DESIGN TO FAB can't get more than 1 straight to fill the run?

[Andy0777]

Hi to the CADmep/Revit Fab community,

I've run into an annoying problem which I have tried to figure out but can't. Im sure it's a simple enough fix, but I can't fix it.

When I use design to fab inside Revit, I select a rebit family ductwork run, filter only duct and fittings then click the design to fab button. All the fittings fill, but the straight duct only has 1 piece of straight. I have gone into CADmep and made sure the length is not locked at 1500 and connectors are not locked either and still, I can't get past it. Any ideas from the more experienced?

Screenshot attached. I have a half tone link of the duct Im tracing over so I can see if I go wrong anywhere but you can see one bit of straight after the taper and 1 bit after the square bend on the pink extract run.

As I say, I'm sure there's a box to check or uncheck somewhere but I can't figure it out.

Any help is greatly appreciated.

Thanks

Andy

[1ito]

Never trusted an ENGs model enough to even think about Design to Fab...

But where you get short pieces I would just extend the straight to the fitting to connect them and then click optimize lengths...

[Andy0777]

Thank you, I was going to resort to that but wondered if there was something obvious that I've missed.

As for trusting eng's models, you are 100% correct. There are usually failures due to poor modelling. I have a bit of a mammoth job that I need to price pretty quickly so tried to utilise the feature. I think I will do as you suggest.

Thanks for your reply. 

Andy

[cadbob]

2 things come to mind, Check your Pressure Class and Also check that your straights are set to auto in length.

I think Auto is the culprit maybe

[Andy0777]

Auto is set but not locked. Pressure class is LV

I did go to that first...

[cadbob]

If you have cad installed, have tried filling in cad with same pressure file/service?
Also try stretching a straight duct in cad.
Just testing to see if same bad result happens in cad as in revit.

[1ito]

Just drew a +50' run in between two elbows with Revit duct. Ran Design to Fab, and it kept the straights fair long, only a short disconnect to one end of the elbow.

So there is a setting somewhere. 

[Andy0777]

Interestingly, when I export RIF and fill in CAD it works.

Maybe I should abandon Revit? I like how Revit fills bends when you join corners and how it connects shoes to main duct though...

If I can get it working in Revit as it does in CAD, Ill be very happy.

[cadbob]

HAHA, Mine dont fill shoes and has tough time with elbows, but fills Straights fine, so like the way CAD does it!

[craigjonnson]

When I use design to fab inside Revit, I select a rebit family ductwork run, filter only duct and fittings then click the design to fab button. All the fittings fill, but the straight duct only has 1 piece of straight. I have gone into CADmep and made sure the length is not locked at 1500 and connectors are not locked either and still, I can't get past it. Any ideas from the more experienced?

Thats normal. You have to Tab select through your run and click the optimise straights button on your ribbon for all of the straights to be divided up as per your specification lengths.

[cadbyken]

Interestingly, when I export RIF and fill in CAD it works.

Maybe I should abandon Revit? I like how Revit fills bends when you join corners and how it connects shoes to main duct though...

If I can get it working in Revit as it does in CAD, Ill be very happy.

Interesting...I didn't know mid point reinforcements showed up in the model.  That is on my to do list in the coming months.

[cadbob]

Interesting...I didn't know mid point reinforcements showed up in the model.  That is on my to do list in the coming months.

Oh yes but adds lots more lines to drawing on paper, I played in past with line weights and Shading for the reinforcements, and decided to leave the check box unchecked. Even in CAD when coordinating adds lots of UN-nessary distraction.

But for each their own!

[cadbyken]

Oh yes but adds lots more lines to drawing on paper, I played in past with line weights and Shading for the reinforcements, and decided to leave the check box unchecked. Even in CAD when coordinating adds lots of UN-nessary distraction.

But for each there own!

Yeah, I see your point.  Is this CAD only or available in Revit?  I figure that is a no since they introduced the new midpoint stiffener family in Revit 2024.

[cadbob]

I'm not sure Ken, good question, I'm CAD 100%
Though use Revit but production CAD

[cadbob]

I was wrong, But Revit is not pulling from the Stiffeners setup up in the Pressure class, they have to be created and added as a family. Kinda Lame.