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Slope Fabrication Ductwork in Revit

Slope Fabrication Ductwork in Revit

We need the ability to slope Fabrication Ductwork (Rectangular and Round) in Revit as you have done with Fabrication Piping. As of the latest release 2018 2.2 this is still not available. We need to be able to slope Grease Duct, Dishwasher, etc.

 

Thanks

Dino Spadoni

17 Comments
Anonymous
Not applicable

If you place a piece of Ductwork, you can select it, and it'll display the slope (none). If you then click on the Slope text, you can change it after placement of the duct. 

 

The remaining pieces will align with the slope. 

Anonymous
Not applicable

Thanks for the response. I forgot about that way. I was checking the new features in the ribbon, and noticed the slope button did not work for ductwork.

Anonymous
Not applicable

Also Multi-Point Routing will not let you slope the ductwork

aaron.tw
Alumni
Status changed to: Gathering Support
 
Martin__Schmid
Autodesk

Does this actually provide the desired result?  I just tried it (see this video)... doesn't seem quite right.

 

Are these assumptions correct:

1) the elbow should remain flat to the world

2) the second duct shouldn't be sloped (rotated) on its center line axis

 

What would be helpful for a bit more understanding here, is how is the slope made up if the fittings (elbows, tees, etc..) remain flat.  My understanding was this was a function of the connection being welded, and thus, having a bit of tolerance/give.  Are there other connection types that we should be aware of, and any insight in how the give is accommodated would be helpful to understand.

 

 

 

 

Anonymous
Not applicable

Someone who's an actual sheetmetal guy can correct me if I'm mistaken but...

 

The Elbows don't remain flat. They're a special fitting/CID. If you took a regular elbow and sloped it, the other end would be rotated. Until there was a special CID to handle this, they's manually tweak the fitting in either CAM and/or the shop to get it close.

 

With the sloped elbow CID (I'd have to look up the pattern number) you can have it adjusted there.

 

An actual grease duct elbow if laying flat on the floor would not lay flat...it would appear a bit twisted.

 

I'd have to ask about how the guys build these....last time I looked at that CID (been a few years) it didn't have the dims/options structured in a way that made it way to set it up properly. 

Anonymous
Not applicable

After checking w/some folks from a few companies, even though who told me were once making a twisted elbow gave up and install flat and miter the straight or make an angled transition to make up the angles going into/coming from an elbow.  The sloped CID just wasn't practical to use.

Anonymous
Not applicable

Seems lie a good area to research what people would like vs what they do to get by.

Anonymous
Not applicable

What we're doing....

Using CID 525 as an angled transition on a flat elbow.

https://autode.sk/2JhjXhJ

 

 

What we'd like to do....

Use CID 1166 for a twisted Elbow. However the inputs make it impractical for use. It doesn't allow for a "slope" or "Angle" input, rather a "length" and "offset" so each instance someone would need to calculate the length/offset for a given size to maintain a particular slope.

https://autode.sk/2uJdWHv

 

 

Note: Slope/Angle is exaggerated for clarity. 

Anonymous
Not applicable
Hi Darren

What we do when we’re running sloped duct is use the angled end duct to get
end 2 square, then use a drop check elbow to get the slope in the elbow.
Then use the angled end duct with the angle at end 1 to get the duct
sloping again.
Anonymous
Not applicable
Using a flat elbow doesn’t keep the slope for Grease duct
Martin__Schmid
Autodesk

Thx, Dinos-- yeah, I had asked about the slope on the grease duct fitting, and the response was that when washing out the ducts, it wasn't an issue, any residual water would evaporate once the system got up to temperature again.. but I had expected that different folks would do this in different ways for different reasons (thus, asking you on this thread about the assumptions).  

 

Do you happen to know what patterns you're using for the Angled End Duct and the Drop Cheek Elbow?

 

Sounds like in your case, your connections remain square, vs. forcing tolerance via weld... what kind of connections are you employing for your sloped layouts?

 

Thanks,

MS

 

Anonymous
Not applicable

I think you'll find a variety of ways people have accomplished this because frankly, there really isn't a "good" way.

 

 

The folks installing elbows flat tell me it's not that big of a deal as each elbow will have a cleanout anyway but I can imagine doing it that way may be regional and subject to local inspectors. The issue is they don't want grease pooling in the system as it's a fire hazard. 

 

Personally, I'd prefer to see a couple new patterns specifically designed to handle sloped rectangular duct (round shouldn't be an issue and doubt anyone has ever done sloped oval).

 

If it draws easily, and fabricates (CAM) easily, people would use it. 

 

 

 

Martin__Schmid
Autodesk

Thx, Darren -- makes sense... What types of fittings would be required?  E.g., radius elbow? mitered elbow?  what about junctions such as tees and wyes? What order of priority for those, and anything else missing?

Anonymous
Not applicable

Dishwasher Exhaust and Grease Exhaust are about the only two systems routinely sloped w/rectangular.

 

NFPA 96 will list some of the grease exhaust requirements if you're interested. 

 

Straight that allows modifying the angles of the ends and Elbows (Square and Radius) would be most common fitting needed. Possibly a transition that allows the ends to be angled.  For Grease, the duct typically runs directly from the hood to the fan so it's not common to have a need for a Tee or Branch but it "could" be done..just not common. Often this type of work is done in CAM (fittings for which there is no CID), by taking a fitting as close as possible and then editing the developments there in CAMduct's Opus.   Dishwasher Exhaust may be more common to have a branch or tee but I haven't spoken to a detailer yet who's done it. Taps would be even less likely and have to be mounted flat on bottom "if" they were used.

 

We do occasionally slope some of the traditional systems at times depending on what's going on. Following a sloped roof line is most common and. This would increase the diversity of fittings needed possibly but in these cases "Maintaining slow" isn't as critical so thyere's added flexibility there in the system layout and fittings used.

 

Had a job a while back that was using very large sloped flat oval due to space considerations. Where the oval branch came off, the oval was angled and we needed to twist it flat again. There's a general lack of patterns to support these handful of unique scenarios. If the adjustments are minor often the field can twist/flex them into place.  If not, the detailer get's something close for coordination and then works with the CAM operator to adjust the developments based on a pattern that's as close as possible. 

JaymesFleming
Explorer

I added a new idea "Mitered Connector on Drop cheek for sloped duct work" specific to the fitting. This has been requested in the past and would be valuable to Fab in Revit as well as Fab in AutoCAD, Remote Entry etc.

rpowersZT29S
Observer

Union Sheetmetal Coordinator here, my two cents.

I have found the lack of a "drop cheek elbow" is huge omission on Autodesk's part. There are several choices in the CAD-Duct section of AutoCAD Fabrication, but not Revit. Most height\size changes can be worked around but the lack of a radius elbow that can change size and rise\fall is a severe limitation.

As a union drafter for sheetmetal installers we are told to eliminate as many fittings as possible.
If we change change size, shape, direction and elevation in one fitting, we do.
We could in AutoCAD Fabrication, we can't in Revit.

I have only recently switched over to Revit and find the out of the box "fabrication parts" to be severely limited.

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