Problems attaching rafters (beam system) to roof

[MKEllis]

I've been getting frsutrated as I try to 'lock' a beam system that I have used for rafters to the underside of my roof.

I've successfully got the walls and gables linked in with the roof, and have set up reference planes for cutting of rafters (that should - I think - mean that rafters can move slightly - or change pitch, whilst maintaining same cut extents at rafter ends).

Trouble is - the rafter Beam System does not update with the roof.

My creation approach for the Beam System was to select the underside of the roof as the 'Working Plane' - then edit the boundary to project beyond the walls and form the overhang. I projected it further than I required to provide the excess needed in case I wanted to push the cut plane outwards.

I assumed that selecting the underside of the roof as the working plane would 'lock' the two together, but it doesn't appear to work.

I've attached the before and after shots of changing the roof pitch below.

Have I missed a straightforward step to link the two elements together ?

Thanks

Martin

[MKEllis]

Following on from above, I'm also trying to work out a way of having a wall extent (in section) be determined by two different elements.

In the attached section - I would like a new wall to extend to the underside of the roof at either end, and to a level or reference plane further up.

So far I can have it attached to either the roof - or the level - is there a way of having the 1 wall be determined by both restrictions (level + attachement to us of roof).

I also tried editing the wall profile manually - which would work, but it would mean that I would have to re-edit it again should roof pitch etc. change).

I realise I could split the wall into 3 sections- but I would then have to adjust those wall extents in plan should the roof pitch change (Hopefully it shouldn't but I was wondering whether there was a more elegant way of linking these bits of geometry to allow them to be flexible.)

Thanks

Martin

[Alfredo_Medina]

Setting the work plane of the bottom face of the roof, and making a sketch that is locked to edges of the roof should be enough to create an association between the beam system and the roof.

About the wall in your second post, maybe Edit Profile is the only solution for a wall in that case. It might not update automatically if the slope changes, though, but it's not a big deal to edit it again if required.

[constantin.stroescu · Accepted solution]

Hi Martin

the steps you did seems to be ok....

• choose Beam System > from Work Plane > Set >Pick a Plane > pick on the underside of the roof....make a rectangle ..extend the base and top so to be able to accept stretches...ok...
• now your Beam System has to move with your roor slab...if ,in section or elevation view, you drag the small arrows of the appex roof , the Beam System follows it (does it?)
• Draw the cutting Reference Planes , one for the ridge and two for the eaves...
• in a profil elevation view select using Tab, an element beam >Geometry >Cut>pick again the  beam element and then the Reference cutting Plane....repeat the process using TAB...till the last beam is cut ( when cutting do not unpin the elements otherwise you will loose the system )
• flex again the appex of the roof ....it will drag the system...

[constantin.stroescu]

In this case I use small trick:

In a Elevation View I make a very thin Roof by Extrusion - a ghost roof:

Roof by Extrusion > Work Plane (choose a grid paralel with the elevation or made a reference plane with a name)>Draw>Pick LInes...click on the underside of the real roof and the underside of the attic floor , lock the lines ..

Now you have a roof with a profil like that from your sketch that is attached to your roof and floor slab...it will move with them.

Attach Top of the wall to this ghost roof.

Hide this ghost roof in the views that you intend to be printed....

[MKEllis]

if ,in section or elevation view, you drag the small arrows of the appex roof , the Beam System follows it (does it?)

Nope - not sure quite why, from tutorials etc. on line, there should be an association so that it does move.

I've figureg out a work-around, which is:

Move roof / change pitch

Pick Beam System,

Edit Work Plane

Pick New Host

Select underside of roof.

This however seems to relocate the relative position of the Beam System boundary relative to the roof plane. Imagine taking the beam system and sliding it parrallel to the roof so that it now overlays only about 1/4 of the roof area. It's almost as if in picking the roof host, you are setting a new origin point for the Beam System - but it seems pretty random - and it spits out a load of errors as most of the rafter geometry now misses the cut planes.

Hmm. Having said the above, I noticed that before assigning the Pick New Host - the original Beam System was "Not Associated" whereas after picking new host, it is labelled as being assigned to the roof assembly. Obviously my original Beam System wasn't correctly assigned (or somehow I had broken the link).

It sounds as though I should try again from first principles (not really needed on this model as it seems I should be able to fix it as above) to establish the proper procedure and try and figure out where I went wrong.

Thanks again Constantin

Martin

[MKEllis]

Thanks - that sounds like quite an ingeneous solution. I take the point from Alfredo that it is probably as easy to use Edit Profile in this case (only 1 wall), but I was sure that there would be a way to lock the wall in somehow.

Your solution means that on a larger project it would be possible to have a whole number of walls locking to this 'ghost roof' profile.

One thing that does still confuse me - is Hidden Geometry.

Hiding the ghost roof from a particulat view - that would mean that is would still schedule out for materials ?

Is it therefore possible to globally hide an element so that it never appears on any 'queries' - ie. schedules ?

Thanks

Martin

[MKEllis]

Thanks Constantin,

I had obviously borked the relationship between the two.

I went through, Picked New Host, clicked underside of roof, then had to re-align the Beam System Boundary (Still not sure why that impacts on the setting out / origin) - and it works.

Now, adjusting pitch updates rafters (See attached - only update one side so far).

Cut planes work a treat, as they maintain eaves profile targets as before.

Many thanks

Martin

[constantin.stroescu]

if I don't want the ghost roof too appear in schedule I have to use a schedule filter:

• First of all the extruded roof I want to use as a target for attach, I call it let's say Ghost roof ..and I'll use this type only for doing such operations (as it does not appear the material of it does not matter)..
• .Now, I select this roof in a 3d axo view and from Properties (instance)>Identity Data >Comments > I call it INVISIBLE.......I shall need this comment in roof schedule...

• Create a roof schedule with fields. It is mandatory to contain the fields: Type and Comments , among others....
• apply: Filter >  Filter by > Comments >does not equal>INVISIBLE
• Now , in the schedule will appear all the roofs but the  Ghost...

[constantin.stroescu]

as for globaly hidden....I think it could be possible something , perhaps using Phasing and (or) View Template ...it's much  to dig on the subject....

[constantin.stroescu]

Hi Martin,

• about the wall attached to a ghost extruded roof ...suppose that the wall is a curved one - the Edit Profil Mode can not be used...

• If the ghost roof as a distinct type of roof and the roof schedule with the prestting filters (on comment) are included in a Project Template , then the method could be more handy.

• A hidden by default of the ghost roof can be, in my opinion, a little dangerous because you can forget about the entity and this could act impredictible.....why not make the entity transparent so to draw attention on it...

Constantin