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nalexandru1-Visitor
1-Visitor
August 10, 2017
Solved

ADVANCED QUESTION: is there an easy and direct way to create a curve of a oblique cut cylinder?

  • August 10, 2017
  • 2 replies
  • 7894 views

Hi,

Is there an easy way to create a curve of the unwraped cut with an oblique line in a cylinder?

I did something for the first "complete cut" of the cylinder. See the image for understanding what I am talking about

I believe is correct. I write here the equation for future use of others and please correct it if I'm wrong.

 

X=Cylinder_Diameter*PI*T
Y=Cylinder_Diameter/2*TAN(Cut_Angle)*(1-SIN(T*360+90))

 

The "+90" should translate the sine curve so it starts from the uncut diameter of the cylinder.

In my model the "From: To:" parameter in the defining the curve, it does not work. Whatever values i put it only makes one complete sine curve (360deg)

Nic.

 

 

Best answer by KenFarley

Now that I look at it, I can define the result without the IF/ELSE/THEN structure. Putting the involved angles back in degrees, also, I get the following:

X = PI * D * t

Y = MIN ( E, E + ( K - D * ( 1 - COS ( t * 360 ) ) / 2 ) * TAN ( alpha ) )

Bonus is that it eliminates the need for the "S" working variable, too. Again, check my math, and you might need manipulate the input angles to the trig functions to get things working properly. Also, I couldn't find any documentation to verify the syntax for the "MIN" function, so am assuming what is shown.

2 replies

K
KenFarley21-Topaz II
21-Topaz II
August 10, 2017

Is there some reason why you aren't just doing a protrusion perpendicular to a plane through the axis of the cylinder?

N
nalexandru1-VisitorAuthor
1-Visitor
August 11, 2017

I don't think I understand your solution. Make a protrusion? Like an extrude cut?

Doing so I will obtain the final geometry like in my image, isn't it right?

K
KenFarley21-Topaz II
21-Topaz II
August 11, 2017

I guess I didn't understand what you were looking for. Looking at it again, it seems like you're trying to create a curve that would define the cut edge of the cylinder if the outer cylindrical surface were flattened. Like creating a flat pattern if the cylinder were made of sheet metal?

D
dschenken1-Visitor
1-Visitor
August 10, 2017

T is evaluated from 0 to 1. You multiplied it by 360 so the range is 0-360. Then you added 90 so the range is from 90 to 450. Which is still a 360 degree segment.

 

Try not multiplying by 360 to change the range to the angle range you want.

N
nalexandru1-VisitorAuthor
1-Visitor
August 11, 2017

That's what i thought: T is evaluated from 0 to 1. So if I change the value of T

From 0.25

To 0.75

I would expect to have just the middle portion of the curve.

Which it is NOT happening. Whatever values I give to T, the curve remains the same: a perfect sine curve from 0 to 360deg.

 

Any idea for the second cut? The "partial" one means that basicaly my sine curve should translate along the Y axis until it starts from the unwraped "K" value of it: K x THETA_ANGLE

D
dschenken1-Visitor
1-Visitor
August 11, 2017

I see you opened another question. However, if the evaluation is not right you need to let people know what version and release of Creo you are using. Also, you can change the equation, even if the evaluation of the limits isn't working right.

 

Errors with fundamental functions are either because there is something wrong with that release or because there is a failure with that particular model file or there is a failure with that particular session of Creo. Of these there is nothing the community can resolve.

 

The workable methods are:

A) Submit the file to PTC

B) Try a new (not from template or copy) model file to see if it still occurs

C) Reboot.

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