Parametric part problem

[Anonymous]

I am attempting to produce a parametric part resembling a circular duct pressed twin bend as defined in DW144 by the HVCA. However I am having trouble constraining the arc I am using to define the path of the duct.

I have created a top view plane, then created 2 arc geometries (total of 3 points as the 'start' point for each arc is incidental). Next I created a circular profile that I have used for the 'modifiers - add path command' to path the circle along the two arcs, and this works fine at the initial diameter.

However when I change the duct diameter, which is linked to the diameter of the curve, the curve paths included angle goes bonkers. Going above 90 degrees if I increase the diameter and below 90 degrees for a decreased diameter.

How do I set up the part so that the included angle is always 90 degrees? I have tried placing a point at the middle of the arc and dimensioning this point to constrain it to set percentages of the diameter but to no avail.

I have uploaded the parametric part to the relevant section of the newsgroup (consumer files or whatever...) under the same subject title.

Thanks for any help you can give me.

Drew Jarvis,
ACDP, Maidenhead.

[Anonymous]

Hi Drew,

I took a look at the part and as far as I can see,
the only thing you have to do is to set up tangent constraints between the arcs
and the straight element that make up the connectors.

Modify part is posted under your topic in customer
files.

Regards

Lars-Ake Johansson

Autodesk BSD QA

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"djarvis" <
href="mailto:djarvis@acdp.co.uk">djarvis@acdp.co.uk> wrote in message

href="news:f1a42aa.-1@WebX.maYIadrTaRb">news:f1a42aa.-1@WebX.maYIadrTaRb...

I
am attempting to produce a parametric part resembling a circular duct pressed
twin bend as defined in DW144 by the HVCA. However I am having trouble
constraining the arc I am using to define the path of the duct.

I have created a top view plane, then created 2 arc geometries (total of 3
points as the 'start' point for each arc is incidental). Next I created a
circular profile that I have used for the 'modifiers - add path command' to
path the circle along the two arcs, and this works fine at the initial
diameter.

However when I change the duct diameter, which is linked to the diameter of
the curve, the curve paths included angle goes bonkers. Going above 90 degrees
if I increase the diameter and below 90 degrees for a decreased diameter.

How do I set up the part so that the included angle is always 90 degrees? I
have tried placing a point at the middle of the arc and dimensioning this
point to constrain it to set percentages of the diameter but to no avail.

I have uploaded the parametric part to the relevant section of the
newsgroup (consumer files or whatever...) under the same subject title.

Thanks for any help you can give me.

Drew Jarvis,
ACDP, Maidenhead.

[Anonymous]

Thanks Lars-Ake, that was very good of you to do the work so I could see what to do.

Drew.

[Ennissl]

what newsgroup are you posting the parts too? I would definitely subscribe to that one also.

[Anonymous]

news://discussion.autodesk.com/autodesk.autocad.customer-files