tabs at a zero degree angle.

2) Using the end of the rafter as my center of rotation, rotate each tab to its desired angle. In my example one is rotated 15 deg counterclockwise and the other 15 deg clockwise.

Then I would attach the rafter to the post and rotate the entire assembly to the required angle.

b16gee: So, have you made any further progress with solving your problem?