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# significance of arrow direction in blend?

#### shweta

##### New member
I have a problem in ProE 2001 in the blend command.

I want to know whether there is any significance of the DIRECTION of the starting arrow on each section.Does it make any difference at all.If yes,what is it.

yes it makes the difference. Arrow direction should be in one direction.

Otherwise it shows uneven surfaces or twisting like surfaces.

better youtry it out and see the acual difference!!

I disagree. The direction of the arrow on each section of the blend is insignificant. It is the position of the vertex of the arrow that is important and should line up from section to section. The direction of the arrow only signifies the direction in which you began sketching. Clockwise or counterclockwise.

Start point vertices should not be more that 180 degrees out and will probably fail somewhere after 90 degrees out. If you want twisting in the blend then create a general blend where you have control of the angle of twist between the sections in x,y, and z. Rotational blends only allow you control of rotation about ay axis.

Yes as mentioned by mpro they should be in same direction. But it is still possible to blend with arrows in different directions. It depends on what kind of blend you are dealing with.............

The DIRECTION the arrow is pointing in a parallel blend is absolutely irrelevent.And I would challenge you to CHANGE the direction once it appears, especially if you divide a circle.However the location of the vertex on which the arrow is attached determines the correct shape of the blend as lhagin said. The first section below shows that the 4 entity square being blended to the 4 entity circle (divided into 4 segments) with the arrows located on the upper left vertex of each section. This produces the correct blend. The second section shows the arrow on a different vertex and the resulting incorrect geometry. If you WANT this kind of gemoetry use the general blend which gives you an angle dimension to change. This would allow you twist it in either direction. In Wildire you can use the Warp function to do this also.

This is explained clearly in the Intro To Pro/ENGINEER.

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Edited by: kvision

Well that Wraps that one up then... Thanks always wanted to know how to do a blend.

Cheers Ilhagin and thanks to kvision for the cool graphics.

Well, kvision thanks for your hard work. But there is nothing like challenge in this post. You should read my previous post. It explains it all.

This is for all of you.........

The arrows should be in same direction ..........Its a good habbit.You will soon find out why in future.

The arrows of both the sections in a blend option should be pointing in the same direction.
No matter its a parellel blend or any other............

Bye

CADJOCKY said "Yes as mentioned by mpro they should be in same direction. But it is still possible to blend with arrows in different directions. It depends on what kind of blend you are dealing with............."

This is a statement not an explaination. An explanation would describe and or show how to produce a blend/ swept blend that SHOWS a case where the direction matters. So I humbly restate my challenge to SHOW me ..

1) a case where the DIRECTION matters.

2) how to alter the direction, say for a divided circle.

POPS WHY? Can you show me?

CADJOCKY & POPS, I also tried the same thing changed the arrow direction but nothing happened. Yes, in other cad packages like CATIA, IDEAS the arrow direction plays an important role. By means of that we can get the twist.But in Pro/E we do it by changing the start point location.It would be nice if you explain it in detail that why it is important to have arrows in same direction.

KVISION, arrows can be easily altered.select the same point and again define that point as start point. the arrow will be altered no matter wether it is a divided circle or not.

kujur

POPS could you please illustrate your reasoning behind why you believe that the arrows should be pointing in the same direction for a blend?

In my 7 years of training PTC software I have not seen an instance where the arrow direction matters for a blend. It definitely matters for a Sweep and the Swept Blend as far as the direction of feature creation along the trajectory but as long as the start points were on the same vertex there was no issue.

I am not trying to be smug I am just dern curious now....

kujur11a said:
CADJOCKY & POPS, I also tried the same thing changed the arrow direction but nothing happened. Yes, in other cad packages like CATIA, IDEAS the arrow direction plays an important role. By means of that we can get the twist.But in Pro/E we do it by changing the start point location.It would be nice if you explain it in detail that why it is important to have arrows in same direction.

KVISION, arrows can be easily altered.select the same point and again define that point as start point. the arrow will be altered no matter wether it is a divided circle or not.

kujur

kujur,

You are correct about changing the direction. Thanks for the insight. I have created about 50 models recently trying all different combinations of start point and arrow direction in swept blends and parallel blends and have found that the direction just doesn't matter.

PS-I've been through this many times with PTC support and they never mentioned that selecting the same start point would change the direction. Probably because it has no useful purpose. I'm gonna guess here but maybe the direction determines sides like red/yellow for planes.
Edited by: kvision

The arrow direction is determined by the direction you start sketching your section. Beyond that "I got nothing" as fas as its significance.

Hi, I have one doubt regarding the blend.Can we add a new section between the existing ones without deleting.I am trying this for a time but didnt know how to do that. If it is possible then tell me how to do that.Thanks KVISION.

kujur

You can insert sections on a rotational and general blend, but NOT a parallel blend.

To add a new section in between previous sketches on a general or rotational blend, redefine theSECTION element of the blend, and you will see the menu pick ADD. When you select ADD, you are prompted to select which section number you wish to sketch, from section 2 to section "X" (e.g. For a general blend of 3 sections, you would select from section 2, 3, or 4)

For a parallel blend, the only thing you can do is delete sections. If the blend feature is made up of many sections and you want to insert a section within the first 2 or 3, it may be easier to recreate the blend feature from scratch, depending on the complexity.

On a related note, you can also insert sections in a swept blend feature, assuming that you have an unused vertex or vertices on the the trajectory.

Well, that is my 2