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Tube and Pipe routes - not running in straight lines

13 REPLIES 13
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Message 1 of 14
andyb
2876 Views, 13 Replies

Tube and Pipe routes - not running in straight lines

Hi

 

I'm pretty new to tube and pipe. Although I've been using Inventor for a good few years I've never had to use the T&P tools. We would normal have done all our piping drawings in ACAD as Isometrics and a GA.

 

I'm seeing a very strange behaviour with the routing though. In the first picture you can see both connection points are lined up in the y plane (measuring 0mm). However in the second picture you can see the route inventor choose for me which is strange. It shows the path moving in the "y" direction before returning in the same direction at the next connection point. I've plenty of room for all bends and piping (I'm using ANSI Schd40 1.5NB - Welded ends). I've tried doing the route manually then connecting the top horizontal section but it again wants to throw an offset or two in there when there is no need. Can anyone shed any light onto what I am doing wrong, if anything?

 

Cheers, Andy

13 REPLIES 13
Message 2 of 14
cbenner
in reply to: andyb

Hi,

 

Tube & pipe offers no margin of error for distances or angles between points.  It looks like your "Y: is certainly at 0mm, though just to be sure you should recheck it with "All Decimals" checked on the precision.  The other possibility that strikes me right off the bat is that there may be a slight angular difference.  Is that tee at the top rotated maybe a degree or two off?

Message 3 of 14
tsreagan
in reply to: cbenner

A good tip for Tube and Pipe:

 

Use the View Cube to restrict the view to a particular plane when moving or adjusting points, then switch the view as you go,  this will give you more control than the 3D view.

 

And when you bend pipe runs,  add a second point just before a strait run.  So a straight section with two elbows will have 2 points at each end (fairly close together).

 

T.S.

Message 4 of 14
cbenner
in reply to: tsreagan

What advantage does the 2 points give you?

 

I tend to use the Include Geometry feature and constrain to the resulting work planes with perpendicular constraints, to ensure I am running in nice straight runs that are perpendicular to the equipment and frame.

 

Everyone's designs will require a different method, that much is true.

Message 5 of 14
andyb
in reply to: cbenner

Hi, thanks for the comments and suggestions.

 

To reply to cbenner - I've checked the distances with all decimels shown and it is still 0mm. I've also checked the angular measurement between flanges and they are 0deg, again with all decimels selected.

 

tsreagan - thanks for the tip re the view cube. I have tried this with still the same result (well it changed where it put the bends but still added none the less). When I also try adding more manual points and constraining them I either get a failed run or it puts in some other whacky runs. This run should only have 1 content centre elbow.

 

I want to use the autoroute function if I can because this pipe work will be changing. This is a premlinary model so I have something on screen. But the point is why is it doing this when it is about as simple as it gets for a pipe run.

Message 6 of 14
cbenner
in reply to: andyb

Andy, others may disagree with me on this, but I strongly advise against Auto-Route.  It is baaaaad.  It makes decisions for you based on how you move things around.  9 times out of ten if I have a route blow up, it's because I forgot to convert the auto route to a sketch and constrain it down.

 

If I have a route that is going to change, I use geometric constraints, and dimensions as needed to lock it down, leaving at least one leg undimensioned (controlled by constraints) so the route can grow or shrink as needed later on.

 

Just my humble opinion.

Message 7 of 14
cbenner
in reply to: andyb

For this specific issue, if I cannot get two points to line up like this, I usually route a short segment from each end point, then take all constraints and dimensions off of them.  Then I use a coincident constraint to joint the two end points, and proceed to add constraints or dimensions to lock the route down.

 

Hard to tell from just the picture what's causing this weird route.

Message 8 of 14
JohnK_TEDCF
in reply to: andyb

If the two fittings are truly lined up, which the picture seems to indicate, then it may be the fittings themselves. Possibly some issue in the authoring process. This is just a guess, as it's tough to see the true problem from pictures.

 

I agree with Chris. Auto-Routes are a dicey option. We teach people how Auto-Routes work, but we recommend they don't use them. Everyone has their own ways that work for them though.

John Koop
Software Engineer/ Inventor Specialist
TEDCF Publishing
www.trainingtutorial.com
Message 9 of 14
tsreagan
in reply to: cbenner

cbenner,

 

The 2 points on a manual run prevent the splining effects and help long runs to remain straight.

There may be another (official way), but I found 2 points works nicely.

 

T.S.

Message 10 of 14
cbenner
in reply to: tsreagan

Message 11 of 14
tsreagan
in reply to: cbenner

It's only applicable to flexible runs.

 

 

TnP 2 Point spline trick 2.jpgTnP 2 Point spline trick 1.jpg

2 points at each end will straighten the run.

Message 12 of 14
cbenner
in reply to: tsreagan
Message 13 of 14
andyb
in reply to: cbenner

The problem I am seeing this on is Rigid Pipe. I have taken your advise cbenner and constrained the route to points and work planes instead of autorouting. I don't know why Autodesk bothers putting tools in there when they are only half baked ideas. Anybody with an understanding of pipework design knows that you take the route with the fewest bends to minimise losses, not one with a race circuit like configuration. A warning in there would be good as well to advise why a straight run isn't possible.

 

Thanks for you help

Message 14 of 14
cbenner
in reply to: andyb

Glad I could help, Andy.  Can't agree more that there is a lot of room for improvement in the T&P module.  Still,... I used to use Pro Piping in Pro Engineer and everytime I get frustrated with Inventor I just think back to that system.  It was a nightmare.

 

Good luck!

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