Problems creating a truss

[MKEllis]

Hi,

continuing my baptism in using Revit.

I've been experimenting with getting trusses to work.

I have managed to bring in a truss family (Pratt Gabled 6 Panel). duplicated it, tweaked slope, and setting out to suit my project's needs, and assigned timber members.

Trouble is the members are not joined (See attached).

I've read that you can edit the members to overlap them - then use 'coping' to cut the joints, but I can't find any options to do this.

Can anybody help ?

Thanks

Martin

[constantin.stroescu]

when I work with structural elements I use cut with succes....I think it will work with truss also..

for this:

select an element of the truss  (in project) using Tab ....unpin it ..then select the drag point and strech the element so to ovelap the others

make some reference planes where you want the cut to happen

From Geometry>Cut ...select the object picking in the part you want to remain and then click on the reference plane...it will cuit the element 

You can apply as many cut planes as you want....

[constantin.stroescu · Accepted solution]

you can also apply the Cope function

make the first steps like in the first method but instead of using cut by reference planes...apply : Geometry> Cope...select first the object that you want to be cut and then the object that cuts..

from Properties>Structural>Coping Distance adjust the gap between the two elements

[MKEllis]

Thanks again Constantin,

I'll try that out tonight.

One thing I did notice, was that I appear to be unable to select the individual truss members whilst in the project view.

I can only pick the dashed line truss (and even then only as a whole and not individual chord / member lines).

In the edit family mode, I can select the individual lines - but it wont let me add reference planes, lines - or infact add any geometry at all. It spits out an error about not working in the correct plane (sorry at work - and I can't access it at the moment to report the exact error).

I have also tried using the Structural Roof Framing Extension - but whilst some of it is quite good and quick at populating trusses, it doesn't appear to be as flexible once the truss is in place - attempts to modify the trusses seem to reset everything to default - and the trusses do not 'lock' with the roof assembly - or even levels. the underside of the truss also appears to be determined by the height of the wall below prior to it being attached to the roof assembly too. Maybe that's just me missing features in its use though.

[constantin.stroescu]

you have to worlk in Project mode..

Place the mouse over the bar you want to select and TAB until the element is selected...then unpin it...now you will be able to strech it...

[constantin.stroescu]

• If you use Cope for cutting, then , streching the truss will not change the relation between the bars , they will follow the new geometry
• if yo use Reference Planes for cutting  and then change the geometry you will have to remake the process because locking the plane to the bar it is seen as an overconstrain and not allowed...

[MKEllis]

Many thanks Constantin,

it's worked a treat in trimming / correcting the truss.

One thing that confused me for a while - in the UK version, COPING is known as NOTCHING, spent a while looking for the coping tool before noticing the icon was the same.

FInished truss attached - One tip that I picked up, is that it is useful to overextend the 'rafter' chord so that when forming the eaves profile with ref-planes + cut - there is some 'spare' to adjust simply by moving the ref-planes.

Another problem I have, is that when trying to Group the truss (before arraying it) it wants to delete 2 elements.

"Last member of group instance was excluded (deleted), removed, or moved to the project. Group instance has been deleted"

Not sure why, as it's Type, and properties is the same as the rest of the members.

Other than that, thanks for the tips - yet again you've helped me pass a revit blockage.

Martin

[constantin.stroescu]

hi Martin,

I don't understand why you need to group the truss before array?...only ,if , maybe you did Remove Truss Family from Modify Truss...otherwise it remain an editable family as a whole.....

I use group before array ,move,copy a Model in place Component  . In this case it seems to be mandatory...

Constantin

[MKEllis]

You're right.

I confused myself with advice that was regarding Model in Place component.

I realised afterwards that as it was a family - I could just edit it and it would update all instances.

I'm still getting to grips with the terminology and the distinction between family types - and their associated workflows.

Thanks Again

Martin