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Helix Cut Problems

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neilc78

neilc78

Mechanical
Feb 22, 2005
103
Hi all. Our Company cut helical cuts in very small tubing. An example would be a tube with an OD=0.090" and ID=0.085". We would then cut a helical cut through the wall of this over a length of tube = 4ft.

The helix itself is a variable pitch helix. It starts with a pitch of 0.02" and transitions to a pitch of 0.09" at the other end of the tube. Normally SW can't do this but its add on Geometry Works can. We would sweep a rectangle along this helix and then use the Combine feature to subtract from the tube.

Heres the problem. On this particular model, once you cross a certain tube length SW will simply hang and not do it. Say this length is 8". If I then split the helix into 6 parts all less than 8" I can individually subtract these. This isn't ideal. I have ask Geometry Works to look at this but they reckon it is a SW problem. It ain't anything to do with machine specs either. I am however basing this off SP0. Anyone know any way around this? Would the newer SP's make a difference.
 
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Scott.
Geometry Works allows the helix to be created as one path (curve). The problem is that the swept curve crosses a 'minimum' subtract it from the tube. When I say I split the helix I mean I split the swept helix. Then it will work as long as each piece of the split swept helix is below this mysterious length value.
 
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So are you running into a Topological issue, where the profile intersects itself as it follows the path of the helix?

Have you tried a similiar feat in SW and SW only, to rule out SW being the problem? This would help to prove which application is truly at fault.

Regards,

Scott Baugh, CSWP [pc2]
3DVision Technologies
faq731-376
faq559-716 - SW Fora Users
 
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Can you do a Swept cut instead of a Swept boss & Combine/subtract?

I do not have access to Geometry Works so cannot check to see if it works it with other SW versions or SPs.

Is the pitch transition, from .02" to .09", smooth or is it incrementally stepped per revolution? If incremantal, make the helixes seperately and do as Scott suggests ... combine the helixes into a composite curve.

Another alternative might be to create a spline which passes through a set of 3D points, which I believe has been covered in previous threads.

Out of curiosity, what are these tiny tubes used for?

[cheers]
Making the best use of this Forum. faq559-716
How to get answers to your SW questions. faq559-1091
Helpful SW websites every user should be aware of. faq559-520
 
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Swept cut doesn't work either. The transition is smooth (linear) so what scott says is difficult. You can download a trial of Geometryworks from Get the 3D Features version. It adds a nice simple toolbar to SW. Trial lasts 30 days.
As for what we use this for.. These are shafts that are used to push stents into position for cardiovascular proceedures. The transition in the cut means that the shaft increases in flexibility as it encounters more 'torturous' anatomy in the body. These shafts can be as long as 1.5 meters. Have a look at this
 
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Interesting ... sorry to go off topic ... but how is the actual part cut?

[cheers]
Making the best use of this Forum. faq559-716
How to get answers to your SW questions. faq559-1091
Helpful SW websites every user should be aware of. faq559-520
 
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It is cut with a laser. Its like a lathe except it has a laser beam instead of the cutting tool. The tube rotates and moves lontitudinally and the laser head remains stationary
 
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Thanks Scott. I'm out of the office today but I'll have a look at it when I get back.
 
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neilc78 ... This sounds perfect for your Stent!

SolidWorks has also introduced a unique Variable Pitch Helix to help machine designers easily create systems for speeding or slowing goods being shuttled through feed or packaging systems.
Click to expand...


[cheers]
Making the best use of this Forum. faq559-716
How to get answers to your SW questions. faq559-1091
Helpful SW websites every user should be aware of. faq559-520
 
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varhelix.gif


varhelixsweep.gif


Jason Capriotti
Smith & Nephew, Inc.
 
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Very nice Jason ... ALSO VERY BIG [shocked]

Does the Helix with "twist" work well? For creating a curly cord or similar?

[cheers]
Making the best use of this Forum. faq559-716
How to get answers to your SW questions. faq559-1091
Helpful SW websites every user should be aware of. faq559-520
 
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What Scott suggested works great for springs...combining the Helix into a composite curve. I did that today making a closed and ground spring.

Best Regards,

Heckler
Sr. Mechanical Engineer
SW2005 SP 2.0 & Pro/E 2001
Dell Precision 370
P4 3.6 GHz, 1GB RAM
XP Pro SP2.0
NIVIDA Quadro FX 1400
o
_`\(,_
(_)/ (_)

Do you trust your intuition or go with the flow?

Read before you write faq731-376

 
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I made this part in Pro/E 2001 - two features 4 minutes regeneration time. No 3rd party products, no work arounds, no waiting for the next release. Pro/E has had variable pitch helical sweep for years - okay the UI is not as good as SW but Pro/E always does the job.
Heckler - why not give it a go - I made the absolute accuracy 0.0001" and the sweep section a circle 0.0025" dia.
neilc - it might be worth giving Pro/E a try.
 
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Ronnie,

I will stay with Pro/e 2001 and hope PTC gets the clue. One other command I miss from pro/e is the var section sweep, Trajpar and evalgraph but overall I prefer SWx. But it's good to know the SWx forum has another Pro/e junkie. It's fun switching between the two programs.

Best Regards,

Heckler
Sr. Mechanical Engineer
SW2005 SP 2.0 & Pro/E 2001
Dell Precision 370
P4 3.6 GHz, 1GB RAM
XP Pro SP2.0
NIVIDA Quadro FX 1400
o
_`\(,_
(_)/ (_)

Do you trust your intuition or go with the flow?

Read before you write faq731-376

 
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I created the part in Solidworks 06. Thin Extrude and a Cut-Sweep around the variable pitch helix.

2.5 seconds rebuild time.
2.4ghz
1gb ram
Fx500 graphics

Jason Capriotti
Smith & Nephew, Inc.
 
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I created the part in Wildfire 3.0 - no features, I just had to imagine what I wanted and the new mind reading UI interpreted it into the model.

0.1 nanoseconds
Sinclair ZX81 1kb ram

One day the truth will come out....
 
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lol
[2thumbsup]

Jason Capriotti
Smith & Nephew, Inc.
 
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Thanks for all the replies. We've been using geometry works quite well for a while now but the new feature in 2006 look to have taken much of the functionality into the main SW program.
 
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