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How to use get uniform pitch in warp/twist

BHOoi
Alexandrite

How to use get uniform pitch in warp/twist

I have been trying to model a twisted bar with uniform pitch, using warp/twist command. However, no matter what i do, the resulted geometry is always non uniform, as shown below. Any idea how to get an uniform twist? I know this is possible in relational sweep, but i just want to know if  this is possible in warp command. Thanks in advance for the tips.

twist.JPG


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14 REPLIES 14

Re: How to use get uniform pitch in warp/twist

I think the key to this is your marquee set up. Try using an 'offset' marquee, experiment with the offset values. I am sure if you think about it, that the offset values could be precisely calculated depending upon the height of your initial extrude & the pitch required.

Hope this helps you on your way.

John

offet-marquee.PNG

Re: How to use get uniform pitch in warp/twist

Thanks, John. Those settings(offset, absolute ...)are basically meant for start and end of warp  feature, not for pitch....

Re: How to use get uniform pitch in warp/twist

Yes I know this, but by manipulating these offsets you can achieve a more uniform pitch. This might give you what you want depending upon your requirements, it might not.

John

twist.PNG

Re: How to use get uniform pitch in warp/twist

yes... pretty close. What i also wanted was the section orientation at the start and end points coincide so that when I form a ring using toroidal bend the ends match perfectly. Possible?

Re: How to use get uniform pitch in warp/twist

Actually, it IS uniform....there's just a lead-in and lead-out variation in pitch to make it tangent to the long axis....by design.  If you actually heat up and twist a piece of square bar stock, this is what you'll get.  If you need something else you'll have to construct it via another method.  VSS (Variable Section Sweep) etc.......

I think the warp commands are pretty cool and certainly very powerful....if lacking in the ability to constrain them as we'd like.

Re: How to use get uniform pitch in warp/twist

hello, Frank. I think you are right, but do you know how do i get rid of those extruded portions ? or.... if i want to trim those away, what is length i should cut?  What I really want is only the helical shape, from start till end so that i can form a ring using Toroidal bend as shown below:

ring.JPG

For this simple rectangle section, i could have used VSS instead of warp/twist. However, i am looking at very irregular shapes (such as chain of rings) that are not possible to be created using VSS. I want to explore if I can use warp to facilitate the end creation.

Re: How to use get uniform pitch in warp/twist

Warp does a very poor job on joining the ends of a 360 degree bend even if you tweak the marquee.

Never underestimate the power of VSS.  You can drive multiple variations including a weave in a weave.  You can drive it with graphs; algebraic functions, or straight math.  It may be a lot of work, but it can be done.

This is a fully 3D cross using various VSS sweeps...

Celtic_Cross.JPG

Spinal bend is a little easier to work with.

Here is the part in the other discussion... trimmed using the known pitch to get a perfect mate on the ends.

Unfortunately, Creo doesn't allow you merge the ends so the seam disappears, no matter what you do!

flyer_stick_bent.PNG

Re: How to use get uniform pitch in warp/twist

Nice cross!  You should cast some in a precious metal!

Re: How to use get uniform pitch in warp/twist

A VSS using trajpar would be perfect for that circle.  You wouldn't need to do a spinal bend on it.

Re: How to use get uniform pitch in warp/twist

D'uh!  Very true, Frank.

Re: How to use get uniform pitch in warp/twist

Funny... even in Creo 3, I can twist it 4 times in one feature, but not 3-1/2.  No Mobius here!

flyer_stick_bent_II.PNG

Creo 3.0 attached

Re: How to use get uniform pitch in warp/twist

Knock Knock!

Who's there?

Mobius, that's who! 

MOBIUS_STRIP-03.jpg

There's a Pro/WORKAROUND to get the 1/2 twists.....

Re: How to use get uniform pitch in warp/twist

Okay, give it up and I'll test it in Creo 3.

It worked fine using the spinal bend but not in a VSS going 360 in a single feature.

Re: How to use get uniform pitch in warp/twist

Yeah, there seems to be a couple limitations in VSS's, one being that you can't do more than 360deg.....supposedly..... 

I'll try and e-mail you the file later today and we can discuss! 

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