Truss with heal height, webs, end cuts etc.

[Thomas Allan Palmer]

Has anyone found a truss library part that has all these parameters:

-Pitch / Angle / x in 12
-Overhang
-Webs
-Cut angle for ends
-Heel height
-Bird's mouth

There are a few objects around (Like TrussPro) but none seem to have all the parameters we need.

Thanks in advance

[Anonymous]

Thomas,

WARNING - you will probably not like this answer!

Here's how our shop does it:

Draw each truss using the slab tool with it's lower-left corner at 0,0,0.5*truss thickness (just like the truss fabricator's layout table)

Save it to a GDL file, using the truss number as the file name. We create a directory (folder) just to contain the truss GDL's. Keep the slabs (trusses) on a hidden layer for easy access in case of edits later. Use the element ID of the slabs to track the trusses by number.

Open each truss GDL, and do the following:

In the 2D Script, add the PROJECT2 3,270,2 command at the top, and comment out the rest of the script.

In the 3D script, comment out the three MUL*** commands (so parameters can't change the truss's size) and add a ROTX 90 command. That will stand the truss up vertically. Save, and then place in the project.

Sounds crazy, but it's not really too tough. I've attached images of a whole roof's worth of trusses and one individual truss as examples. This house has about 40 truss types, at about 10 minutes each, so a little less than a day's work to have a fully modeled truss roof.

The truss profiles can be derived by dead reckoning, tracing the sections or based on the truss fabricator's shop drawings. Normally, we do all the proposed trusses initially with just top and bottom chords, as well any architectural elements we want present. These show in the sections we send to the truss company so they have an idea what we're after. They do their package, Then we fill in the webs on each truss, and re-write them to their respective GDL files. Yes.. you have to do the aforementioned code hacks again, but that's only a small portion of the time required. The most labor-intensive part is actually back-checking the truss fabricator's shop drawings... same as the old days.

Yeah... We're crazy. BUT... Everything fits / works / falls together like the kit on the jobsite. Priceless. A day or two's work checking the truss design is worth the trouble saved at the other end of the python, as it were.

Hope that helps.

[Anonymous]

Individual truss... This is a single GDL, which may occur multiple times in the project itself.

[Thomas Allan Palmer]

Thanks Dave. We sometimes create them as you described but we are able to skip the code writing by just viewing the front elevation of the object drawn with slabs and then saving as a library part. This achieves the correct rotation without having to write the code. Sometimes we edit the 2d to get rid of elements we don't want or add those that we need (extra hot spots, etc.).

Anyway, still looking for the one create truss library part.

Thanks.
Thomas

[Gerald Hoffman]

Thomas,

The OBJECTiVE addon will do this in section drawing the truss with fills and then saving it as a part in one step. The tool also allows you to change the part later on if a parameter changes by extracting the profile, making the change to the fill that was extracted and then re-saving the part with the modified fill. You also can cut parts in section or plan. eg. intersection of jack truss with hip truss.

I have never come across a single library object that can do trusses properly but it would be a tall order as there are a lot of variables.

Cheers,

[Thomas Allan Palmer]

Gerald,

We checked out the OBJECTiVE add-on. This is a great versatile tool.

Thanks.